1. OurJud

    OurJud Contributor Contributor

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    Photo editing tech help required

    Discussion in 'The Lounge' started by OurJud, Mar 18, 2018.

    Before I ask the question, can I ask that people don't simply point me to a wiki site or other tech-heavy explanation. I need an answer in layman's terms (if indeed the answer can be given as such).

    When I resize my photos (using GIMP) to 620px wide (the same width as the post area on my tumblr) the XY resolution is set to 72.00 px/in by default. I'm guessing this is a fairly low resolution, but when I up this to 300 px/in the image doesn't come out at 620px (even though that's the size I set). It comes out much smaller.

    How do I get the size I want but with a higher resolution?
     
  2. big soft moose

    big soft moose An Admoostrator Staff Supporter Contributor Community Volunteer

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    I don't know about gimp , but in most applications if you want to change the resolution without effecting the dimensions you need to untick the box that says "constrain proportions" or similar (sometimes shown as a little chain). Make sure you retick it before you alter dimensions or you'll distort the picturde

    Basically pixels per inch controls the number of pixels in a square inch so if you only have a finite number of pixels, if you quadruple the number of pixels in a square inch the pixels are more densely packed and therefore cover a smaller area. If you want them to cover the same area you need to quadruple the number of pixels (by a process called interpolation but lets not worry about that)

    That said if you only want onscreen display 72ppi will be fine - the resolution only really matters if you want to print
     
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  3. Wreybies

    Wreybies Thrice Retired Supporter Contributor

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    First off, I do use GIMP for everything. ;)

    Agreed with Moose, in that 72 px/in is not as low res as it might sound for on-screen viewing. 300 px/in is whoppingly high res for mortal beings. Yes, some photo expert is going to come along and indicate why you pretty much need to save photos at terabyte size for "real" resolution, but assuming you are a regular Joe like moi, this is not the case.

    The only time I render an imported image at anything about 200 px/in is when I am working on crime scene schematics. The originals that come from the Forensic Sciences Institute of Puerto Rico are printed on very large sheets of paper, appropriate for putting up on a tack-easel that can be viewed at a distance by those in the courtroom. The physical size of the item means I need to bring it in at high res otherwise the output pixelates dramatically. The translation work I am doing on said document is all the little notations in the original schematic, from Spanish to English.

    Try bumping it up to like 100 px/in if you're looking for something that stays a little cleaner upon zooming. 300 px/in is wicked high. I'm not surprised a threshold is being crossed where there's a conflict causing this problem.
     
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  4. OurJud

    OurJud Contributor Contributor

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    @big soft moose, @Wreybies - thank you both. As my photos are only for my tumblr (they don't even link to a bigger version) I'm happy to continue posting them at 72.00 px/in. I was just making the assumption I was losing a lot of quality. I've now compared the originals with the resized and I think it's simply the much smaller dimensions, plus my failing eyesight that led me to believe they were losing clarity.

    Thanks again.
     
  5. big soft moose

    big soft moose An Admoostrator Staff Supporter Contributor Community Volunteer

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    Yeah you stuck me as someone who might be into that ;)

    Personally I'm a straight vanilla adobe boy
     
  6. Wreybies

    Wreybies Thrice Retired Supporter Contributor

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    In related news... The gimp shack is coming along nicely. :whistle:

    It's really my new toolshed. Never did find most of the old Home Depot plastic jobbie that Maria blew away. :bigconfused:

    And for the sake of remaining on-topic, this image is 800 x 600 at 72 px/in. :-D

    IMG_0474.JPG
     
  7. big soft moose

    big soft moose An Admoostrator Staff Supporter Contributor Community Volunteer

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    looking good, but won't it be a bit cold and wet without a roof :D
     
  8. newjerseyrunner

    newjerseyrunner Contributor Contributor

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    I'm confused, if you have your image currently at 72, how would upscaling it increase quality? Upscaling would just do an interpolation.
     
  9. big soft moose

    big soft moose An Admoostrator Staff Supporter Contributor Community Volunteer

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    if it was a massive dimensioned file originally ( a lot of cameras output in 72 ppi native so your 20MP file wins up being 1m x 1.5m or something) but jud was reducing the dimensions first ... he could alter the ppi first then alter the dimension and retain more detail
     
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  10. Iain Sparrow

    Iain Sparrow Banned Contributor

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    72ppi is screen resolution, 300ppi and higher is print resolution. Personally, images that I work with that are destined for print are set to 432ppi. Changing pixel resolution should not effect the dimensions of the image. And don't use GIMP.
     
  11. big soft moose

    big soft moose An Admoostrator Staff Supporter Contributor Community Volunteer

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    It does you know ... in photoshop as well as gimp (unless you have the resample box ticked, or constrain proportions unticked)
     
  12. Iain Aschendale

    Iain Aschendale Aunt? Supporter Contributor

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    And I bet @Wreybies learned how by just asking him nicely:

    [​IMG]

    Sorry, I'll show myself out of the thread.
     
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  13. Cave Troll

    Cave Troll It's Coffee O'clock everywhere. Contributor

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    Isn't he running for something?
    Gimp Whitely.jpg
     
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  14. OurJud

    OurJud Contributor Contributor

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    What’s wrong with GIMP? It’s more than adequate for my needs.
     
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  15. OurJud

    OurJud Contributor Contributor

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    It does change the size as you say, but the proportion constraints is only there if you need to alter the width:height proportions. Unchecking this won’t stop the overall dimensions changing when you change resolution.
     
  16. Steerpike

    Steerpike Felis amatus Contributor

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    Yeah. It’s what I use as well, though my needs are relatively limited.
     
  17. big soft moose

    big soft moose An Admoostrator Staff Supporter Contributor Community Volunteer

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    It should do . It does in photoshop
     
  18. big soft moose

    big soft moose An Admoostrator Staff Supporter Contributor Community Volunteer

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    Gimp is fine - the User interface is different from photoshop which can take some getting used to if you are a long term adobe user ,although there is a plug in to make it more photoshop-alike.

    It isnt the most intuitive thing to learn to use, and some prefer irfanview if their needs are simple
     
  19. OurJud

    OurJud Contributor Contributor

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    I have that too. Loads in the blink of an eye, but I only use it if all I need to do is a quick crop or resize.
     
  20. newjerseyrunner

    newjerseyrunner Contributor Contributor

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    I find GIMP very intuitive. I use it professionally and personally and use most of the tools. It’s only unintuitive if your used to high end software. It’s workflow is quite similar other open source editing software. Geeks like keyboard shortcuts, it makes using the software very fast, but also gives it a very steep learning curve. This is the biggest hurdle to things like Gimp or Blender or tools from that pipeline.
     

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