Har du billeder, som fylder meget på disken, kan du få dem til at fylde mindre uden at ændre billedets dimensioner. Den bedste billedkomprimering fås med JPG-formatet, men selv hvis billedet allerede er i dette format, kan du sædvanligvis få det til at fylde mindre, da JPG-formatet kan komprimeres i forskellige grader. Men jo hårdere et billede komprimeres, og dermed fylder mindre, desto flere detaljer mistes. Du skal også være opmærksom på, at åbnes og gemmes et billede gentagne gange i JPG-formatet, tabes kvalitet hver gang.

Images are loaded and saved as .XCF files. Your JPG image has been loaded as XCF. GIMP offers you to Overwrite image-name.jpg or File → Export As to open the “Export Image” dialog.

The dialog opens with the file name already typed in the Name box, with the default .png extension. Delete the existing extension and type JPG instead, and GIMP will determine the file type from the file extension. Use the file extension list, marked with red in the figure above, to see the types supported by GIMP. The supported extensions change depending on your installed libraries. If GIMP complains, or if “JPEG” is disabled in the list of extensions, cancel and step through Afsnit 4.7, “Skift tilstanden”. Once you have done this, click Export. This opens the “Export Image as JPEG” dialog that contains the Quality control.

Dialogen “Eksportér billede som JPEG” bruger standardværdier, som reducerer filstørrelsen, mens en høj kvalitet opretholdes. Dette er den sikreste og hurtigste måde at gøre det på.

Reduce the image Quality to make the image even smaller. Reduced quality degrades the image, so be certain to check “Show preview in image window” to visually gauge the degradation. A Quality setting of 10 produces a very poor quality image that uses very little disk space. A quality of 75 produces a reasonable image using much less disk space, which will, in turn, load much faster on a web page. Although the image is somewhat degraded, it is acceptable for the intended purpose.

Til sidst er her en sammenligning af det samme billede med forskellige grader af komprimering: