How to Choose Image Compression Quality Without Guessing

What the percentage does and does not mean

An 80% quality setting does not mean the output keeps exactly 80% of its pixels, looks 80% as good, or becomes 20% smaller. It is an instruction to the encoder. Its practical effect depends on the picture, format, and browser. Do not compare quality numbers across unrelated tools as though they were a shared measurement scale.

CorvexsDigital offers quality control for JPG and WebP. PNG uses a different approach here, and the slider is disabled for PNG output. If you are judging a quality setting specifically, select No limit so a target-size search does not choose a lower value on your behalf.

Choose three meaningful inspection areas

Before exporting, identify what must remain legible or attractive. In a product photograph, this might be a printed label, a textured surface, and a smooth background. In a portrait, it could be hair, eyes, and a softly shaded wall. Having inspection areas prevents you from accepting a smaller result just because the thumbnail looks fine.

Compare at the intended display size first, then zoom in to inspect suspicious changes. Pixel-level differences that cannot be seen in the intended use may be an acceptable tradeoff. Visible damage to important text is usually a stronger reason to keep more detail.

A repeatable three-export comparison

Choose JPG or supported WebP, select No limit, set one maximum width and keep that width unchanged. Export at 80% first. From the same original, export at 65% and 90%. These are comparison settings, not recommended quality scores for every image.

Record each filename, actual bytes, output width and height, and whether your three inspection areas pass. Reject any copy with unreadable required text or objectionable artifacts. Among the remaining copies, choose the smallest. If none passes, revisit dimensions or the source instead of increasing the number of exports.

Check dimensions and format before blaming quality

If the file is still large at an acceptable quality, consider whether it carries unnecessary pixels. An image intended for a narrow column may not need its full camera resolution. Conversely, if text is unreadable because the output was resized too far, raising encoding quality will not recreate those missing pixels.

Changing format is another controlled experiment. Keep dimensions consistent while comparing JPG with WebP, if the receiving system accepts both. Otherwise you are changing several variables at once and cannot tell what caused the difference.

Know when to stop

Choose the smallest version that still meets the actual purpose of the image, and leave a little room for future uses. An archival master, a printable document, and a website thumbnail have different goals. One compressed file should not automatically replace all three.

For a strict upload limit, target mode can make the size decision for you, but you still need to decide whether the result is useful. A technically valid attachment with unreadable details is not a successful outcome.

Common question: can higher quality restore detail?

No. Increasing an export setting cannot undo damage already present in the input. If a previous compressed image looks poor, return to the original capture or the best available master. Quality controls influence the next encoding step; they are not restoration tools.

Questions & answers

Your next step

Compare a small set of exports from the same original and inspect the important detail, not only the file size.

What changed on 7 October 2026

Replaced vague experimentation advice with a fixed-dimensions, three-export comparison.