Fix issue #43

Former-commit-id: b595749cba5c62e8a95dc1bf16d367b1078559ae

src/ImageProcessor/Processors/Resize.cs

@@ -367,10 +367,12 @@ namespace ImageProcessor.Processors
 				// Constrain the image to fit the maximum possible height or width.
 				if (resizeMode == ResizeMode.Max)
 				{
-                    if (sourceWidth > width || sourceHeight > height)
+					//If either is 0, we don't need to figure out orientation
+					if (width > 0 && height > 0)
 					{
-                        double ratio = Math.Abs(height / width);
+						//integers must be cast to doubles to get needed precision
-                        double sourceRatio = Math.Abs(sourceHeight / sourceWidth);
+						double ratio = (double)height / width;
+						double sourceRatio = (double)sourceHeight / sourceWidth;
 
 						if (sourceRatio < ratio)
 						{