Index: source/blender/makesdna/DNA_node_types.h
===================================================================
--- source/blender/makesdna/DNA_node_types.h	(revision 51103)
+++ source/blender/makesdna/DNA_node_types.h	(working copy)
@@ -686,6 +686,7 @@
 
 typedef struct NodeKeyingData {
 	float screen_balance;
+	float screen_subtract;
 	float despill_factor;
 	float despill_balance;
 	int edge_kernel_radius;
Index: source/blender/compositor/nodes/COM_KeyingNode.h
===================================================================
--- source/blender/compositor/nodes/COM_KeyingNode.h	(revision 51103)
+++ source/blender/compositor/nodes/COM_KeyingNode.h	(working copy)
@@ -36,6 +36,8 @@
 	OutputSocket *setupDilateErode(ExecutionSystem *graph, OutputSocket *dilateErodeInput, int distance);
 	OutputSocket *setupFeather(ExecutionSystem *graph, CompositorContext *context, OutputSocket *featherInput,
 	                           int falloff, int distance);
+	OutputSocket *setupScreenSubtract(ExecutionSystem *graph, OutputSocket *key, OutputSocket *subtractInput,
+	                                  OutputSocket *inputScreen, float factor);
 	OutputSocket *setupDespill(ExecutionSystem *graph, OutputSocket *despillInput, OutputSocket *inputSrceen,
 	                           float factor, float colorBalance);
 	OutputSocket *setupClip(ExecutionSystem *graph, OutputSocket *clipInput, int kernelRadius, float kernelTolerance,
Index: source/blender/compositor/nodes/COM_KeyingNode.cpp
===================================================================
--- source/blender/compositor/nodes/COM_KeyingNode.cpp	(revision 51103)
+++ source/blender/compositor/nodes/COM_KeyingNode.cpp	(working copy)
@@ -31,11 +31,14 @@
 #include "COM_KeyingClipOperation.h"
 
 #include "COM_MathBaseOperation.h"
+#include "COM_MixSubtractOperation.h"
+#include "COM_MixDivideOperation.h"
 
 #include "COM_SeparateChannelOperation.h"
 #include "COM_CombineChannelsOperation.h"
 #include "COM_ConvertRGBToYCCOperation.h"
 #include "COM_ConvertYCCToRGBOperation.h"
+#include "COM_ConvertKeyToPremulOperation.h"
 #include "COM_SetValueOperation.h"
 
 #include "COM_DilateErodeOperation.h"
@@ -186,6 +189,47 @@
 	return operationy->getOutputSocket();
 }
 
+OutputSocket *KeyingNode::setupScreenSubtract(ExecutionSystem *graph, OutputSocket *key, OutputSocket *subtractInput,
+                                              OutputSocket *inputScreen, float factor)
+{
+	SetValueOperation *one = new SetValueOperation();
+	SetValueOperation *factorOperation = new SetValueOperation();
+	MathSubtractOperation *invertOperation = new MathSubtractOperation();
+	MixSubtractOperation *subtractOperation = new MixSubtractOperation();
+	MixBaseOperation *mixOperation = new MixBaseOperation();
+	MixDivideOperation *unpremultOperation = new MixDivideOperation();
+	ConvertKeyToPremulOperation *premultOperation = new ConvertKeyToPremulOperation();
+	one->setValue(1.0f);
+	factorOperation->setValue(factor);
+
+	addLink(graph, one->getOutputSocket(), invertOperation->getInputSocket(0));
+	addLink(graph, key, invertOperation->getInputSocket(1));
+
+	addLink(graph, invertOperation->getOutputSocket(), subtractOperation->getInputSocket(0));
+	addLink(graph, subtractInput, subtractOperation->getInputSocket(1));
+	addLink(graph, inputScreen, subtractOperation->getInputSocket(2));
+
+	addLink(graph, one->getOutputSocket(), unpremultOperation->getInputSocket(0));
+	addLink(graph, subtractOperation->getOutputSocket(), unpremultOperation->getInputSocket(1));
+	addLink(graph, key, unpremultOperation->getInputSocket(2));
+
+	addLink(graph, unpremultOperation->getOutputSocket(), premultOperation->getInputSocket(0));
+
+	addLink(graph, factorOperation->getOutputSocket(), mixOperation->getInputSocket(0));
+	addLink(graph, subtractInput, mixOperation->getInputSocket(1));
+	addLink(graph, premultOperation->getOutputSocket(), mixOperation->getInputSocket(2));
+
+	graph->addOperation(one);
+	graph->addOperation(factorOperation);
+	graph->addOperation(invertOperation);
+	graph->addOperation(subtractOperation);
+	graph->addOperation(mixOperation);
+	graph->addOperation(unpremultOperation);
+	graph->addOperation(premultOperation);
+
+	return mixOperation->getOutputSocket();
+}
+
 OutputSocket *KeyingNode::setupDespill(ExecutionSystem *graph, OutputSocket *despillInput, OutputSocket *inputScreen,
                                        float factor, float colorBalance)
 {
@@ -326,6 +370,13 @@
 
