Part 2 of D1082 by Troy Sobotka, remove our functions that do luma

calculations and use the OCIO one instead.

25 files changed, 131 insertions, 126 deletions

diff --git a/source/blender/blenkernel/intern/colortools.c b/source/blender/blenkernel/intern/colortools.c
index 89c3e4b0cfc..616e8a0486b 100644
--- a/source/blender/blenkernel/intern/colortools.c
+++ b/source/blender/blenkernel/intern/colortools.c
@@ -994,7 +994,7 @@ void BKE_histogram_update_sample_line(Histogram *hist, ImBuf *ibuf, const ColorM
 				copy_v3_v3(rgb, fp);
 				IMB_colormanagement_processor_apply_v3(cm_processor, rgb);
 
-				hist->data_luma[i]  = rgb_to_luma(rgb);
+				hist->data_luma[i]  = IMB_colormanagement_get_luminance(rgb);
 				hist->data_r[i]     = rgb[0];
 				hist->data_g[i]     = rgb[1];
 				hist->data_b[i]     = rgb[2];
@@ -1002,7 +1002,7 @@ void BKE_histogram_update_sample_line(Histogram *hist, ImBuf *ibuf, const ColorM
 			}
 			else if (ibuf->rect) {
 				cp = (unsigned char *)(ibuf->rect + y * ibuf->x + x);
-				hist->data_luma[i]  = (float)rgb_to_luma_byte(cp) / 255.0f;
+				hist->data_luma[i]  = (float)IMB_colormanagement_get_luminance_byte(cp) / 255.0f;
 				hist->data_r[i]     = (float)cp[0] / 255.0f;
 				hist->data_g[i]     = (float)cp[1] / 255.0f;
 				hist->data_b[i]     = (float)cp[2] / 255.0f;
@@ -1124,7 +1124,7 @@ void scopes_update(Scopes *scopes, ImBuf *ibuf, const ColorManagedViewSettings *
 			}
 
 			/* we still need luma for histogram */
-			luma = rgb_to_luma(rgba);
+			luma = IMB_colormanagement_get_luminance(rgba);
 
 			/* check for min max */
 			if (ycc_mode == -1) {
diff --git a/source/blender/blenlib/BLI_math_color.h b/source/blender/blenlib/BLI_math_color.h
index 55e57b14d09..5652c8056c0 100644
--- a/source/blender/blenlib/BLI_math_color.h
+++ b/source/blender/blenlib/BLI_math_color.h
@@ -80,13 +80,6 @@ void rgb_to_xyz(float r, float g, float b, float *x, float *y, float *z);
 unsigned int rgb_to_cpack(float r, float g, float b);
 unsigned int hsv_to_cpack(float h, float s, float v);
 
-MINLINE float rgb_to_bw(const float rgb[3]);
-MINLINE float rgb_to_grayscale(const float rgb[3]);
-MINLINE unsigned char rgb_to_grayscale_byte(const unsigned char rgb[3]);
-MINLINE float rgb_to_luma(const float rgb[3]);
-MINLINE unsigned char rgb_to_luma_byte(const unsigned char rgb[3]);
-MINLINE float rgb_to_luma_y(const float rgb[3]);
-
 /**************** Profile Transformations *****************/
 
 float srgb_to_linearrgb(float c);
diff --git a/source/blender/blenlib/intern/math_color_inline.c b/source/blender/blenlib/intern/math_color_inline.c
index dc62d04ad55..96aa4b55201 100644
--- a/source/blender/blenlib/intern/math_color_inline.c
+++ b/source/blender/blenlib/intern/math_color_inline.c
@@ -200,61 +200,6 @@ MINLINE void cpack_cpy_3ub(unsigned char r_col[3], const unsigned int pack)
 	r_col[2] = ((pack) >> 16) & 0xFF;
 }
 
-/* TODO:
- *
- * regarding #rgb_to_bw vs #rgb_to_grayscale,
- * it seems nobody knows why we have both functions which convert color to grays
- * but with different influences, this is quite stupid, and should be resolved
- * by someone who knows this stuff: see this thread
- * http://lists.blender.org/pipermail/bf-committers/2012-June/037180.html
- *
- * Only conclusion is that rgb_to_grayscale is used more for compositing.
- */
-MINLINE float rgb_to_bw(const float rgb[3])
-{
-	return 0.35f * rgb[0] + 0.45f * rgb[1] + 0.2f * rgb[2];
-}
-
-/* non-linear luma from ITU-R BT.601-2
- * see: http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC11
- * note: the values used for are not exact matches to those documented above,
- * but they are from the same */
-MINLINE float rgb_to_grayscale(const float rgb[3])
-{
-	return 0.3f * rgb[0] + 0.58f * rgb[1] + 0.12f * rgb[2];
-}
-
-MINLINE unsigned char rgb_to_grayscale_byte(const unsigned char rgb[3])
-{
-	return (unsigned char)(((76  * (unsigned short)rgb[0]) +
-	                        (148 * (unsigned short)rgb[1]) +
-	                        (31  * (unsigned short)rgb[2])) / 255);
-}
-
-/* luma from defined by 'YCC_JFIF', see #rgb_to_ycc */
-MINLINE float rgb_to_luma(const float rgb[3])
-{
-	return 0.299f * rgb[0] + 0.587f * rgb[1] + 0.114f * rgb[2];
-}
-
-MINLINE unsigned char rgb_to_luma_byte(const unsigned char rgb[3])
-{
-	return (unsigned char)(((76  * (unsigned short)rgb[0]) +
-	                        (150 * (unsigned short)rgb[1]) +
-	                        (29  * (unsigned short)rgb[2])) / 255);
-}
-
-/* gamma-corrected RGB --> CIE XYZ
- * for this function we only get the Y component
- * see: http://software.intel.com/sites/products/documentation/hpc/ipp/ippi/ippi_ch6/ch6_color_models.html
- *
- * also known as:
- * luminance rec. 709 */
-MINLINE float rgb_to_luma_y(const float rgb[3])
-{
-	return 0.212671f * rgb[0] + 0.71516f * rgb[1] + 0.072169f * rgb[2];
-}
-
 MINLINE int compare_rgb_uchar(const unsigned char col_a[3], const unsigned char col_b[3], const int limit)
 {
 	const int r = (int)col_a[0] - (int)col_b[0];
diff --git a/source/blender/compositor/operations/COM_CalculateMeanOperation.cpp b/source/blender/compositor/operations/COM_CalculateMeanOperation.cpp
index a2954a20e90..54b0e37c791 100644
--- a/source/blender/compositor/operations/COM_CalculateMeanOperation.cpp
+++ b/source/blender/compositor/operations/COM_CalculateMeanOperation.cpp
@@ -24,7 +24,9 @@
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
 
