Tomato keying screen: small fixes and improvements

- Fixed issues with calculating matte with balance != 0.5
  It used to be used concave combination of minimal and maximal
  channel values which could be inpredictable.
  Use concave combination of two non-major channels sorted
  by their index, so such combination would always use the same
  coefficients for particular non-major channels.

- Added despill balance slider which defines balance between
  non-major channels used for calculating average of two
  colors. Difference between average value and pixel value of
  major screen channel defines amount of despill. Balance of
  0.5 gives the same behavior as it was before this slider
  was added.

5 files changed, 23 insertions, 9 deletions

diff --git a/source/blender/compositor/nodes/COM_KeyingNode.cpp b/source/blender/compositor/nodes/COM_KeyingNode.cpp
index 7c39765fbf1..efd50a44a51 100644
--- a/source/blender/compositor/nodes/COM_KeyingNode.cpp
+++ b/source/blender/compositor/nodes/COM_KeyingNode.cpp
@@ -184,11 +184,13 @@ OutputSocket *KeyingNode::setupFeather(ExecutionSystem *graph, CompositorContext
 	return operationy->getOutputSocket();
 }
 
-OutputSocket *KeyingNode::setupDespill(ExecutionSystem *graph, OutputSocket *despillInput, OutputSocket *inputScreen, float factor)
+OutputSocket *KeyingNode::setupDespill(ExecutionSystem *graph, OutputSocket *despillInput, OutputSocket *inputScreen,
+                                       float factor, float colorBalance)
 {
 	KeyingDespillOperation *despillOperation = new KeyingDespillOperation();
 
 	despillOperation->setDespillFactor(factor);
+	despillOperation->setColorBalance(colorBalance);
 
 	addLink(graph, despillInput, despillOperation->getInputSocket(0));
 	addLink(graph, inputScreen, despillOperation->getInputSocket(1));
@@ -292,7 +294,8 @@ void KeyingNode::convertToOperations(ExecutionSystem *graph, CompositorContext *
 	if (keying_data->despill_factor > 0.0f) {
 		postprocessedImage = setupDespill(graph, postprocessedImage,
 		                                  keyingOperation->getInputSocket(1)->getConnection()->getFromSocket(),
-		                                  keying_data->despill_factor);
+		                                  keying_data->despill_factor,
+		                                  keying_data->despill_balance);
 	}
 
 	/* connect result to output sockets */
diff --git a/source/blender/compositor/nodes/COM_KeyingNode.h b/source/blender/compositor/nodes/COM_KeyingNode.h
index 294a27bb52c..6ab6a60a44d 100644
--- a/source/blender/compositor/nodes/COM_KeyingNode.h
+++ b/source/blender/compositor/nodes/COM_KeyingNode.h
@@ -36,7 +36,8 @@ protected:
 	OutputSocket *setupDilateErode(ExecutionSystem *graph, OutputSocket *dilateErodeInput, int distance);
 	OutputSocket *setupFeather(ExecutionSystem *graph, CompositorContext *context, OutputSocket *featherInput,
 	                           int falloff, int distance);
-	OutputSocket *setupDespill(ExecutionSystem *graph, OutputSocket *despillInput, OutputSocket *inputSrceen, float factor);
+	OutputSocket *setupDespill(ExecutionSystem *graph, OutputSocket *despillInput, OutputSocket *inputSrceen,
+	                           float factor, float colorBalance);
 	OutputSocket *setupClip(ExecutionSystem *graph, OutputSocket *clipInput, int kernelRadius, float kernelTolerance,
 	                        float clipBlack, float clipWhite, bool edgeMatte);
 public:
diff --git a/source/blender/compositor/operations/COM_KeyingDespillOperation.cpp b/source/blender/compositor/operations/COM_KeyingDespillOperation.cpp
index 081d9f723e8..9798ddcee94 100644
--- a/source/blender/compositor/operations/COM_KeyingDespillOperation.cpp
+++ b/source/blender/compositor/operations/COM_KeyingDespillOperation.cpp
@@ -47,6 +47,7 @@ KeyingDespillOperation::KeyingDespillOperation() : NodeOperation()
 	this->addOutputSocket(COM_DT_COLOR);
 
