Question: Why did JPEGmini skip some of my photos?
Answer: JPEGmini will skip over photos if they are highly compressed.
JPEGmini has a built in quality detector that scans every image that goes in, in order to determine the amount of optimization that can be done to the photo without harming the quality of the photo. If the photo you are trying to compress were to be optimized any further, artifacts may be introduced into the photo and we would never want that to happen.
We take photo quality very, very seriously. We always recommend putting the original images through JPEGmini for optimal results.