Screenshots are the worst case for image compression and the most common slide asset. A UI capture is mostly flat colour and hard edges, including small text, which is exactly what a JPEG encoder discards first: it spends bits on the smooth gradients it can predict and leaves blocky noise around glyphs. That is why a slide screenshot can look sharp on your monitor and smeared on a projector at the back of a room. Two rules follow. Keep screenshots as PNG, because lossless is the only mode that treats small text fairly. And cut the pixel count to the frame instead of leaning on quality sliders: a 3000 px capture displayed at 1920 x 1080 px is storing more than three times the pixels the room can resolve, and resizing down before compression removes most of the weight with no visible loss at all. If a screenshot must be JPEG, oversize it slightly and compress gently rather than compressing hard at native size. Skwish keeps PNG and JPEG as separate output choices and shows the before and after, so a deck's screenshots stay legible.