How does compressing an image work?
Drop one image or a whole set onto the grid. Then press the single Compress button. Each file comes back smaller in the same format it went in as, your JPG as a JPG, your PNG as a PNG. A real progress bar tracks the work. When it finishes, you download one file on its own, or your set as a single zip. There is nothing to configure first. You add your pictures and press one button.