Fixes to Color Balance node:

* The Lift/Gamma/Gain formula previously was incorrect, fixed this and 
removed conversions - now the RNA values are the same as what goes into 
the formula.
* Because of this, added the ability for the Value slider to map to a wider range 
than 0.0-1.0. The black/white gradient remains the same, in this case just 
indicating darker/brighter rather than absolute colour values. Also added ability 
for color wheels to be locked at full brightness (useful for this case, where the 
color value itself is dark).
* Added an alternate formula - offset/power/slope (asc-cdl). This fits the standard 
Color Decision List formula, here for compatibility with other systems, though 
default Lift/Gamma/Gain is easier to use and gives nicer results.

1 files changed, 64 insertions, 24 deletions

diff --git a/source/blender/nodes/intern/CMP_nodes/CMP_colorbalance.c b/source/blender/nodes/intern/CMP_nodes/CMP_colorbalance.c
index 9d3a670fad2..09dccd8e3c4 100644
--- a/source/blender/nodes/intern/CMP_nodes/CMP_colorbalance.c
+++ b/source/blender/nodes/intern/CMP_nodes/CMP_colorbalance.c
@@ -43,34 +43,66 @@ static bNodeSocketType cmp_node_colorbalance_out[]={
 	{-1,0,""}
 };
 
-DO_INLINE float colorbalance(float in, float slope, float offset, float power)
+DO_INLINE float colorbalance_cdl(float in, float offset, float power, float slope)
 {
 	float x = in * slope + offset;
 	
 	/* prevent NaN */
 	if (x < 0.f) x = 0.f;
 	
-	return powf(x, power);
+	//powf(in * slope + offset, power)
+	return powf(x, 1.f/power);
 }
 
-static void do_colorbalance(bNode *node, float* out, float *in)
+DO_INLINE float colorbalance_lgg(float in, float lift, float gamma, float gain)
+{
+	float x = gain*(in+lift*(1-in));
+	
+	/* prevent NaN */
+	if (x < 0.f) x = 0.f;
+	
+	return powf(x, (1.f/gamma));
+}
+
+static void do_colorbalance_cdl(bNode *node, float* out, float *in)
 {
 	NodeColorBalance *n= (NodeColorBalance *)node->storage;
 	
-	out[0] = colorbalance(in[0], n->slope[0], n->offset[0], n->power[0]);
-	out[1] = colorbalance(in[1], n->slope[1], n->offset[1], n->power[1]);
-	out[2] = colorbalance(in[2], n->slope[2], n->offset[2], n->power[2]);
+	out[0] = colorbalance_cdl(in[0], n->lift[0], n->gamma[0], n->gain[0]);
+	out[1] = colorbalance_cdl(in[1], n->lift[1], n->gamma[1], n->gain[1]);
+	out[2] = colorbalance_cdl(in[2], n->lift[2], n->gamma[2], n->gain[2]);
 	out[3] = in[3];
 }
 
-static void do_colorbalance_fac(bNode *node, float* out, float *in, float *fac)
+static void do_colorbalance_cdl_fac(bNode *node, float* out, float *in, float *fac)
 {
 	NodeColorBalance *n= (NodeColorBalance *)node->storage;
 	const float mfac= 1.0f - *fac;
 	
