nesdev.org

How does the Snes convert 15-bit RGB into an NTSC/PAL signal?

At a basic level, I believe it converts the 15-bit RGB to YUV, uses the UV to adjust the phase and amplitude of the color carrier sine wave, yielding chroma, adds Y to that, attenuates based on the brightness register, adds sync information, and outputs. That is, I don't think there's any filtering applied to Y before it's mixed with the chroma. Every scanline it shifts the color carrier phase 120 degrees, unlike the usual 180 degrees. The above yields a result similar to the NES in its artifacts.

I guess the above is kind of obvious, as that's what it would pretty much have to do. Why do you ask?

blargg wrote:At a basic level, I believe it converts the 15-bit RGB to YUV, uses the UV to adjust the phase and amplitude of the color carrier sine wave, yielding chroma, adds Y to that, attenuates based on the brightness register, adds sync information, and outputs. That is, I don't think there's any filtering applied to Y before it's mixed with the chroma. Every scanline it shifts the color carrier phase 120 degrees, unlike the usual 180 degrees. The above yields a result similar to the NES in its artifacts.

I guess the above is kind of obvious, as that's what it would pretty much have to do. Why do you ask?

For some odd reason, I expected it did it some non traditional way, that involved converting RGB to the wave height at 0 degrees, 120 degrees, and 240 degrees and cycling through the 3 phases.

psycopathicteen wrote:For some odd reason, I expected it did it some non traditional way, that involved converting RGB to the wave height at 0 degrees, 120 degrees, and 240 degrees and cycling through the 3 phases.

You probably expected that because the Apple II does exactly what you describe, except with four phases instead of three.

How does the Super Nintendo display NTSC illegal colors?

I Didn't know snes had blacker then black colours.

Illegal as in pure red, pure yellow, pure cyan and pure blue.