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Atari 'System 1' colour palette - What are the colours?


DarkAvenger

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I'm trying to get the correct colours in my screenshots of Atari System 1 arcade games, namely Gauntlet, Paperboy, Road Runner and Roadblasters. I know the system 1 board can do 256 colours from a palette of 1024, but what those 1024 colours are or how exactly the palette is defined is my question. The only bit of information I've been able to find on the net so far is this:



The palette is 16-bit IRGB (4-4-4-4)



Colours are encoded this way:


----------------------------------


| Intensity | Red | Green | Blue |


|---------------------------------


| F | 0 | 0 | 0 |


----------------------------------


Each one can range 0-F, to set colour and brightness. Change to 70F0 for a darker green, FFFF for bright white etc.



The above information doesn't make sense though since if Red, Green and Blue can each be set in the range 0 to 15 (Hex 0-F) this would give 16 intensity levels of each for a palette of 4096 colours not 1024 and why the need for the Intensity (I) parameter if Red, Green and Blue (RGB) can be set individually? However many of the colours I see in screenshots on the net (assuming the colours are accurate) are outside the range of a 12-bit palette (4096 colours) though they would fit into a 15-bit palette (32,768 colours ie 32 intensity levels each for R, G and B), but again the hardware specs of the Atari System 1 board state the palette is 1024 colours, not 4096 or 32,768 so I'm at a loss as to how the palette is defined? Maybe those 1024 colours are a subset of a 15-bit palette?



Take the attached screenshot of Gauntlet's title screen as an example. The RGB values of some pixels seem to correspond to a 12-bit palette while other seem to correspond to a 15-bit palette, while yet others still seem to correspond to I don't know what? It's a real 'mish-mash' - again assuming the colours in the screenshot are even correct which they may well not be - how would I know?.



If anyone can help me I would be appreciative as I'd like the colours in my screenshots to be 100% correct.

post-36871-0-07357700-1378134309_thumb.png

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