If you use xat, you have to play with it to get to know how it works. I have always used the free version, and the compression feature, the symbol with the "fist" will get the file size down a lot. Cropping doesn't do that much, except clean up what we want the picture to show. I start with cropping and then compress, sometimes to 30% of original values, and when you save the optimized image, you will find it is full size to view and still good quality.