Difference between revisions of "Atari 7800 Color Documentation"
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Revision as of 19:42, 15 November 2015
Contents
Overview
The process by which the Atari 7800 creates colors is directly related to the way NTSC and PAL encode colors within the signal. To understand 7800 colors, it's important to have an understanding of NTSC and PAL color encoding.
Hue component of 7800 colors
Both NTSC and PAL expect a short colorburst reference signal near the beginning of each scanline. The colorburst serves 2 purposes. Its presence indicates that the scanline contains color information, but also serves as a reference for any color information contained in the rest of the scanline. When the color frequency is detected by the TV during the display of a pixel, its phase is compared to the colorburst, and the phase difference determines the actual hue the TV will display the pixel with.
NTSC TVs generally use the YIQ colorspace for this color determination, while PAL TVs use the YUV colorspace.
Y=0.5 UV colorspace Y=0.5 IQ 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
