A gig image is the whole pitch in one picture: it has to carry a service name, a visual hook, and enough polish to justify a click in a crowded grid. That combination of text and artwork is exactly what generic compression handles badly — fine lettering smears first, and busy backgrounds turn blocky before anything else degrades. So the job is to shrink the file without touching the parts a buyer actually reads. Skwish resizes to the marketplace's recommended frame and compresses in the browser with a live size readout, so you can step the quality down until the thumbnail is light and stop the moment the text starts to soften. Run a whole set of gigs through in one batch and export them together, all without uploading your designs anywhere.