ffx_fsr1.h
   1  //_____________________________________________________________/\_______________________________________________________________
   2  //==============================================================================================================================
   3  //
   4  //
   5  //                    AMD FidelityFX SUPER RESOLUTION [FSR 1] ::: SPATIAL SCALING & EXTRAS - v1.20210629
   6  //
   7  //
   8  //------------------------------------------------------------------------------------------------------------------------------
   9  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  10  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  11  //------------------------------------------------------------------------------------------------------------------------------
  12  // FidelityFX Super Resolution Sample
  13  //
  14  // Copyright (c) 2021 Advanced Micro Devices, Inc. All rights reserved.
  15  // Permission is hereby granted, free of charge, to any person obtaining a copy
  16  // of this software and associated documentation files(the "Software"), to deal
  17  // in the Software without restriction, including without limitation the rights
  18  // to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
  19  // copies of the Software, and to permit persons to whom the Software is
  20  // furnished to do so, subject to the following conditions :
  21  // The above copyright notice and this permission notice shall be included in
  22  // all copies or substantial portions of the Software.
  23  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  24  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  25  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
  26  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  27  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  28  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  29  // THE SOFTWARE.
  30  //------------------------------------------------------------------------------------------------------------------------------
  31  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  32  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  33  //------------------------------------------------------------------------------------------------------------------------------
  34  // ABOUT
  35  // =====
  36  // FSR is a collection of algorithms relating to generating a higher resolution image.
  37  // This specific header focuses on single-image non-temporal image scaling, and related tools.
  38  // 
  39  // The core functions are EASU and RCAS:
  40  //  [EASU] Edge Adaptive Spatial Upsampling ....... 1x to 4x area range spatial scaling, clamped adaptive elliptical filter.
  41  //  [RCAS] Robust Contrast Adaptive Sharpening .... A non-scaling variation on CAS.
  42  // RCAS needs to be applied after EASU as a separate pass.
  43  // 
  44  // Optional utility functions are:
  45  //  [LFGA] Linear Film Grain Applicator ........... Tool to apply film grain after scaling.
  46  //  [SRTM] Simple Reversible Tone-Mapper .......... Linear HDR {0 to FP16_MAX} to {0 to 1} and back.
  47  //  [TEPD] Temporal Energy Preserving Dither ...... Temporally energy preserving dithered {0 to 1} linear to gamma 2.0 conversion.
  48  // See each individual sub-section for inline documentation.
  49  //------------------------------------------------------------------------------------------------------------------------------
  50  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  51  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  52  //------------------------------------------------------------------------------------------------------------------------------
  53  // FUNCTION PERMUTATIONS
  54  // =====================
  55  // *F() ..... Single item computation with 32-bit.
  56  // *H() ..... Single item computation with 16-bit, with packing (aka two 16-bit ops in parallel) when possible.
  57  // *Hx2() ... Processing two items in parallel with 16-bit, easier packing.
  58  //            Not all interfaces in this file have a *Hx2() form.
  59  //==============================================================================================================================
  60  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  61  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  62  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  63  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  64  //_____________________________________________________________/\_______________________________________________________________
  65  //==============================================================================================================================
  66  //
  67  //                                        FSR - [EASU] EDGE ADAPTIVE SPATIAL UPSAMPLING
  68  //
  69  //------------------------------------------------------------------------------------------------------------------------------
  70  // EASU provides a high quality spatial-only scaling at relatively low cost.
  71  // Meaning EASU is appropiate for laptops and other low-end GPUs.
  72  // Quality from 1x to 4x area scaling is good.
  73  //------------------------------------------------------------------------------------------------------------------------------
  74  // The scalar uses a modified fast approximation to the standard lanczos(size=2) kernel.
  75  // EASU runs in a single pass, so it applies a directionally and anisotropically adaptive radial lanczos.
  76  // This is also kept as simple as possible to have minimum runtime.
  77  //------------------------------------------------------------------------------------------------------------------------------
  78  // The lanzcos filter has negative lobes, so by itself it will introduce ringing.
  79  // To remove all ringing, the algorithm uses the nearest 2x2 input texels as a neighborhood,
  80  // and limits output to the minimum and maximum of that neighborhood.
  81  //------------------------------------------------------------------------------------------------------------------------------
  82  // Input image requirements:
  83  // 
  84  // Color needs to be encoded as 3 channel[red, green, blue](e.g.XYZ not supported)
  85  // Each channel needs to be in the range[0, 1]
  86  // Any color primaries are supported
  87  // Display / tonemapping curve needs to be as if presenting to sRGB display or similar(e.g.Gamma 2.0)
  88  // There should be no banding in the input
  89  // There should be no high amplitude noise in the input
  90  // There should be no noise in the input that is not at input pixel granularity
  91  // For performance purposes, use 32bpp formats
  92  //------------------------------------------------------------------------------------------------------------------------------
  93  // Best to apply EASU at the end of the frame after tonemapping 
  94  // but before film grain or composite of the UI.
  95  //------------------------------------------------------------------------------------------------------------------------------
  96  // Example of including this header for D3D HLSL :
  97  // 
  98  //  #define A_GPU 1
  99  //  #define A_HLSL 1
 100  //  #define A_HALF 1
 101  //  #include "ffx_a.h"
 102  //  #define FSR_EASU_H 1
 103  //  #define FSR_RCAS_H 1
 104  //  //declare input callbacks
 105  //  #include "ffx_fsr1.h"
 106  // 
 107  // Example of including this header for Vulkan GLSL :
 108  // 
 109  //  #define A_GPU 1
 110  //  #define A_GLSL 1
 111  //  #define A_HALF 1
 112  //  #include "ffx_a.h"
 113  //  #define FSR_EASU_H 1
 114  //  #define FSR_RCAS_H 1
 115  //  //declare input callbacks
 116  //  #include "ffx_fsr1.h"
 117  // 
 118  // Example of including this header for Vulkan HLSL :
 119  // 
 120  //  #define A_GPU 1
 121  //  #define A_HLSL 1
 122  //  #define A_HLSL_6_2 1
 123  //  #define A_NO_16_BIT_CAST 1
 124  //  #define A_HALF 1
 125  //  #include "ffx_a.h"
 126  //  #define FSR_EASU_H 1
 127  //  #define FSR_RCAS_H 1
 128  //  //declare input callbacks
 129  //  #include "ffx_fsr1.h"
 130  // 
 131  //  Example of declaring the required input callbacks for GLSL :
 132  //  The callbacks need to gather4 for each color channel using the specified texture coordinate 'p'.
 133  //  EASU uses gather4 to reduce position computation logic and for free Arrays of Structures to Structures of Arrays conversion.
 134  // 
 135  //  AH4 FsrEasuRH(AF2 p){return AH4(textureGather(sampler2D(tex,sam),p,0));}
 136  //  AH4 FsrEasuGH(AF2 p){return AH4(textureGather(sampler2D(tex,sam),p,1));}
 137  //  AH4 FsrEasuBH(AF2 p){return AH4(textureGather(sampler2D(tex,sam),p,2));}
 138  //  ...
 139  //  The FsrEasuCon function needs to be called from the CPU or GPU to set up constants.
 140  //  The difference in viewport and input image size is there to support Dynamic Resolution Scaling.
 141  //  To use FsrEasuCon() on the CPU, define A_CPU before including ffx_a and ffx_fsr1.
 142  //  Including a GPU example here, the 'con0' through 'con3' values would be stored out to a constant buffer.
 143  //  AU4 con0,con1,con2,con3;
 144  //  FsrEasuCon(con0,con1,con2,con3,
 145  //    1920.0,1080.0,  // Viewport size (top left aligned) in the input image which is to be scaled.
 146  //    3840.0,2160.0,  // The size of the input image.
 147  //    2560.0,1440.0); // The output resolution.
 148  //==============================================================================================================================
 149  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 150  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 151  //_____________________________________________________________/\_______________________________________________________________
 152  //==============================================================================================================================
 153  //                                                      CONSTANT SETUP
 154  //==============================================================================================================================
 155  // Call to setup required constant values (works on CPU or GPU).
 156  A_STATIC void FsrEasuCon(
 157  outAU4 con0,
 158  outAU4 con1,
 159  outAU4 con2,
 160  outAU4 con3,
 161  // This the rendered image resolution being upscaled
 162  AF1 inputViewportInPixelsX,
 163  AF1 inputViewportInPixelsY,
 164  // This is the resolution of the resource containing the input image (useful for dynamic resolution)
 165  AF1 inputSizeInPixelsX,
 166  AF1 inputSizeInPixelsY,
 167  // This is the display resolution which the input image gets upscaled to
 168  AF1 outputSizeInPixelsX,
 169  AF1 outputSizeInPixelsY){
 170   // Output integer position to a pixel position in viewport.
 171   con0[0]=AU1_AF1(inputViewportInPixelsX*ARcpF1(outputSizeInPixelsX));
 172   con0[1]=AU1_AF1(inputViewportInPixelsY*ARcpF1(outputSizeInPixelsY));
 173   con0[2]=AU1_AF1(AF1_(0.5)*inputViewportInPixelsX*ARcpF1(outputSizeInPixelsX)-AF1_(0.5));
 174   con0[3]=AU1_AF1(AF1_(0.5)*inputViewportInPixelsY*ARcpF1(outputSizeInPixelsY)-AF1_(0.5));
 175   // Viewport pixel position to normalized image space.
 176   // This is used to get upper-left of 'F' tap.
 177   con1[0]=AU1_AF1(ARcpF1(inputSizeInPixelsX));
 178   con1[1]=AU1_AF1(ARcpF1(inputSizeInPixelsY));
 179   // Centers of gather4, first offset from upper-left of 'F'.
