Re: [Tuxpaint-stamps] Reducing size of Tux Paint stamp files by optimising PNG files
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From: Albert C. <aca...@gm...> - 2013-03-18 15:13:40
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On Sat, Mar 16, 2013 at 3:59 PM, Karl Ove Hufthammer <ka...@hu...> wrote: > la. den 16. 03. 2013 klokka 20.16 (+0100) skreiv Pere Pujal i > Carabantes: >> If the transparent part of the images is not afected(not blanqued out >> to white or black), then it is OK for me too. >> A couple of files with worked transparent stuff that should not be >> lost are the two fireman*png in the people directory, there are >> others. > > The transparency part is not affected, in that each pixel will still be > rendered identically. However, the procedure *does* clean the RGB part > of *fully* transparent pixels. I don’t think will be a problem. (For the > fireman images, these pixels only contain garbage.) Nope, that is not garbage. The stuff around the edge of the fireman was carefully painted to minimize edge effects that occur when a stamp is scaled. Scaling causes the content of fully transparent pixels to bleed into the image. By painting the transparent pixels to match the edge of the object, this problem goes away. Edges of objects need to be painted anyway, to eliminate the background halo at 1:1 size, so you might as well paint the background out while you're at it. Getting rid of the background will fix halo problems at scaled sizes. Imagine a JPEG picture of a socket wrench on a green table. There will be bits of greenness on the wrench. You need to zoom in and paint that away. If you don't do this, then there will be a green edge when a Tux Paint user places the socket wrench on a non-green canvas. If you fix that, but don't paint the background, scaling the image to small sizes will bring back the halo. |