[babl] extensions/float: add ~ variants of conversions

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 4ea6b4ceace8a83e41080d124511c78f2c78417c
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Jul 12 01:22:35 2018 +0200

    extensions/float: add ~ variants of conversions

 extensions/float.c | 219 ++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 193 insertions(+), 26 deletions(-)
---
diff --git a/extensions/float.c b/extensions/float.c
index 4012366..bce0de7 100644
--- a/extensions/float.c
+++ b/extensions/float.c
@@ -26,8 +26,10 @@
 #include "extensions/util.h"
 #include "base/util.h"
 
+static const Babl *trc_srgb = NULL;
+
 static void
-conv_rgbaF_linear_rgbAF_gamma (const Babl *conversion,unsigned char *src,
+conv_rgbaF_linear_rgbAF_nonlinear (const Babl *conversion,unsigned char *src,
                                unsigned char *dst,
                                long           samples)
 {
@@ -49,10 +51,30 @@ conv_rgbaF_linear_rgbAF_gamma (const Babl *conversion,unsigned char *src,
 }
 
 static void
-conv_rgbAF_linear_rgbAF_gamma (const Babl    *conversion,
-                               unsigned char *src,
-                               unsigned char *dst,
-                               long           samples)
+conv_rgbaF_linear_rgbAF_perceptual (const Babl *conversion,unsigned char *src,
+                                    unsigned char *dst,
+                                    long           samples)
+{
+   float *fsrc = (float *) src;
+   float *fdst = (float *) dst;
+   int n = samples;
+
+   while (n--)
+     {
+       float alpha = fsrc[3];
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * alpha;
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * alpha;
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * alpha;
+       *fdst++ = *fsrc++;
+     }
+}
+
+
+static void
+conv_rgbAF_linear_rgbAF_nonlinear (const Babl    *conversion,
+                                   unsigned char *src,
+                                   unsigned char *dst,
+                                   long           samples)
 {
    const Babl  *space = babl_conversion_get_destination_space (conversion);
    const Babl **trc   = (void*)space->space.trc;
@@ -91,9 +113,50 @@ conv_rgbAF_linear_rgbAF_gamma (const Babl    *conversion,
 }
 
 static void
-conv_rgbaF_linear_rgbaF_gamma (const Babl *conversion,unsigned char *src, 
-                               unsigned char *dst, 
-                               long           samples)
+conv_rgbAF_linear_rgbAF_perceptual (const Babl    *conversion,
+                                    unsigned char *src,
+                                    unsigned char *dst,
+                                    long           samples)
+{
+
+   float *fsrc = (float *) src;
+   float *fdst = (float *) dst;
+   int n = samples;
+
+   while (n--)
+     {
+       float alpha = fsrc[3];
+       if (alpha < BABL_ALPHA_THRESHOLD)
+         {
+           *fdst++ = 0.0;
+           *fdst++ = 0.0;
+           *fdst++ = 0.0;
+           *fdst++ = 0.0;
+           fsrc+=4;
+         }
+       else if (alpha >= 1.0)
+         {
+           *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * alpha;
+           *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * alpha;
+           *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * alpha;
+           *fdst++ = *fsrc++;
+         }
+       else
+         {
+           float alpha_recip = 1.0 / alpha;
+           *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++ * alpha_recip) * alpha;
+           *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++ * alpha_recip) * alpha;
+           *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++ * alpha_recip) * alpha;
+           *fdst++ = *fsrc++;
+         }
+     }
+}
+
+
+static void
+conv_rgbaF_linear_rgbaF_nonlinear (const Babl *conversion,unsigned char *src, 
+                                   unsigned char *dst, 
+                                   long           samples)
 {
    const Babl  *space = babl_conversion_get_destination_space (conversion);
    const Babl **trc   = (void*)space->space.trc;
@@ -112,9 +175,28 @@ conv_rgbaF_linear_rgbaF_gamma (const Babl *conversion,unsigned char *src,
 }
 
 static void
-conv_rgbF_linear_rgbF_gamma (const Babl *conversion,unsigned char *src, 
-                             unsigned char *dst, 
-                             long           samples)
+conv_rgbaF_linear_rgbaF_perceptual (const Babl *conversion,unsigned char *src, 
+                                    unsigned char *dst, 
+                                    long           samples)
+{
+   float *fsrc = (float *) src;
+   float *fdst = (float *) dst;
+   int n = samples;
+
+   while (n--)
+     {
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++);
+       *fdst++ = *fsrc++;
+     }
+}
+
+
+static void
+conv_rgbF_linear_rgbF_nonlinear (const Babl *conversion,unsigned char *src,
+                                 unsigned char *dst,
+                                 long           samples)
 {
    const Babl  *space = babl_conversion_get_destination_space (conversion);
    const Babl **trc   = (void*)space->space.trc;
@@ -130,11 +212,28 @@ conv_rgbF_linear_rgbF_gamma (const Babl *conversion,unsigned char *src,
      }
 }
 
