logoalt Hacker News

adrian_byesterday at 8:47 AM7 repliesview on HN

While it is true that some saturated blue-green colors will never be reproducible with only 3 primary colors, the CIE 1931 chromaticity diagram used in TFA overemphasizes their importance, because human vision cannot distinguish many colors in that area of the diagram.

In reality, the greatest defect of the sRGB color space, which is still too frequently the default color space, is that it is not able to reproduce many saturated orange/red/purple colors, which are very frequently encountered around us, e.g. in flowers, fruits and clothes.

The missing orange-red-purple corner appears small in the diagram in comparison with the missing blue-green corner, but in reality humans perceive much more different colors in the orange/red/purple corner, so the relation between those areas would be opposite in a uniform color space.

The Display P3 color space is much better than sRGB for reproducing orange/red/purple colors and now it is available even in many cheap monitors. However many monitors that can reproduce Display P3 come configured by default to use just sRGB. Such monitors should always be reconfigured to use Display P3.

Monitors that can reproduce an even greater part of the Rec. 2020 color space are obviously better than those that can do only Display P3, but such monitors with a higher color gamut are usually more expensive. The full Rec. 2020 color space can be reproduced only with laser projectors, because it uses monochromatic primary colors.


Replies

js2yesterday at 4:34 PM

> The full Rec. 2020 color space can be reproduced only with laser projectors, because it uses monochromatic primary colors.

All of the non-commercial triple laser projectors I'm aware of are single-chip DLP, so they suffer rainbow artifacts and have poor black levels. They're also liable to laser speckle[^1] if you're not careful on your screen selection.

The JVC (LCoS), Sony (LcoS) and Epson (LCD) laser projectors all use a single blue LED laser and phosphor wheel to make white light, then use prisms and filters to split it to RGB and can only get 87-98% of DCI P3. They have better blacks and no rainbow artifacts, but the color reproduction is not as complete.

Which is to say, it's still a compromise in projector land, unless you've got $400K for a https://www.christiedigital.com/products/projectors/all-proj...

[^1]: https://www.valerion.com/blog/triple-laser-speckle

show 1 reply
kadobanyesterday at 9:47 PM

Stupid question: does the computer or whatever the monitor is hooked up to need to know to do something special to then show those colors, or it's just normal rgb color levels and in a less-good-color-space monitor those would have been shifted to less accurate colors?

red75primeyesterday at 10:03 AM

> the relation between those areas would be opposite in a uniform color space.

If I understand correctly fig. 3 in [1] should be perceptually uniform. The bluegreens missing from sRGB, but present in BT.2020 comprise a sizeable chunk comparable to redyellows.

[1] https://www.researchgate.net/publication/345252499_Evaluatin...

show 1 reply
fmajidyesterday at 11:42 AM

Not to mention the Color Rendering Index (CRI) metric Ra does not weigh the R9 (deep red) so many forms of lighting don't try to render it correctly to save costs.

show 2 replies
jfengelyesterday at 5:50 PM

As I understand it, JPEG cuts out a lot of detail in the blue range, because we don't see it as well. Is that due to the same thing as you're saying here?

show 1 reply
szmarczakyesterday at 12:03 PM

There's color space and there's color depth. You may be using D-P3 with 8 bit, which is worse (less accurate?) than sRGB with 8 bit. And there's bandwidth. Your monitor may not be able to handle 4k 240fps 16 bit.

show 4 replies