 180   //      +---+---+
 181   //      |   |   |
 182   //      +--(0)--+
 183   //      | b | c |
 184   //  +---F---+---+---+
 185   //  | e | f | g | h |
 186   //  +--(1)--+--(2)--+
 187   //  | i | j | k | l |
 188   //  +---+---+---+---+
 189   //      | n | o |
 190   //      +--(3)--+
 191   //      |   |   |
 192   //      +---+---+
 193   con1[2]=AU1_AF1(AF1_( 1.0)*ARcpF1(inputSizeInPixelsX));
 194   con1[3]=AU1_AF1(AF1_(-1.0)*ARcpF1(inputSizeInPixelsY));
 195   // These are from (0) instead of 'F'.
 196   con2[0]=AU1_AF1(AF1_(-1.0)*ARcpF1(inputSizeInPixelsX));
 197   con2[1]=AU1_AF1(AF1_( 2.0)*ARcpF1(inputSizeInPixelsY));
 198   con2[2]=AU1_AF1(AF1_( 1.0)*ARcpF1(inputSizeInPixelsX));
 199   con2[3]=AU1_AF1(AF1_( 2.0)*ARcpF1(inputSizeInPixelsY));
 200   con3[0]=AU1_AF1(AF1_( 0.0)*ARcpF1(inputSizeInPixelsX));
 201   con3[1]=AU1_AF1(AF1_( 4.0)*ARcpF1(inputSizeInPixelsY));
 202   con3[2]=con3[3]=0;}
 203  
 204  //If the an offset into the input image resource
 205  A_STATIC void FsrEasuConOffset(
 206      outAU4 con0,
 207      outAU4 con1,
 208      outAU4 con2,
 209      outAU4 con3,
 210      // This the rendered image resolution being upscaled
 211      AF1 inputViewportInPixelsX,
 212      AF1 inputViewportInPixelsY,
 213      // This is the resolution of the resource containing the input image (useful for dynamic resolution)
 214      AF1 inputSizeInPixelsX,
 215      AF1 inputSizeInPixelsY,
 216      // This is the display resolution which the input image gets upscaled to
 217      AF1 outputSizeInPixelsX,
 218      AF1 outputSizeInPixelsY,
 219      // This is the input image offset into the resource containing it (useful for dynamic resolution)
 220      AF1 inputOffsetInPixelsX,
 221      AF1 inputOffsetInPixelsY) {
 222      FsrEasuCon(con0, con1, con2, con3, inputViewportInPixelsX, inputViewportInPixelsY, inputSizeInPixelsX, inputSizeInPixelsY, outputSizeInPixelsX, outputSizeInPixelsY);
 223      con0[2] = AU1_AF1(AF1_(0.5) * inputViewportInPixelsX * ARcpF1(outputSizeInPixelsX) - AF1_(0.5) + inputOffsetInPixelsX);
 224      con0[3] = AU1_AF1(AF1_(0.5) * inputViewportInPixelsY * ARcpF1(outputSizeInPixelsY) - AF1_(0.5) + inputOffsetInPixelsY);
 225  }
 226  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 227  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 228  //_____________________________________________________________/\_______________________________________________________________
 229  //==============================================================================================================================
 230  //                                                   NON-PACKED 32-BIT VERSION
 231  //==============================================================================================================================
 232  #if defined(A_GPU)&&defined(FSR_EASU_F)
 233   // Input callback prototypes, need to be implemented by calling shader
 234   AF4 FsrEasuRF(AF2 p);
 235   AF4 FsrEasuGF(AF2 p);
 236   AF4 FsrEasuBF(AF2 p);
 237  //------------------------------------------------------------------------------------------------------------------------------
 238   // Filtering for a given tap for the scalar.
 239   void FsrEasuTapF(
 240   inout AF3 aC, // Accumulated color, with negative lobe.
 241   inout AF1 aW, // Accumulated weight.
 242   AF2 off, // Pixel offset from resolve position to tap.
 243   AF2 dir, // Gradient direction.
 244   AF2 len, // Length.
 245   AF1 lob, // Negative lobe strength.
 246   AF1 clp, // Clipping point.
 247   AF3 c){ // Tap color.
 248    // Rotate offset by direction.
 249    AF2 v;
 250    v.x=(off.x*( dir.x))+(off.y*dir.y);
 251    v.y=(off.x*(-dir.y))+(off.y*dir.x);
 252    // Anisotropy.
 253    v*=len;
 254    // Compute distance^2.
 255    AF1 d2=v.x*v.x+v.y*v.y;
 256    // Limit to the window as at corner, 2 taps can easily be outside.
 257    d2=min(d2,clp);
 258    // Approximation of lancos2 without sin() or rcp(), or sqrt() to get x.
 259    //  (25/16 * (2/5 * x^2 - 1)^2 - (25/16 - 1)) * (1/4 * x^2 - 1)^2
 260    //  |_______________________________________|   |_______________|
 261    //                   base                             window
 262    // The general form of the 'base' is,
 263    //  (a*(b*x^2-1)^2-(a-1))
 264    // Where 'a=1/(2*b-b^2)' and 'b' moves around the negative lobe.
 265    AF1 wB=AF1_(2.0/5.0)*d2+AF1_(-1.0);
 266    AF1 wA=lob*d2+AF1_(-1.0);
 267    wB*=wB;
 268    wA*=wA;
 269    wB=AF1_(25.0/16.0)*wB+AF1_(-(25.0/16.0-1.0));
 270    AF1 w=wB*wA;
 271    // Do weighted average.
 272    aC+=c*w;aW+=w;}
 273  //------------------------------------------------------------------------------------------------------------------------------
 274   // Accumulate direction and length.
 275   void FsrEasuSetF(
 276   inout AF2 dir,
 277   inout AF1 len,
 278   AF2 pp,
 279   AP1 biS,AP1 biT,AP1 biU,AP1 biV,
 280   AF1 lA,AF1 lB,AF1 lC,AF1 lD,AF1 lE){
 281    // Compute bilinear weight, branches factor out as predicates are compiler time immediates.
 282    //  s t
 283    //  u v
 284    AF1 w = AF1_(0.0);
 285    if(biS)w=(AF1_(1.0)-pp.x)*(AF1_(1.0)-pp.y);
 286    if(biT)w=           pp.x *(AF1_(1.0)-pp.y);
 287    if(biU)w=(AF1_(1.0)-pp.x)*           pp.y ;
 288    if(biV)w=           pp.x *           pp.y ;
 289    // Direction is the '+' diff.
 290    //    a
 291    //  b c d
 292    //    e
 293    // Then takes magnitude from abs average of both sides of 'c'.
 294    // Length converts gradient reversal to 0, smoothly to non-reversal at 1, shaped, then adding horz and vert terms.
 295    AF1 dc=lD-lC;
 296    AF1 cb=lC-lB;
 297    AF1 lenX=max(abs(dc),abs(cb));
 298    lenX=APrxLoRcpF1(lenX);
 299    AF1 dirX=lD-lB;
 300    dir.x+=dirX*w;
 301    lenX=ASatF1(abs(dirX)*lenX);
 302    lenX*=lenX;
 303    len+=lenX*w;
 304    // Repeat for the y axis.
 305    AF1 ec=lE-lC;
 306    AF1 ca=lC-lA;
 307    AF1 lenY=max(abs(ec),abs(ca));
 308    lenY=APrxLoRcpF1(lenY);
 309    AF1 dirY=lE-lA;
 310    dir.y+=dirY*w;
 311    lenY=ASatF1(abs(dirY)*lenY);
 312    lenY*=lenY;
 313    len+=lenY*w;}
 314  //------------------------------------------------------------------------------------------------------------------------------
 315   void FsrEasuF(
 316   out AF3 pix,
 317   AU2 ip, // Integer pixel position in output.
 318   AU4 con0, // Constants generated by FsrEasuCon().
 319   AU4 con1,
 320   AU4 con2,
 321   AU4 con3){
 322  //------------------------------------------------------------------------------------------------------------------------------
 323    // Get position of 'f'.
 324    AF2 pp=AF2(ip)*AF2_AU2(con0.xy)+AF2_AU2(con0.zw);
 325    AF2 fp=floor(pp);
 326    pp-=fp;
 327  //------------------------------------------------------------------------------------------------------------------------------
 328    // 12-tap kernel.
 329    //    b c
 330    //  e f g h
 331    //  i j k l
 332    //    n o
 333    // Gather 4 ordering.
 334    //  a b
 335    //  r g
 336    // For packed FP16, need either {rg} or {ab} so using the following setup for gather in all versions,
 337    //    a b    <- unused (z)
 338    //    r g
 339    //  a b a b
 340    //  r g r g
 341    //    a b
 342    //    r g    <- unused (z)
 343    // Allowing dead-code removal to remove the 'z's.
 344    AF2 p0=fp*AF2_AU2(con1.xy)+AF2_AU2(con1.zw);
 345    // These are from p0 to avoid pulling two constants on pre-Navi hardware.
 346    AF2 p1=p0+AF2_AU2(con2.xy);
 347    AF2 p2=p0+AF2_AU2(con2.zw);
 348    AF2 p3=p0+AF2_AU2(con3.xy);
 349    AF4 bczzR=FsrEasuRF(p0);
 350    AF4 bczzG=FsrEasuGF(p0);
 351    AF4 bczzB=FsrEasuBF(p0);
 352    AF4 ijfeR=FsrEasuRF(p1);
 353    AF4 ijfeG=FsrEasuGF(p1);
 354    AF4 ijfeB=FsrEasuBF(p1);
 355    AF4 klhgR=FsrEasuRF(p2);
 356    AF4 klhgG=FsrEasuGF(p2);
 357    AF4 klhgB=FsrEasuBF(p2);
 358    AF4 zzonR=FsrEasuRF(p3);
 359    AF4 zzonG=FsrEasuGF(p3);
 360    AF4 zzonB=FsrEasuBF(p3);
 361  //------------------------------------------------------------------------------------------------------------------------------
 362    // Simplest multi-channel approximate luma possible (luma times 2, in 2 FMA/MAD).
