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Rescale Image to larger size

lingreonlingreon Registered Users Posts: 82 Big grins

Hi ~ I was wondering if I can scale a 300dpi 11x14 jpg to a larger size ~ to 16x20 and 24x36 without compromising image quality ~ don't want it being pixelated.
and what's the best way to go about it?
Currently using Gimp and Photopea.
Thanks!

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    paddler5paddler5 Registered Users Posts: 4 Big grins
    Are you sure your numbers are correct? Image files have no inherent dpi; dpi refers to the dot pitch of the printer.

    What you need is the number of pixels. I don't use either of those editors, but I assume you they will tell you the dimensions in pixels. If not, you can get it from Irfanview, a free and very useful image viewer.

    So-called uprezzing--increasing the resolution to print larger--will compromise image quality, but that's not the question. The question is when it will damage quality enough that the print isn't good enough for you. That depends on the number of pixels and the quality of the printing software. For example, I have an 11 x 19 print made from an 8 megapixel file cropped from an original 12 megapixel camera, and it looks quite good, printed by Lightroom.

    Smugmug published a table of resolution requirements for printing years ago. You can find it here: https://www.smugmughelp.com/en/articles/452-resolution-requirements-for-printing
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    pathfinderpathfinder Super Moderators Posts: 14,700 moderator
    edited July 4, 2023

    Hi lingreon, paddler 5 gave you a good answer.

    I don't use Gimp or Photopea, so I can't advise you on their abilities at uprezzing images. For years, most uprezzing was done in Photoshop as discussed in my gallery - here - note this gallery about image size was written about 15 or more years ago, but is still correct I believe

    https://pathfinder.smugmug.com/Landscapes/Other/Resolution-Resizing-and-Dots/i-DCGwcNG

    I suspect your 300 pixels per inch file will be adequate to print a 16 inch x 20 inch image as is, but will be better if uprezzed to a more appropriate number of total pixels, maybe 200 pixels per inch x 16 inches, would require 3200 total pixels at a minimum, along the short side of the final print. Be aware, we are discussing pixels per inch and total pixels in the image. As paddler5 pointed out, DPI is a printer's term, and refers to dots per inch placed on paper by an inkjet style printer. A printer may easily print 4-8 or 10 dots per each individual pixel in the image, on paper.

    My preferred technique to uprez images today - especially images that are woefully too small in total pixels for adequate enlargements - is PhotoAI by Topaz, but there are a number of AI software programs out there now to uprez images by creating pixels that are not present in the original image scan. Topaz AI will uprez an image, help reduce image luminance and color noise, sharpen the image if needed or desired, recognize and help clarify facial features, and will work alone or in conjunction with Photoshop and Lightroom Classic. Topaz AI is not always perfect, but none of the AI softwares are always perfect either. But Topaz AI can by adjusted by the user to help direct it towards the desired goal of sharpening, enlarging, and noise reduction. I find it quite helpful with old scans of old images. I frequently receive scans from family members that might have been better done initially, or had more pixels, but TP AI has rescued me many times, Just sayin'

    Incidentally, Topaz AI works with RAW, DNG, tif and jpg files, so it should be able to be used with your workflow with Gimp is some manner I think. I don't used gimp, as I said, but it's current capabilities look quite impressive. It was always some folks preferred editor, in lieu of Photoshop, but seemed to have a very similar set of steps and procedures.

    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
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