Enter new values into the fields Resolution Horizontal or/and Resolution Vertical.
In this case the total amount of pixels in the image will stay the same. You can resize that smaller image back to its original size, but it'll look fuzzier than the original. For example making an image smaller makes it less clear. Each change you make has the potential of losing information. We recommend using image files of less than 500 KB for best results, though the limit for an individual image upload is 20 If you're adding multiple images to a page, keep your overall page size in mind.