 363    AF4 bczzL=bczzB*AF4_(0.5)+(bczzR*AF4_(0.5)+bczzG);
 364    AF4 ijfeL=ijfeB*AF4_(0.5)+(ijfeR*AF4_(0.5)+ijfeG);
 365    AF4 klhgL=klhgB*AF4_(0.5)+(klhgR*AF4_(0.5)+klhgG);
 366    AF4 zzonL=zzonB*AF4_(0.5)+(zzonR*AF4_(0.5)+zzonG);
 367    // Rename.
 368    AF1 bL=bczzL.x;
 369    AF1 cL=bczzL.y;
 370    AF1 iL=ijfeL.x;
 371    AF1 jL=ijfeL.y;
 372    AF1 fL=ijfeL.z;
 373    AF1 eL=ijfeL.w;
 374    AF1 kL=klhgL.x;
 375    AF1 lL=klhgL.y;
 376    AF1 hL=klhgL.z;
 377    AF1 gL=klhgL.w;
 378    AF1 oL=zzonL.z;
 379    AF1 nL=zzonL.w;
 380    // Accumulate for bilinear interpolation.
 381    AF2 dir=AF2_(0.0);
 382    AF1 len=AF1_(0.0);
 383    FsrEasuSetF(dir,len,pp,true, false,false,false,bL,eL,fL,gL,jL);
 384    FsrEasuSetF(dir,len,pp,false,true ,false,false,cL,fL,gL,hL,kL);
 385    FsrEasuSetF(dir,len,pp,false,false,true ,false,fL,iL,jL,kL,nL);
 386    FsrEasuSetF(dir,len,pp,false,false,false,true ,gL,jL,kL,lL,oL);
 387  //------------------------------------------------------------------------------------------------------------------------------
 388    // Normalize with approximation, and cleanup close to zero.
 389    AF2 dir2=dir*dir;
 390    AF1 dirR=dir2.x+dir2.y;
 391    AP1 zro=dirR<AF1_(1.0/32768.0);
 392    dirR=APrxLoRsqF1(dirR);
 393    dirR=zro?AF1_(1.0):dirR;
 394    dir.x=zro?AF1_(1.0):dir.x;
 395    dir*=AF2_(dirR);
 396    // Transform from {0 to 2} to {0 to 1} range, and shape with square.
 397    len=len*AF1_(0.5);
 398    len*=len;
 399    // Stretch kernel {1.0 vert|horz, to sqrt(2.0) on diagonal}.
 400    AF1 stretch=(dir.x*dir.x+dir.y*dir.y)*APrxLoRcpF1(max(abs(dir.x),abs(dir.y)));
 401    // Anisotropic length after rotation,
 402    //  x := 1.0 lerp to 'stretch' on edges
 403    //  y := 1.0 lerp to 2x on edges
 404    AF2 len2=AF2(AF1_(1.0)+(stretch-AF1_(1.0))*len,AF1_(1.0)+AF1_(-0.5)*len);
 405    // Based on the amount of 'edge',
 406    // the window shifts from +/-{sqrt(2.0) to slightly beyond 2.0}.
 407    AF1 lob=AF1_(0.5)+AF1_((1.0/4.0-0.04)-0.5)*len;
 408    // Set distance^2 clipping point to the end of the adjustable window.
 409    AF1 clp=APrxLoRcpF1(lob);
 410  //------------------------------------------------------------------------------------------------------------------------------
 411    // Accumulation mixed with min/max of 4 nearest.
 412    //    b c
 413    //  e f g h
 414    //  i j k l
 415    //    n o
 416    AF3 min4=min(AMin3F3(AF3(ijfeR.z,ijfeG.z,ijfeB.z),AF3(klhgR.w,klhgG.w,klhgB.w),AF3(ijfeR.y,ijfeG.y,ijfeB.y)),
 417                 AF3(klhgR.x,klhgG.x,klhgB.x));
 418    AF3 max4=max(AMax3F3(AF3(ijfeR.z,ijfeG.z,ijfeB.z),AF3(klhgR.w,klhgG.w,klhgB.w),AF3(ijfeR.y,ijfeG.y,ijfeB.y)),
 419                 AF3(klhgR.x,klhgG.x,klhgB.x));
 420    // Accumulation.
 421    AF3 aC=AF3_(0.0);
 422    AF1 aW=AF1_(0.0);
 423    FsrEasuTapF(aC,aW,AF2( 0.0,-1.0)-pp,dir,len2,lob,clp,AF3(bczzR.x,bczzG.x,bczzB.x)); // b
 424    FsrEasuTapF(aC,aW,AF2( 1.0,-1.0)-pp,dir,len2,lob,clp,AF3(bczzR.y,bczzG.y,bczzB.y)); // c
 425    FsrEasuTapF(aC,aW,AF2(-1.0, 1.0)-pp,dir,len2,lob,clp,AF3(ijfeR.x,ijfeG.x,ijfeB.x)); // i
 426    FsrEasuTapF(aC,aW,AF2( 0.0, 1.0)-pp,dir,len2,lob,clp,AF3(ijfeR.y,ijfeG.y,ijfeB.y)); // j
 427    FsrEasuTapF(aC,aW,AF2( 0.0, 0.0)-pp,dir,len2,lob,clp,AF3(ijfeR.z,ijfeG.z,ijfeB.z)); // f
 428    FsrEasuTapF(aC,aW,AF2(-1.0, 0.0)-pp,dir,len2,lob,clp,AF3(ijfeR.w,ijfeG.w,ijfeB.w)); // e
 429    FsrEasuTapF(aC,aW,AF2( 1.0, 1.0)-pp,dir,len2,lob,clp,AF3(klhgR.x,klhgG.x,klhgB.x)); // k
 430    FsrEasuTapF(aC,aW,AF2( 2.0, 1.0)-pp,dir,len2,lob,clp,AF3(klhgR.y,klhgG.y,klhgB.y)); // l
 431    FsrEasuTapF(aC,aW,AF2( 2.0, 0.0)-pp,dir,len2,lob,clp,AF3(klhgR.z,klhgG.z,klhgB.z)); // h
 432    FsrEasuTapF(aC,aW,AF2( 1.0, 0.0)-pp,dir,len2,lob,clp,AF3(klhgR.w,klhgG.w,klhgB.w)); // g
 433    FsrEasuTapF(aC,aW,AF2( 1.0, 2.0)-pp,dir,len2,lob,clp,AF3(zzonR.z,zzonG.z,zzonB.z)); // o
 434    FsrEasuTapF(aC,aW,AF2( 0.0, 2.0)-pp,dir,len2,lob,clp,AF3(zzonR.w,zzonG.w,zzonB.w)); // n
 435  //------------------------------------------------------------------------------------------------------------------------------
 436    // Normalize and dering.
 437    pix=min(max4,max(min4,aC*AF3_(ARcpF1(aW))));}
 438  #endif
 439  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 440  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 441  //_____________________________________________________________/\_______________________________________________________________
 442  //==============================================================================================================================
 443  //                                                    PACKED 16-BIT VERSION
 444  //==============================================================================================================================
 445  #if defined(A_GPU)&&defined(A_HALF)&&defined(FSR_EASU_H)
 446  // Input callback prototypes, need to be implemented by calling shader
 447   AH4 FsrEasuRH(AF2 p);
 448   AH4 FsrEasuGH(AF2 p);
 449   AH4 FsrEasuBH(AF2 p);
 450  //------------------------------------------------------------------------------------------------------------------------------
 451   // This runs 2 taps in parallel.
 452   void FsrEasuTapH(
 453   inout AH2 aCR,inout AH2 aCG,inout AH2 aCB,
 454   inout AH2 aW,
 455   AH2 offX,AH2 offY,
 456   AH2 dir,
 457   AH2 len,
 458   AH1 lob,
 459   AH1 clp,
 460   AH2 cR,AH2 cG,AH2 cB){
 461    AH2 vX,vY;
 462    vX=offX*  dir.xx +offY*dir.yy;
 463    vY=offX*(-dir.yy)+offY*dir.xx;
 464    vX*=len.x;vY*=len.y;
 465    AH2 d2=vX*vX+vY*vY;
 466    d2=min(d2,AH2_(clp));
 467    AH2 wB=AH2_(2.0/5.0)*d2+AH2_(-1.0);
 468    AH2 wA=AH2_(lob)*d2+AH2_(-1.0);
 469    wB*=wB;
 470    wA*=wA;
 471    wB=AH2_(25.0/16.0)*wB+AH2_(-(25.0/16.0-1.0));
 472    AH2 w=wB*wA;
 473    aCR+=cR*w;aCG+=cG*w;aCB+=cB*w;aW+=w;}
 474  //------------------------------------------------------------------------------------------------------------------------------
 475   // This runs 2 taps in parallel.
 476   void FsrEasuSetH(
 477   inout AH2 dirPX,inout AH2 dirPY,
 478   inout AH2 lenP,
 479   AH2 pp,
 480   AP1 biST,AP1 biUV,
 481   AH2 lA,AH2 lB,AH2 lC,AH2 lD,AH2 lE){
 482    AH2 w = AH2_(0.0);
 483    if(biST)w=(AH2(1.0,0.0)+AH2(-pp.x,pp.x))*AH2_(AH1_(1.0)-pp.y);
 484    if(biUV)w=(AH2(1.0,0.0)+AH2(-pp.x,pp.x))*AH2_(          pp.y);
 485    // ABS is not free in the packed FP16 path.
