m + add CIE XYZ support + add libglitter_per_channel_desaturate_{double,float}

Signed-off-by: Mattias Andrée <maandree@kth.se>

8 files changed, 135 insertions, 25 deletions

diff --git a/Makefile b/Makefile
index 7db2755..8714567 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,8 @@ OBJ =\
 	libglitter_free_render_context.o\
 	libglitter_get_colour_space_conversion_matrix_double.o\
 	libglitter_get_colour_space_conversion_matrix_float.o\
+	libglitter_per_channel_desaturate_double.o\
+	libglitter_per_channel_desaturate_float.o\
 	libglitter_split_uint32_raster.o\
 	libglitter_split_uint64_raster.o\
 	libglitter_update_render_context.o
@@ -49,6 +51,7 @@ libglitter_compose_uint32.o: libglitter_compose_uint64.c libglitter_compose_doub
 libglitter_compose_uint64.o: libglitter_compose_double.c
 libglitter_compose_uint8.o: libglitter_compose_uint64.c libglitter_compose_double.c
 libglitter_desaturate_float.o: libglitter_desaturate_double.c
+libglitter_per_channel_desaturate_float.o: libglitter_per_channel_desaturate_double.c
 libglitter_split_uint32_raster.o: libglitter_split_uint64_raster.c
 
 .c.o:
diff --git a/TODO b/TODO
index 549f3cc..4a19051 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,4 @@
 Add colour space conversion
-Add transfer function application function
 Add support for GPU-acceleration
 Add man pages
 Add tests
diff --git a/libglitter.h b/libglitter.h
index 7263ec7..50d451d 100644
--- a/libglitter.h
+++ b/libglitter.h
@@ -212,27 +212,67 @@ void libglitter_split_uint32_raster(uint8_t *[3], uint8_t **, uint32_t *, uint32
  * @param  height      The vertical number of pixels in the rasters
  * @param  saturation  The subpixel rendering saturation, 1 for regular
  *                     subpixel rendering, 0 for greyscale, values
- *                     inbetween for a compromise
+ *                     in between for a compromise
  * @param  primary_ys  The CIE Y value (in e.g. CIE xyY or CIE XYZ) for
  *                     each subpixel colour; or `NULL` for the sRGB values
  *                     (this is only allowed if there are exactly 3 rasters)
  */
-void libglitter_desaturate_double(double **, size_t, size_t, size_t, size_t, size_t, double, const double *);
+void libglitter_desaturate_double(double **, size_t, size_t, size_t, size_t, size_t, double, const double *restrict);
 
 /**
  * This value is identical to `libglitter_desaturate_double`,
  * apart from it parameter types, see `libglitter_desaturate_double`
  * for details about this function
  */
-void libglitter_desaturate_float(float **, size_t, size_t, size_t, size_t, size_t, float, const float *);
+void libglitter_desaturate_float(float **, size_t, size_t, size_t, size_t, size_t, float, const float *restrict);
+
+/**
+ * Transform rasters from fully using subpixel rendering to
+ * balance between subpixel rendering and greyscale antialiasing
+ * 
+ * @param  rasters      Array of rasters, one for each subpixel colour.
+ *                      The function may change the offset for each raster,
+ *                      as such, the given pointer shall not be used anywhere
+ *                      else during the execution of the function and the
+ *                      inner pointers shall be considered undefined after
+ *                      the execution of the function
+ * @param  nrasters     The number of rasters
+ * @param  rowsize      The number of cells in a row in each raster
+ * @param  cellsize     The number of values stored in each raster,
+ *                      between each cell, plus 1 (that is, the number of
+ *                      values per cell)
+ * @param  width        The horizontal number of pixels in the rasters
+ * @param  height       The vertical number of pixels in the rasters
+ * @param  saturations  The subpixel rendering saturation for each raster,
+ *                      1 for regular subpixel rendering, 0 for greyscale,
+ *                      values in between for a compromise
+ * @param  primary_ys   The CIE Y value (in e.g. CIE xyY or CIE XYZ) for
+ *                      each subpixel colour; or `NULL` for the sRGB values
+ *                      (this is only allowed if there are exactly 3 rasters)
+ */
+void libglitter_per_channel_desaturate_double(double **, size_t, size_t, size_t, size_t, size_t,
+                                              const double *restrict, const double *restrict);
+
+/**
+ * This value is identical to `libglitter_per_channel_desaturate_double`,
+ * apart from it parameter types, see `libglitter_per_channel_desaturate_double`
+ * for details about this function
+ */
+void libglitter_per_channel_desaturate_float(float **, size_t, size_t, size_t, size_t, size_t,
+                                             const float *restrict, const float *restrict);
 
