I saw on the Internet that an image ppi /dpi can be changed within gimp. I think I have seen before that you cannot change an image to look good if the ppi is changed.
Assuming the image is already large but has a small ppi - 72. Can it be successfully converted to 300?
What I saw -
How Do I Make an Image 300 DPI Without Photoshop?
(09-07-2023, 03:44 AM)sallyanne Wrote: [ -> ]I saw on the Internet that an image ppi /dpi can be changed within gimp. I think I have seen before that you cannot change an image to look good if the ppi is changed.
Assuming the image is already large but has a small ppi - 72. Can it be successfully converted to 300?
What I saw -
How Do I Make an Image 300 DPI Without Photoshop?
Ofnuts did a nice page to catch the concept of ppi/dpi/pixels/inch that I can only recommend >
https://www.gimp-forum.net/Thread-Image-size-in-Gimp
It's worth the reading
(09-07-2023, 03:44 AM)sallyanne Wrote: [ -> ]I saw on the Internet that an image ppi /dpi can be changed within gimp. I think I have seen before that you cannot change an image to look good if the ppi is changed.
Assuming the image is already large but has a small ppi - 72. Can it be successfully converted to 300?
What I saw -
How Do I Make an Image 300 DPI Without Photoshop?
I saw your post on pixls.us "What is high resolution" in connection with improving scanned photographs. Gimp is raster based and the rule of thumb is 300 pixels-per-inch (ppi) = high enough resolution for quality printing.
That articles says "
With GIMP, you can open your low-resolution image and change the DPI setting to 300. This will give you a high-quality image that is ready for print." which is unlikely to be true in most circumstances.
If you take a common photo size say 4"x 6" then the pixel size in Gimp depends on the scan resolution.
72 ppi = 288 x 432 pix
300 ppi = 1200 x 1800 pix
and say 600 ppi = 2400 x 3600 pix
Changing the ppi using
Image -> Print Size does not change the image size in pixels just the print size. Change the 72 ppi to 300 ppi, pixel size remains 288 x 432 but the image prints at 0.96 x 1.44 inches, scarcely larger than a postage stamp.
Try it, make an image 4" x 6" @ 72 ppi Change the ppi to 300 Image -> Print Size, set the zoom level to 100% and then into the View menu and turn off dot-for-dot and that is what the image looks like printed. The only way to get back to 4" X 6" @ 300 ppi is
scale the image and risk the interpolation leading to degradation.
If the scan is greater than 300 ppi then generally just leave alone. If it goes to print, the printer software does the work for you.
Thank you Pix and Rich for your answers
I will check out that article later Pix and Rich I didn't think it could be done.
The image is already 2000+ on one side and probably a bit smaller on the other, but still only 72 dpi