> Here are some images that may help show some problems -- colour photos > tend to hide problems, partly because the eye sees the subject more > easily and auto-corrects flaws, and partly because the hardest thing > for rescaling is often preserving both texture and sharpness. Of > course, most people are working with colour photos these days...) Personally I think the test is being run under flawed conditions (using nonlinear sRGB rather than linear RGB, which produces errors of up to 50% because interpolation is done linearly despite the colorspace being nonlinear.). However, those are the conditions the user is predominantly working under. I'm considering doing a separate test run where I first convert to linear RGB and finally convert back to sRGB. > > For potential problems with vertical artifacts, see the > 1600x1200 image at > http://www.fromoldbooks.org/Green-ShortHistory/pages/0187-Remains-of-Cloisters/ > (I had to resize it to 1024x768 using cubic and then sharpen) > > The 1518x916 one at > http://www.fromoldbooks.org/YouthsInstructer/pages/072-New-Post-Office-London/ > has near-horizontal lines which are difficult. > > http://www.fromoldbooks.org/YouthsInstructer/pages/181-Dunluce-Castle/181-Dunluce-Castle-q59-1447x923.jpg > has diagonals and is an RGB image instead of grayscale. > > http://www.fromoldbooks.org/ThomasBewick-WoodEngravings/pages/30-the-horse/1790x1307-q75.html > is a fairly clean woodcut. All these seem good, so I've included them. I'm currently searching for Geert's images. _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