 
 /**
  * Get the matrix each pixel shall be multiplied with
  * to convert it from the output's colour space to sRGB
+ * or CIE XYZ
  * 
- * This is useful when the output does not use sRGB,
- * but the application does
+ * This is useful when the output does not use sRGB, or
+ * CIE XYZ, but the application does. If the application
+ * uses some other colour space, this function can output
+ * the conversion matrix for the CIE XYZ colour space,
+ * which can that be right-hand multiplied to get the
+ * conversion matrix for some other colour
  * 
  * @param  matrix   Output buffer for the conversion matrix
  * @param  c1x      The CIE x value (as in CIE xyY) of the output's first primary colour
@@ -244,13 +284,14 @@ void libglitter_desaturate_float(float **, size_t, size_t, size_t, size_t, size_
  * @param  white_x  The CIE x value (as in CIE xyY) of the output's white point
  * @param  white_y  The CIE y value (as in CIE xyY) of the output's white point
  * @param  white_Y  The CIE Y value (as in CIE xyY) of the output's white point, normally 1
+ * @param  xyz      Whether the output conversion matrix should be to CIE XYZ rather the sRGB
  * 
  * `LIBGLITTER_ILLUMINANT_D65` can be input in place of
  * `white_x, white_y, white_Y` (it expands to three arguments)
  * if the output's whitepoint is the D65 illuminant
  */
 void libglitter_get_colour_space_conversion_matrix_double(double[3][3], double, double, double, double,
-                                                          double, double, double, double, double);
+                                                          double, double, double, double, double, int);
 
 /**
  * This value is identical to `libglitter_get_colour_space_conversion_matrix_double`,
@@ -258,7 +299,7 @@ void libglitter_get_colour_space_conversion_matrix_double(double[3][3], double,
  * for details about this function
  */
 void libglitter_get_colour_space_conversion_matrix_float(float[3][3], float, float, float, float,
-                                                         float, float, float, float, float);
+                                                         float, float, float, float, float, int);
 
 
 #endif
diff --git a/libglitter_desaturate_double.c b/libglitter_desaturate_double.c
index 62eaa3a..43fc990 100644
--- a/libglitter_desaturate_double.c
+++ b/libglitter_desaturate_double.c
@@ -9,7 +9,7 @@
 
 void
 libglitter_desaturate_double(double **rasters, size_t nrasters, size_t rowsize, size_t cellsize,
-                             size_t width, size_t height, double saturation, const double *primary_ys)
+                             size_t width, size_t height, double saturation, const double *restrict primary_ys)
 {
 	size_t y, x, ch, raster_y, raster_i;
 	double intensity;
diff --git a/libglitter_get_colour_space_conversion_matrix_double.c b/libglitter_get_colour_space_conversion_matrix_double.c
index fd3ecbc..3ee734d 100644
--- a/libglitter_get_colour_space_conversion_matrix_double.c
+++ b/libglitter_get_colour_space_conversion_matrix_double.c
@@ -48,7 +48,7 @@ invert(double m[3][4])
 void
 libglitter_get_colour_space_conversion_matrix_double(double matrix[3][3], double c1x, double c1y,
                                                      double c2x, double c2y, double c3x, double c3y,
-                                                     double white_x, double white_y, double white_Y)
+                                                     double white_x, double white_y, double white_Y, int xyz)
 {
 	double mat[3][4];
 	double x1, x2, x3;
@@ -74,17 +74,29 @@ libglitter_get_colour_space_conversion_matrix_double(double matrix[3][3], double
 	y3 = mat[2][3];
 
