Gameboy RGB colors?

Discussion of programming and development for the original Game Boy and Game Boy Color.
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Zepper
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Gameboy RGB colors?

Post by Zepper »

4 shades of green, but what are the RGB values of them? Same for the Pocket version (shades of gray).
tepples
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Re: Gameboy RGB colors?

Post by tepples »

The exact shades depend on the lighting, the contrast dial, the battery voltage, and several other factors.
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tokumaru
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Re: Gameboy RGB colors?

Post by tokumaru »

This is a tough one... The screen is green (or gray) because of the materials used, not because someone put together a nice selections of greens (or grays). And even if you were to exclude the lighting conditions, the contrast dial alone will create hundreds of combinations.

Also note that colors aren't the only defing characteristic of the Game Boy display: if you're serious about simulating a GB screen, the blurring is another very important aspect.
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Dwedit
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Re: Gameboy RGB colors?

Post by Dwedit »

I'm using "175,203,70" "121,170,109" "34,111,95" "8,41,85"

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One alternative is to use the default GBC palette for unrecognized games (or Wario Blast), which has green and blue colors, vaguely like the GB 'pea soup' palette.
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Zepper
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Re: Gameboy RGB colors?

Post by Zepper »

tokumaru wrote:This is a tough one... The screen is green (or gray) because of the materials used, not because someone put together a nice selections of greens (or grays). And even if you were to exclude the lighting conditions, the contrast dial alone will create hundreds of combinations.

Also note that colors aren't the only defing characteristic of the Game Boy display: if you're serious about simulating a GB screen, the blurring is another very important aspect.
You're not understanding. We have Gameboy emulators. How do they generate the palette values?

EDIT: awesome result! ^_^;;
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Rockman (J) 00F.bmp
Rockman (J) 00E.bmp
Last edited by Zepper on Sun Mar 22, 2015 5:14 pm, edited 1 time in total.
tepples
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Re: Gameboy RGB colors?

Post by tepples »

I think Game Boy emulators just hardcode a gray palette or let the user specify one. So given the precedent of the Wide Boy accessory, you could just hardcode the RGB colors that correspond to the four grays in the NES palette: #000000, #666666, #B2B2B2, #FFFFFF.
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tokumaru
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Re: Gameboy RGB colors?

Post by tokumaru »

Zepper wrote:We have Gameboy emulators. How do they generate the palette values?
The colors are probably arbitrary, whatever the emulator authors think looks good. If you like the colors in a particular emulator, just grab a screenshot from that and get the RGB values you need.
EDIT: awesome result! ^_^;;
Are you trying to make NES games look like GB games? Looks interesting. Is it automatic or does the user need to configure each game/palette?
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Zepper
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Re: Gameboy RGB colors?

Post by Zepper »

I was using these 4 shades of gray.

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You take the bright level (R+G+B DIV 3) ANDed with $C0.
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Rockman (J) 007.bmp
tepples
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Re: Gameboy RGB colors?

Post by tepples »

I prefer this mapping from NES colors to 2-bit gray shades:

$20, $30-$3C: White
$10, $21-$2C, $3D: Light gray
$00, $11-$1C, $2D: Dark gray
Others: Black
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Re: Gameboy RGB colors?

Post by Shonumi »

The colors are arbitrary in emulators, and for technical reasons. The LCD itself had no "colors", just a single shade that was 0% On, 33% On, 66% On, and 100% On. It's not like the hardware had a specific RGB value for that shade, so there's a lot of leeway to make "GameBoy" like palettes. It comes down to taste when choosing which is the best kind of "green" to use.

Personally, I just use pure black as the 100% shade (I always had a GB Pocket, so I never had that affinity for the "green"). I'm going to add custom palettes for those that want something more.
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Zepper
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Re: Gameboy RGB colors?

Post by Zepper »

tepples wrote:I prefer this mapping from NES colors to 2-bit gray shades:

$20, $30-$3C: White
$10, $21-$2C, $3D: Light gray
$00, $11-$1C, $2D: Dark gray
Others: Black
Here's the result. ^_^;;
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Rockman (J) 014.bmp
Rockman (J) 015.bmp
lidnariq
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Re: Gameboy RGB colors?

Post by lidnariq »

Now you just need to add something like half a second of motion blurring and you'll be all set! :P
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Re: Gameboy RGB colors?

Post by Drag »

The Gameboy is using an STN LCD screen. STN LCD screens work by changing the color of light rather than TN LCD screens, which work by variably blocking light. TN LCDs give you black and white but crappy contrast ratio unless you can create a big voltage difference between "off" and "on" pixels, possible on a Game & Watch or a wristwatch where each segment gets powered directly, but impossible on a dot matrix screen controlled one scanline at a time if you have more than 32 scanlines.

Hence, STN LCD screens, which give you a much better contrast ratio without needing a huge difference between the "off" voltage and "on" voltage, but with a side effect that you don't have pure black and white, your grayscale is a rainbow now (look up a Michel-Levy chart or birefringence chart to take a look at it), and a specific portion of the rainbow is selected as the "off" and "on" colors to behave like a grayscale and also not look like ass. Usually, this ends up as dark violet on green or blue on silver (also available are the inverted versions where it's green on dark violet and silver on blue).

STN LCDs also sometimes have filters or compensation methods on them to improve the colors and/or make them less colorful. I don't think the Gameboy uses any, but the later models like the Gameboy Pocket probably do.


Also, off topic, but the reason I know any of this is because I've seen a couple of kid's toys and a casio graphing calculator that somehow have a passive matrix LCD capable of multiple colors without using RGB, and I wanted to know what it was. As it turns out, it's likely that they're just STNs that span a wider portion of the birefringence rainbow, treating it like muticolored steps rather than grayscale steps. This looks terrible for motion though, so only low-framerate stuff is acceptable.
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Re: Gameboy RGB colors?

Post by lidnariq »

Drag wrote:your grayscale is a rainbow now (look up a Michel-Levy chart or birefringence chart to take a look at it),
I have been looking for the answer to this question for years! Thank you very much!

(I used to work for a company where my boss mentioned wanting to use the color technology of these multicolor hand-held games, and I didn't have any idea where to start. The closest I ever got was noticing that our FSTN-based products, when mistuned, could display clear, black, and navy blue)
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Re: Gameboy RGB colors?

Post by tepples »

lidnariq wrote:Now you just need to add something like half a second of motion blurring and you'll be all set! :P
Has anyone publicly characterized the actual motion blur behavior of the Game Boy models' displays?
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