The ChipGuide will accept photo images as PNG, GIF or JPG formats. GIF and JPG's are compressed formats, to reduce image size. PNG format is not compressed. That is why there is a difference in size, even though they may look the same. The ChipGuide has a maximum file size of 500K, the PNG was greater than 500K and that is why it was rejected. The jpg was less than 500K and was accepted.