When inserting a raster PNG image into Microsoft Visio 2007, it tries to make it smoother by interpolating pixel colors. It seems like Visio interpolates border pixels with white as if image was surrounded by white border. Since the image was created to have background that matches the background on the page, it is important that border pixel color is unchanged, which is not the case. In print this border is clearly visible.
Compare image in Visio (background is created by the filled rectangle):
with actual image in Paint:
As you can see lighter border is not present in the original image. How to get rid of it?