I've got horizontal colored bands in photos copied to my computer that were not there when I viewed the photos on the camera. I eventually ruled out everything else and determined that the USB card reader was the problem. How do the photos get changed during the copy process?
The card reader claimed to be USB 3.0 compatible. The computer in question has USB 2.0 (Lenovo X220). The images in question are all JPG.
I got rid of the problem by copying the photos with another reader.
Here's the photo with the colored bands: