I have a small tiling .gif image animation (16 bytes by 32 bytes, 2 layers) that uses too much cpu time and I want to make it bigger. I have no experience with Gimp and I have found the only way to solve my problem is to run an HTML file with this tiling as a background image and take a few screen shots till I have a big image of each layer. I have managed to do that.

The next step is to get a screen shot of those images starting and ending at a precise pixel (-> Acquire -> Screen Shot -> Single Window -> Select Window After 1 Seconds Delay -> Grab After 100 Seconds Delay) to obtain an exact multiple of the initial file, horizontally and vertically.

The problem is if I insure that all of the wanted portion is in the screen, 1 pixel is so tiny that even if I get the cursor at the right location, the simple action of releasing the button of the mouse puts it out of alignment. And if I zoom into the image then the wanted image is partly outside the screen and Gimp does not scroll.

(There is no help yet in the user manual on this subject.)

Can anyone advise how to overcome this problem? Is there a way to enter the top left corner values and the bottom right values? If I get an image slightly bigger than wanted how can I adjust it to the pixel?

I understand if I manage to solve this precision problem then it is only a matter of opening the first image and drag and drop the second in the tool box and this will automatically create the second layer and an animated .gif.

Any advise most welcome.

Thank you for your help.

I stumbled by accident on the "crop" tool that did the job perfectly, allowing to enter the coordinates. I used it to adjust the new and bigger files to the pixel, saved each then opened the first and dragged the second onto the first, which gave a single image with two layers, which the Gimp only allowed to save as animation, which was perfect.

It was a lot easier than I anticipated.

If you use Image Magick's "import" you can add the exact size and x-y-coordinates of your image at the command line and import will just grab exactly this.

See man import for (many more) details.

Image Magick is a must-have even though if you already have Gimp.

Thanks to Su-Shee for the tip. It looks like you are correct, I had to use it, under guidance, a few months ago.