-
+extern "C" {
+#include "IMB_colormanagement.h"
+}
 
 CalculateMeanOperation::CalculateMeanOperation() : NodeOperation()
 {
@@ -96,7 +98,7 @@ void CalculateMeanOperation::calculateMean(MemoryBuffer *tile)
 			switch (this->m_setting) {
 				case 1:
 				{
-					sum += rgb_to_bw(&buffer[offset]);
+					sum += IMB_colormanagement_get_luminance(&buffer[offset]);
 					break;
 				}
 				case 2:
diff --git a/source/blender/compositor/operations/COM_CalculateStandardDeviationOperation.cpp b/source/blender/compositor/operations/COM_CalculateStandardDeviationOperation.cpp
index 0c67da2d552..32c5fc1adc7 100644
--- a/source/blender/compositor/operations/COM_CalculateStandardDeviationOperation.cpp
+++ b/source/blender/compositor/operations/COM_CalculateStandardDeviationOperation.cpp
@@ -24,7 +24,9 @@
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
 
-
+extern "C" {
+#include "IMB_colormanagement.h"
+}
 
 CalculateStandardDeviationOperation::CalculateStandardDeviationOperation() : CalculateMeanOperation()
 {
@@ -55,7 +57,7 @@ void *CalculateStandardDeviationOperation::initializeTileData(rcti *rect)
 				switch (this->m_setting) {
 					case 1:  /* rgb combined */
 					{
-						float value = rgb_to_bw(&buffer[offset]);
+						float value = IMB_colormanagement_get_luminance(&buffer[offset]);
 						sum += (value - mean) * (value - mean);
 						break;
 					}
diff --git a/source/blender/compositor/operations/COM_ColorCorrectionOperation.cpp b/source/blender/compositor/operations/COM_ColorCorrectionOperation.cpp
index 19209951005..54e0fb41abf 100644
--- a/source/blender/compositor/operations/COM_ColorCorrectionOperation.cpp
+++ b/source/blender/compositor/operations/COM_ColorCorrectionOperation.cpp
@@ -23,6 +23,10 @@
 #include "COM_ColorCorrectionOperation.h"
 #include "BLI_math.h"
 
+extern "C" {
+#include "IMB_colormanagement.h"
+}
+
 ColorCorrectionOperation::ColorCorrectionOperation() : NodeOperation()
 {
 	this->addInputSocket(COM_DT_COLOR);
@@ -90,7 +94,7 @@ void ColorCorrectionOperation::executePixelSampled(float output[4], float x, flo
 	lift += (levelShadows * this->m_data->shadows.lift) + (levelMidtones * this->m_data->midtones.lift) + (levelHighlights * this->m_data->highlights.lift);
 	
 	float invgamma = 1.0f / gamma;
-	float luma = rgb_to_luma_y(inputImageColor);
+	float luma = IMB_colormanagement_get_luminance(inputImageColor);
 
 	r = inputImageColor[0];
 	g = inputImageColor[1];
diff --git a/source/blender/compositor/operations/COM_ConvertOperation.cpp b/source/blender/compositor/operations/COM_ConvertOperation.cpp
index 977586acb60..8b8e8408208 100644
--- a/source/blender/compositor/operations/COM_ConvertOperation.cpp
+++ b/source/blender/compositor/operations/COM_ConvertOperation.cpp
@@ -22,6 +22,9 @@
 
 #include "COM_ConvertOperation.h"
 
+extern "C" {
+#include "IMB_colormanagement.h"
+}
 
 ConvertBaseOperation::ConvertBaseOperation()
 {
@@ -84,7 +87,7 @@ void ConvertColorToBWOperation::executePixelSampled(float output[4], float x, fl
 {
 	float inputColor[4];
 	this->m_inputOperation->readSampled(inputColor, x, y, sampler);
-	output[0] = rgb_to_bw(inputColor);
+	output[0] = IMB_colormanagement_get_luminance(inputColor);
 }
 
 
diff --git a/source/blender/compositor/operations/COM_GlareThresholdOperation.cpp b/source/blender/compositor/operations/COM_GlareThresholdOperation.cpp
index 78e1e80cafc..d2bd7cbeeab 100644
--- a/source/blender/compositor/operations/COM_GlareThresholdOperation.cpp
+++ b/source/blender/compositor/operations/COM_GlareThresholdOperation.cpp
@@ -23,6 +23,10 @@
 #include "COM_GlareThresholdOperation.h"
 #include "BLI_math.h"
 
+extern "C" {
+#include "IMB_colormanagement.h"
+}
+
 GlareThresholdOperation::GlareThresholdOperation() : NodeOperation()
 {
 	this->addInputSocket(COM_DT_COLOR, COM_SC_FIT);
@@ -47,7 +51,7 @@ void GlareThresholdOperation::executePixelSampled(float output[4], float x, floa
 	const float threshold = this->m_settings->threshold;
 	
 	this->m_inputProgram->readSampled(output, x, y, sampler);
-	if (rgb_to_luma_y(output) >= threshold) {
+	if (IMB_colormanagement_get_luminance(output) >= threshold) {
 		output[0] -= threshold, output[1] -= threshold, output[2] -= threshold;
 		output[0] = max(output[0], 0.0f);
 		output[1] = max(output[1], 0.0f);
diff --git a/source/blender/compositor/operations/COM_TonemapOperation.cpp b/source/blender/compositor/operations/COM_TonemapOperation.cpp
index e8a578fa131..54ba218b802 100644
--- a/source/blender/compositor/operations/COM_TonemapOperation.cpp
+++ b/source/blender/compositor/operations/COM_TonemapOperation.cpp
@@ -24,6 +24,10 @@
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
 
+extern "C" {
+#include "IMB_colormanagement.h"
+}
+
 TonemapOperation::TonemapOperation() : NodeOperation()
 {
 	this->addInputSocket(COM_DT_COLOR, COM_SC_NO_RESIZE);
@@ -69,7 +73,7 @@ void PhotoreceptorTonemapOperation::executePixel(float output[4], int x, int y,
 
 	this->m_imageReader->read(output, x, y, NULL);
 
-	const float L = rgb_to_luma_y(output);
+	const float L = IMB_colormanagement_get_luminance(output);
 	float I_l = output[0] + ic * (L - output[0]);
 	float I_g = avg->cav[0] + ic * (avg->lav - avg->cav[0]);
 	float I_a = I_l + ia * (I_g - I_l);
@@ -125,7 +129,7 @@ void *TonemapOperation::initializeTileData(rcti *rect)
 		float Lav = 0.f;
 		float cav[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 		while (p--) {
-			float L = rgb_to_luma_y(bc);
+			float L = IMB_colormanagement_get_luminance(bc);
 			Lav += L;
 			add_v3_v3(cav, bc);
 			lsum += logf(MAX2(L, 0.0f) + 1e-5f);
diff --git a/source/blender/editors/interface/interface_draw.c b/source/blender/editors/interface/interface_draw.c
index 07d580b9138..414903fa194 100644
--- a/source/blender/editors/interface/interface_draw.c
+++ b/source/blender/editors/interface/interface_draw.c
@@ -1453,7 +1453,7 @@ void ui_draw_but_CURVE(ARegion *ar, uiBut *but, uiWidgetColors *wcol, const rcti
 			glEnd();
 		}
 		else if (cumap->cur == 3) {
-			float lum = rgb_to_bw(cumap->sample);
+			float lum = IMB_colormanagement_get_luminance(cumap->sample);
 			glColor3ub(240, 240, 240);
 			
 			glBegin(GL_LINES);
diff --git a/source/blender/editors/interface/interface_regions.c b/source/blender/editors/interface/interface_regions.c
index 6e5f6af3c5f..adcd615368b 100644
--- a/source/blender/editors/interface/interface_regions.c
+++ b/source/blender/editors/interface/interface_regions.c
@@ -237,8 +237,8 @@ static void ui_tooltip_region_draw_cb(const bContext *UNUSED(C), ARegion *ar)
 
 	/* find the brightness difference between background and text colors */
 	
-	tone_bg = rgb_to_grayscale(background_color);
-	/* tone_fg = rgb_to_grayscale(main_color); */
+	tone_bg = IMB_colormanagement_get_luminance(background_color);
+	/* tone_fg = IMB_colormanagement_get_luminance(main_color); */
 
 	/* mix the colors */
 	rgb_tint(value_color,  0.0f, 0.0f, tone_bg, 0.2f);  /* light grey */
@@ -261,7 +261,7 @@ static void ui_tooltip_region_draw_cb(const bContext *UNUSED(C), ARegion *ar)
 
 			/* override text-style */
 			fstyle_header.shadow = 1;
-			fstyle_header.shadowcolor = rgb_to_luma(tip_colors[UI_TIP_LC_MAIN]);
+			fstyle_header.shadowcolor = IMB_colormanagement_get_luminance(tip_colors[UI_TIP_LC_MAIN]);
 			fstyle_header.shadx = fstyle_header.shady = 0;
 			fstyle_header.shadowalpha = 1.0f;
 
diff --git a/source/blender/editors/interface/interface_widgets.c b/source/blender/editors/interface/interface_widgets.c
index 91186a14b49..9020522bb59 100644
--- a/source/blender/editors/interface/interface_widgets.c
+++ b/source/blender/editors/interface/interface_widgets.c
@@ -56,6 +56,7 @@
 #include "UI_interface.h"
 #include "UI_interface_icons.h"
 
+#include "IMB_colormanagement.h"
 
 #include "interface_intern.h"
 
@@ -3027,7 +3028,7 @@ static void widget_swatch(uiBut *but, uiWidgetColors *wcol, rcti *rect, int stat
 		float width = rect->xmax - rect->xmin;
 		float height = rect->ymax - rect->ymin;
 		/* find color luminance and change it slightly */
-		float bw = rgb_to_bw(col);
+		float bw = IMB_colormanagement_get_luminance(col);
 
 		bw += (bw < 0.5f) ? 0.5f : -0.5f;
 		
diff --git a/source/blender/editors/sculpt_paint/paint_image_2d.c b/source/blender/editors/sculpt_paint/paint_image_2d.c
index eb96d1d20d5..4f71bea7cd2 100644
--- a/source/blender/editors/sculpt_paint/paint_image_2d.c
+++ b/source/blender/editors/sculpt_paint/paint_image_2d.c
@@ -889,7 +889,7 @@ static void paint_2d_lift_soften(ImagePaintState *s, ImBuf *ibuf, ImBuf *ibufb,
 
 					/* now rgba_ub contains the edge result, but this should be converted to luminance to avoid
 					 * colored speckles appearing in final image, and also to check for threshold */
-					outrgb[0] = outrgb[1] = outrgb[2] = rgb_to_grayscale(outrgb);
+					outrgb[0] = outrgb[1] = outrgb[2] = IMB_colormanagement_get_luminance(outrgb);
 					if (fabsf(outrgb[0]) > threshold) {
 						float mask = BKE_brush_alpha_get(s->scene, s->brush);
 						float alpha = rgba[3];
diff --git a/source/blender/editors/sculpt_paint/paint_image_proj.c b/source/blender/editors/sculpt_paint/paint_image_proj.c
index 098f0d04d78..805c271f2d1 100644
--- a/source/blender/editors/sculpt_paint/paint_image_proj.c
+++ b/source/blender/editors/sculpt_paint/paint_image_proj.c
@@ -4207,7 +4207,7 @@ static void do_projectpaint_soften_f(ProjPaintState *ps, ProjPixel *projPixel, f
 
 			/* now rgba_ub contains the edge result, but this should be converted to luminance to avoid
 			 * colored speckles appearing in final image, and also to check for threshold */
-			rgba[0] = rgba[1] = rgba[2] = rgb_to_grayscale(rgba);
+			rgba[0] = rgba[1] = rgba[2] = IMB_colormanagement_get_luminance(rgba);
 			if (fabsf(rgba[0]) > ps->brush->sharp_threshold) {
 				float alpha = projPixel->pixel.f_pt[3];
 				projPixel->pixel.f_pt[3] = rgba[3] = mask;
@@ -4268,7 +4268,7 @@ static void do_projectpaint_soften(ProjPaintState *ps, ProjPixel *projPixel, flo
 			sub_v3_v3v3(rgba, rgba_pixel, rgba);
 			/* now rgba_ub contains the edge result, but this should be converted to luminance to avoid
 			 * colored speckles appearing in final image, and also to check for threshold */
-			rgba[0] = rgba[1] = rgba[2] = rgb_to_grayscale(rgba);
+			rgba[0] = rgba[1] = rgba[2] = IMB_colormanagement_get_luminance(rgba);
 			if (fabsf(rgba[0]) > ps->brush->sharp_threshold) {
 				float alpha = rgba_pixel[3];
 				rgba[3] = rgba_pixel[3] = mask;
diff --git a/source/blender/editors/sculpt_paint/paint_vertex.c b/source/blender/editors/sculpt_paint/paint_vertex.c
index e87dd6c2810..9bca0fd2976 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex.c
@@ -37,6 +37,7 @@
 
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
+#include "IMB_colormanagement.h"
 
 #include "DNA_armature_types.h"
 #include "DNA_mesh_types.h"
@@ -768,7 +769,7 @@ BLI_INLINE unsigned int mcol_lighten(unsigned int col1, unsigned int col2, int f
 
 	/* See if are lighter, if so mix, else don't do anything.
 	 * if the paint col is darker then the original, then ignore */
-	if (rgb_to_grayscale_byte(cp1) > rgb_to_grayscale_byte(cp2)) {
+	if (IMB_colormanagement_get_luminance_byte(cp1) > IMB_colormanagement_get_luminance_byte(cp2)) {
 		return col1;
 	}
 
@@ -801,7 +802,7 @@ BLI_INLINE unsigned int mcol_darken(unsigned int col1, unsigned int col2, int fa
 
 	/* See if were darker, if so mix, else don't do anything.
 	 * if the paint col is brighter then the original, then ignore */
-	if (rgb_to_grayscale_byte(cp1) < rgb_to_grayscale_byte(cp2)) {
+	if (IMB_colormanagement_get_luminance_byte(cp1) < IMB_colormanagement_get_luminance_byte(cp2)) {
 		return col1;
 	}
 
diff --git a/source/blender/editors/space_sequencer/sequencer_scopes.c b/source/blender/editors/space_sequencer/sequencer_scopes.c
index 24b3776da6d..b4bcfb4eb07 100644
--- a/source/blender/editors/space_sequencer/sequencer_scopes.c
+++ b/source/blender/editors/space_sequencer/sequencer_scopes.c
@@ -32,6 +32,7 @@
 #include "BLI_math_color.h"
 #include "BLI_utildefines.h"
 
+#include "IMB_colormanagement.h"
 #include "IMB_imbuf_types.h"
 #include "IMB_imbuf.h"
 
@@ -167,7 +168,7 @@ static ImBuf *make_waveform_view_from_ibuf_byte(ImBuf *ibuf)
 
 		for (x = 0; x < ibuf->x; x++) {
 			const unsigned char *rgb = src + 4 * (ibuf->x * y + x);
-			float v = (float)rgb_to_luma_byte(rgb) / 255.0f;
+			float v = (float)IMB_colormanagement_get_luminance_byte(rgb) / 255.0f;
 			unsigned char *p = tgt;
 			p += 4 * (w * ((int) (v * (h - 3)) + 1) + x + 1);
 
@@ -207,7 +208,7 @@ static ImBuf *make_waveform_view_from_ibuf_float(ImBuf *ibuf)
 
 		for (x = 0; x < ibuf->x; x++) {
 			const float *rgb = src + 4 * (ibuf->x * y + x);
-			float v = rgb_to_luma(rgb);
+			float v = IMB_colormanagement_get_luminance(rgb);
 			unsigned char *p = tgt;
 
 			CLAMP(v, 0.0f, 1.0f);
diff --git a/source/blender/imbuf/IMB_colormanagement.h b/source/blender/imbuf/IMB_colormanagement.h
index 262e87bedf5..9407750c039 100644
--- a/source/blender/imbuf/IMB_colormanagement.h
+++ b/source/blender/imbuf/IMB_colormanagement.h
@@ -71,6 +71,9 @@ void IMB_colormanagement_assign_rect_colorspace(struct ImBuf *ibuf, const char *
 const char *IMB_colormanagement_get_float_colorspace(struct ImBuf *ibuf);
 const char *IMB_colormanagement_get_rect_colorspace(struct ImBuf *ibuf);
 
