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Thread: GIMP Pixel Problem

  1. #1
      Zirojtan is offline
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    Default GIMP Pixel Problem

    I am positive that someone has already asked this at some point but I thought I'd post a thread real fast since I don't want to go scouring the forum for an old topic on this matter.


    So I know how to do four things on GIMP, really. These four things are selecting, cutting, moving the selection, and rotating it. Now, after I'm done doing these simple tasks, every time I save my modified gimp image, the pixels of the selection are messed up. As in, around the borders of where colors change, the colors are no longer solid, but some sort of weird transitional deal where they're all different.


    Do you know what I mean?


    This is especially annoying when my primary tool is Microsoft Paint. Every time I use GIMP to do something, I have to go back over with the pencil tool or the bucket tool and recolor all of the pixels that for no apparent reason changed to different color shades. Does anyone know how to get around this problem?

  2. #2
      Azelor is offline
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    I think I know what you mean. This can happen if you change the file extension while saving and reduce the quality at the same time. Or not reducing the quality but saving in GIF.

    So, how did you saved the file?

    Another thing I need to say. If you go back and forth from a file extension to another (well actually it depend on the extension used), it mean that every time you do it the picture lose some of its quality. For example, I know a professional photographer that always modified his file in Photoshop and then compressed everything in a jpeg with no back up. And he could do this a couple of time with the same file. It does a very bad job.

    To conclude, my advice is : if you can manage to use Gimp, you should stop using MSpaint since Gimp offers way more possibilities.

  3. #3
      Zirojtan is offline
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    What do you mean by "file extension"? I'm sorry, I really am not tach savvy at all.


    That being said, I usually just open the file that has been painted in MS Paint and then save it in GIMP and reopen it in MS Paint again, so I think I know what you mean here, but I'm not sure.


    Also, I find GIMP to be incredibly complicated and frustrating, personally. Maybe that's cuz I haven't learned how to use it properly, but just what I have to go through to move a selected piece of an image and rotate it (right click here, right click there, go to this option, go to that option) is just... annoying. To me at least.

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      Larb is online now
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    The type of file you save your image as has an effect on what information it stores and what quality the end result is.

    It sounds like you are working on an image, then saving it as a .jpg file. This is a "flat" compressed image file suitable for viewing on the web. The compression process results in a loss of quality - specifically the transitional area between colours and edges. It goes all weird close up (it is sometimes referred to as "jpg artifacting").

    Basically you shouldn't use .jpg for a work-in-progress image.

    If you are working between MS Paint and GIMP then I suggest saving your work-in-progress image as a TIFF file (.tif) or a bitmap (.bmp). You'll have the option to do that when you go to "save as". Only save your final ready image as a jpg if you intend to upload it somewhere. And keep a backup of your work-in-progress version so you always have a higher quality original should you ever need it.

    Also! I'd suggest digging up some beginner GIMP tutorials on youtube or the web or wherever. I don't know what ones to recommend as I use photoshop myself but they will be really useful for getting to grips with the basics and it's stuff you'll pick up much quicker than you might think. Perhaps someone else can suggest some good ones.
    Last edited by Larb; 12-25-2013 at 01:09 AM.

  5. #5
      Zirojtan is offline
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    Thank you, but I'm saving the file as the same png that it was before. The thing is that this kind of file compression or loss of resolution (when the pixels go crazy) is only happening on the piece of my map that I selected and moved to another spot. The rest of the image remains the same. It's really odd, and really kind of frustrating too.


    I could probably do that later this week... I mean, I'm not really doing anything tomorrow, except working out. But I don't really want to hassle with learning a new computer program on Christmas day. Have you seen my map? My world is called Eurydice, and I have a topic on it in the Regional/World Mapping section. If you want, check it out. The only reason I ask is cuz I want to know if you think it would be easier to do what I'm doing in GIMP.

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      Falconius is offline
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    It could be the anti-aliasing or lack of, on your selection tool or perhaps you are feathering the edges on your selection tool. Try turning those off in the check boxes and see if you still have the same problem. Perhaps it could also be the interpolation of your selection transform tools? Try changing it to none and see if the problem still occurs.

  7. #7
      Ghostman is offline
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    You might get better advice from us if you'd post some example pictures of before & after the editing. That way we could see for ourselves what you mean by changed pixel colors.

  8. #8
      Zirojtan is offline
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    You might get better advice from us if you'd post some example pictures of before & after the editing. That way we could see for ourselves what you mean by changed pixel colors.

    Now there's an idea! Where did you come by that sharp mind of yours? lol.


    Ok, here's a picture of my world post editing on GIMP:

    GIMP Pixel Problem-eurydice-today-altitudes-adjustments.png


    I'm not exactly sure you can see exactly what's going on because of the maximum resolution that the image gets on this site, but can you see where I tried to use the bucket tool and the pixels have changed? Those hollow areas of color used to be solid right up to the edge, and so I could have used to bucket tool to change the color and there would have been no border remaining... before I edited it on GIMP. After I edited it on GIMP, the pixels change and they sort of blur the lines between colors where they were previously sharp, making it impossible for me to use the bucket tool to paint an entire section that is a certain color another color. I have to use the bucket tool, and it paints the interior only, and then I have to use a widened pencil tool for the edges. It's really, really annoying.

  9. #9
      Zirojtan is offline
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    It could be the anti-aliasing or lack of, on your selection tool or perhaps you are feathering the edges on your selection tool. Try turning those off in the check boxes and see if you still have the same problem. Perhaps it could also be the interpolation of your selection transform tools? Try changing it to none and see if the problem still occurs.

    So I just did both of these things, as you suggested, and the selection was unable to rotate. I would rotate it, and it would bring up a loading bar at the bottom that said "rotating" and then it would just stay put...

  10. #10
      Falconius is offline
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    That could be a hardware or software issue, when I tried it it worked fine. Maybe try a clean install of GIMP? Or eliminate/consolidate layers where you can.

    From the quick tests I did, I'm pretty sure that it is the interpolation causing the issue you describe.

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