I was working on a photo catalogue and had no image quality issues using jpg but found that rotation issues drove me nuts until I figured out the cause. Windows icon cache file doesn't get rebuilt just because you rotate an image. I lost hair because I'd rotate in any one of 3 photo apps and see a different orientation in file folder so I never knew what I was going to end up with on my form. This was a big problem because I was batch flipping and rotating images with vba and often ended up with upside down images. Turns out that if you do the operations then change the folder icon settings to something else (e.g. list) then back again, the correct orientation is shown. By creating new images, you might have overcome the issue because I'd say it's not jpc vs png - it's Windows icon cache that's the problem.