+float IMB_colormanagement_get_luminance(const float rgb[3]);
+unsigned char IMB_colormanagement_get_luminance_byte(const unsigned char[3]);
+
 /* ** Color space transformation functions ** */
 void IMB_colormanagement_transform(float *buffer, int width, int height, int channels,
                                    const char *from_colorspace, const char *to_colorspace, bool predivide);
diff --git a/source/blender/imbuf/intern/colormanagement.c b/source/blender/imbuf/intern/colormanagement.c
index 95e166b2f8b..588d81f9a75 100644
--- a/source/blender/imbuf/intern/colormanagement.c
+++ b/source/blender/imbuf/intern/colormanagement.c
@@ -90,6 +90,11 @@ static int global_tot_display = 0;
 static int global_tot_view = 0;
 static int global_tot_looks = 0;
 
+/* Set to ITU-BT.709 / sRGB primaries weight. Brute force stupid, but only
+ * option with no colormanagement in place.
+ */
+static float luma_coefficients[3] = { 0.2126729f, 0.7151522f, 0.0721750f };
+
 /* lock used by pre-cached processors getters, so processor wouldn't
  * be created several times
  * LOCK_COLORMANAGE can not be used since this mutex could be needed to
@@ -545,6 +550,9 @@ static void colormanage_load_config(OCIO_ConstConfigRcPtr *config)
 
 		colormanage_look_add(name, process_space, false);
 	}
+
+	/* Load luminance coefficients. */
+	OCIO_configGetDefaultLumaCoefs(config, luma_coefficients);
 }
 
 static void colormanage_free_config(void)
@@ -1222,6 +1230,34 @@ const char *IMB_colormanagement_get_rect_colorspace(ImBuf *ibuf)
 	return ibuf->rect_colorspace->name;
 }
 
+/* Convert a float RGB triplet to the correct luminance weighted average.
+ *
+ * Grayscale, or Luma is a distillation of RGB data values down to a weighted average
+ * based on the luminance positions of the red, green, and blue primaries.
+ * Given that the internal reference space may be arbitrarily set, any
+ * effort to glean the luminance coefficients must be aware of the reference
+ * space primaries.
+ *
+ * See http://wiki.blender.org/index.php/User:Nazg-gul/ColorManagement#Luminance
+ */
+
+float IMB_colormanagement_get_luminance(const float rgb[3])
+{
+ return dot_v3v3(luma_coefficients, rgb);
+}
+
+/* Byte equivalent of IMB_colormanagement_get_luminance(). */
+unsigned char IMB_colormanagement_get_luminance_byte(const unsigned char rgb[3])
+{
+ float rgbf[3];
+
+ rgbf[0] = (float) rgb[0] / 255.0f;
+ rgbf[1] = (float) rgb[1] / 255.0f;
+ rgbf[2] = (float) rgb[2] / 255.0f;
+
+ return FTOCHAR(dot_v3v3(luma_coefficients, rgbf));
+}
+
 /*********************** Threaded display buffer transform routines *************************/
 
 typedef struct DisplayBufferThread {
diff --git a/source/blender/imbuf/intern/divers.c b/source/blender/imbuf/intern/divers.c
index 65abf22ff2c..3417fe2fc1d 100644
--- a/source/blender/imbuf/intern/divers.c
+++ b/source/blender/imbuf/intern/divers.c
@@ -775,12 +775,12 @@ void IMB_color_to_bw(ImBuf *ibuf)
 
 	if (rct_fl) {
 		for (i = ibuf->x * ibuf->y; i > 0; i--, rct_fl += 4)
-			rct_fl[0] = rct_fl[1] = rct_fl[2] = rgb_to_grayscale(rct_fl);
+			rct_fl[0] = rct_fl[1] = rct_fl[2] = IMB_colormanagement_get_luminance(rct_fl);
 	}
 
 	if (rct) {
 		for (i = ibuf->x * ibuf->y; i > 0; i--, rct += 4)
-			rct[0] = rct[1] = rct[2] = rgb_to_grayscale_byte(rct);
+			rct[0] = rct[1] = rct[2] = IMB_colormanagement_get_luminance_byte(rct);
 	}
 }
 
diff --git a/source/blender/imbuf/intern/png.c b/source/blender/imbuf/intern/png.c
index 683bdabcd6c..f3ff6659e1c 100644
--- a/source/blender/imbuf/intern/png.c
+++ b/source/blender/imbuf/intern/png.c
@@ -312,7 +312,7 @@ int imb_savepng(struct ImBuf *ibuf, const char *name, int flags)
 							rgb[0] = chanel_colormanage_cb(from_straight[0]);
 							rgb[1] = chanel_colormanage_cb(from_straight[1]);
 							rgb[2] = chanel_colormanage_cb(from_straight[2]);
-							to16[0] = ftoshort(rgb_to_bw(rgb));
+							to16[0] = ftoshort(IMB_colormanagement_get_luminance(rgb));
 							to16++; from_float += 4;
 						}
 					}
@@ -321,7 +321,7 @@ int imb_savepng(struct ImBuf *ibuf, const char *name, int flags)
 							rgb[0] = chanel_colormanage_cb(from_float[0]);
 							rgb[1] = chanel_colormanage_cb(from_float[1]);
 							rgb[2] = chanel_colormanage_cb(from_float[2]);
-							to16[0] = ftoshort(rgb_to_bw(rgb));
+							to16[0] = ftoshort(IMB_colormanagement_get_luminance(rgb));
 							to16++; from_float += 3;
 						}
 					}
diff --git a/source/blender/nodes/shader/nodes/node_shader_valToRgb.c b/source/blender/nodes/shader/nodes/node_shader_valToRgb.c
index fa5d9b43ee7..72942cce9c5 100644
--- a/source/blender/nodes/shader/nodes/node_shader_valToRgb.c
+++ b/source/blender/nodes/shader/nodes/node_shader_valToRgb.c
@@ -31,6 +31,7 @@
 
 
 #include "node_shader_util.h"
+#include "IMB_colormanagement.h"
 
 /* **************** VALTORGB ******************** */
 static bNodeSocketTemplate sh_node_valtorgb_in[] = {
@@ -106,7 +107,7 @@ static void node_shader_exec_rgbtobw(void *UNUSED(data), int UNUSED(thread), bNo
 	float col[3];
 	nodestack_get_vec(col, SOCK_VECTOR, in[0]);
 
