GIMP :: Cannot Change Image Pixel Dimensions From Print Size Dialogue

"Image > Print Size" really IS the command you are looking for.

The key is to pay attention to the units-of-measure shown on the Print Size dialogue box:- The "Width" and "Height" values under Print Size are displayed in real-world units (inches, mm, etc.), not image pixels.- The "Resolution" values are displayed in pixels-per-unit.- You cannot change your image's pixel dimensions (aka scale the image) from the Print Size dialogue. That's what the "Scale Image" command is for.Remember the relation between pixel and print sizes is:(print size) = (pixel size) / (print resolution)

When you change the image's print resolution, of course the real-world size (the "width" or "height" shown in the Print Size dialog) of your image will update to reflect the new print resolution -- that value is calculated from your image's actual pixel size and whatever resolution value you just entered. This is totally normal behavior -- in fact, it's expected. If you change an image's resolution from, say, 150 pixels/inch to 75 pixels/inch, this doubles the print size of your image but only the print size; the image's pixel size remains precisely the same as before. (You can confirm this by comparing "Image > Canvas Size..." before and after changing the resolution.)

And as others have stated, if you're using the image for Web viewing then its print resolution has absolutely zero effect on how it will appear onscreen (print resolution only affects, well, actual printing), in which case you'll want to use the "Scale Image" command to actually scale your image larger or smaller.