From 5e5e1f6c598e7ee29846563874900ae3d0810149 Mon Sep 17 00:00:00 2001
From: jaspervdg <jaspervdg@users.sourceforge.net>
Date: Mon, 22 Dec 2008 17:19:13 +0000
Subject: [PATCH] Some accuracy improvements for nr-filter-colormatrix
 (including some changes to let it use premultiplied colors if possible) +
 author entry I forgot to add in revision 20391.

---
 src/display/nr-filter-colormatrix.cpp        | 156 ++++++++++++-------
 src/display/nr-filter-component-transfer.cpp |   1 +
 2 files changed, 100 insertions(+), 57 deletions(-)

diff --git a/src/display/nr-filter-colormatrix.cpp b/src/display/nr-filter-colormatrix.cpp
index 10181a16e..e640ce4fb 100644
--- a/src/display/nr-filter-colormatrix.cpp
+++ b/src/display/nr-filter-colormatrix.cpp
@@ -3,6 +3,7 @@
  *
  * Authors:
  *   Felipe Corrêa da Silva Sanches <felipe.sanches@gmail.com>
+ *   Jasper van de Gronde <th.v.d.gronde@hccnet.nl>
  *
  * Copyright (C) 2007 authors
  *
@@ -37,17 +38,28 @@ int FilterColorMatrix::render(FilterSlot &slot, FilterUnits const &/*units*/) {
 
     NRPixBlock *out = new NRPixBlock;
 
-    nr_pixblock_setup_fast(out, NR_PIXBLOCK_MODE_R8G8B8A8N,
-                           in->area.x0, in->area.y0, in->area.x1, in->area.y1,
-                           true);
+    bool premultiplied;
+    if ((type==COLORMATRIX_SATURATE || type==COLORMATRIX_HUEROTATE) && in->mode != NR_PIXBLOCK_MODE_R8G8B8A8N) {
+        // saturate and hueRotate do not touch the alpha channel and are linear (per-pixel) operations, so no premultiplied -> non-premultiplied operation is necessary
+        nr_pixblock_setup_fast(out, NR_PIXBLOCK_MODE_R8G8B8A8P,
+                               in->area.x0, in->area.y0, in->area.x1, in->area.y1,
+                               true);
+        premultiplied = true;
+    } else {
+        nr_pixblock_setup_fast(out, NR_PIXBLOCK_MODE_R8G8B8A8N,
+                               in->area.x0, in->area.y0, in->area.x1, in->area.y1,
+                               true);
+        premultiplied = false;
+    }
 
     // this primitive is defined for non-premultiplied RGBA values,
     // thus convert them to that format
+    //   However, since not all operations care, the input is only transformed if necessary.
     bool free_in_on_exit = false;
-    if (in->mode != NR_PIXBLOCK_MODE_R8G8B8A8N) {
+    if (in->mode != out->mode) {
         NRPixBlock *original_in = in;
         in = new NRPixBlock;
-        nr_pixblock_setup_fast(in, NR_PIXBLOCK_MODE_R8G8B8A8N,
+        nr_pixblock_setup_fast(in, out->mode,
                                original_in->area.x0, original_in->area.y0,
                                original_in->area.x1, original_in->area.y1,
                                true);
@@ -59,7 +71,6 @@ int FilterColorMatrix::render(FilterSlot &slot, FilterUnits const &/*units*/) {
     unsigned char *out_data = NR_PIXBLOCK_PX(out);
     unsigned char r,g,b,a;
     int x,y,x0,y0,x1,y1,i;
-    double a00,a01,a02,a10,a11,a12,a20,a21,a22, coshue, sinhue;
     x0=in->area.x0;
     y0=in->area.y0;
     x1=in->area.x1;
@@ -67,64 +78,95 @@ int FilterColorMatrix::render(FilterSlot &slot, FilterUnits const &/*units*/) {
 
