Difference between revisions of "Atari 7800 Color Documentation"
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| − | The | + | [[File:600px-YIQ_IQ_plane_-_7800_factory.png|thumb|Atari factory-calibrated 7800 color values, overlaid on Y=0.5 IQ colorspace.]] |
| + | The the color system in the 7800 is designed to efficiently generate color signals that are PAL or NTSC ready, with very little silicon and support circuitry. To better understand 7800 colors, it helps to have an understanding of NTSC and PAL color encoding. | ||
| − | + | Both NTSC and PAL TV standards have a short [https://en.wikipedia.org/wiki/NTSC#Color_encoding colorburst] signal near the beginning of each scanline. The colorburst serves 2 purposes. Its presence signals to the TV that the scanline will contain color information, but the colorburst signal also serves as a phase reference. If the same frequency is later detected by the TV during the display of a pixel, the TV will compare the phase of the frequency to the phase of the colorburst, and use the difference to determine which hue should be displayed for the pixel. | |
| − | + | NTSC TVs generally use the YIQ colorspace for this color determination, while PAL TVs use the YUV colorspace. | |
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Revision as of 06:02, 16 November 2015
Contents
Overview
The the color system in the 7800 is designed to efficiently generate color signals that are PAL or NTSC ready, with very little silicon and support circuitry. To better understand 7800 colors, it helps to have an understanding of NTSC and PAL color encoding.
Both NTSC and PAL TV standards have a short colorburst signal near the beginning of each scanline. The colorburst serves 2 purposes. Its presence signals to the TV that the scanline will contain color information, but the colorburst signal also serves as a phase reference. If the same frequency is later detected by the TV during the display of a pixel, the TV will compare the phase of the frequency to the phase of the colorburst, and use the difference to determine which hue should be displayed for the pixel.
NTSC TVs generally use the YIQ colorspace for this color determination, while PAL TVs use the YUV colorspace.
Luminance component of 7800 colors
Saturation component of 7800 colors
T 7800 uses a constant saturation level of for color for all of the levels of b
Colorspace Model
The
