What image compression does
Compression stores image information more efficiently. Lossy formats such as JPG and WebP can discard subtle detail that is hard to notice, producing much smaller files. PNG uses lossless compression, so its quality does not behave like a JPG quality slider.
How to choose a quality level
For a photographic JPG, 80–85% is a practical starting range. Inspect fine hair, text, gradients and high-contrast edges. Raise quality if block artifacts or banding become visible; lower it if the result remains clean and the file is still too large.
Target-size mode
A target such as 200 KB is useful for upload limits. GetResizer searches for a nearby JPG or WebP quality, but the exact result depends on image complexity. Highly detailed photographs need more bytes than flat graphics.
JPG, PNG or WebP?
- JPG: compatible and efficient for photographs without transparency.
- PNG: best for transparency, screenshots and crisp flat graphics.
- WebP: a strong web default when modern browser support is acceptable.
A practical compression comparison
Export two versions before publishing: one near 90% quality and another near 80%. Compare them at 100% zoom, then check the actual byte size. If the visual difference is negligible, keep the smaller version. For a website, also test the image at the dimensions visitors will really see instead of judging only a zoomed source.
Do not repeatedly compress the downloaded JPG. Return to the original image when another size or quality is needed, because each lossy generation can add artifacts. Keep important originals separately and name exported files so the chosen dimensions and quality remain understandable.
Compression is not a substitute for descriptive filenames, useful alternative text or responsive image markup. Those are separate publishing decisions made after export.