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Comment by cseelus | Hacker News Reader

That must have been one of the nightly builds from end of September 2017.

For anyone who wants to see whats coming when Mojave gets released without subpixel AA, I made a few comparison screenshots on a non-Retina display:

iTerm2 dark subpixel AA enabled: https://static.imeos.com/images/iTerm2-3.1.7.png

iTerm2 dark subpixel AA disabled: https://static.imeos.com/images/iTerm2-3_1_20170924-nightly....

iTerm2 light subpixel AA enabled: https://static.imeos.com/images/iTerm2-3.1.7-light.png

iTerm2 light subpixel AA disabled: https://static.imeos.com/images/iTerm2-3_1_20170924-nightly-...

On Retina screens, I don't see much of a difference:

iTerm2 light subpixel AA enabled on Retina display: https://static.imeos.com/images/iTerm2-3.1.7-light-retina.pn...

iTerm2 light subpixel AA disabled on Retina display: https://static.imeos.com/images/iTerm2-3_1_20170924-nightly-...

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I'm confused. Are the screenshots somehow different so that the retina and non-retina screenshots will appear different even when viewing both on non-retina (or retina) display?

It depends on your hardware. If your RGB are in a different spatial order from the originator it actually makes it worse.

Consider the 3 and 4th images, the "on light" AA and non-AA versions… Look at line number 10, the "let arr1 =…" line. Look at the vertical stroke of the "l" of "let". In the anti aliased version there is a red glow on the left side and a blue-green glow on the right when you zoom in. On the non anti-aliased one there is not such glow. Now lets lay that into pixels on a scanline…

    RGBRGBR_________GBRGBRGB   subpixel AA
    RGBRGB_________RGBRGBRGB   non-subpixel AA

So both are just a black gap in an interwise solid line of GBRGBRG dots (I'm hiding the 'rgb' deliberately there, it doesn't exist in the real world on the LCDs where AA works)

If we turn that back into what the computer abstracts as pixels we get…

    RGB RGB R__ ___ ___ _GB RGB RGB   subpixel AA  (see R and GB? halos)
    RGB RGB ___ ___ ___ RGB RGB RGB   non-subpixel AA

On 150dpi desktop displays it doesn't matter, your eyes aren't good enough. On displays which can be rotated it is a bad idea because the sub pixel AA hack only works in one orientation and that is just confusing.

On my desktop display I see a difference in the light screens. It's a very subtle difference, but enough that it might theoretically irritate me if I had to stare at text all day. Probably not in practice, it's not a massive problem or anything; but yeah, AA looks better.

Where I notice it the most is on the curly quotes and parentheses. Without AA they look... harsh I guess? Or maybe blocky. You notice the vertical lines making up the curves more. You also lose some of the definition around letters - for example without AA the dot on the "i" is much less noticeable.

On the dark theme it doesn't look nearly as bad, I have a really hard time seeing the difference there at all. Maybe that's because they're scaled differently? Or maybe dark themes just don't need it as much?

> “Without AA they look... harsh I guess?”

I’m noticing this misunderstanding quite a bit in the thread. None of those images have antialiasing disabled. What’s been disabled is subpixel antialiasing. So those images are comparing subpixel antialiasing and greyscale antialiasing.

Opinions between the two are mixed:

I’m one of the people that hates greyscale antialiasing (I find it makes text look fuzzier) and prefer subpixel antialiasing (which does a much better job of preserving the intended shape of the font glyphs).

On the other side, there are people who hate subpixel antialiasing (because they can see the colour fringes on the glyphs) and prefer greyscale antialiasing. Here’s an example from 1897235235 lower down in the thread:

“This is actually better for me. I wrote to Steve Jobs a long time ago and asked him if he could switch to gray-scale font smoothing because the tricks they use with colours don't actually work with people like me who are red green colour blind. The end result was that text on apple products looked terrible to me and I couldn't use any of their products until the retina displays came out. In windows, you can use grayscale font smoothing easily.

Anyway, he replied "we don't have any plans to do this" or something like that. Turns out I won in the end.”

Now if antialiasing was actually fully disabled, the difference would be extremely obvious, to say the least.

Thanks for the catch.

I wonder if this is part of the reason why I can't really tell the difference in the dark mode pictures, at least without zooming in all the way. I guess the colors from subpixel antialiasing would be less noticable when overlayed or transitioning from dark to light rather than from light to dark?

> the tricks they use with colours don't actually work with people like me who are red green colour blind.

Oh crud, this never occurred to me. It doesn't seem to matter how many times I remind myself that red/green doesn't work for everyone, I still find myself forgetting about it all the time.

I can see a difference between pairs of each screen shot. I'm pretty confident though that I won't be able to tell when I don't have these nice comparison images, or care about the difference in practice.

I can't tell which is which even when I blow them up to the point where I can see the individual pixels.

I opened them in my browser in separate tabs and flipped back and forth between them. Very subtle difference for me, but I could see it.

Yes, I can see the difference too. I just can't tell which one is supposed to be the "blurry" one. They both look equally sharp to me.

Zoom in on the pics.

Yeah, I put them both at normal zoom level and realized that they're both the same, except the retina is much higher pixel density so the text looks a lot bigger when it is set at 1x zoom.

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