Image Quality Compare

How to use it

1. Pick an image file. It is resized internally if either dimension exceeds 1600 pixels, so the comparison stays fast.
2. The four panels render JPEG quality 0.9, 0.7, 0.5 and 0.3 of the same picture, each with its exact file size.
3. Zoom in on flat areas, edges and text - that is where compression artifacts show first.
4. Click Download under the panel whose trade-off between size and quality you accept.

Common use cases

• Choosing a blog image setting - see how far you can push quality down before artifacts appear.
• E-commerce and marketplace photos - meet strict file size limits while keeping products recognizable.
• Email and chat attachments - pick the level that keeps a screenshot readable at a fraction of the size.
• Learning JPEG behavior - watch blocky artifacts appear at 0.3 while 0.9 stays close to the original.

Why it stays private

Compression and previewing run entirely on canvases in your browser. The picture is never uploaded, and downloads are produced from local blobs.

FAQ

Q: Why do the four panels show the decoded JPEG instead of the original pixels? A: Each panel re-draws the encoded result, so blocky artifacts and ringing are visible exactly as they will appear in the saved file.

Q: Does quality 0.9 always look identical to the original? A: Not always. JPEG is lossy at every setting, but at 0.9 the difference is usually invisible. Compare text and thin lines to spot exceptions.

Q: Can I compare PNG output or other formats too? A: This tool focuses on JPEG levels because they share one encoder and one scale. For lossless formats the sizes are usually far larger, so the side-by-side ratio would not be informative.