Are "pixel" traps a thing?

Johannes Neumeier

Hey folks,

I've been looking into some references for screen-use typefaces and to my astonishment found some humanist sans with "ink" traps - although those fonts seem to be explicitly designed for screen use. For example PT Sans, or Open Sans.

Has pixel and subpixel antialiasing come to a point where this is a viable option for screen fonts, or are those just exotic exceptions (although those examples are quite mainstream, in terms of web fonts in the wild)? Would those "pixel" traps behave differently from traditional ink traps, or is it a one to one transfer of the same principle?

Curious to hear your thoughts. And I'd happily study more references with similar features, if any come to your mind.

Thanks,
Johannes

Mike Duggan

whenever two diagonals meet, that heaviness, or percieved dark spot, can be lightened by adding an ink trap, and is relevant for onscreen rendering, in that it can lighten the rendering onscreen also. the effect may be subtle, but a slight lighening in number of glyphs, v w  V W, can improve the overall typographic color.

Jasper de Waard

This is especially the case for webfonts displayed on a Mac. On windows, the thickness of joints could be adjusted using hints, and most glyphs are rendered fairly light to begin with. On a Mac glyphs get quite dark real often, and especially the insides of v w M V W and such get clogged. So yes, pixeltraps are useful.

Nick Shinn

What Mike said. But if we’re talking about readability pure and simple, it is a bit of an affectation, because the alternative in letters like V is to taper the strokes with an even line, and that looks better at all sizes—the abrupt traps just draw attention unnecessarily at display size, which is a legitimate size on screen.

However, if that is the intention—to add a garment of detail in headlines, for visual interest—that’s OK, and I’ve designed several typefaces like that.

Ultimately, it doesn’t even matter if the traps are non-functional on screen below a certain size, design features that are redundant in certain usages are not fundamentally problematic, they are a feature when active, not a bug elsewhere.

Furthermore, size-specific designs are not necessarily a best practice, if one can design typefaces that perform well at many sizes. 

Cory Maylett

It might be obvious but worth pointing out that ink traps are meant to compensate for dot gain (ink spreading out) in printed text — especially on uncoated paper. At display sizes, those traps amount to little more than visual flaws in the glyph.

I can't think of a digital equivalent of dot gain that would warrant a "pixel trap." Hinting, antialiasing and subpixel rendering algorithms are supposed to compensate for that kind of thing. As Nick mentioned, tapering the connecting strokes a bit seems a better alternative to slimming down the thick spots than carving little notches into the glyphs.