fix static_cast to allow subtraction of negative min.x and min.y values

Author: michaeldsmith

lib/IlmImfCtl/ImfCtlApplyTransforms.cpp

@@ -487,8 +487,8 @@ applyTransforms
     // Determine how many samples we will process.
     //
 
-    size_t totalSamples = (static_cast<size_t>(transformWindow.max.x) - static_cast<size_t>(transformWindow.min.x + 1)) *
-			  (static_cast<size_t>(transformWindow.max.y) - static_cast<size_t>(transformWindow.min.y + 1));
+	size_t totalSamples = static_cast<size_t>(transformWindow.max.x - transformWindow.min.x + 1) *
+	  static_cast<size_t>(transformWindow.max.y - transformWindow.min.y + 1);
 
     if (totalSamples <= 0)
 	return;