-	out[0]->vec[0] = rgb_to_bw(col);
+	out[0]->vec[0] = IMB_colormanagement_get_luminance(col);
 }
 
 static int gpu_shader_rgbtobw(GPUMaterial *mat, bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)
diff --git a/source/blender/nodes/texture/nodes/node_texture_valToRgb.c b/source/blender/nodes/texture/nodes/node_texture_valToRgb.c
index 7f8adab2da5..a49d82d27a9 100644
--- a/source/blender/nodes/texture/nodes/node_texture_valToRgb.c
+++ b/source/blender/nodes/texture/nodes/node_texture_valToRgb.c
@@ -32,6 +32,7 @@
 
 #include "node_texture_util.h"
 #include "NOD_texture.h"
+#include "IMB_colormanagement.h"
 
 /* **************** VALTORGB ******************** */
 static bNodeSocketTemplate valtorgb_in[] = {
@@ -91,7 +92,7 @@ static void rgbtobw_valuefn(float *out, TexParams *p, bNode *UNUSED(node), bNode
 {
 	float cin[4];
 	tex_input_rgba(cin, in[0], p, thread);
-	*out = rgb_to_bw(cin);
+	*out = IMB_colormanagement_get_luminance(cin);
 }
 
 static void rgbtobw_exec(void *data, int UNUSED(thread), bNode *node, bNodeExecData *execdata, bNodeStack **in, bNodeStack **out)
diff --git a/source/blender/render/intern/source/render_texture.c b/source/blender/render/intern/source/render_texture.c
index 17039bca63a..531c31848a6 100644
--- a/source/blender/render/intern/source/render_texture.c
+++ b/source/blender/render/intern/source/render_texture.c
@@ -1982,14 +1982,14 @@ static int ntap_bump_compute(NTapBump *ntap_bump, ShadeInput *shi, MTex *mtex, T
 
 		/* use texres for the center sample, set rgbnor */
 		rgbnor = multitex_mtex(shi, mtex, STll, dxt, dyt, texres, pool, skip_load_image);
-		Hll = (fromrgb) ? rgb_to_grayscale(&texres->tr) : texres->tin;
+		Hll = (fromrgb) ? IMB_colormanagement_get_luminance(&texres->tr) : texres->tin;
 
 		/* use ttexr for the other 2 taps */
 		multitex_mtex(shi, mtex, STlr, dxt, dyt, &ttexr, pool, skip_load_image);
-		Hlr = (fromrgb) ? rgb_to_grayscale(&ttexr.tr) : ttexr.tin;
+		Hlr = (fromrgb) ? IMB_colormanagement_get_luminance(&ttexr.tr) : ttexr.tin;
 
 		multitex_mtex(shi, mtex, STul, dxt, dyt, &ttexr, pool, skip_load_image);
-		Hul = (fromrgb) ? rgb_to_grayscale(&ttexr.tr) : ttexr.tin;
+		Hul = (fromrgb) ? IMB_colormanagement_get_luminance(&ttexr.tr) : ttexr.tin;
 
 		dHdx = Hscale*(Hlr - Hll);
 		dHdy = Hscale*(Hul - Hll);
@@ -2020,17 +2020,17 @@ static int ntap_bump_compute(NTapBump *ntap_bump, ShadeInput *shi, MTex *mtex, T
 
 		/* use texres for the center sample, set rgbnor */
 		rgbnor = multitex_mtex(shi, mtex, STc, dxt, dyt, texres, pool, skip_load_image);
-		/* Hc = (fromrgb) ? rgb_to_grayscale(&texres->tr) : texres->tin; */ /* UNUSED */
+		/* Hc = (fromrgb) ? IMB_colormanagement_get_luminance(&texres->tr) : texres->tin; */ /* UNUSED */
 
 		/* use ttexr for the other taps */
 		multitex_mtex(shi, mtex, STl, dxt, dyt, &ttexr, pool, skip_load_image);
-		Hl = (fromrgb) ? rgb_to_grayscale(&ttexr.tr) : ttexr.tin;
+		Hl = (fromrgb) ? IMB_colormanagement_get_luminance(&ttexr.tr) : ttexr.tin;
 		multitex_mtex(shi, mtex, STr, dxt, dyt, &ttexr, pool, skip_load_image);
-		Hr = (fromrgb) ? rgb_to_grayscale(&ttexr.tr) : ttexr.tin;
+		Hr = (fromrgb) ? IMB_colormanagement_get_luminance(&ttexr.tr) : ttexr.tin;
 		multitex_mtex(shi, mtex, STd, dxt, dyt, &ttexr, pool, skip_load_image);
-		Hd = (fromrgb) ? rgb_to_grayscale(&ttexr.tr) : ttexr.tin;
+		Hd = (fromrgb) ? IMB_colormanagement_get_luminance(&ttexr.tr) : ttexr.tin;
 		multitex_mtex(shi, mtex, STu, dxt, dyt, &ttexr, pool, skip_load_image);
-		Hu = (fromrgb) ? rgb_to_grayscale(&ttexr.tr) : ttexr.tin;
+		Hu = (fromrgb) ? IMB_colormanagement_get_luminance(&ttexr.tr) : ttexr.tin;
 
 		dHdx = Hscale*(Hr - Hl);
 		dHdy = Hscale*(Hu - Hd);
@@ -2328,7 +2328,7 @@ void do_material_tex(ShadeInput *shi, Render *re)
 			/* texture output */
 
 			if ((rgbnor & TEX_RGB) && (mtex->texflag & MTEX_RGBTOINT)) {
-				texres.tin = rgb_to_grayscale(&texres.tr);
+				texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				rgbnor -= TEX_RGB;
 			}
 			if (mtex->texflag & MTEX_NEGATIVE) {
@@ -2568,7 +2568,7 @@ void do_material_tex(ShadeInput *shi, Render *re)
 				}
 				
