Mostly white images cannot be decoded

[tanabi]

I'm not sure what the problem is exactly. When I try to encode a message (any message) into the attached image, the image cannot be recovered. The pixel setter somehow is not able to encode the message, and when the message is extracted it's completely scrambled and I am unable to make sense of it.

At first, I thought maybe it was a problem with greyscale -- but this is an 8 bit color PNG so it doesn't seem to be the problem. Maybe the problem is that the image is mostly white, and the entire block of pixels that we want to encode into is all white.

This isn't a show stopper for my application as I think this is an edge case, but if you happen to know how to fix it, that would be awesome ...!

Thanks!