On Tue, Jan 08, 2013 at 01:28:25AM +0000, Micael wrote: > On Mon, Jan 7, 2013 at 11:22 PM, spin <[email protected]> wrote: > > 'Feather' is basically antialias value in pixels. Edge fades out across set > > value. > > Yes. This is exacly what the "antialiasing" brush setting is doing in > mypaint (notice that it's maximum value is > 1.0), which is why I > purpose changing it's name to "feather".
Maybe photoshop likes to specify everyhing in pixels? MyPaint has a scalable vector brush dab shape, most settings are relative to the brush radius and not in pixels. >From the name "feather" I would expect that this effect can be scaled together with the brush, not that it has a very special behaviour with respect to scaling. And I would not understand why it should be limited to a small number of pixels. Maybe the name should include the word "pixel". I have renamed it to "Pixel feather" in current git. > Anti-aliasing's purpose is to remove aliased lines which occur because > we have a finite resolution. It has technically nothing to do with a > "1 pixel fade-out border". Yes it has, because we blur the dab edge by one pixel in the vector shape of the dab, before the dab is rasterized. Aliasing happens when the image contains features that have a high spatial frequency component, like very sharp edges, that change faster than the sampling points (pixels) can capture. When you have one or two pixels of fade-out, you remove most of those high-frequency components, which prevents aliasing. It's not a very nice way to prevent it, but it does prevent it. > That said, true antialiasing can only either be ON (desired) or OFF > (undesired). I guess "true antialiasing" means that you work at infinite resolution, and before you display the image, you blur it with a sinc filter to throw away any high-frequency components. That's not something that can be implemented quickly. (Problems start with "infinite resolution" and continue with the sinc filter, which needs to consider the full image to calculate every single pixel, in theory. And finally, you cannot render many individually anti-aliased dabs over each other and expect the result to be anti-aliased correctly.) > However, it's actually doing the feather effect, and not the AA effect, so > it should be named as such. It's the best way we currently have to prevent aliasing for large dabs. If a better way exists to prevent aliasing in general (e.g. one that also works for very large dabs with 100% hardness) I would be happy to get rid of this setting entirely. -- Martin Renold _______________________________________________ Mypaint-discuss mailing list [email protected] https://mail.gna.org/listinfo/mypaint-discuss
