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please could you tell what is the best common quality export value for .jpg image export in the GIMP? For example I set up the 100% for .jpg and for example for image 1,5 MB I will get the 5,2 MB or even more then 7 MB. Is it really better quality than the original photo? Is there any advantages to keep photo in this high quality?

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    \$\begingroup\$ How are you defining "best"? JPEG quality is just about a perfect example of a trade-off you have to make. \$\endgroup\$
    – Philip Kendall ♦
    Commented Jan 22, 2019 at 7:11
  • \$\begingroup\$ "Best" for what end use of the image? The reason we have choices is because different intended usages and different quality versus size priorities benefit from different compression/quality settings. \$\endgroup\$
    – Michael C
    Commented Jan 22, 2019 at 8:06

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Saving at 100% quality will never restore whatever loss has already occurred, and the image from your camera is usually at 95-97 quality. If you save at 100% quality you can as well use a lossless format such as PNG or TIFF (any compression except Jpeg).

In practice, quality depends on intended usage.

  • If you want to keep the picture as a source for further edits(*), good quality is important, otherwise JPEG compression artifacts are going to get in the way (when doing selections, etc...). So keep the quality at 95 and make sure that the "Subsampling" (see the "advanced options" in the JPEG export dialog) is set to 4:4:4 (best quality).
  • If it is a final version (for the web, or print), you can easily lower the quality to 80-85 and use a more aggressive subsampling: 4:2:2 or even 4:2:0. Tick the Show preview in image window option to see in real time the influence of the JPG options on the final output (this also gives you an instant evaluation of the resulting file size) and adjust to your liking. "Sharper" pictures (or pictures with text added) will often require a better quality setting.

(*) while you work on a picture with Gimp, save it as XCF of course, to keep all the layers/channels/paths/selection.

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"Best" practices:

  1. Keep a copy of your original files safe and away from edits.

  2. "Use quality settings from original image" – if the original was a JPEG and your edits were localized.

    When resaving JPEGs, quality loss is limited when the image is unchanged or the changes are localized. Significant degradation occurs when quality settings are changed or when edits are global. See What factors cause or prevent "generational loss" when JPEGs are recompressed multiple times?

  3. Otherwise, use X% at 4:4:4. (X = Your favorite number between 95 and 100.)

  4. For upload to web, use a JPEG minimizer, such as JPEGmini or jpeg-recompress from jpeg-archive.

    Or see What quality to choose when converting to JPG?

Use quality settings from original image

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  • \$\begingroup\$ Sure about 2.? I'd expect that to end up in localized edits at the price of globalized quality loss..... \$\endgroup\$
    – rackandboneman
    Commented Jan 22, 2019 at 13:15
  • \$\begingroup\$ @rackandboneman When resaving JPEGs, quality loss is limited when the image is unchanged or the changes are localized. Significant degradation occurs when quality settings are changed or when edits are global. See What factors cause or prevent "generational loss" when JPEGs are recompressed multiple times? \$\endgroup\$
    – xiota
    Commented Jan 22, 2019 at 16:19

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