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Graphics > System Gammas (GBA, SP, DS, GBP/TV, VGA)

#33312 - sgeos - Sat Jan 01, 2005 9:30 pm

What are the system gammas of the original GBA, the SP, the Gameboy Player (TV), the DS, and a (PC) VGA monitor? Should each RGB component necessarily have the same gamma correction?

-Brendan

#45384 - Puffin - Fri Jun 10, 2005 3:20 am

I have a question that I think is somewhat related to this. I don't quite understand how all of this works, so you'll have to humor me.

Essentially, I want to create as accurate a rendering as possible on my LCD computer monitor while developing/drawing art for my GBA SP project.

I'm *guessing* it has something to do with gamma values for these devices, but I'm not entirely sure.

I could just guess and check my way to something that looks OK, but I don't think that will satisfy me. What sort of things should I be learning to help me create a quantitative solution to this problem?

#45483 - tepples - Sat Jun 11, 2005 4:19 am

In my experience, gamma is the same across RGB components but differs across screen types.

CRTs "should" be set to 2.2 gamma. This is specified in the NTSC (TV), PAL (TV), and sRGB (PC) standards; a TV set that does not match this is miscalibrated.

For systems with front-lit reflective screens (GBA or GBA SP), assume gamma = 3 to 4. My test backs this up for the most part. For Game Boy Player and emulators that don't do color correction (e.g. VBA), assume gamma = 2.2. In casual play of homebrew games, Nintendo DS's back-lit transmissive screen tends to make things look bright like an emulator or a Game Boy Player rather than dark like a GBA.

If you want to make a quantitative solution, then fill quadrants 1 and 3 of the screen with a solid gray and the other quadrants with dithered pure black and pure white pixels. Squint at the screen and adjust the density of the dither noise until the line between the two becomes hard to see. Then the percentage of pixels that are white is the (linear) light power corresponding to a given luma value.
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