I realize it’s probably too late, but as a graphics person, every time I read about text antialiasing, I wish we could rewind and fix the terminology of “Subpixel antialiasing” and “Greyscale antialiasing”. It seems problematic that greyscale antialiasing involves subpixel sampling and color channels.
I’d suggest “LCD antialiasing” to replace “subpixel antialiasing”. And regular antialiasing doesn’t really need a term, it was already established long before LCDs existed. AFAICT “Greyscale antialiasing” was made up only to differentiate regular antialiasing from LCD antialiasing.
"Subpixel" makes more sense than "LCD": the technique applies to any screen with illumination units smaller than a pixel (eg. LED screens) so "subpixel" makes perfect sense.
Yes, it makes sense. My beef is not that subpixel doesn’t make sense, it’s that the term is overloaded. Standard antialiasing also involves subpixels and the term makes perfect sense there too. From my perspective, “subpixel” fails to differentiate.
Now, using “Greyscale” to mean color, just not LCD color, that one doesn’t make as much sense to me. Some articles call it “whole pixel anatialiasing” or “traditional antialiasing”, those seem better, but maybe we can assume antialiasing is the regular kind, and only need a term to talk about LCD style antialiasing.
It’s common in both software and especially hardware to render at a higher resolution and then filter & downsample. The 2x2 or 3x3 or 4x4 etc pixels in the higher resolution that correspond to the 1 pixel at final resolution, those are called subpixels. For example, you can read about subpixels in descriptions of traditional aliasing as well as GPU antialiasing.
The term subpixel is often referring to virtual pixels used to compute some final pixel value, as opposed to the LCD specific idea of a physical subpixel that’s red, green, or blue. Look around, for example, for discussions on subpixel resolution, subpixel positioning, subpixel animation, etc. Those are usually talking about the virtual kind used in traditional antialiasing, not the physical LCD subpixels.
Yes that’s an interesting point, the “fragment” terminology can be confusing at first. But I think of fragments as something slightly different. “Fragment” means basically pixel or subpixel geometry, it’s output from the rasterizer. The fragment shader is what takes a fragment as input and then outputs the pixel or subpixel color. Fragments aren’t necessarily involved in GPU antialiasing, you can have subpixels in OpenGL without fragments, if you’re doing image processing without rasterizing. In any case, it’s a good thing that they picked a different word to define, and didn’t just call it “subpixel”, right?
Sure, that’s fair. Maybe LCD is a bad suggestion. It’s not like I’ll be able to change it, but just for fun, is there a better term that isn’t confusing? Because subpixel and especially greyscale seem pretty confusing.
I’d suggest “LCD antialiasing” to replace “subpixel antialiasing”. And regular antialiasing doesn’t really need a term, it was already established long before LCDs existed. AFAICT “Greyscale antialiasing” was made up only to differentiate regular antialiasing from LCD antialiasing.