I am trying to change an image to 2688x1242.

But GIMP changes to 2688 to 2606. What should I change, interpolation?

CodePudding user response：

By default, Gimp keeps the aspect ratio (height/width constant). If you want to scale these independently, you click the chain link icon between the width and height fields to open it:

You can then use arbitrary values, with the caveat that this can make your image look distorted (flattened/stretched). Usually, you scale the image keeping the aspect ratio, and either add margins on the side that is too small, or crop some on the side that is too big.