How to make image not stretch?

Stretch="None" should do exactly that. If there is a difference in how the Image is displayed that may be due to pixels ending up "on edge".

You could try setting SnapsToDevicePixels="True" to avoid this.

Try using RenderOptions.BitmapScalingMode="NearestNeighbor".

You may want to read these:

• My images are blurry! Why isn't WPF's SnapsToDevicePixels working?
• Blurry Bitmaps - Dwayne Need

Adding Stretch = None keeps the image from rezising

<ImageBrush ImageSource="rtgEnhanced.png" AlignmentX="Left" AlignmentY="Bottom" Stretch="None"></ImageBrush>