Durian request: Added 'Color Balance' node to compositor. uses Lift/Gamma/Gain

similar to sequence editor.

--> http://mke3.net/blender/devel/2.5/color_balance_node.jpg

Also added 0 key (zero key) shortcut when mouse is over a button, to reset it to its default value.
Same as the RMB menu ->Reset to Default, except for color wheels, it only resets the hue/sat/value
components that that widget affects.

Peter/Xavier: The existing color balance code can generate NaNs (fractional power of a negative),
which causes havoc along the image pipeline. I added a check in the node code to prevent this.

Still plenty of potential for lots of better colour correction tools in the compositor, just needs time...

2 files changed, 18 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_math_color.h b/source/blender/blenlib/BLI_math_color.h
index 2123765643e..41cce59c2b9 100644
--- a/source/blender/blenlib/BLI_math_color.h
+++ b/source/blender/blenlib/BLI_math_color.h
@@ -73,6 +73,10 @@ void linearrgb_to_srgb_v3_v3(float *col_to, float *col_from);
 
 int constrain_rgb(float *r, float *g, float *b);
 void minmax_rgb(short c[3]);
+	
+/***************** lift/gamma/gain / ASC-CDL conversion *****************/
+
+void lift_gamma_gain_to_asc_cdl(float *lift, float *gamma, float *gain, float *offset, float *slope, float *power);
 
 void rgb_byte_to_float(char *in, float *out);
 void rgb_float_to_byte(float *in, char *out);
diff --git a/source/blender/blenlib/intern/math_color.c b/source/blender/blenlib/intern/math_color.c
index a4bd11a4bc8..044f1ca743e 100644
--- a/source/blender/blenlib/intern/math_color.c
+++ b/source/blender/blenlib/intern/math_color.c
@@ -386,3 +386,17 @@ int constrain_rgb(float *r, float *g, float *b)
     return 0;                         /* Color within RGB gamut */
 }
 
+/* ********************************* lift/gamma/gain / ASC-CDL conversion ********************************* */
+
+void lift_gamma_gain_to_asc_cdl(float *lift, float *gamma, float *gain, float *offset, float *slope, float *power)
+{
+	int c;
+	for(c=0; c<3; c++) {
+		offset[c]= lift[c]*gain[c];
+		slope[c]=  gain[c]*(1.0f-lift[c]);
+		if(gamma[c] == 0)
+			power[c]= FLT_MAX;
+		else
+			power[c]= 1.0f/gamma[c];
+	}
+}