Q: Why is the file size sometimes bigger after compression?
If you compress a jpg that has already been compressed you probably won’t see any reduction in file size, in fact, the file may even be bigger!
If you compress a high-quality image with very little compression, you’re going to see great savings. This is when Squash really shines.
If you’re still unhappy with the amount Squash has compressed your file, do the following: Try lowering the compression rate in the preferences, move it down in 10% increments, and then compress the original image again. By doing this you can look at the image after each export and make sure you’re happy with the look of the file and its size.