Regarding the new version: I do think that it’s an improvement over the 1.8.1 version–the reduction in missed edges alone is enough to make it a worthwhile inclusion, methinks.
One thing that I notice: the edges in the new version seem to be a lighter colour than in the 1.8.1 screenshots–is that intentional?
Hmm… Looking at the lines, the jaggedness of the edges does seem reduced. Looking closely, the antialiasing pixels seem a bit light–could they be deepened a bit, to make the antialiasing a little stronger?
I don’t think that this will likely help in my case–as you mention a little further on in your post, there’s a variable-length loop involved. In short, I was experimenting with using a count of sample colours (which are effectively object ids in my implementation, recall) when detecting edges in order to antialias my lines somewhat–the idea being that a point the samples of which are heavily biased towards one colour or another is presumably further from the edge than one that has a nearly even distribution, and can thus be rendered as “partially-inked”, hopefully shading the line a little.
Hmm… Perhaps… I might go back and have another shot at a non-if version (the nested-if version replaced a non-if version that wasn’t working); it will likely be cleaner, at any rate.