Google is disapproving my images. Why could this be happening?

As a rule image issues have to do with the images being sent with the feed which are the ones uploaded in the store. The key is checking the images in the feed for those items and compare against Google's guidelines. Typical issues include text on the images, incorrectly sized images, too much white space, other items in the image, etc. You can download the feed from the google merchant center and you should be able to even see the image urls and images in the feed as well. It can also be related to encoding.  For more information see:

https://support.google.com/merchants/answer/6183365?hl=en

https://support.google.com/merchants/answer/6098289?hl=en