Color Test Patterns

[old_tv_nut]

Originally Posted by W.B.

I think I can help. The I and Q matrices are on the outer quadrants (-I / +Q left, +I / -Q right), the inner quadrants are:
- Top left: R-Y
- Top right: G-Y=0
- Bottom left: (G-Y)
- Bottom right: B-Y

If my cards are played right, they should be at 40% color saturation.

Thanks.

I calculated the NTSC Y signal for a few of them from the R,G,B values indicated in the Photoshop color picker, and it comes out to 126 for all that I checked. Good start. (Probably 127 would be ideal.) In other words, the Y signal is 126 ~= 0.5/1.0.

However, for 40% saturation, it seems to me that the smallest of R, G, or B should be 60% of 126, that is, 100% saturation occurs when the smallest just goes to 0 x 126 =0, and 40% saturation occurs when the smallest is 60% of the Y signal, = 76.

However, the value of the smallest of the primaries in this pattern varies from color patch to color patch, so it seems to me the saturation is not consistently 40%.