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Re: true color executor/D
In article <4e5gg2$f6@newsstand.cit.cornell.edu>,
William Magro <wmagro@msc.cornell.edu> wrote:
>Scott Shuchart (shuchart@fas.harvard.edu) wrote:
>
>: This situation doesn't make sense to me. 640x480x256 is 1Mb Vram, no matter
>: what the colors are. And grays are just some colors. [...]
>
>The catch here is that the 256 colors of VGA are chosen from a palette
>of 256k (or fewer) colors with standard VGA cards. Since each gray
>must have equal components of red, green, and blue, this reduces the
>effective number of true grays to 64 [=262144^(1/3)]. It takes a
>24-bit D/A converter (8-bits in each channel) to generate 256 grays.
>
>In the end, the number of grays you can generate depends on the bitness
>of your DAC and the smarts of the video driver.
But most all cards capable of doing more than 256 colors also have 24-bit (as
opposed to 18-bit) DACs. My s3-968 based card can do 256 greyscales when in
8-bit pseudocolor mode. So can just about any modern graphics card.
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|Trent Piepho (xyzzy@u.washington.edu) -- Metallica |
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