Is the PNG optimized? Macromedia Fireworks has a great export control which allows you to take a 32k PNG and optimize it down to about 6k for embedding. I use PNG8 / 256 Colors / Indexed Transparency.
What are your export settings for the PNG background strip?
Failing that... A basic set of unit tests would be good place to start and it's easy...
Test A - Is there a "one off" error some where?
1) provide a strip which is a single color except for a single pixel of a different color (all blue strip with a red pixel in middle)
2) have your developers render the strip and check to see if the red pixel walks across the screen diagonaly... if it does then there is a "one-off" or more error somewhere in the rendering loop...
Test B - can the PNG renderer handle a 1 pixel wide strip?
1) provide a strip which is half the height of the display and 1 pixel in width to your developers
2) have them display a single instance of the strip centered in the display... does it look correct?
3) have them display 2, 3, 4, ... etc side beside also centered in the display... do these look correct...
Test C - Is the bitmap PNG being mangled by resource packing?
1) Most likely your strip is being embedded as an embedded resource
2) have your programmers load the PNG from a file resource such as the SD Card Store (easily done with the simulators)
3) is the background correct? If it is then the bitmap is being mangled when embedded as a resource..
