Originally Posted by angryht
I've been trying to get the colors right on my Westinghouse LCD (LTV-40w1 HDC) using HCFR and a I1 LT colorimeter. It doesn't have CMS so I am limited to saturation and hue controls. Grayscale has been adjusted to fairly close to D65. Based on Tom Huffman's guide, I adjusted the saturation so that the red brightness is very close to the target (adjusted slightly based on my specific gamut). I then adjusted the hue control to get the cyan aligned with the target. This adjustment rotated all of the secondaries counterclockwise. Prior to the hue adjustment, the magenta was very close to the target but the yellow was already on the green side. After the hue adjustment, the cyan was spot on but yellow was even closer to green and magenta was shifted closer to red.
And when I put on some actual content with faces (skintones) - it looked horrendous!! Everybody looked sunburn (red push?) with a little bit of a greenish (sickly) look. Any suggestions?
Well, I looked at your Excel and HCFR data files for your TV. I used Bruce Lindbloom's CIE Color calculator to get an optimum Y=luminance value for the RED primary color. I put the combined data into the table (below) with an example of the Excel Red x,y data in Bruce's calculator. The table rows contain the 3 color data runs: HCFR x,y,Y color coordinates, dE for Red and Yellow colors, Yellow's Red and Green RGB (%) and Bruce's RGB calculated values. The first row is the Rec 709 standard data for Red.
The Bruce Y row is calculated by entering Red x,y data and guessing at Y values to make R=255. This is the best Y value to prevent clipping for the color you entered, in this case Red.
So, looking at the Color data, the C=28 H=26 run is clipping at R=263 or 264 with Y=23.3% of White. Therefore, I would reduce it slightly to the Y=21.61% value close to the Rec 709 standard of 21.26% but still above it. This increased luminance is probably because Red is under saturated (located inside the CIE Rec 709 reference triangle) for your TV.
The Tint Hue RG data for Yellow is well balanced for C=28 H=26 @ 108-107% for R and G levels respectively. The C=25 and H=25 Tint values of R=106% and G=107% are also good. So, H=25 or 26 is going to be right depending on the Y change effect previously mentioned (above).
I hope this review helps. I would be interested in a subjective assessment of these implemented suggestions with a before and after comparison of real video material.