 486    AH2 dc=lD-lC;
 487    AH2 cb=lC-lB;
 488    AH2 lenX=max(abs(dc),abs(cb));
 489    lenX=ARcpH2(lenX);
 490    AH2 dirX=lD-lB;
 491    dirPX+=dirX*w;
 492    lenX=ASatH2(abs(dirX)*lenX);
 493    lenX*=lenX;
 494    lenP+=lenX*w;
 495    AH2 ec=lE-lC;
 496    AH2 ca=lC-lA;
 497    AH2 lenY=max(abs(ec),abs(ca));
 498    lenY=ARcpH2(lenY);
 499    AH2 dirY=lE-lA;
 500    dirPY+=dirY*w;
 501    lenY=ASatH2(abs(dirY)*lenY);
 502    lenY*=lenY;
 503    lenP+=lenY*w;}
 504  //------------------------------------------------------------------------------------------------------------------------------
 505   void FsrEasuH(
 506   out AH3 pix,
 507   AU2 ip,
 508   AU4 con0,
 509   AU4 con1,
 510   AU4 con2,
 511   AU4 con3){
 512  //------------------------------------------------------------------------------------------------------------------------------
 513    AF2 pp=AF2(ip)*AF2_AU2(con0.xy)+AF2_AU2(con0.zw);
 514    AF2 fp=floor(pp);
 515    pp-=fp;
 516    AH2 ppp=AH2(pp);
 517  //------------------------------------------------------------------------------------------------------------------------------
 518    AF2 p0=fp*AF2_AU2(con1.xy)+AF2_AU2(con1.zw);
 519    AF2 p1=p0+AF2_AU2(con2.xy);
 520    AF2 p2=p0+AF2_AU2(con2.zw);
 521    AF2 p3=p0+AF2_AU2(con3.xy);
 522    AH4 bczzR=FsrEasuRH(p0);
 523    AH4 bczzG=FsrEasuGH(p0);
 524    AH4 bczzB=FsrEasuBH(p0);
 525    AH4 ijfeR=FsrEasuRH(p1);
 526    AH4 ijfeG=FsrEasuGH(p1);
 527    AH4 ijfeB=FsrEasuBH(p1);
 528    AH4 klhgR=FsrEasuRH(p2);
 529    AH4 klhgG=FsrEasuGH(p2);
 530    AH4 klhgB=FsrEasuBH(p2);
 531    AH4 zzonR=FsrEasuRH(p3);
 532    AH4 zzonG=FsrEasuGH(p3);
 533    AH4 zzonB=FsrEasuBH(p3);
 534  //------------------------------------------------------------------------------------------------------------------------------
 535    AH4 bczzL=bczzB*AH4_(0.5)+(bczzR*AH4_(0.5)+bczzG);
 536    AH4 ijfeL=ijfeB*AH4_(0.5)+(ijfeR*AH4_(0.5)+ijfeG);
 537    AH4 klhgL=klhgB*AH4_(0.5)+(klhgR*AH4_(0.5)+klhgG);
 538    AH4 zzonL=zzonB*AH4_(0.5)+(zzonR*AH4_(0.5)+zzonG);
 539    AH1 bL=bczzL.x;
 540    AH1 cL=bczzL.y;
 541    AH1 iL=ijfeL.x;
 542    AH1 jL=ijfeL.y;
 543    AH1 fL=ijfeL.z;
 544    AH1 eL=ijfeL.w;
 545    AH1 kL=klhgL.x;
 546    AH1 lL=klhgL.y;
 547    AH1 hL=klhgL.z;
 548    AH1 gL=klhgL.w;
 549    AH1 oL=zzonL.z;
 550    AH1 nL=zzonL.w;
 551    // This part is different, accumulating 2 taps in parallel.
 552    AH2 dirPX=AH2_(0.0);
 553    AH2 dirPY=AH2_(0.0);
 554    AH2 lenP=AH2_(0.0);
 555    FsrEasuSetH(dirPX,dirPY,lenP,ppp,true, false,AH2(bL,cL),AH2(eL,fL),AH2(fL,gL),AH2(gL,hL),AH2(jL,kL));
 556    FsrEasuSetH(dirPX,dirPY,lenP,ppp,false,true ,AH2(fL,gL),AH2(iL,jL),AH2(jL,kL),AH2(kL,lL),AH2(nL,oL));
 557    AH2 dir=AH2(dirPX.r+dirPX.g,dirPY.r+dirPY.g);
 558    AH1 len=lenP.r+lenP.g;
 559  //------------------------------------------------------------------------------------------------------------------------------
 560    AH2 dir2=dir*dir;
 561    AH1 dirR=dir2.x+dir2.y;
 562    AP1 zro=dirR<AH1_(1.0/32768.0);
 563    dirR=APrxLoRsqH1(dirR);
 564    dirR=zro?AH1_(1.0):dirR;
 565    dir.x=zro?AH1_(1.0):dir.x;
 566    dir*=AH2_(dirR);
 567    len=len*AH1_(0.5);
 568    len*=len;
 569    AH1 stretch=(dir.x*dir.x+dir.y*dir.y)*APrxLoRcpH1(max(abs(dir.x),abs(dir.y)));
 570    AH2 len2=AH2(AH1_(1.0)+(stretch-AH1_(1.0))*len,AH1_(1.0)+AH1_(-0.5)*len);
 571    AH1 lob=AH1_(0.5)+AH1_((1.0/4.0-0.04)-0.5)*len;
 572    AH1 clp=APrxLoRcpH1(lob);
 573  //------------------------------------------------------------------------------------------------------------------------------
 574    // FP16 is different, using packed trick to do min and max in same operation.
 575    AH2 bothR=max(max(AH2(-ijfeR.z,ijfeR.z),AH2(-klhgR.w,klhgR.w)),max(AH2(-ijfeR.y,ijfeR.y),AH2(-klhgR.x,klhgR.x)));
 576    AH2 bothG=max(max(AH2(-ijfeG.z,ijfeG.z),AH2(-klhgG.w,klhgG.w)),max(AH2(-ijfeG.y,ijfeG.y),AH2(-klhgG.x,klhgG.x)));
 577    AH2 bothB=max(max(AH2(-ijfeB.z,ijfeB.z),AH2(-klhgB.w,klhgB.w)),max(AH2(-ijfeB.y,ijfeB.y),AH2(-klhgB.x,klhgB.x)));
 578    // This part is different for FP16, working pairs of taps at a time.
 579    AH2 pR=AH2_(0.0);
 580    AH2 pG=AH2_(0.0);
 581    AH2 pB=AH2_(0.0);
 582    AH2 pW=AH2_(0.0);
 583    FsrEasuTapH(pR,pG,pB,pW,AH2( 0.0, 1.0)-ppp.xx,AH2(-1.0,-1.0)-ppp.yy,dir,len2,lob,clp,bczzR.xy,bczzG.xy,bczzB.xy);
 584    FsrEasuTapH(pR,pG,pB,pW,AH2(-1.0, 0.0)-ppp.xx,AH2( 1.0, 1.0)-ppp.yy,dir,len2,lob,clp,ijfeR.xy,ijfeG.xy,ijfeB.xy);
 585    FsrEasuTapH(pR,pG,pB,pW,AH2( 0.0,-1.0)-ppp.xx,AH2( 0.0, 0.0)-ppp.yy,dir,len2,lob,clp,ijfeR.zw,ijfeG.zw,ijfeB.zw);
 586    FsrEasuTapH(pR,pG,pB,pW,AH2( 1.0, 2.0)-ppp.xx,AH2( 1.0, 1.0)-ppp.yy,dir,len2,lob,clp,klhgR.xy,klhgG.xy,klhgB.xy);
 587    FsrEasuTapH(pR,pG,pB,pW,AH2( 2.0, 1.0)-ppp.xx,AH2( 0.0, 0.0)-ppp.yy,dir,len2,lob,clp,klhgR.zw,klhgG.zw,klhgB.zw);
 588    FsrEasuTapH(pR,pG,pB,pW,AH2( 1.0, 0.0)-ppp.xx,AH2( 2.0, 2.0)-ppp.yy,dir,len2,lob,clp,zzonR.zw,zzonG.zw,zzonB.zw);
 589    AH3 aC=AH3(pR.x+pR.y,pG.x+pG.y,pB.x+pB.y);
 590    AH1 aW=pW.x+pW.y;
 591  //------------------------------------------------------------------------------------------------------------------------------
 592    // Slightly different for FP16 version due to combined min and max.
 593    pix=min(AH3(bothR.y,bothG.y,bothB.y),max(-AH3(bothR.x,bothG.x,bothB.x),aC*AH3_(ARcpH1(aW))));}
 594  #endif
 595  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 596  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 597  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 598  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 599  //_____________________________________________________________/\_______________________________________________________________
 600  //==============================================================================================================================
 601  //
 602  //                                      FSR - [RCAS] ROBUST CONTRAST ADAPTIVE SHARPENING
 603  //
 604  //------------------------------------------------------------------------------------------------------------------------------
 605  // CAS uses a simplified mechanism to convert local contrast into a variable amount of sharpness.
 606  // RCAS uses a more exact mechanism, solving for the maximum local sharpness possible before clipping.
 607  // RCAS also has a built in process to limit sharpening of what it detects as possible noise.
 608  // RCAS sharper does not support scaling, as it should be applied after EASU scaling.
 609  // Pass EASU output straight into RCAS, no color conversions necessary.
 610  //------------------------------------------------------------------------------------------------------------------------------
 611  // RCAS is based on the following logic.
 612  // RCAS uses a 5 tap filter in a cross pattern (same as CAS),
 613  //    w                n
 614  //  w 1 w  for taps  w m e 
 615  //    w                s
 616  // Where 'w' is the negative lobe weight.
 617  //  output = (w*(n+e+w+s)+m)/(4*w+1)
 618  // RCAS solves for 'w' by seeing where the signal might clip out of the {0 to 1} input range,
 619  //  0 == (w*(n+e+w+s)+m)/(4*w+1) -> w = -m/(n+e+w+s)
 620  //  1 == (w*(n+e+w+s)+m)/(4*w+1) -> w = (1-m)/(n+e+w+s-4*1)
 621  // Then chooses the 'w' which results in no clipping, limits 'w', and multiplies by the 'sharp' amount.