     switch(type){
         case COLORMATRIX_MATRIX:
-            if (values.size()!=20) {
-                g_warning("ColorMatrix: values parameter error. Wrong size: %i.", static_cast<int>(values.size()));
-                return -1;
-            }
-            for (x=x0;x<x1;x++){
-                for (y=y0;y<y1;y++){
-                    i = ((x-x0) + (x1-x0)*(y-y0))*4;
-                    r = in_data[i];
-                    g = in_data[i+1];
-                    b = in_data[i+2];
-                    a = in_data[i+3];
-                    out_data[i] = CLAMP_D_TO_U8( r*values[0] + g*values[1] + b*values[2] + a*values[3] + 255*values[4] );
-                    out_data[i+1] = CLAMP_D_TO_U8( r*values[5] + g*values[6] + b*values[7] + a*values[8] + 255*values[9] );
-                    out_data[i+2] = CLAMP_D_TO_U8( r*values[10] + g*values[11] + b*values[12] + a*values[13] + 255*values[14] );
-                    out_data[i+3] = CLAMP_D_TO_U8( r*values[15] + g*values[16] + b*values[17] + a*values[18] + 255*values[19] );
+            {
+                if (values.size()!=20) {
+                    g_warning("ColorMatrix: values parameter error. Wrong size: %i.", static_cast<int>(values.size()));
+                    return -1;
+                }
+                double a04 = 255*values[4] + .5;
+                double a14 = 255*values[9] + .5;
+                double a24 = 255*values[14] + .5;
+                double a34 = 255*values[19] + .5;
+                for (x=x0;x<x1;x++){
+                    for (y=y0;y<y1;y++){
+                        i = ((x-x0) + (x1-x0)*(y-y0))*4;
+                        r = in_data[i];
+                        g = in_data[i+1];
+                        b = in_data[i+2];
+                        a = in_data[i+3];
+                        out_data[i] = CLAMP_D_TO_U8( r*values[0] + g*values[1] + b*values[2] + a*values[3] + a04 );
+                        out_data[i+1] = CLAMP_D_TO_U8( r*values[5] + g*values[6] + b*values[7] + a*values[8] + a14 );
+                        out_data[i+2] = CLAMP_D_TO_U8( r*values[10] + g*values[11] + b*values[12] + a*values[13] + a24 );
+                        out_data[i+3] = CLAMP_D_TO_U8( r*values[15] + g*values[16] + b*values[17] + a*values[18] + a34 );
+                    }
                 }
             }
             break;
         case COLORMATRIX_SATURATE:
-            for (x=x0;x<x1;x++){
-                for (y=y0;y<y1;y++){
-                    i = ((x-x0) + (x1-x0)*(y-y0))*4;
-                    r = in_data[i];
-                    g = in_data[i+1];
-                    b = in_data[i+2];
-                    a = in_data[i+3];
-                    out_data[i] = CLAMP_D_TO_U8( r*(0.213+0.787*value) + g*(0.715-0.715*value) + b*(0.072-0.072*value) );
-                    out_data[i+1] = CLAMP_D_TO_U8( r*(0.213-0.213*value) + g*(0.715+0.285*value) + b*(0.072-0.072*value) );
-                    out_data[i+2] = CLAMP_D_TO_U8( r*(0.213-0.213*value) + g*(0.715-0.715*value) + b*(0.072+0.928*value) );
-                    out_data[i+3] = a;
+            {
+                double v = std::max(0.0,std::min(1.0,value)); // The standard says it should be between 0 and 1, and clamping it here makes it unnecessary to clamp the color values.
+                double a00 = 0.213+0.787*v, a01 = 0.715-0.715*v, a02 = 0.072-0.072*v;
+                double a10 = 0.213-0.213*v, a11 = 0.715+0.285*v, a12 = 0.072-0.072*v;
+                double a20 = 0.213-0.213*v, a21 = 0.715-0.715*v, a22 = 0.072+0.928*v;
+                for (x=x0;x<x1;x++){
+                    for (y=y0;y<y1;y++){
+                        i = ((x-x0) + (x1-x0)*(y-y0))*4;
+                        r = in_data[i];
+                        g = in_data[i+1];
+                        b = in_data[i+2];
+                        a = in_data[i+3];
+                        out_data[i]   = static_cast<unsigned char>( r*a00 + g*a01 + b*a02 + .5 );
+                        out_data[i+1] = static_cast<unsigned char>( r*a10 + g*a11 + b*a12 + .5 );
+                        out_data[i+2] = static_cast<unsigned char>( r*a20 + g*a21 + b*a22 + .5 );
+                        out_data[i+3] = a;
+                    }
                 }
             }
             break;
         case COLORMATRIX_HUEROTATE:
-            coshue = cos(value * M_PI/180.0);
-            sinhue = sin(value * M_PI/180.0);
-            a00 = 0.213 + coshue*( 0.787) + sinhue*(-0.213);
-            a01 = 0.715 + coshue*(-0.715) + sinhue*(-0.715);