 	/* [[x1, x2, x3], [y1, y2, y3], [z1, z2, z3]] is
-	 * the output RGB-to-CIE XYZ conversion matrix. It
-	 * is multiplied by the CIE XYZ-to-sRGB conversion
-	 * matrix to get the output RGB-to-sRGB conversion
-	 * matrix. */
-	matrix[0][0] = x1 * srgb[0][0] + x2 * srgb[1][0] + x3 * srgb[2][0];
-	matrix[0][1] = x1 * srgb[0][1] + x2 * srgb[1][1] + x3 * srgb[2][1];
-	matrix[0][2] = x1 * srgb[0][2] + x2 * srgb[1][2] + x3 * srgb[2][2];
-	matrix[1][0] = y1 * srgb[0][0] + y2 * srgb[1][0] + y3 * srgb[2][0];
-	matrix[1][1] = y1 * srgb[0][1] + y2 * srgb[1][1] + y3 * srgb[2][1];
-	matrix[1][2] = y1 * srgb[0][2] + y2 * srgb[1][2] + y3 * srgb[2][2];
-	matrix[2][0] = z1 * srgb[0][0] + z2 * srgb[1][0] + z3 * srgb[2][0];
-	matrix[2][1] = z1 * srgb[0][1] + z2 * srgb[1][1] + z3 * srgb[2][1];
-	matrix[2][2] = z1 * srgb[0][2] + z2 * srgb[1][2] + z3 * srgb[2][2];
+	 * the output RGB-to-CIE XYZ conversion matrix.
+	 * If sRGB is desired, it is multiplied by the
+	 * CIE XYZ-to-sRGB conversion matrix to get the
+	 * output RGB-to-sRGB conversion matrix. */
+	if (!xyz) {
+		matrix[0][0] = x1 * srgb[0][0] + x2 * srgb[1][0] + x3 * srgb[2][0];
+		matrix[0][1] = x1 * srgb[0][1] + x2 * srgb[1][1] + x3 * srgb[2][1];
+		matrix[0][2] = x1 * srgb[0][2] + x2 * srgb[1][2] + x3 * srgb[2][2];
+		matrix[1][0] = y1 * srgb[0][0] + y2 * srgb[1][0] + y3 * srgb[2][0];
+		matrix[1][1] = y1 * srgb[0][1] + y2 * srgb[1][1] + y3 * srgb[2][1];
+		matrix[1][2] = y1 * srgb[0][2] + y2 * srgb[1][2] + y3 * srgb[2][2];
+		matrix[2][0] = z1 * srgb[0][0] + z2 * srgb[1][0] + z3 * srgb[2][0];
+		matrix[2][1] = z1 * srgb[0][1] + z2 * srgb[1][1] + z3 * srgb[2][1];
+		matrix[2][2] = z1 * srgb[0][2] + z2 * srgb[1][2] + z3 * srgb[2][2];
+	} else {
+		matrix[0][0] = x1;
+		matrix[0][1] = x2;
+		matrix[0][2] = x3;
+		matrix[1][0] = y1;
+		matrix[1][1] = y2;
+		matrix[1][2] = y3;
+		matrix[2][0] = z1;
+		matrix[2][1] = z2;
+		matrix[2][2] = z3;
+	}
 }
diff --git a/libglitter_get_colour_space_conversion_matrix_float.c b/libglitter_get_colour_space_conversion_matrix_float.c
index 022c2a4..6e215c9 100644
--- a/libglitter_get_colour_space_conversion_matrix_float.c
+++ b/libglitter_get_colour_space_conversion_matrix_float.c
@@ -5,14 +5,14 @@
 void
 libglitter_get_colour_space_conversion_matrix_float(float matrix[3][3], float c1x, float c1y,
                                                     float c2x, float c2y, float c3x, float c3y,
-                                                    float white_x, float white_y, float white_Y)
+                                                    float white_x, float white_y, float white_Y, int xyz)
 {
 	double double_matrix[3][3];
 	libglitter_get_colour_space_conversion_matrix_double(double_matrix,
 	                                                     (double)c1x, (double)c1y,
 	                                                     (double)c2x, (double)c2y,
 	                                                     (double)c3x, (double)c3y,