 622  // This solution above has issues with MSAA input as the steps along the gradient cause edge detection issues.
 623  // So RCAS uses 4x the maximum and 4x the minimum (depending on equation)in place of the individual taps.
 624  // As well as switching from 'm' to either the minimum or maximum (depending on side), to help in energy conservation.
 625  // This stabilizes RCAS.
 626  // RCAS does a simple highpass which is normalized against the local contrast then shaped,
 627  //       0.25
 628  //  0.25  -1  0.25
 629  //       0.25
 630  // This is used as a noise detection filter, to reduce the effect of RCAS on grain, and focus on real edges.
 631  //
 632  //  GLSL example for the required callbacks :
 633  // 
 634  //  AH4 FsrRcasLoadH(ASW2 p){return AH4(imageLoad(imgSrc,ASU2(p)));}
 635  //  void FsrRcasInputH(inout AH1 r,inout AH1 g,inout AH1 b)
 636  //  {
 637  //    //do any simple input color conversions here or leave empty if none needed
 638  //  }
 639  //  
 640  //  FsrRcasCon need to be called from the CPU or GPU to set up constants.
 641  //  Including a GPU example here, the 'con' value would be stored out to a constant buffer.
 642  // 
 643  //  AU4 con;
 644  //  FsrRcasCon(con,
 645  //   0.0); // The scale is {0.0 := maximum sharpness, to N>0, where N is the number of stops (halving) of the reduction of sharpness}.
 646  // ---------------
 647  // RCAS sharpening supports a CAS-like pass-through alpha via,
 648  //  #define FSR_RCAS_PASSTHROUGH_ALPHA 1
 649  // RCAS also supports a define to enable a more expensive path to avoid some sharpening of noise.
 650  // Would suggest it is better to apply film grain after RCAS sharpening (and after scaling) instead of using this define,
 651  //  #define FSR_RCAS_DENOISE 1
 652  //==============================================================================================================================
 653  // This is set at the limit of providing unnatural results for sharpening.
 654  #define FSR_RCAS_LIMIT (0.25-(1.0/16.0))
 655  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 656  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 657  //_____________________________________________________________/\_______________________________________________________________
 658  //==============================================================================================================================
 659  //                                                      CONSTANT SETUP
 660  //==============================================================================================================================
 661  // Call to setup required constant values (works on CPU or GPU).
 662  A_STATIC void FsrRcasCon(
 663  outAU4 con,
 664  // The scale is {0.0 := maximum, to N>0, where N is the number of stops (halving) of the reduction of sharpness}.
 665  AF1 sharpness){
 666   // Transform from stops to linear value.
 667   sharpness=AExp2F1(-sharpness);
 668   varAF2(hSharp)=initAF2(sharpness,sharpness);
 669   con[0]=AU1_AF1(sharpness);
 670   con[1]=AU1_AH2_AF2(hSharp);
 671   con[2]=0;
 672   con[3]=0;}
 673  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 674  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 675  //_____________________________________________________________/\_______________________________________________________________
 676  //==============================================================================================================================
 677  //                                                   NON-PACKED 32-BIT VERSION
 678  //==============================================================================================================================
 679  #if defined(A_GPU)&&defined(FSR_RCAS_F)
 680   // Input callback prototypes that need to be implemented by calling shader
 681   AF4 FsrRcasLoadF(ASU2 p);
 682   void FsrRcasInputF(inout AF1 r,inout AF1 g,inout AF1 b);
 683  //------------------------------------------------------------------------------------------------------------------------------
 684   void FsrRcasF(
 685   out AF1 pixR, // Output values, non-vector so port between RcasFilter() and RcasFilterH() is easy.
 686   out AF1 pixG,
 687   out AF1 pixB,
 688   #ifdef FSR_RCAS_PASSTHROUGH_ALPHA
 689    out AF1 pixA,
 690   #endif
 691   AU2 ip, // Integer pixel position in output.
 692   AU4 con){ // Constant generated by RcasSetup().
 693    // Algorithm uses minimal 3x3 pixel neighborhood.
 694    //    b 
 695    //  d e f
 696    //    h
 697    ASU2 sp=ASU2(ip);
 698    AF3 b=FsrRcasLoadF(sp+ASU2( 0,-1)).rgb;
 699    AF3 d=FsrRcasLoadF(sp+ASU2(-1, 0)).rgb;
 700    #ifdef FSR_RCAS_PASSTHROUGH_ALPHA
 701     AF4 ee=FsrRcasLoadF(sp);
 702     AF3 e=ee.rgb;pixA=ee.a;
 703    #else
 704     AF3 e=FsrRcasLoadF(sp).rgb;
 705    #endif
 706    AF3 f=FsrRcasLoadF(sp+ASU2( 1, 0)).rgb;
 707    AF3 h=FsrRcasLoadF(sp+ASU2( 0, 1)).rgb;
 708    // Rename (32-bit) or regroup (16-bit).
 709    AF1 bR=b.r;
 710    AF1 bG=b.g;
 711    AF1 bB=b.b;
 712    AF1 dR=d.r;
 713    AF1 dG=d.g;
 714    AF1 dB=d.b;
 715    AF1 eR=e.r;
 716    AF1 eG=e.g;
 717    AF1 eB=e.b;
 718    AF1 fR=f.r;
 719    AF1 fG=f.g;
 720    AF1 fB=f.b;
 721    AF1 hR=h.r;
 722    AF1 hG=h.g;
 723    AF1 hB=h.b;
 724    // Run optional input transform.
 725    FsrRcasInputF(bR,bG,bB);
 726    FsrRcasInputF(dR,dG,dB);
 727    FsrRcasInputF(eR,eG,eB);
 728    FsrRcasInputF(fR,fG,fB);
 729    FsrRcasInputF(hR,hG,hB);
 730    // Luma times 2.
 731    AF1 bL=bB*AF1_(0.5)+(bR*AF1_(0.5)+bG);
 732    AF1 dL=dB*AF1_(0.5)+(dR*AF1_(0.5)+dG);
 733    AF1 eL=eB*AF1_(0.5)+(eR*AF1_(0.5)+eG);
 734    AF1 fL=fB*AF1_(0.5)+(fR*AF1_(0.5)+fG);
 735    AF1 hL=hB*AF1_(0.5)+(hR*AF1_(0.5)+hG);
 736    // Noise detection.
 737    AF1 nz=AF1_(0.25)*bL+AF1_(0.25)*dL+AF1_(0.25)*fL+AF1_(0.25)*hL-eL;
 738    nz=ASatF1(abs(nz)*APrxMedRcpF1(AMax3F1(AMax3F1(bL,dL,eL),fL,hL)-AMin3F1(AMin3F1(bL,dL,eL),fL,hL)));
 739    nz=AF1_(-0.5)*nz+AF1_(1.0);
 740    // Min and max of ring.
 741    AF1 mn4R=min(AMin3F1(bR,dR,fR),hR);
 742    AF1 mn4G=min(AMin3F1(bG,dG,fG),hG);
 743    AF1 mn4B=min(AMin3F1(bB,dB,fB),hB);
 744    AF1 mx4R=max(AMax3F1(bR,dR,fR),hR);
 745    AF1 mx4G=max(AMax3F1(bG,dG,fG),hG);
 746    AF1 mx4B=max(AMax3F1(bB,dB,fB),hB);
 747    // Immediate constants for peak range.
 748    AF2 peakC=AF2(1.0,-1.0*4.0);
 749    // Limiters, these need to be high precision RCPs.
 750    AF1 hitMinR=min(mn4R,eR)*ARcpF1(AF1_(4.0)*mx4R);
 751    AF1 hitMinG=min(mn4G,eG)*ARcpF1(AF1_(4.0)*mx4G);
 752    AF1 hitMinB=min(mn4B,eB)*ARcpF1(AF1_(4.0)*mx4B);
 753    AF1 hitMaxR=(peakC.x-max(mx4R,eR))*ARcpF1(AF1_(4.0)*mn4R+peakC.y);
 754    AF1 hitMaxG=(peakC.x-max(mx4G,eG))*ARcpF1(AF1_(4.0)*mn4G+peakC.y);
 755    AF1 hitMaxB=(peakC.x-max(mx4B,eB))*ARcpF1(AF1_(4.0)*mn4B+peakC.y);
 756    AF1 lobeR=max(-hitMinR,hitMaxR);
 757    AF1 lobeG=max(-hitMinG,hitMaxG);
 758    AF1 lobeB=max(-hitMinB,hitMaxB);
 759    AF1 lobe=max(AF1_(-FSR_RCAS_LIMIT),min(AMax3F1(lobeR,lobeG,lobeB),AF1_(0.0)))*AF1_AU1(con.x);
 760    // Apply noise removal.
 761    #ifdef FSR_RCAS_DENOISE
 762     lobe*=nz;
 763    #endif
 764    // Resolve, which needs the medium precision rcp approximation to avoid visible tonality changes.
 765    AF1 rcpL=APrxMedRcpF1(AF1_(4.0)*lobe+AF1_(1.0));
 766    pixR=(lobe*bR+lobe*dR+lobe*hR+lobe*fR+eR)*rcpL;
 767    pixG=(lobe*bG+lobe*dG+lobe*hG+lobe*fG+eG)*rcpL;
 768    pixB=(lobe*bB+lobe*dB+lobe*hB+lobe*fB+eB)*rcpL;
 769    return;} 
 770  #endif
 771  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 772  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 773  //_____________________________________________________________/\_______________________________________________________________
 774  //==============================================================================================================================
 775  //                                                  NON-PACKED 16-BIT VERSION
 776  //==============================================================================================================================
 777  #if defined(A_GPU)&&defined(A_HALF)&&defined(FSR_RCAS_H)
 778   // Input callback prototypes that need to be implemented by calling shader
 779   AH4 FsrRcasLoadH(ASW2 p);
 780   void FsrRcasInputH(inout AH1 r,inout AH1 g,inout AH1 b);
 781  //------------------------------------------------------------------------------------------------------------------------------
 782   void FsrRcasH(
 783   out AH1 pixR, // Output values, non-vector so port between RcasFilter() and RcasFilterH() is easy.