-            a02 = 0.072 + coshue*(-0.072) + sinhue*( 0.928);
-            a10 = 0.213 + coshue*(-0.213) + sinhue*( 0.143);
-            a11 = 0.715 + coshue*( 0.285) + sinhue*( 0.140);
-            a12 = 0.072 + coshue*(-0.072) + sinhue*(-0.283);
-            a20 = 0.213 + coshue*(-0.213) + sinhue*(-0.787);
-            a21 = 0.715 + coshue*(-0.715) + sinhue*( 0.715);
-            a22 = 0.072 + coshue*( 0.928) + sinhue*( 0.072);
-
-            for (x=x0;x<x1;x++){
-                for (y=y0;y<y1;y++){
-                    i = ((x-x0) + (x1-x0)*(y-y0))*4;
-                    r = in_data[i];
-                    g = in_data[i+1];
-                    b = in_data[i+2];
-                    a = in_data[i+3];
-
-                    out_data[i] = CLAMP_D_TO_U8( r*a00 + g*a01 + b*a02 );
-                    out_data[i+1] = CLAMP_D_TO_U8( r*a10 + g*a11 + b*a12 );
-                    out_data[i+2] = CLAMP_D_TO_U8( r*a20 + g*a21 + b*a22 );
-                    out_data[i+3] = a;
+            {
+                double coshue = cos(value * M_PI/180.0);
+                double sinhue = sin(value * M_PI/180.0);
+                double a00 = 0.213 + coshue*( 0.787) + sinhue*(-0.213);
+                double a01 = 0.715 + coshue*(-0.715) + sinhue*(-0.715);
+                double a02 = 0.072 + coshue*(-0.072) + sinhue*( 0.928);
+                double a10 = 0.213 + coshue*(-0.213) + sinhue*( 0.143);
+                double a11 = 0.715 + coshue*( 0.285) + sinhue*( 0.140);
+                double a12 = 0.072 + coshue*(-0.072) + sinhue*(-0.283);
+                double a20 = 0.213 + coshue*(-0.213) + sinhue*(-0.787);
+                double a21 = 0.715 + coshue*(-0.715) + sinhue*( 0.715);
+                double a22 = 0.072 + coshue*( 0.928) + sinhue*( 0.072);
+                if (premultiplied) {
+                    // Although it does not change the alpha channel, it can give "out-of-bound" results, and in this case the bound is determined by the alpha channel
+                    for (x=x0;x<x1;x++){
+                        for (y=y0;y<y1;y++){
+                            i = ((x-x0) + (x1-x0)*(y-y0))*4;
+                            r = in_data[i];
+                            g = in_data[i+1];
+                            b = in_data[i+2];
+                            a = in_data[i+3];
+
+                            out_data[i]   = static_cast<unsigned char>(std::max(0.0,std::min((double)a, r*a00 + g*a01 + b*a02 + .5 )));
+                            out_data[i+1] = static_cast<unsigned char>(std::max(0.0,std::min((double)a, r*a10 + g*a11 + b*a12 + .5 )));
+                            out_data[i+2] = static_cast<unsigned char>(std::max(0.0,std::min((double)a, r*a20 + g*a21 + b*a22 + .5 )));
+                            out_data[i+3] = a;
+                        }
+                    }
+                } else {
+                    for (x=x0;x<x1;x++){
+                        for (y=y0;y<y1;y++){
+                            i = ((x-x0) + (x1-x0)*(y-y0))*4;
+                            r = in_data[i];
+                            g = in_data[i+1];
+                            b = in_data[i+2];
+                            a = in_data[i+3];
+
+                            out_data[i]   = CLAMP_D_TO_U8( r*a00 + g*a01 + b*a02 + .5 );
+                            out_data[i+1] = CLAMP_D_TO_U8( r*a10 + g*a11 + b*a12 + .5 );
+                            out_data[i+2] = CLAMP_D_TO_U8( r*a20 + g*a21 + b*a22 + .5 );
+                            out_data[i+3] = a;
+                        }
+                    }
                 }
             }
             break;
@@ -138,7 +180,7 @@ int FilterColorMatrix::render(FilterSlot &slot, FilterUnits const &/*units*/) {
                     out_data[i] = 0;
                     out_data[i+1] = 0;
                     out_data[i+2] = 0;
-                    out_data[i+3] = CLAMP_D_TO_U8( r*0.2125 + g*0.7154 + b*0.0721);
+                    out_data[i+3] = static_cast<unsigned char>( r*0.2125 + g*0.7154 + b*0.0721 + .5 );
                 }
             }
             break;
diff --git a/src/display/nr-filter-component-transfer.cpp b/src/display/nr-filter-component-transfer.cpp
index dbf5c44ed..caf053bcf 100644
--- a/src/display/nr-filter-component-transfer.cpp
+++ b/src/display/nr-filter-component-transfer.cpp
@@ -3,6 +3,7 @@
  *
  * Authors:
  *   Felipe Corrêa da Silva Sanches <felipe.sanches@gmail.com>
+ *   Jasper van de Gronde <th.v.d.gronde@hccnet.nl>
  *
  * Copyright (C) 2007 authors
  *
-- 
2.30.2