Comment by praash | Hacker News Reader

Comment by praash | Hacker News Reader

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> [The challenge image] has a curious bit of coloring in it. What gives? Shouldn’t it just be black and white since the text is black?

> I’m actually not 100% sure why this happens (and sometimes doesn’t), but it’s an artifact of the rasterization process when text is rendered to screen.

This is a brilliant technique called subpixel rendering.[0] A "typical" computer screen's pixels are split into three columns of red, green and blue, instead of lighting up as a solid square. Using color fringing at non-pixel-aligned edges of characters can effectively triple the perceived horizontal resolution.

Wrong assumptions about the pixel layout will show up very badly, as shown in [1]. HiDPI displays (also mobile, not just 4K) get no real benefit from this and usually have a more complex subpixel layout anyway. I remember seeing old iPads usually showing awful fringes as subpixel rendering was enabled without considering the actual orientation of the display.

[0] https://en.m.wikipedia.org/wiki/Subpixel_rendering

[1] http://www.lagom.nl/lcd-test/subpixel.php

I remember that Windows had a calibration tool which let you tune the system params for subpixel rendering to look good on your screen.

It also switched it off globally when the "magnifying glass" tool was active.

It still does - for fonts. It's called "ClearType Text Tuner" and it's part of Windows. It allows you to select one of several different subpixel rendering types to pick one that looks best on your screen.

Irritatingly, some windows applications implement their own subpixel rendering. As somebody on a 1440p BGR panel, those applications become extremely obvious to me as the aliasing is exactly backwards to what it should be. One irritating example is the web version of MS Word, as it doesn’t use the browser font rendering and instead implements it’s own (in canvas I think?) - giving all text eye-straining fringes on my display. Google Docs has the good sense to stick to black-and-white anti-aliasing at least.

How is this a Windows issue?

Most of these issues exist on other platforms as well. Try running a QT or GTK app in Mac, or an opposing widget kit app on Gnome or KDE.

Things have certainly gotten better (similar to HiDPI support, multi-monitor, etc) as developers have standardized or learned the tools, but an individual app can choose to do it’s own bespoke rendering on any platform.

Fair, it's not a windows issue. I only use windows, so I've only experienced it on windows and I didn't want to overstate - but obviously that was poor wording on my part.

You should try the Dark Reader plugin that reverse all the colors and make the subpixel rendering of the web version of MS Word become BGR subpixel rendering. I know it because the text looked weird on my RGB display with the plugin on.

I was about to get a monitor that was too good to be true for the price. Turns out it was BGR. At the time, I didn't know what that meant. But the reviews said it was not good, so I avoided it.

I appreciate that reviewer every time I think about it.

Honestly, BGR is mostly fine. I was apprehensive when I bought mine, but so far it's only a small handful of things that don't play nice.

There was an article describing it in detail on the frontpage a few days ago: https://news.ycombinator.com/item?id=30330144

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