 	postprocessedImage = alphaOperation->getOutputSocket();
 
+	/* subtract screen from image */
+	if (keying_data->screen_subtract > 0.0f) {
+		postprocessedImage = setupScreenSubtract(graph, keyingOperation->getOutputSocket(), postprocessedImage,
+		                                         keyingOperation->getInputSocket(1)->getConnection()->getFromSocket(),
+		                                         keying_data->screen_subtract);
+	}
+
 	/* despill output image */
 	if (keying_data->despill_factor > 0.0f) {
 		postprocessedImage = setupDespill(graph, postprocessedImage,
Index: source/blender/makesrna/intern/rna_nodetree.c
===================================================================
--- source/blender/makesrna/intern/rna_nodetree.c	(revision 51103)
+++ source/blender/makesrna/intern/rna_nodetree.c	(working copy)
@@ -3758,6 +3758,12 @@
 	RNA_def_property_ui_text(prop, "Screen Balance", "Balance between two non-primary channels primary channel is comparing against");
 	RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
 
+	prop = RNA_def_property(srna, "screen_subtract", PROP_FLOAT, PROP_FACTOR);
+	RNA_def_property_float_sdna(prop, NULL, "screen_subtract");
+	RNA_def_property_range(prop, 0.0f, 1.0f);
+	RNA_def_property_ui_text(prop, "Screen Subtract", "Factor of the background subtraction process");
+	RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
+
 	prop = RNA_def_property(srna, "despill_factor", PROP_FLOAT, PROP_FACTOR);
 	RNA_def_property_float_sdna(prop, NULL, "despill_factor");
 	RNA_def_property_range(prop, 0.0f, 1.0f);
Index: source/blender/nodes/composite/nodes/node_composite_keying.c
===================================================================
--- source/blender/nodes/composite/nodes/node_composite_keying.c	(revision 51103)
+++ source/blender/nodes/composite/nodes/node_composite_keying.c	(working copy)
@@ -74,6 +74,7 @@
 	data = MEM_callocN(sizeof(NodeKeyingData), "node keying data");
 
 	data->screen_balance = 0.5f;
+	data->screen_subtract = 1.0f;
 	data->despill_balance = 0.5f;
 	data->despill_factor = 1.0f;
 	data->edge_kernel_radius = 3;
Index: source/blender/editors/space_node/drawnode.c
===================================================================
--- source/blender/editors/space_node/drawnode.c	(revision 51103)
+++ source/blender/editors/space_node/drawnode.c	(working copy)
@@ -2599,6 +2599,7 @@
 
 	uiItemR(layout, ptr, "blur_pre", 0, NULL, ICON_NONE);
 	uiItemR(layout, ptr, "screen_balance", 0, NULL, ICON_NONE);
+	uiItemR(layout, ptr, "screen_subtract", 0, NULL, ICON_NONE);
 	uiItemR(layout, ptr, "despill_factor", 0, NULL, ICON_NONE);
 	uiItemR(layout, ptr, "despill_balance", 0, NULL, ICON_NONE);
 	uiItemR(layout, ptr, "edge_kernel_radius", 0, NULL, ICON_NONE);