New C64 color measurements
May 2021
Another quick hack to illustrate the odd/even line mismatch of the PAL VIC-II output.
All captures made from composite output with bt848 chip (Video Highway Xtreme capture card), contrast, brightness, saturation default, chroma AGC on, comb filter off. Sampling frequency is 4*PAL color burst, about 17.73 Mhz.
Select one of the links below, it will hopefully display a screen capture plus a list of sample averages. You might need to zoom into the images to see the odd/even effect (Hanover bars).
The averages were taken over an entere line of the picture (after chopping off some of the left and right margin.) Lines were chosen such that even-numbered lines correspond to odd-numbered raster lines on the c64 and odd- numbered lines correspond to even-numbered raster lines. (Yes, this is confusing, sorry.)
ycbcr are the average y, cb, and cr values, as returned by the capture card. The rgb values are computed based off those, as well as the chroma peak-to-peak voltage (vpp) and the color angle in degrees. An 'X' following the sample line indicates that the color falls outside the RGB gamut.