-	                                                     (double)white_x, (double)white_y, (double)white_Y);
+	                                                     (double)white_x, (double)white_y, (double)white_Y, xyz);
 	matrix[0][0] = (float)double_matrix[0][0];
 	matrix[0][1] = (float)double_matrix[0][1];
 	matrix[0][2] = (float)double_matrix[0][2];
diff --git a/libglitter_per_channel_desaturate_double.c b/libglitter_per_channel_desaturate_double.c
new file mode 100644
index 0000000..8561708
--- /dev/null
+++ b/libglitter_per_channel_desaturate_double.c
@@ -0,0 +1,49 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+#if defined(__GNUC__) && !defined(__clang__)
+# pragma GCC diagnostic ignored "-Wunsuffixed-float-constants"
+#endif
+
+
+void
+libglitter_per_channel_desaturate_double(double **rasters, size_t nrasters, size_t rowsize,
+                                         size_t cellsize, size_t width, size_t height,
+                                         const double *saturations, const double *primary_ys)
+{
+	size_t y, x, ch, raster_y, raster_i;
+	double intensity;
+
+	rowsize *= cellsize;
+
+	if (nrasters == 3) {
+		double *raster1 = rasters[0], saturation1 = saturations[0];
+		double *raster2 = rasters[1], saturation2 = saturations[1];
+		double *raster3 = rasters[2], saturation3 = saturations[2];
+		double primary1_y = primary_ys ? primary_ys[0] : (double)0.212673370378408277403536885686;
+		double primary2_y = primary_ys ? primary_ys[1] : (double)0.715151730491031756287156895269;
+		double primary3_y = primary_ys ? primary_ys[2] : (double)0.072174899130559869164791564344;
+		for (y = 0, raster_y = 0; y < height; y++, raster_y += rowsize) {
+			for (x = 0, raster_i = raster_y; x < width; x++, raster_i += cellsize) {
+				intensity  = raster1[raster_i] * primary1_y;
+				intensity += raster2[raster_i] * primary2_y;
+				intensity += raster3[raster_i] * primary3_y;
+				raster1[raster_i] = fma(raster1[raster_i] - intensity, saturation1, intensity);
+				raster2[raster_i] = fma(raster2[raster_i] - intensity, saturation2, intensity);
+				raster3[raster_i] = fma(raster3[raster_i] - intensity, saturation3, intensity);
+			}
+		}
+
+	} else {
+		for (y = 0, raster_y = 0; y < height; y++, raster_y += rowsize) {
+			for (x = 0, raster_i = raster_y; x < width; x++, raster_i += cellsize) {
+				intensity = 0;
+				for (ch = 0; ch < nrasters; ch++)
+					intensity += rasters[ch][raster_i] * primary_ys[ch];
+				for (ch = 0; ch < nrasters; ch++)
+					rasters[ch][raster_i] = fma(rasters[ch][raster_i] - intensity, saturations[ch], intensity);
+			}
+		}
+	}
+}
diff --git a/libglitter_per_channel_desaturate_float.c b/libglitter_per_channel_desaturate_float.c
new file mode 100644
index 0000000..fd522ed
--- /dev/null
+++ b/libglitter_per_channel_desaturate_float.c
@@ -0,0 +1,6 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#define libglitter_per_channel_desaturate_double libglitter_per_channel_desaturate_float
+#define double float
+#define fma fmaf
+#include "libglitter_per_channel_desaturate_double.c"