 				if (rgbnor & TEX_RGB) {
-					texres.tin = rgb_to_grayscale(&texres.tr);
+					texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				}
 
 				factt= (0.5f-texres.tin)*mtex->dispfac*stencilTin; facmm= 1.0f-factt;
@@ -2596,7 +2596,7 @@ void do_material_tex(ShadeInput *shi, Render *re)
 				
 				if (rgbnor & TEX_RGB) {
 					if (texres.talpha) texres.tin = texres.ta;
-					else               texres.tin = rgb_to_grayscale(&texres.tr);
+					else               texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				}
 
 				if (mtex->mapto & MAP_REF) {
@@ -2767,7 +2767,7 @@ void do_volume_tex(ShadeInput *shi, const float *xyz, int mapto_flag, float col_
 			/* texture output */
 
 			if ((rgbnor & TEX_RGB) && (mtex->texflag & MTEX_RGBTOINT)) {
-				texres.tin = rgb_to_grayscale(&texres.tr);
+				texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				rgbnor -= TEX_RGB;
 			}
 			if (mtex->texflag & MTEX_NEGATIVE) {
@@ -2836,7 +2836,7 @@ void do_volume_tex(ShadeInput *shi, const float *xyz, int mapto_flag, float col_
 				/* convert RGB to intensity if intensity info isn't provided */
 				if (rgbnor & TEX_RGB) {
 					if (texres.talpha)  texres.tin = texres.ta;
-					else                texres.tin = rgb_to_grayscale(&texres.tr);
+					else                texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				}
 				
 				if ((mapto_flag & MAP_EMISSION) && (mtex->mapto & MAP_EMISSION)) {
@@ -2934,7 +2934,7 @@ void do_halo_tex(HaloRen *har, float xn, float yn, float col_r[4])
 
 	/* texture output */
 	if (rgb && (mtex->texflag & MTEX_RGBTOINT)) {
-		texres.tin = rgb_to_bw(&texres.tr);
+		texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 		rgb= 0;
 	}
 	if (mtex->texflag & MTEX_NEGATIVE) {
@@ -3006,7 +3006,7 @@ void do_halo_tex(HaloRen *har, float xn, float yn, float col_r[4])
 				texres.tin = texres.ta;
 			}
 			else {
-				texres.tin = rgb_to_bw(&texres.tr);
+				texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 			}
 		}
 
@@ -3140,7 +3140,7 @@ void do_sky_tex(const float rco[3], float lo[3], const float dxyview[2], float h
 			
 			/* texture output */
 			if (rgb && (mtex->texflag & MTEX_RGBTOINT)) {
-				texres.tin = rgb_to_bw(&texres.tr);
+				texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				rgb= 0;
 			}
 			if (mtex->texflag & MTEX_NEGATIVE) {
@@ -3215,7 +3215,7 @@ void do_sky_tex(const float rco[3], float lo[3], const float dxyview[2], float h
 				}
 			}
 			if (mtex->mapto & WOMAP_BLEND) {
-				if (rgb) texres.tin = rgb_to_bw(&texres.tr);
+				if (rgb) texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				
 				*blend= texture_value_blend(mtex->def_var, *blend, texres.tin, mtex->blendfac, mtex->blendtype);
 			}
@@ -3356,7 +3356,7 @@ void do_lamp_tex(LampRen *la, const float lavec[3], ShadeInput *shi, float col_r
 
 			/* texture output */
 			if (rgb && (mtex->texflag & MTEX_RGBTOINT)) {
-				texres.tin = rgb_to_bw(&texres.tr);
+				texres.tin = IMB_colormanagement_get_luminance(&texres.tr);
 				rgb= 0;
 			}
 			if (mtex->texflag & MTEX_NEGATIVE) {
@@ -3455,7 +3455,7 @@ int externtex(MTex *mtex, const float vec[3], float *tin, float *tr, float *tg,
 	rgb = multitex(tex, texvec, dxt, dyt, 0, &texr, thread, mtex->which_output, pool, skip_load_image);
 	
 	if (rgb) {
-		texr.tin = rgb_to_bw(&texr.tr);
+		texr.tin = IMB_colormanagement_get_luminance(&texr.tr);
 	}
 	else {
 		texr.tr= mtex->r;
diff --git a/source/blender/render/intern/source/shadeoutput.c b/source/blender/render/intern/source/shadeoutput.c
index 63a97a04b39..586345d1eb4 100644
--- a/source/blender/render/intern/source/shadeoutput.c
+++ b/source/blender/render/intern/source/shadeoutput.c
@@ -55,6 +55,8 @@
 
 #include "shading.h" /* own include */
 
+#include "IMB_colormanagement.h"
+
 /* could enable at some point but for now there are far too many conversions */
 #ifdef __GNUC__
 #  pragma GCC diagnostic ignored "-Wdouble-promotion"
@@ -948,7 +950,7 @@ static void ramp_diffuse_result(float *diff, ShadeInput *shi)
 
 	if (ma->ramp_col) {
 		if (ma->rampin_col==MA_RAMP_IN_RESULT) {
-			float fac = rgb_to_grayscale(diff);
+			float fac = IMB_colormanagement_get_luminance(diff);
 			do_colorband(ma->ramp_col, fac, col);
 			
 			/* blending method */
@@ -980,7 +982,7 @@ static void add_to_diffuse(float *diff, ShadeInput *shi, float is, float r, floa
 			/* input */
 			switch (ma->rampin_col) {
 			case MA_RAMP_IN_ENERGY:
-				/* should use 'rgb_to_grayscale' but we only have a vector version */
+				/* should use 'IMB_colormanagement_get_luminance' but we only have a vector version */
 				fac= 0.3f*r + 0.58f*g + 0.12f*b;
 				break;
 			case MA_RAMP_IN_SHADER:
@@ -1023,7 +1025,7 @@ static void ramp_spec_result(float spec_col[3], ShadeInput *shi)
 
 	if (ma->ramp_spec && (ma->rampin_spec==MA_RAMP_IN_RESULT)) {
 		float col[4];
-		float fac = rgb_to_grayscale(spec_col);
+		float fac = IMB_colormanagement_get_luminance(spec_col);
 
 		do_colorband(ma->ramp_spec, fac, col);
 		
