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+--- Thread: Very beginner question - image resize (/Thread-Very-beginner-question-image-resize)
Very beginner question - image resize - nmw01223 - 05-24-2025
I've just started using GIMP (2.10.14) after using an old copy of Photoshop for years (decades). So, my general knowledge of image editing is OK, but my knowledge of GIMP - zero.
So, very dumb question, want to scale the pixels/inch of an image. I've got a scanned image (B/W, TIF) that is very long and thin - one of those old school pictures taken with a panning camera. It was scanned and stitched together at 1600ppi, which is really way too big for my needs. So, want to down convert it to 600ppi. Should be simple ... .
So, started GIMP, dragged the image in, and it loads OK. Go to scale image and it shows the image as roughly 58000x8000 pixels at 1600ppi X and Y. X and Y are linked, so change X to 600ppi, and, yes, Y changes to 600ppi. , Click scale, so far so good.
Export as TIF, writes OK. But, load it up again, and it still says 58000x8000, 1600ppi. Same size file, too.
So, tried again, but this time just saved it as its native format, and reloaded it. This time it said 600ppi - good, but still listed the overall resolution as 58000x8000 - which it clearly wasn't or there would have been a lot of blank space.
Confused, should be very simple, what am I doing wrong?
RE: Very beginner question - image resize - rich2005 - 05-24-2025
First a question ? Why Gimp 2.10.14 - nothing wrong with Gimp 2.10 but the last version was Gimp 2.10.38
..then of course there is now a Gimp 3.0.4 (but makes no difference to your question)
In pictures, it is all about the sequence. Using Image -> Scale Image
[attachment=13508]
First change the width and height (1) I am using a percentage here, but you can see the size in pixels has changed.
I could leave it like that but I then change the resolution to half what it was (2). Why do that ? It is about print size. Go to Image -> Print Size and that keeps the original size in real world units (remember Gimp works in pixels) if you want to print it.
[attachment=13509]
Now Export your 50 % scaled image (with a better scaling interpolation (3) ) and a new name to keep the original safe.
Edit: Just reading your post again 1600 ppi -> 600 ppi That is 37 % -ish I normally would not recommend going much below 50 % but up-to-you