-	out[0] = mfac*in[0] + *fac * colorbalance(in[0], n->slope[0], n->offset[0], n->power[0]);
-	out[1] = mfac*in[1] + *fac * colorbalance(in[1], n->slope[1], n->offset[1], n->power[1]);
-	out[2] = mfac*in[2] + *fac * colorbalance(in[2], n->slope[2], n->offset[2], n->power[2]);
+	out[0] = mfac*in[0] + *fac * colorbalance_cdl(in[0], n->lift[0], n->gamma[0], n->gain[0]);
+	out[1] = mfac*in[1] + *fac * colorbalance_cdl(in[1], n->lift[1], n->gamma[1], n->gain[1]);
+	out[2] = mfac*in[2] + *fac * colorbalance_cdl(in[2], n->lift[2], n->gamma[2], n->gain[2]);
+	out[3] = in[3];
+}
+
+static void do_colorbalance_lgg(bNode *node, float* out, float *in)
+{
+	NodeColorBalance *n= (NodeColorBalance *)node->storage;
+	
+	out[0] = colorbalance_lgg(in[0], n->lift[0], n->gamma[0], n->gain[0]);
+	out[1] = colorbalance_lgg(in[1], n->lift[1], n->gamma[1], n->gain[1]);
+	out[2] = colorbalance_lgg(in[2], n->lift[2], n->gamma[2], n->gain[2]);
+	out[3] = in[3];
+}
+
+static void do_colorbalance_lgg_fac(bNode *node, float* out, float *in, float *fac)
+{
+	NodeColorBalance *n= (NodeColorBalance *)node->storage;
+	const float mfac= 1.0f - *fac;
+	
+	out[0] = mfac*in[0] + *fac * colorbalance_lgg(in[0], n->lift[0], n->gamma[0], n->gain[0]);
+	out[1] = mfac*in[1] + *fac * colorbalance_lgg(in[1], n->lift[1], n->gamma[1], n->gain[1]);
+	out[2] = mfac*in[2] + *fac * colorbalance_lgg(in[2], n->lift[2], n->gamma[2], n->gain[2]);
 	out[3] = in[3];
 }
 
@@ -90,12 +122,24 @@ static void node_composit_exec_colorbalance(void *data, bNode *node, bNodeStack
 	
 	if (cbuf) {
 		stackbuf= alloc_compbuf(cbuf->x, cbuf->y, CB_RGBA, 1); /* create output based on image input */
-				
-		if ((in[0]->data==NULL) && (in[0]->vec[0] == 1.f)) {
-			composit1_pixel_processor(node, stackbuf, in[1]->data, in[1]->vec, do_colorbalance, CB_RGBA);
-		}
-		else {
-			composit2_pixel_processor(node, stackbuf, in[1]->data, in[1]->vec, in[0]->data, in[0]->vec, do_colorbalance_fac, CB_RGBA, CB_VAL);
+			
+		if (node->custom1 == 0) {
+			/* lift gamma gain */
+			if ((in[0]->data==NULL) && (in[0]->vec[0] >= 1.f)) {
+				composit1_pixel_processor(node, stackbuf, in[1]->data, in[1]->vec, do_colorbalance_lgg, CB_RGBA);
+			}
+			else {
+				composit2_pixel_processor(node, stackbuf, in[1]->data, in[1]->vec, in[0]->data, in[0]->vec, do_colorbalance_lgg_fac, CB_RGBA, CB_VAL);
+			}
+		} else {
+			/* offset/power/slope : ASC-CDL */
+			if ((in[0]->data==NULL) && (in[0]->vec[0] >= 1.f)) {
+				composit1_pixel_processor(node, stackbuf, in[1]->data, in[1]->vec, do_colorbalance_cdl, CB_RGBA);
+			}
+			else {
+				composit2_pixel_processor(node, stackbuf, in[1]->data, in[1]->vec, in[0]->data, in[0]->vec, do_colorbalance_cdl_fac, CB_RGBA, CB_VAL);
+			}
+			
 		}
 
 		out[0]->data=stackbuf;
@@ -105,14 +149,10 @@ static void node_composit_exec_colorbalance(void *data, bNode *node, bNodeStack
 static void node_composit_init_colorbalance(bNode *node)
 {
 	NodeColorBalance *n= node->storage= MEM_callocN(sizeof(NodeColorBalance), "node colorbalance");
-	n->slope[0] = n->slope[1] = n->slope[2] = 1.f;
-	n->offset[0] = n->offset[1] = n->offset[2] = 0.f;
-	n->power[0] = n->power[1] = n->power[2] = 1.f;
-	
-	/* for ui, converted to slope/offset/power in RNA */
-	n->lift[0] = n->lift[1] = n->lift[2] = 0.5f;
-	n->gamma[0] = n->gamma[1] = n->gamma[2] = 0.5f;
-	n->gain[0] = n->gain[1] = n->gain[2] = 0.5f;
+
+	n->lift[0] = n->lift[1] = n->lift[2] = 0.0f;
+	n->gamma[0] = n->gamma[1] = n->gamma[2] = 1.0f;
+	n->gain[0] = n->gain[1] = n->gain[2] = 1.0f;
 }
 
 bNodeType cmp_node_colorbalance={