 784   out AH1 pixG,
 785   out AH1 pixB,
 786   #ifdef FSR_RCAS_PASSTHROUGH_ALPHA
 787    out AH1 pixA,
 788   #endif
 789   AU2 ip, // Integer pixel position in output.
 790   AU4 con){ // Constant generated by RcasSetup().
 791    // Sharpening algorithm uses minimal 3x3 pixel neighborhood.
 792    //    b 
 793    //  d e f
 794    //    h
 795    ASW2 sp=ASW2(ip);
 796    AH3 b=FsrRcasLoadH(sp+ASW2( 0,-1)).rgb;
 797    AH3 d=FsrRcasLoadH(sp+ASW2(-1, 0)).rgb;
 798    #ifdef FSR_RCAS_PASSTHROUGH_ALPHA
 799     AH4 ee=FsrRcasLoadH(sp);
 800     AH3 e=ee.rgb;pixA=ee.a;
 801    #else
 802     AH3 e=FsrRcasLoadH(sp).rgb;
 803    #endif
 804    AH3 f=FsrRcasLoadH(sp+ASW2( 1, 0)).rgb;
 805    AH3 h=FsrRcasLoadH(sp+ASW2( 0, 1)).rgb;
 806    // Rename (32-bit) or regroup (16-bit).
 807    AH1 bR=b.r;
 808    AH1 bG=b.g;
 809    AH1 bB=b.b;
 810    AH1 dR=d.r;
 811    AH1 dG=d.g;
 812    AH1 dB=d.b;
 813    AH1 eR=e.r;
 814    AH1 eG=e.g;
 815    AH1 eB=e.b;
 816    AH1 fR=f.r;
 817    AH1 fG=f.g;
 818    AH1 fB=f.b;
 819    AH1 hR=h.r;
 820    AH1 hG=h.g;
 821    AH1 hB=h.b;
 822    // Run optional input transform.
 823    FsrRcasInputH(bR,bG,bB);
 824    FsrRcasInputH(dR,dG,dB);
 825    FsrRcasInputH(eR,eG,eB);
 826    FsrRcasInputH(fR,fG,fB);
 827    FsrRcasInputH(hR,hG,hB);
 828    // Luma times 2.
 829    AH1 bL=bB*AH1_(0.5)+(bR*AH1_(0.5)+bG);
 830    AH1 dL=dB*AH1_(0.5)+(dR*AH1_(0.5)+dG);
 831    AH1 eL=eB*AH1_(0.5)+(eR*AH1_(0.5)+eG);
 832    AH1 fL=fB*AH1_(0.5)+(fR*AH1_(0.5)+fG);
 833    AH1 hL=hB*AH1_(0.5)+(hR*AH1_(0.5)+hG);
 834    // Noise detection.
 835    AH1 nz=AH1_(0.25)*bL+AH1_(0.25)*dL+AH1_(0.25)*fL+AH1_(0.25)*hL-eL;
 836    nz=ASatH1(abs(nz)*APrxMedRcpH1(AMax3H1(AMax3H1(bL,dL,eL),fL,hL)-AMin3H1(AMin3H1(bL,dL,eL),fL,hL)));
 837    nz=AH1_(-0.5)*nz+AH1_(1.0);
 838    // Min and max of ring.
 839    AH1 mn4R=min(AMin3H1(bR,dR,fR),hR);
 840    AH1 mn4G=min(AMin3H1(bG,dG,fG),hG);
 841    AH1 mn4B=min(AMin3H1(bB,dB,fB),hB);
 842    AH1 mx4R=max(AMax3H1(bR,dR,fR),hR);
 843    AH1 mx4G=max(AMax3H1(bG,dG,fG),hG);
 844    AH1 mx4B=max(AMax3H1(bB,dB,fB),hB);
 845    // Immediate constants for peak range.
 846    AH2 peakC=AH2(1.0,-1.0*4.0);
 847    // Limiters, these need to be high precision RCPs.
 848    AH1 hitMinR=min(mn4R,eR)*ARcpH1(AH1_(4.0)*mx4R);
 849    AH1 hitMinG=min(mn4G,eG)*ARcpH1(AH1_(4.0)*mx4G);
 850    AH1 hitMinB=min(mn4B,eB)*ARcpH1(AH1_(4.0)*mx4B);
 851    AH1 hitMaxR=(peakC.x-max(mx4R,eR))*ARcpH1(AH1_(4.0)*mn4R+peakC.y);
 852    AH1 hitMaxG=(peakC.x-max(mx4G,eG))*ARcpH1(AH1_(4.0)*mn4G+peakC.y);
 853    AH1 hitMaxB=(peakC.x-max(mx4B,eB))*ARcpH1(AH1_(4.0)*mn4B+peakC.y);
 854    AH1 lobeR=max(-hitMinR,hitMaxR);
 855    AH1 lobeG=max(-hitMinG,hitMaxG);
 856    AH1 lobeB=max(-hitMinB,hitMaxB);
 857    AH1 lobe=max(AH1_(-FSR_RCAS_LIMIT),min(AMax3H1(lobeR,lobeG,lobeB),AH1_(0.0)))*AH2_AU1(con.y).x;
 858    // Apply noise removal.
 859    #ifdef FSR_RCAS_DENOISE
 860     lobe*=nz;
 861    #endif
 862    // Resolve, which needs the medium precision rcp approximation to avoid visible tonality changes.
 863    AH1 rcpL=APrxMedRcpH1(AH1_(4.0)*lobe+AH1_(1.0));
 864    pixR=(lobe*bR+lobe*dR+lobe*hR+lobe*fR+eR)*rcpL;
 865    pixG=(lobe*bG+lobe*dG+lobe*hG+lobe*fG+eG)*rcpL;
 866    pixB=(lobe*bB+lobe*dB+lobe*hB+lobe*fB+eB)*rcpL;}
 867  #endif
 868  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 869  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 870  //_____________________________________________________________/\_______________________________________________________________
 871  //==============================================================================================================================
 872  //                                                     PACKED 16-BIT VERSION
 873  //==============================================================================================================================
 874  #if defined(A_GPU)&&defined(A_HALF)&&defined(FSR_RCAS_HX2)
 875   // Input callback prototypes that need to be implemented by the calling shader
 876   AH4 FsrRcasLoadHx2(ASW2 p);
 877   void FsrRcasInputHx2(inout AH2 r,inout AH2 g,inout AH2 b);
 878  //------------------------------------------------------------------------------------------------------------------------------
 879   // Can be used to convert from packed Structures of Arrays to Arrays of Structures for store.
 880   void FsrRcasDepackHx2(out AH4 pix0,out AH4 pix1,AH2 pixR,AH2 pixG,AH2 pixB){
 881    #ifdef A_HLSL
 882     // Invoke a slower path for DX only, since it won't allow uninitialized values.
 883     pix0.a=pix1.a=0.0;
 884    #endif
 885    pix0.rgb=AH3(pixR.x,pixG.x,pixB.x);
 886    pix1.rgb=AH3(pixR.y,pixG.y,pixB.y);}
 887  //------------------------------------------------------------------------------------------------------------------------------
 888   void FsrRcasHx2(
 889   // Output values are for 2 8x8 tiles in a 16x8 region.
 890   //  pix<R,G,B>.x =  left 8x8 tile
 891   //  pix<R,G,B>.y = right 8x8 tile
 892   // This enables later processing to easily be packed as well.
 893   out AH2 pixR,
 894   out AH2 pixG,
 895   out AH2 pixB,
 896   #ifdef FSR_RCAS_PASSTHROUGH_ALPHA
 897    out AH2 pixA,
 898   #endif
 899   AU2 ip, // Integer pixel position in output.
 900   AU4 con){ // Constant generated by RcasSetup().
 901    // No scaling algorithm uses minimal 3x3 pixel neighborhood.
 902    ASW2 sp0=ASW2(ip);
 903    AH3 b0=FsrRcasLoadHx2(sp0+ASW2( 0,-1)).rgb;
 904    AH3 d0=FsrRcasLoadHx2(sp0+ASW2(-1, 0)).rgb;
 905    #ifdef FSR_RCAS_PASSTHROUGH_ALPHA
 906     AH4 ee0=FsrRcasLoadHx2(sp0);
 907     AH3 e0=ee0.rgb;pixA.r=ee0.a;
 908    #else
 909     AH3 e0=FsrRcasLoadHx2(sp0).rgb;
 910    #endif
 911    AH3 f0=FsrRcasLoadHx2(sp0+ASW2( 1, 0)).rgb;
 912    AH3 h0=FsrRcasLoadHx2(sp0+ASW2( 0, 1)).rgb;
 913    ASW2 sp1=sp0+ASW2(8,0);
 914    AH3 b1=FsrRcasLoadHx2(sp1+ASW2( 0,-1)).rgb;
 915    AH3 d1=FsrRcasLoadHx2(sp1+ASW2(-1, 0)).rgb;
 916    #ifdef FSR_RCAS_PASSTHROUGH_ALPHA
 917     AH4 ee1=FsrRcasLoadHx2(sp1);
 918     AH3 e1=ee1.rgb;pixA.g=ee1.a;
 919    #else
 920     AH3 e1=FsrRcasLoadHx2(sp1).rgb;
 921    #endif
 922    AH3 f1=FsrRcasLoadHx2(sp1+ASW2( 1, 0)).rgb;
 923    AH3 h1=FsrRcasLoadHx2(sp1+ASW2( 0, 1)).rgb;
 924    // Arrays of Structures to Structures of Arrays conversion.
