[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
With GIMP 2.8.4 it's not reproduce able for me. Please try to reproduce this with this GIMP version I used. Thank you very much! ** Changed in: gimp (Ubuntu) Status: New = Invalid ** Changed in: gimp (Ubuntu) Status: Invalid = Incomplete -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in Ubuntu. https://bugs.launchpad.net/bugs/648379 Title: Artifacts when scaling down with Sinc Lanczos3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gimp/+bug/648379/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
And for the next version (2.10) it is planned, that Sinc (Lanczos3) Interpolation will be replaced by a new one that works together with GEGL. Look here please: http://www.gimpusers.com/tutorials/whats-new-in- gimp-2-10 I'm setting this bug due the link to confirmed. ** Changed in: gimp (Ubuntu) Status: Incomplete = Opinion ** Changed in: gimp (Ubuntu) Status: Opinion = Confirmed -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in Ubuntu. https://bugs.launchpad.net/bugs/648379 Title: Artifacts when scaling down with Sinc Lanczos3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gimp/+bug/648379/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
Given the symptoms: 1) Occurs during resizing using factors that are not powers of 2 (i.e., 2, 4, 8, etc.). Comment #2 2) The thatched pattern is the color (254, 254, 254), where pure white is (255, 255, 255). Attachment to Comment #1 3) Only occurs for pure white (255, 255, 255) starting image. Comment #3 I would strongly suspect that this is not a bug, but a rounding error inherent in filter. It just happens that only images starting from pure white end up with rounding errors large enough to change a pixel value by one. The Lanczos filter actually takes on negative values at places, so that might be enough to put a resampled pixel one value below where it should be when the scaling isn't a nice power of 2. In other words, this is a limitation of the filter, not a programming bug. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in Ubuntu. https://bugs.launchpad.net/bugs/648379 Title: Artifacts when scaling down with Sinc Lanczos3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gimp/+bug/648379/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
I forgot to say this: for my screen is not perfect, I couln't directly notice the weird thatched-pattern. In order to reveal the artifacts, I set the bucket-fill tool's threshold at 0 and then randomly clicked the area. If the scaling went fine, the whole image should be filled. When resizing at 1/5 and 1/6, only bits of the picture or the pattern itself would be filled. So, in my case, I was not able to see the artifacts because of my screen's quality and settings, but these artifacts did exist. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in Ubuntu. https://bugs.launchpad.net/bugs/648379 Title: Artifacts when scaling down with Sinc Lanczos3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gimp/+bug/648379/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
I can confirm that resizing at 1/5 of the original size can cause the appearance of some artifacts. I have tried with the sizes you have been using, and with an original size of 1000x1000. I have also tried with a 1200x1200 picture resized to 200x200, and the same problem occurs. Maybe the range is wider than you thought, as it also happens around a 1/6 ratio. Also, it seem to occur only with white. I haven't been able to reproduce the bug if the image is filled with another color. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in Ubuntu. https://bugs.launchpad.net/bugs/648379 Title: Artifacts when scaling down with Sinc Lanczos3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gimp/+bug/648379/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
I can't reproduce this at all. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in Ubuntu. https://bugs.launchpad.net/bugs/648379 Title: Artifacts when scaling down with Sinc Lanczos3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gimp/+bug/648379/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
** Attachment added: scaling-artifacts.png https://bugs.edge.launchpad.net/bugs/648379/+attachment/1640813/+files/scaling-artifacts.png ** Attachment added: Dependencies.txt https://bugs.edge.launchpad.net/bugs/648379/+attachment/1640814/+files/Dependencies.txt -- Artifacts when scaling down with Sinc Lanczos3 https://bugs.launchpad.net/bugs/648379 You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in ubuntu. -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
[Bug 648379] Re: Artifacts when scaling down with Sinc Lanczos3
Okay, definitely depends on resolutions, specifically the ratio of original to final size. For example, I created a white-filled 1600x1600 RGB image and tried scaling to a few different sizes: 1/4: 1600x1600 = 400x400 Okay 1/5: 1600x1600 = 320x320 Artifacts 1/8: 1600x1600 = 200x200 Okay In my original image I was scaling each side to approximately 1/4.7 the size. So it seems that it's at least around this ratio that the bug appears. -- Artifacts when scaling down with Sinc Lanczos3 https://bugs.launchpad.net/bugs/648379 You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gimp in ubuntu. -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
