ImageStats : Fix handling of min/max outside data window

Changes.md

@@ -46,7 +46,9 @@ Fixes
   - Stopped failed jobs jumping to the end of the Local Jobs UI.
   - Fixed message log update.
   - Fixed `Job.statistics()` errors on Windows, ensuring that a `pid` is always returned when available.
-- ImageStats : Fixed output of infinite values, which were previously being clamped.
+- ImageStats :
+  - Fixed output of infinite values, which were previously being clamped.
+  - Results for min/max now correctly reflect zero values outside the data window.
 - NodeMenu, NodeEditor : `userDefault` metadata is now evaluated in the script context, so it can depend on script variables.
 
 API

python/GafferImageTest/ImageStatsTest.py

@@ -188,6 +188,40 @@ def testROI( self ) :
 		self.__assertColour( s["min"].getValue(), imath.Color4f( 0.25, 0, 0, 0.5 ) )
 		self.__assertColour( s["max"].getValue(), imath.Color4f( 0.5, 0.5, 0, 0.75 ) )
 
+		# Offset the colors in the image so we can see the effects of whether or not we include pixels outside
+		# the data window.
+
+		g = GafferImage.Grade()
+		g["in"].setInput( r["out"] )
+		g['channels'].setValue( "*" )
+		g['blackClamp'].setValue( False )
+		g['whiteClamp'].setValue( False )
+		g['offset'].setValue( imath.Color4f( 1 ) )
+
+		s["in"].setInput( g["out"] )
+
+		s["area"].setValue( imath.Box2i( imath.V2i( 20, 20 ), imath.V2i( 25, 25 ) ) )
+		self.__assertColour( s["average"].getValue(), imath.Color4f( 1.5, 1, 1, 1.5 ) )
+		self.__assertColour( s["max"].getValue(), imath.Color4f( 1.5, 1, 1, 1.5 ) )
+		self.__assertColour( s["min"].getValue(), imath.Color4f( 1.5, 1, 1, 1.5 ) )
+
+		s["area"].setValue( imath.Box2i( imath.V2i( 19, 20 ), imath.V2i( 24, 25 ) ) )
+		self.__assertColour( s["average"].getValue(), imath.Color4f( 1.2, 0.8, 0.8, 1.2 ) )
+		self.__assertColour( s["max"].getValue(), imath.Color4f( 1.5, 1, 1, 1.5 ) )
+		self.__assertColour( s["min"].getValue(), imath.Color4f( 0, 0, 0, 0 ) )
+
+		g['offset'].setValue( imath.Color4f( -2 ) )
+
+		s["area"].setValue( imath.Box2i( imath.V2i( 20, 20 ), imath.V2i( 25, 25 ) ) )
+		self.__assertColour( s["average"].getValue(), imath.Color4f( -1.5, -2, -2, -1.5 ) )
+		self.__assertColour( s["max"].getValue(), imath.Color4f( -1.5, -2, -2, -1.5 ) )
+		self.__assertColour( s["min"].getValue(), imath.Color4f( -1.5, -2, -2, -1.5 ) )
+
+		s["area"].setValue( imath.Box2i( imath.V2i( 19, 20 ), imath.V2i( 24, 25 ) ) )
+		self.__assertColour( s["average"].getValue(), imath.Color4f( -1.2, -1.6, -1.6, -1.2 ) )
+		self.__assertColour( s["max"].getValue(), imath.Color4f( 0, 0, 0, 0 ) )
+		self.__assertColour( s["min"].getValue(), imath.Color4f( -1.5, -2, -2, -1.5 ) )
+
 	# Test only tiles which intersect a changed boundary have modified hashes
 	def testROIHash( self ) :
 

src/GafferImage/ImageStats.cpp

@@ -337,6 +337,7 @@ void ImageStats::hash( const ValuePlug *output, const Context *context, IECore::
 	}
 
 	Imath::Box2i boundsIntersection;
+	bool beyondDataWindow;
 	double areaMult;
 
 	{
@@ -363,6 +364,7 @@ void ImageStats::hash( const ValuePlug *output, const Context *context, IECore::
 		}
 		const Imath::Box2i dataWindow = flattenedInPlug()->dataWindowPlug()->getValue();
 		boundsIntersection = BufferAlgo::intersection( area, dataWindow );
+		beyondDataWindow = boundsIntersection != area;
 		areaMult = double(area.size().x) * area.size().y;
 	}
 
@@ -384,6 +386,8 @@ void ImageStats::hash( const ValuePlug *output, const Context *context, IECore::
 			return;
 		}
 
+		h.append( beyondDataWindow );
+
 		// We traverse in TopToBottom order because otherwise the hash could change just based on
 		// the order in which hashes are combined
 		ImageAlgo::parallelGatherTiles(
@@ -442,6 +446,7 @@ void ImageStats::compute( ValuePlug *output, const Context *context ) const
 	}
 
 	Imath::Box2i boundsIntersection;
+	bool beyondDataWindow;
 	double areaMult;
 
 	{
@@ -468,6 +473,7 @@ void ImageStats::compute( ValuePlug *output, const Context *context ) const
 		}
 		const Imath::Box2i dataWindow = flattenedInPlug()->dataWindowPlug()->getValue();
 		boundsIntersection = BufferAlgo::intersection( area, dataWindow );
+		beyondDataWindow = boundsIntersection != area;
 		areaMult = double(area.size().x) * area.size().y;
 	}
 
@@ -510,6 +516,12 @@ void ImageStats::compute( ValuePlug *output, const Context *context ) const
 		float max = -std::numeric_limits<float>::infinity();
 		double sum = 0.;
 
+		if( beyondDataWindow )
+		{
+			min = 0.;
+			max = 0.;
+		}
+
 		// We traverse in TopToBottom order because floating point precision means that changing
 		// the order to sum in could produce slightly non-deterministic results
 		ImageAlgo::parallelGatherTiles(