Comment by tropo | Hacker News Reader

Comment by tropo | Hacker News Reader

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Composite would get you a different amount of horizontal blur for different colors. In an analog sort of way, it's like resolution is reduced for each color component, but the red-green color axis is done differently from the blue-yellow color axis. For each 4 "pixels" (again, analog filtering) of brightness value you get 2 pixels worth of data for one color axis and just 1 pixel worth of data for the other color axis.

You also need to account for blooming, phosphor delay (different for each of red/green/blue), a "black" that is grey...

If you want faithful emulation, you need all these things. If you want performance, you want none. For the most attractive display, you need SOME of these things, and it varies from game to game. Probably some can be done in a GPU. You might want to let the user know if a real (not just MesaGL) GPU is available and able to handle something, if a GPU can do a half-good job, if something will just munch CPU time, etc.

> a "black" that is grey... I hear this a lot. Why is an incorrectly biased monitor's bad black levels so widely considered the way it is supposed to be?

There is nothing incorrect. It's just old technology. This is how things were, and full compatibility -- if you want it -- demands that you make things match. SNES and Genesis artwork was designed for the old hardware.

The monitors looked grey even without being plugged in.

To be clear, this is tube technology, which was widely used right up to the end of the last century. Screens were often thicker front-to-back than they were wide. They were really heavy too, with thick leaded glass (to stop X-rays) at the front and big copper magnet coils at the back. There was a fine-pitch metal grid inside the glass, and some phosphors printed on inside of the glass. That stuff wasn't black. In operation the situation got slightly worse, from stray electrons probably, but fundamentally the displays just couldn't ever be black. It's the same as printing on brown paper: don't blame the settings of the printer when you don't get any white.

Even the oldest CRT televisions have a "brightness" control, and it's supposed to be used to set the black level to black, not grey. The face of the tube has a grey color while it's off because that's how the surface of the tube looks - but that's not the result of emission from the tube, and even by the eighties tubes had dark anti-glare tinting for this. Unless you're shining a light on the tube, the black levels should be black.

Are we to say that the black level of an OLED display isn't black because external light can raise it through reflection?

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