[Gimp-developer] bug #464466: lanczos corner artifacts
Hello: This is not directly related to the bug, although the following provides a possible alternative to fixing the corner pixel proglems of the existing lanczos... A student of mine and I have put together a gimp plug-in which ENLARGES images using a method which is analogous to global cubic splines, that is, which gives results analogous to lanczos. The plug-in should be ready for distribution in about 1 month. Features: --two related methods can be used: the first one---exact area natural biquadratic histosplines---uses the center image size convention (like gimp and imagemagick), the other---interpolatory box filtered natural biquadratic histosplines, which is almost the same as natural cubic splines---the corner image size convention (like most image enlargement programs) --the first method is strongly sharpening, the second, less so. Both give very smooth images. --the user can specify the gamma of the input image, and the gamma of the output image. The default is 2.2 for both. --the plug-ins are fast: we are not quite done optimizing the code, but as it stands, they produce large enlargements of large images faster than the gimp built-in bicubic, and slower than the gimp buil-in bilinear. --the drawback of both methods is that they are fairly memory intensive: we have several versions around, but the most likely candidates for release requires the creation of a temporary int16 or float array with as many entries as the input image. On the plus side, we use a moderate size tile cache: gimp_tile_cache_ntiles (((nnm) ? nn : m) / gimp_tile_width () + 1); where nn is the width, in pixels of the output (enlarged) image, and m is the height, in pixels, of the input (to be enlarged) image. We would be quite happy to integrate the plug-in into the built-in gimp image resize functionality (some assistance would make this happen faster: we don't quite know how to interact directly with the gimp core). Nicolas Robidoux, Department of Mathematics and Computer Science, Laurentian University ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] bug #464466: lanczos corner artifacts
On Thu, 07 Aug 2008 22:20:00 +0200, Nicolas Robidoux [EMAIL PROTECTED] wrote: A student of mine and I have put together a gimp plug-in which ENLARGES images using a method which is analogous to global cubic splines, that is, which gives results analogous to lanczos. Hi, in what way do you mean the results are analogous to lancsoz? Could you perhaps compare results of your plugin with the comparitive results on the kingfisher head shot? http://svenfoo.org/scaletest/133-9.html http://svenfoo.org/scaletest/133Z8g.png http://svenfoo.org/scaletest/133C8g.png and/or the pixel graphic: http://svenfoo.org/scaletest/133-8.html http://svenfoo.org/scaletest/133Z8g.png http://svenfoo.org/scaletest/133C8g.png these two images scaled to 133% seemed to be the best cases in that test group for differentiating cubic and lancsoz. It would be interesting to see your plugin results next to those tests. The originals are provided on those html pages. regards. -- ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] bug #464466: lanczos corner artifacts
Hi, On Fri, Aug 8, 2008 at 7:30 AM, [EMAIL PROTECTED] wrote: On Thu, 07 Aug 2008 22:20:00 +0200, Nicolas Robidoux [EMAIL PROTECTED] wrote: A student of mine and I have put together a gimp plug-in which ENLARGES images using a method which is analogous to global cubic splines, that is, which gives results analogous to lanczos. Hi, in what way do you mean the results are analogous to lancsoz? Could you perhaps compare results of your plugin with the comparitive results on the kingfisher head shot? http://svenfoo.org/scaletest/133-9.html http://svenfoo.org/scaletest/133Z8g.png http://svenfoo.org/scaletest/133C8g.png and/or the pixel graphic: http://svenfoo.org/scaletest/133-8.html http://svenfoo.org/scaletest/133Z8g.png http://svenfoo.org/scaletest/133C8g.png these two images scaled to 133% seemed to be the best cases in that test 133.33% please. If you use just 133.00%, the result will be the wrong dimensions and so, uncomparable. ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
