I had a problem like that too. I'd edited a image in photoshop and then tried converting it and it wouldn't work.

When I tried a different image, one that I didn't do any weird editing on, aside from cropping and reducing color depth, it worked fine.

Pretty sure I was using .png's in both cases.


You probably need to move the logo.png out of the mounted boot.img directory. I had to in order to be able to edit anything in the boot.img. Only logo.16 is used anyway. So just mv logo.png up one level. Do your editing and move it back when your done. It will become an incomplete file and just fill space, because you will most likely be slightly increasing the size of fixed-size boot.img, and there won't be enough room to move the whole file back, only part of it. As I asid, its seems to be there only to fill space anyway.