Originally Posted by mrtickleuk
Perhaps you are not understanding my question. I know I will not eliminate the negative effects of simultaneous contrast. I will not be buying a calibrated paint from anywhere, it is too expensive and ridiculous to me. I was asking for a recommended paint that you can buy from anywhere that people have found to be reasonably close to neutral grey. Never mind :-)
I have understand the question and posted a link from FSI site where it has a formula for DIY paint but that paint brand is available only to USA stores.
There professional which own small post-production houses who have tried to find a cheap alternative also, but it was very difficult to find a close match, if you look colorist's forums you will notice how many people failed with DIY solutions and their 'grey' shade had another color bias inside.
Even trying DIY formulas, there variations from batch to batch which make the formula slightly different depending on when you get it mixed. And there's the problem of knowing exactly what that mixture should be since for precise colorimetry a complex formula is required.
To give you an idea, I went with Munsell N5 sample of the calibrated paint to 3 stores where they had devices to create paint from sample, all failed so much, the shade was totally different not even a close match, you will laugh if you see how far was the shade difference.
Not all White's are the same also in display calibration, while we use D65 which has 6504K, for each colorspace (REC.709/REC.2020 etc) while they have the same xy to create the D65, it's using different mixture of colors) while they have 6504K.
You can have 6504K temperature with different RGB channels mixture.
When you are using a meter/calibration software but you check only the Color Temperature Chart for the Grayscale, while the Color Temperature Graph can be perfect, the same time the RGB Balance Chart can be off.
This is happening because just a number 6504K is not the same as when we say D65 for a specific colorspace.
When you see the RGB Balance Chart of a calibration software and you see the three (R/G/B) Channels Bars at exact 100% = 0 dE; doesn't mean that you have used equal percentage of each color channel.
The calibration software it's doing the normalizing internally according to the selected colorspace target options to give you better presentation for easier calibration.
D65 White Point for REC.709 Color Space is using Red 21.27%, Green 71.52%, Blue 7.22% which gives 6504K.
REC.601 (PAL) D65: Red 22.20%, Green 70.67%, Blue 7.13%which gives 6504K.
REC.601 (NTSC) D65: Red 21.24%, Green 70.11%, Blue 8.66%.which gives 6504K.
REC.2020 (UltraHD Movies) D65: Red 26.27%, Green 67.80%, Blue 5.93%. which gives 6504K.