How many composite colors does CGA have?

In 640-pixel high-resolution mode there are 16 distinct four-pixel patterns, producing about 16 composite artifact colors. With more elaborate dot patterns (the basis of the 'CGA in 1024 colors' trick) many more shades are possible, because a pixel's color depends on its neighbors within a color-carrier cycle.

Are composite artifact colors part of the CGA palette?

Not in the usual sense. They are not RGBI colors a programmer selects directly; they emerge when CGA's digital pixels are encoded into an analog NTSC signal and decoded by a TV. Many of them don't exist among the 16 RGBI colors at all.

CGA composite colors

On a composite TV, CGA shows colors that aren't in its 16-color palette at all — artifact colors created by the NTSC signal. Below are the 16 high-resolution artifact colors with exact hex codes, decoded from the real composite signal (not sampled from RGBI, the way most references get it wrong). Click any swatch to copy.

The 16 high-resolution artifact colors

These come from the 16 possible four-pixel on/off patterns in 640×200 mode, decoded at the default monitor calibration (white pixels on black). The label shows the pixel pattern that produces each color.

These are computed, not copied. The swatches above are generated in your browser by actually decoding the composite signal with a faithful port of reenigne's chroma-multiplexer algorithm — the same model DOSBox uses. Black and white land exactly on #000000 and #FFFFFF; the other 14 are genuine artifact hues outside the RGBI palette. The method and sources are on the accuracy page.

Why these colors exist

CGA's pixel clock is 14.31818 MHz — exactly four times the NTSC color subcarrier of 3.579545 MHz. Because of that 4:1 ratio, a horizontal pattern of pixels looks to a TV like a color subcarrier: the pattern's phase sets the hue, its amplitude sets the saturation, and its average level sets the brightness. So a repeating dot pattern is a color — one a TV displays even though no single pixel has that color.

This is why the same CGA game looked so different on an RGB monitor versus a composite TV, and why some games were authored specifically for composite. The colors here are the high-resolution case; the medium-resolution 320×200 mode and clever per-scanline tricks (the "CGA in 1024 colors" technique) expand the count dramatically, because a pixel's apparent color depends on its neighbors.

Crucially, these values depend on the monitor's hue/saturation calibration — adjust those knobs and the whole wheel rotates. The set above is the conventional default.

See them in action

Put any image through composite and compare it to RGB on the CGA composite simulator, or convert and download with the image converter (set the monitor to "NTSC composite"). For the sharp RGB palette instead, see the CGA palette, and for the full theory read how CGA color works.

Frequently asked

Why do most "composite CGA" tools look wrong?: They sample the 16 RGBI colors directly instead of modeling the NTSC signal. That can't produce the real artifact hues, because those colors come from the dot pattern across neighboring pixels, not from any single pixel's RGBI value.
Can I get different artifact colors?: Yes — they shift with the palette, the dithering pattern, and the monitor's hue/saturation. The values here are the standard high-res set at default calibration; the simulator lets you vary all of it.
Is this the same as the 1024-color mode?: Related but not identical. The 1024-color technique uses carefully chosen character patterns and per-scanline tricks to pack far more distinct dot patterns — and therefore far more colors — into the same signal.