 925    AH2 bR=AH2(b0.r,b1.r);
 926    AH2 bG=AH2(b0.g,b1.g);
 927    AH2 bB=AH2(b0.b,b1.b);
 928    AH2 dR=AH2(d0.r,d1.r);
 929    AH2 dG=AH2(d0.g,d1.g);
 930    AH2 dB=AH2(d0.b,d1.b);
 931    AH2 eR=AH2(e0.r,e1.r);
 932    AH2 eG=AH2(e0.g,e1.g);
 933    AH2 eB=AH2(e0.b,e1.b);
 934    AH2 fR=AH2(f0.r,f1.r);
 935    AH2 fG=AH2(f0.g,f1.g);
 936    AH2 fB=AH2(f0.b,f1.b);
 937    AH2 hR=AH2(h0.r,h1.r);
 938    AH2 hG=AH2(h0.g,h1.g);
 939    AH2 hB=AH2(h0.b,h1.b);
 940    // Run optional input transform.
 941    FsrRcasInputHx2(bR,bG,bB);
 942    FsrRcasInputHx2(dR,dG,dB);
 943    FsrRcasInputHx2(eR,eG,eB);
 944    FsrRcasInputHx2(fR,fG,fB);
 945    FsrRcasInputHx2(hR,hG,hB);
 946    // Luma times 2.
 947    AH2 bL=bB*AH2_(0.5)+(bR*AH2_(0.5)+bG);
 948    AH2 dL=dB*AH2_(0.5)+(dR*AH2_(0.5)+dG);
 949    AH2 eL=eB*AH2_(0.5)+(eR*AH2_(0.5)+eG);
 950    AH2 fL=fB*AH2_(0.5)+(fR*AH2_(0.5)+fG);
 951    AH2 hL=hB*AH2_(0.5)+(hR*AH2_(0.5)+hG);
 952    // Noise detection.
 953    AH2 nz=AH2_(0.25)*bL+AH2_(0.25)*dL+AH2_(0.25)*fL+AH2_(0.25)*hL-eL;
 954    nz=ASatH2(abs(nz)*APrxMedRcpH2(AMax3H2(AMax3H2(bL,dL,eL),fL,hL)-AMin3H2(AMin3H2(bL,dL,eL),fL,hL)));
 955    nz=AH2_(-0.5)*nz+AH2_(1.0);
 956    // Min and max of ring.
 957    AH2 mn4R=min(AMin3H2(bR,dR,fR),hR);
 958    AH2 mn4G=min(AMin3H2(bG,dG,fG),hG);
 959    AH2 mn4B=min(AMin3H2(bB,dB,fB),hB);
 960    AH2 mx4R=max(AMax3H2(bR,dR,fR),hR);
 961    AH2 mx4G=max(AMax3H2(bG,dG,fG),hG);
 962    AH2 mx4B=max(AMax3H2(bB,dB,fB),hB);
 963    // Immediate constants for peak range.
 964    AH2 peakC=AH2(1.0,-1.0*4.0);
 965    // Limiters, these need to be high precision RCPs.
 966    AH2 hitMinR=min(mn4R,eR)*ARcpH2(AH2_(4.0)*mx4R);
 967    AH2 hitMinG=min(mn4G,eG)*ARcpH2(AH2_(4.0)*mx4G);
 968    AH2 hitMinB=min(mn4B,eB)*ARcpH2(AH2_(4.0)*mx4B);
 969    AH2 hitMaxR=(peakC.x-max(mx4R,eR))*ARcpH2(AH2_(4.0)*mn4R+peakC.y);
 970    AH2 hitMaxG=(peakC.x-max(mx4G,eG))*ARcpH2(AH2_(4.0)*mn4G+peakC.y);
 971    AH2 hitMaxB=(peakC.x-max(mx4B,eB))*ARcpH2(AH2_(4.0)*mn4B+peakC.y);
 972    AH2 lobeR=max(-hitMinR,hitMaxR);
 973    AH2 lobeG=max(-hitMinG,hitMaxG);
 974    AH2 lobeB=max(-hitMinB,hitMaxB);
 975    AH2 lobe=max(AH2_(-FSR_RCAS_LIMIT),min(AMax3H2(lobeR,lobeG,lobeB),AH2_(0.0)))*AH2_(AH2_AU1(con.y).x);
 976    // Apply noise removal.
 977    #ifdef FSR_RCAS_DENOISE
 978     lobe*=nz;
 979    #endif
 980    // Resolve, which needs the medium precision rcp approximation to avoid visible tonality changes.
 981    AH2 rcpL=APrxMedRcpH2(AH2_(4.0)*lobe+AH2_(1.0));
 982    pixR=(lobe*bR+lobe*dR+lobe*hR+lobe*fR+eR)*rcpL;
 983    pixG=(lobe*bG+lobe*dG+lobe*hG+lobe*fG+eG)*rcpL;
 984    pixB=(lobe*bB+lobe*dB+lobe*hB+lobe*fB+eB)*rcpL;}
 985  #endif
 986  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 987  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 988  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 989  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 990  //_____________________________________________________________/\_______________________________________________________________
 991  //==============================================================================================================================
 992  //
 993  //                                          FSR - [LFGA] LINEAR FILM GRAIN APPLICATOR
 994  //
 995  //------------------------------------------------------------------------------------------------------------------------------
 996  // Adding output-resolution film grain after scaling is a good way to mask both rendering and scaling artifacts.
 997  // Suggest using tiled blue noise as film grain input, with peak noise frequency set for a specific look and feel.
 998  // The 'Lfga*()' functions provide a convenient way to introduce grain.
 999  // These functions limit grain based on distance to signal limits.
1000  // This is done so that the grain is temporally energy preserving, and thus won't modify image tonality.
1001  // Grain application should be done in a linear colorspace.
1002  // The grain should be temporally changing, but have a temporal sum per pixel that adds to zero (non-biased).
1003  //------------------------------------------------------------------------------------------------------------------------------
1004  // Usage,
1005  //   FsrLfga*(
1006  //    color, // In/out linear colorspace color {0 to 1} ranged.
1007  //    grain, // Per pixel grain texture value {-0.5 to 0.5} ranged, input is 3-channel to support colored grain.
1008  //    amount); // Amount of grain (0 to 1} ranged.
1009  //------------------------------------------------------------------------------------------------------------------------------
1010  // Example if grain texture is monochrome: 'FsrLfgaF(color,AF3_(grain),amount)'
1011  //==============================================================================================================================
1012  #if defined(A_GPU)
1013   // Maximum grain is the minimum distance to the signal limit.
1014   void FsrLfgaF(inout AF3 c,AF3 t,AF1 a){c+=(t*AF3_(a))*min(AF3_(1.0)-c,c);}
1015  #endif
1016  //==============================================================================================================================
1017  #if defined(A_GPU)&&defined(A_HALF)
1018   // Half precision version (slower).
1019   void FsrLfgaH(inout AH3 c,AH3 t,AH1 a){c+=(t*AH3_(a))*min(AH3_(1.0)-c,c);}
1020  //------------------------------------------------------------------------------------------------------------------------------
1021   // Packed half precision version (faster).
1022   void FsrLfgaHx2(inout AH2 cR,inout AH2 cG,inout AH2 cB,AH2 tR,AH2 tG,AH2 tB,AH1 a){
1023    cR+=(tR*AH2_(a))*min(AH2_(1.0)-cR,cR);cG+=(tG*AH2_(a))*min(AH2_(1.0)-cG,cG);cB+=(tB*AH2_(a))*min(AH2_(1.0)-cB,cB);}
1024  #endif
1025  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1026  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1027  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1028  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1029  //_____________________________________________________________/\_______________________________________________________________
1030  //==============================================================================================================================
1031  //
1032  //                                          FSR - [SRTM] SIMPLE REVERSIBLE TONE-MAPPER
1033  //
1034  //------------------------------------------------------------------------------------------------------------------------------
1035  // This provides a way to take linear HDR color {0 to FP16_MAX} and convert it into a temporary {0 to 1} ranged post-tonemapped linear.
1036  // The tonemapper preserves RGB ratio, which helps maintain HDR color bleed during filtering.
1037  //------------------------------------------------------------------------------------------------------------------------------
1038  // Reversible tonemapper usage,
1039  //  FsrSrtm*(color); // {0 to FP16_MAX} converted to {0 to 1}.
1040  //  FsrSrtmInv*(color); // {0 to 1} converted into {0 to 32768, output peak safe for FP16}.
1041  //==============================================================================================================================
1042  #if defined(A_GPU)
1043   void FsrSrtmF(inout AF3 c){c*=AF3_(ARcpF1(AMax3F1(c.r,c.g,c.b)+AF1_(1.0)));}
1044   // The extra max solves the c=1.0 case (which is a /0).