@@ -1619,10 +1621,10 @@ static void shade_lamp_loop_only_shadow(ShadeInput *shi, ShadeResult *shr)
 
 				if (shi->mat->shadowonly_flag == MA_SO_OLD) {
 					/* Old "Shadows Only" */
-					accum+= (1.0f-visifac) + (visifac)*rgb_to_grayscale(shadfac)*shadfac[3];
+					accum+= (1.0f-visifac) + (visifac)*IMB_colormanagement_get_luminance(shadfac)*shadfac[3];
 				}
 				else {
-					shaded += rgb_to_grayscale(shadfac)*shadfac[3] * visifac * lar->energy;
+					shaded += IMB_colormanagement_get_luminance(shadfac)*shadfac[3] * visifac * lar->energy;
 
 					if (shi->mat->shadowonly_flag == MA_SO_SHADOW) {
 						lightness += visifac * lar->energy;
@@ -1671,26 +1673,26 @@ static void shade_lamp_loop_only_shadow(ShadeInput *shi, ShadeResult *shr)
 			
 			if (R.wrld.aomix==WO_AOADD) {
 				if (shi->mat->shadowonly_flag == MA_SO_OLD) {
-					f= f*(1.0f - rgb_to_grayscale(shi->ao));
+					f= f*(1.0f - IMB_colormanagement_get_luminance(shi->ao));
 					shr->alpha= (shr->alpha + f)*f;
 				}
 				else {
-					shr->alpha -= f*rgb_to_grayscale(shi->ao);
+					shr->alpha -= f*IMB_colormanagement_get_luminance(shi->ao);
 					if (shr->alpha<0.0f) shr->alpha=0.0f;
 				}
 			}
 			else /* AO Multiply */
-				shr->alpha= (1.0f - f)*shr->alpha + f*(1.0f - (1.0f - shr->alpha)*rgb_to_grayscale(shi->ao));
+				shr->alpha= (1.0f - f)*shr->alpha + f*(1.0f - (1.0f - shr->alpha)*IMB_colormanagement_get_luminance(shi->ao));
 		}
 
 		if (R.wrld.mode & WO_ENV_LIGHT) {
 			if (shi->mat->shadowonly_flag == MA_SO_OLD) {
-				f= R.wrld.ao_env_energy*shi->amb*(1.0f - rgb_to_grayscale(shi->env));
+				f= R.wrld.ao_env_energy*shi->amb*(1.0f - IMB_colormanagement_get_luminance(shi->env));
 				shr->alpha= (shr->alpha + f)*f;
 			}
 			else {
 				f= R.wrld.ao_env_energy*shi->amb;
-				shr->alpha -= f*rgb_to_grayscale(shi->env);
+				shr->alpha -= f*IMB_colormanagement_get_luminance(shi->env);
 				if (shr->alpha<0.0f) shr->alpha=0.0f;
 			}
 		}
diff --git a/source/blender/render/intern/source/volumetric.c b/source/blender/render/intern/source/volumetric.c
index d5c4c407bf6..2c0917243a3 100644
--- a/source/blender/render/intern/source/volumetric.c
+++ b/source/blender/render/intern/source/volumetric.c
@@ -41,6 +41,8 @@
 
 #include "RE_shader_ext.h"
 
+#include "IMB_colormanagement.h"
+
 #include "DNA_material_types.h"
 #include "DNA_group_types.h"
 #include "DNA_lamp_types.h"
@@ -504,7 +506,7 @@ static void vol_shade_one_lamp(struct ShadeInput *shi, const float co[3], const
 		
 		if (shi->mat->vol.shadeflag & MA_VOL_RECV_EXT_SHADOW) {
 			mul_v3_fl(lacol, vol_get_shadow(shi, lar, co));
-			if (rgb_to_luma_y(lacol) < 0.001f) return;
+			if (IMB_colormanagement_get_luminance(lacol) < 0.001f) return;
 		}
 		
 		/* find minimum of volume bounds, or lamp coord */
@@ -538,7 +540,7 @@ static void vol_shade_one_lamp(struct ShadeInput *shi, const float co[3], const
 		}
 	}
 	
-	if (rgb_to_luma_y(lacol) < 0.001f) return;
+	if (IMB_colormanagement_get_luminance(lacol) < 0.001f) return;
 	
 	normalize_v3(lv);
 	p = vol_get_phasefunc(shi, shi->mat->vol.asymmetry, view, lv);
@@ -620,7 +622,7 @@ static void volumeintegrate(struct ShadeInput *shi, float col[4], const float co
 			
 			if (t0 > t1 * 0.25f) {
 				/* only use depth cutoff after we've traced a little way into the volume */
-				if (rgb_to_luma_y(tr) < shi->mat->vol.depth_cutoff) break;
+				if (IMB_colormanagement_get_luminance(tr) < shi->mat->vol.depth_cutoff) break;
 			}
 			
 			vol_get_emission(shi, emit_col, p);
@@ -649,7 +651,7 @@ static void volumeintegrate(struct ShadeInput *shi, float col[4], const float co
 	add_v3_v3(col, radiance);
 	
 	/* alpha <-- transmission luminance */
-	col[3] = 1.0f - rgb_to_luma_y(tr);
+	col[3] = 1.0f - IMB_colormanagement_get_luminance(tr);
 }
 
 /* the main entry point for volume shading */
@@ -790,7 +792,7 @@ void shade_volume_shadow(struct ShadeInput *shi, struct ShadeResult *shr, struct
 
 	
 	copy_v3_v3(shr->combined, tr);
-	shr->combined[3] = 1.0f - rgb_to_luma_y(tr);
+	shr->combined[3] = 1.0f - IMB_colormanagement_get_luminance(tr);
 	shr->alpha = shr->combined[3];
 }