+static void
+conv_rgbF_linear_rgbF_perceptual (const Babl *conversion,unsigned char *src,
+                                  unsigned char *dst,
+                                  long           samples)
+{
+   float *fsrc = (float *) src;
+   float *fdst = (float *) dst;
+   int n = samples;
+
+   while (n--)
+     {
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++);
+     }
+}
+
 
 static void
-conv_rgbaF_gamma_rgbaF_linear (const Babl *conversion,unsigned char *src, 
-                               unsigned char *dst, 
-                               long           samples)
+conv_rgbaF_nonlinear_rgbaF_linear (const Babl *conversion,unsigned char *src,
+                                   unsigned char *dst,
+                                   long           samples)
 {
    const Babl  *space = babl_conversion_get_destination_space (conversion);
    const Babl **trc   = (void*)space->space.trc;
@@ -152,9 +251,28 @@ conv_rgbaF_gamma_rgbaF_linear (const Babl *conversion,unsigned char *src,
 }
 
 static void
-conv_rgbF_gamma_rgbF_linear (const Babl *conversion,unsigned char *src, 
-                             unsigned char *dst, 
-                             long           samples)
+conv_rgbaF_perceptual_rgbaF_linear (const Babl *conversion,unsigned char *src,
+                                    unsigned char *dst,
+                                    long           samples)
+{
+   float *fsrc = (float *) src;
+   float *fdst = (float *) dst;
+   int n = samples;
+
+   while (n--)
+     {
+       *fdst++ = babl_trc_to_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_to_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_to_linear (trc_srgb, *fsrc++);
+       *fdst++ = *fsrc++;
+     }
+}
+
+
+static void
+conv_rgbF_nonlinear_rgbF_linear (const Babl *conversion,unsigned char *src,
+                                 unsigned char *dst,
+                                 long           samples)
 {
    const Babl  *space = babl_conversion_get_destination_space (conversion);
    const Babl **trc   = (void*)space->space.trc;
@@ -170,6 +288,24 @@ conv_rgbF_gamma_rgbF_linear (const Babl *conversion,unsigned char *src,
      }
 }
 
+static void
+conv_rgbF_perceptual_rgbF_linear (const Babl *conversion,unsigned char *src,
+                                  unsigned char *dst,
+                                  long           samples)
+{
+   float *fsrc = (float *) src;
+   float *fdst = (float *) dst;
+   int n = samples;
+
+   while (n--)
+     {
+       *fdst++ = babl_trc_to_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_to_linear (trc_srgb, *fsrc++);
+       *fdst++ = babl_trc_to_linear (trc_srgb, *fsrc++);
+     }
+}
+
+
 #define o(src, dst) \
   babl_conversion_new (src, dst, "linear", conv_ ## src ## _ ## dst, NULL)
 
@@ -194,7 +330,7 @@ init (void)
     babl_component ("Ba"),
     babl_component ("A"),
     NULL);
-  const Babl *rgbaF_gamma = babl_format_new (
+  const Babl *rgbaF_nonlinear = babl_format_new (
     babl_model ("R'G'B'A"),
     babl_type ("float"),
     babl_component ("R'"),
@@ -202,7 +338,15 @@ init (void)
     babl_component ("B'"),
     babl_component ("A"),
     NULL);
-  const Babl *rgbAF_gamma = babl_format_new (
+  const Babl *rgbaF_perceptual = babl_format_new (
+    babl_model ("R~G~B~A"),
+    babl_type ("float"),
+    babl_component ("R~"),
+    babl_component ("G~"),
+    babl_component ("B~"),
+    babl_component ("A"),
+    NULL);
+  const Babl *rgbAF_nonlinear = babl_format_new (
     babl_model ("R'aG'aB'aA"),
     babl_type ("float"),
     babl_component ("R'a"),
@@ -210,6 +354,14 @@ init (void)
     babl_component ("B'a"),
     babl_component ("A"),
     NULL);
+  const Babl *rgbAF_perceptual = babl_format_new (
+    babl_model ("R~aG~aB~aA"),
+    babl_type ("float"),
+    babl_component ("R~a"),
+    babl_component ("G~a"),
+    babl_component ("B~a"),
+    babl_component ("A"),
+    NULL);
   const Babl *rgbF_linear = babl_format_new (
     babl_model ("RGB"),
     babl_type ("float"),
@@ -217,20 +369,35 @@ init (void)
     babl_component ("G"),
     babl_component ("B"),
     NULL);
-  const Babl *rgbF_gamma = babl_format_new (
+  const Babl *rgbF_nonlinear = babl_format_new (
     babl_model ("R'G'B'"),
     babl_type ("float"),
     babl_component ("R'"),
     babl_component ("G'"),
     babl_component ("B'"),
     NULL);
+  const Babl *rgbF_perceptual = babl_format_new (
+    babl_model ("R~G~B~"),
+    babl_type ("float"),
+    babl_component ("R~"),
+    babl_component ("G~"),
+    babl_component ("B~"),
+    NULL);
+  trc_srgb = babl_trc("sRGB");
+
+  o (rgbAF_linear, rgbAF_nonlinear);
+  o (rgbaF_linear, rgbAF_nonlinear);
+  o (rgbaF_linear, rgbaF_nonlinear);
+  o (rgbaF_nonlinear,  rgbaF_linear);
+  o (rgbF_linear, rgbF_nonlinear);
+  o (rgbF_nonlinear,  rgbF_linear);
 
-  o (rgbAF_linear, rgbAF_gamma);
-  o (rgbaF_linear, rgbAF_gamma);
-  o (rgbaF_linear, rgbaF_gamma);
-  o (rgbaF_gamma,  rgbaF_linear);
-  o (rgbF_linear, rgbF_gamma);
-  o (rgbF_gamma,  rgbF_linear);
+  o (rgbAF_linear, rgbAF_perceptual);
+  o (rgbaF_linear, rgbAF_perceptual);
+  o (rgbaF_linear, rgbaF_perceptual);
+  o (rgbaF_perceptual,  rgbaF_linear);
+  o (rgbF_linear, rgbF_perceptual);
+  o (rgbF_perceptual,  rgbF_linear);
 
   return 0;
 }