A modern open freeware Anti-Alias Filter for Photoshop, made by anime production specialists OLM in Japan. It comes in the standard .8BF filter format. Works all the way back to CS4, and is available in 32-bit or 64-bit flavours. Jaggies… begone!
What else did I find on my hunt, before I found this solution? Well, there was an old freeware filter called ‘Fine Threshold’, which obviated the need for the native Threshold filter… by expanding what Photoshop’s native Threshold filter could do. But that’s very old and no longer works in 64-bit. The old paid Power Retouche suite had a filter that claims to do this, though its 32-bit doesn’t work in 64-bit Photoshop… and I’m not sure if the suite ever went to 64-bit. G’MIC has an ‘Anti-alias’, but the results are not great.
But this free filter work very nicely. It can’t save settings presets, but works well enough on default that it can be included in an automated Action in Photoshop. Loads and works quickly.
What it won’t do is to also remove isolated speckles and grunge of a certain size, so that you end up with both anti-aliased and clean line art…
The native Photoshop Despeckle can, it seems, only clear very tiny speckles. The only free solution to do robust despeckle, which I know of, is at the very foot of the comments in this post and involves Paint.NET.
Update: G’MIC’s ‘Repair | Despeckle’ will sort-of do it in Photoshop, but must be run before and not after the Threshold anti-aliasing. Not as good as Koch’s now-unavailable computational filter, but it does 90% of the job and is Photoshop native and thus can be put in an Action. It will struggle with a Threshold-filtered render that started off dark and with grungy textures.
2D digital art and painting 