Compression changes image colors or transparent edges: how do you compare export settings?

Preserve the original and record the actual export format

This applies to duller product colors, dark transparent-edge halos and differences between the editor and website. Record dimensions, actual format and transparency, not just the extension. Disable unnecessary automatic enhancement during comparison so viewer color-management differences are not mistaken for compression-induced pixel changes.

Check color profiles, transparency and resizing separately

Check required ICC profile preservation and color-mode conversion. Inspect Alpha loss or compositing against the wrong background, especially along partially transparent edges. JPEG generally cannot retain Alpha, so conversion needs an explicit background choice. Repeated lossy saves can damage small text and lines; raising quality on the last save cannot restore them.

Change one export parameter at a time

Re-export from the original and compare candidates differing only in quality or format rather than repeatedly compressing the output. Use transparency-supporting output where required and handle color according to the destination. Validate resizing separately from compression and retain reproducible export settings. Removing metadata and indiscriminately discarding color profiles are different operations.

Reopen the final file and compare colors and edges

Reopen exported files and compare important color regions, fine lines and transparent edges at the same scale and background, then test the destination website. Acceptance requires both size limits and acceptable visual deviation. Precise color requires defined color conditions and appropriate measurements; ordinary screen inspection does not establish print color accuracy.

This article compressed no private images and offers no setting that losslessly shrinks arbitrary files. Format support and encoder options vary by version, so consult current export documentation. Displays affect appearance. Separate opacity problems from color processing instead of attributing every color change to transport or caching.