 	this->m_despillFactor = 0.5f;
+	this->m_colorBalance = 0.5f;
 
 	this->m_pixelReader = NULL;
 	this->m_screenReader = NULL;
@@ -73,16 +74,22 @@ void KeyingDespillOperation::executePixel(float *color, float x, float y, PixelS
 	this->m_screenReader->read(screenColor, x, y, sampler, inputBuffers);
 
 	int screen_primary_channel = get_pixel_primary_channel(screenColor);
+	int other_1 = (screen_primary_channel + 1) % 3;
+	int other_2 = (screen_primary_channel + 2) % 3;
+
+	int min_channel = MIN2(other_1, other_2);
+	int max_channel = MAX2(other_1, other_2);
+
 	float average_value, amount;
 
-	average_value = (pixelColor[0] + pixelColor[1] + pixelColor[2] - pixelColor[screen_primary_channel]) / 2.0f;
-	amount = pixelColor[screen_primary_channel] - average_value;
+	average_value = this->m_colorBalance * pixelColor[min_channel] + (1.0f - this->m_colorBalance) * pixelColor[max_channel];
+	amount = (pixelColor[screen_primary_channel] - average_value);
 
 	color[0] = pixelColor[0];
 	color[1] = pixelColor[1];
 	color[2] = pixelColor[2];
 	color[3] = pixelColor[3];
-	
+
 	if (this->m_despillFactor * amount > 0) {
 		color[screen_primary_channel] = pixelColor[screen_primary_channel] - this->m_despillFactor * amount;
 	}
diff --git a/source/blender/compositor/operations/COM_KeyingDespillOperation.h b/source/blender/compositor/operations/COM_KeyingDespillOperation.h
index 4fea9b578a1..3485bf1952f 100644
--- a/source/blender/compositor/operations/COM_KeyingDespillOperation.h
+++ b/source/blender/compositor/operations/COM_KeyingDespillOperation.h
@@ -34,6 +34,7 @@ protected:
 	SocketReader *m_pixelReader;
 	SocketReader *m_screenReader;
 	float m_despillFactor;
+	float m_colorBalance;
 
 public:
 	KeyingDespillOperation();
@@ -42,6 +43,7 @@ public:
 	void deinitExecution();
 
 	void setDespillFactor(float value) {this->m_despillFactor = value;}
+	void setColorBalance(float value) {this->m_colorBalance = value;}
 
 	void executePixel(float *color, float x, float y, PixelSampler sampler, MemoryBuffer *inputBuffers[]);
 };
diff --git a/source/blender/compositor/operations/COM_KeyingOperation.cpp b/source/blender/compositor/operations/COM_KeyingOperation.cpp
index e92e5c84c2d..48d1967b5b3 100644
--- a/source/blender/compositor/operations/COM_KeyingOperation.cpp
+++ b/source/blender/compositor/operations/COM_KeyingOperation.cpp
@@ -45,9 +45,10 @@ static float get_pixel_saturation(float pixelColor[4], float screen_balance, int
 	int other_1 = (primary_channel + 1) % 3;
 	int other_2 = (primary_channel + 2) % 3;
 
-	float min = MIN2(pixelColor[other_1], pixelColor[other_2]);
-	float max = MAX2(pixelColor[other_1], pixelColor[other_2]);
-	float val = screen_balance * min + (1.0f - screen_balance) * max;
+	int min_channel = MIN2(other_1, other_2);
+	int max_channel = MAX2(other_1, other_2);
+
+	float val = screen_balance * pixelColor[min_channel] + (1.0f - screen_balance) * pixelColor[max_channel];
 
 	return (pixelColor[primary_channel] - val) * fabsf(1.0f - val);
 }