1045   void FsrSrtmInvF(inout AF3 c){c*=AF3_(ARcpF1(max(AF1_(1.0/32768.0),AF1_(1.0)-AMax3F1(c.r,c.g,c.b))));}
1046  #endif
1047  //==============================================================================================================================
1048  #if defined(A_GPU)&&defined(A_HALF)
1049   void FsrSrtmH(inout AH3 c){c*=AH3_(ARcpH1(AMax3H1(c.r,c.g,c.b)+AH1_(1.0)));}
1050   void FsrSrtmInvH(inout AH3 c){c*=AH3_(ARcpH1(max(AH1_(1.0/32768.0),AH1_(1.0)-AMax3H1(c.r,c.g,c.b))));}
1051  //------------------------------------------------------------------------------------------------------------------------------
1052   void FsrSrtmHx2(inout AH2 cR,inout AH2 cG,inout AH2 cB){
1053    AH2 rcp=ARcpH2(AMax3H2(cR,cG,cB)+AH2_(1.0));cR*=rcp;cG*=rcp;cB*=rcp;}
1054   void FsrSrtmInvHx2(inout AH2 cR,inout AH2 cG,inout AH2 cB){
1055    AH2 rcp=ARcpH2(max(AH2_(1.0/32768.0),AH2_(1.0)-AMax3H2(cR,cG,cB)));cR*=rcp;cG*=rcp;cB*=rcp;}
1056  #endif
1057  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1058  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1059  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1060  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
1061  //_____________________________________________________________/\_______________________________________________________________
1062  //==============================================================================================================================
1063  //
1064  //                                       FSR - [TEPD] TEMPORAL ENERGY PRESERVING DITHER
1065  //
1066  //------------------------------------------------------------------------------------------------------------------------------
1067  // Temporally energy preserving dithered {0 to 1} linear to gamma 2.0 conversion.
1068  // Gamma 2.0 is used so that the conversion back to linear is just to square the color.
1069  // The conversion comes in 8-bit and 10-bit modes, designed for output to 8-bit UNORM or 10:10:10:2 respectively.
1070  // Given good non-biased temporal blue noise as dither input,
1071  // the output dither will temporally conserve energy.
1072  // This is done by choosing the linear nearest step point instead of perceptual nearest.
1073  // See code below for details.
1074  //------------------------------------------------------------------------------------------------------------------------------
1075  // DX SPEC RULES FOR FLOAT->UNORM 8-BIT CONVERSION
1076  // ===============================================
1077  // - Output is 'uint(floor(saturate(n)*255.0+0.5))'.
1078  // - Thus rounding is to nearest.
1079  // - NaN gets converted to zero.
1080  // - INF is clamped to {0.0 to 1.0}.
1081  //==============================================================================================================================
1082  #if defined(A_GPU)
1083   // Hand tuned integer position to dither value, with more values than simple checkerboard.
1084   // Only 32-bit has enough precision for this compddation.
1085   // Output is {0 to <1}.
1086   AF1 FsrTepdDitF(AU2 p,AU1 f){
1087    AF1 x=AF1_(p.x+f);
1088    AF1 y=AF1_(p.y);
1089    // The 1.61803 golden ratio.
1090    AF1 a=AF1_((1.0+sqrt(5.0))/2.0);
1091    // Number designed to provide a good visual pattern.
1092    AF1 b=AF1_(1.0/3.69);
1093    x=x*a+(y*b);
1094    return AFractF1(x);}
1095  //------------------------------------------------------------------------------------------------------------------------------
1096   // This version is 8-bit gamma 2.0.
1097   // The 'c' input is {0 to 1}.
1098   // Output is {0 to 1} ready for image store.
1099   void FsrTepdC8F(inout AF3 c,AF1 dit){
1100    AF3 n=sqrt(c);
1101    n=floor(n*AF3_(255.0))*AF3_(1.0/255.0);
1102    AF3 a=n*n;
1103    AF3 b=n+AF3_(1.0/255.0);b=b*b;
1104    // Ratio of 'a' to 'b' required to produce 'c'.
1105    // APrxLoRcpF1() won't work here (at least for very high dynamic ranges).
1106    // APrxMedRcpF1() is an IADD,FMA,MUL.
1107    AF3 r=(c-b)*APrxMedRcpF3(a-b);
1108    // Use the ratio as a cutoff to choose 'a' or 'b'.
1109    // AGtZeroF1() is a MUL.
1110    c=ASatF3(n+AGtZeroF3(AF3_(dit)-r)*AF3_(1.0/255.0));}
1111  //------------------------------------------------------------------------------------------------------------------------------
1112   // This version is 10-bit gamma 2.0.
1113   // The 'c' input is {0 to 1}.
1114   // Output is {0 to 1} ready for image store.
1115   void FsrTepdC10F(inout AF3 c,AF1 dit){
1116    AF3 n=sqrt(c);
1117    n=floor(n*AF3_(1023.0))*AF3_(1.0/1023.0);
1118    AF3 a=n*n;
1119    AF3 b=n+AF3_(1.0/1023.0);b=b*b;
1120    AF3 r=(c-b)*APrxMedRcpF3(a-b);
1121    c=ASatF3(n+AGtZeroF3(AF3_(dit)-r)*AF3_(1.0/1023.0));}
1122  #endif
1123  //==============================================================================================================================
1124  #if defined(A_GPU)&&defined(A_HALF)
1125   AH1 FsrTepdDitH(AU2 p,AU1 f){
1126    AF1 x=AF1_(p.x+f);
1127    AF1 y=AF1_(p.y);
1128    AF1 a=AF1_((1.0+sqrt(5.0))/2.0);
1129    AF1 b=AF1_(1.0/3.69);
1130    x=x*a+(y*b);
1131    return AH1(AFractF1(x));}
1132  //------------------------------------------------------------------------------------------------------------------------------
1133   void FsrTepdC8H(inout AH3 c,AH1 dit){
1134    AH3 n=sqrt(c);
1135    n=floor(n*AH3_(255.0))*AH3_(1.0/255.0);
1136    AH3 a=n*n;
1137    AH3 b=n+AH3_(1.0/255.0);b=b*b;
1138    AH3 r=(c-b)*APrxMedRcpH3(a-b);
1139    c=ASatH3(n+AGtZeroH3(AH3_(dit)-r)*AH3_(1.0/255.0));}
1140  //------------------------------------------------------------------------------------------------------------------------------
1141   void FsrTepdC10H(inout AH3 c,AH1 dit){
1142    AH3 n=sqrt(c);
1143    n=floor(n*AH3_(1023.0))*AH3_(1.0/1023.0);
1144    AH3 a=n*n;
1145    AH3 b=n+AH3_(1.0/1023.0);b=b*b;
1146    AH3 r=(c-b)*APrxMedRcpH3(a-b);
1147    c=ASatH3(n+AGtZeroH3(AH3_(dit)-r)*AH3_(1.0/1023.0));}
1148  //==============================================================================================================================
1149   // This computes dither for positions 'p' and 'p+{8,0}'.
1150   AH2 FsrTepdDitHx2(AU2 p,AU1 f){
1151    AF2 x;
1152    x.x=AF1_(p.x+f);
1153    x.y=x.x+AF1_(8.0);
1154    AF1 y=AF1_(p.y);
1155    AF1 a=AF1_((1.0+sqrt(5.0))/2.0);
1156    AF1 b=AF1_(1.0/3.69);
1157    x=x*AF2_(a)+AF2_(y*b);
1158    return AH2(AFractF2(x));}
1159  //------------------------------------------------------------------------------------------------------------------------------
1160   void FsrTepdC8Hx2(inout AH2 cR,inout AH2 cG,inout AH2 cB,AH2 dit){
1161    AH2 nR=sqrt(cR);
1162    AH2 nG=sqrt(cG);
1163    AH2 nB=sqrt(cB);
1164    nR=floor(nR*AH2_(255.0))*AH2_(1.0/255.0);
1165    nG=floor(nG*AH2_(255.0))*AH2_(1.0/255.0);
1166    nB=floor(nB*AH2_(255.0))*AH2_(1.0/255.0);
1167    AH2 aR=nR*nR;
1168    AH2 aG=nG*nG;
1169    AH2 aB=nB*nB;
1170    AH2 bR=nR+AH2_(1.0/255.0);bR=bR*bR;
1171    AH2 bG=nG+AH2_(1.0/255.0);bG=bG*bG;
1172    AH2 bB=nB+AH2_(1.0/255.0);bB=bB*bB;
1173    AH2 rR=(cR-bR)*APrxMedRcpH2(aR-bR);
1174    AH2 rG=(cG-bG)*APrxMedRcpH2(aG-bG);
1175    AH2 rB=(cB-bB)*APrxMedRcpH2(aB-bB);
1176    cR=ASatH2(nR+AGtZeroH2(dit-rR)*AH2_(1.0/255.0));
1177    cG=ASatH2(nG+AGtZeroH2(dit-rG)*AH2_(1.0/255.0));
1178    cB=ASatH2(nB+AGtZeroH2(dit-rB)*AH2_(1.0/255.0));}
1179  //------------------------------------------------------------------------------------------------------------------------------
1180   void FsrTepdC10Hx2(inout AH2 cR,inout AH2 cG,inout AH2 cB,AH2 dit){
1181    AH2 nR=sqrt(cR);
1182    AH2 nG=sqrt(cG);
1183    AH2 nB=sqrt(cB);
1184    nR=floor(nR*AH2_(1023.0))*AH2_(1.0/1023.0);
1185    nG=floor(nG*AH2_(1023.0))*AH2_(1.0/1023.0);
1186    nB=floor(nB*AH2_(1023.0))*AH2_(1.0/1023.0);
1187    AH2 aR=nR*nR;
1188    AH2 aG=nG*nG;
1189    AH2 aB=nB*nB;
1190    AH2 bR=nR+AH2_(1.0/1023.0);bR=bR*bR;
1191    AH2 bG=nG+AH2_(1.0/1023.0);bG=bG*bG;
1192    AH2 bB=nB+AH2_(1.0/1023.0);bB=bB*bB;
1193    AH2 rR=(cR-bR)*APrxMedRcpH2(aR-bR);
1194    AH2 rG=(cG-bG)*APrxMedRcpH2(aG-bG);
1195    AH2 rB=(cB-bB)*APrxMedRcpH2(aB-bB);
1196    cR=ASatH2(nR+AGtZeroH2(dit-rR)*AH2_(1.0/1023.0));
1197    cG=ASatH2(nG+AGtZeroH2(dit-rG)*AH2_(1.0/1023.0));
1198    cB=ASatH2(nB+AGtZeroH2(dit-rB)*AH2_(1.0/1023.0));}
1199  #endif