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# Tag Info

Accepted

### Alpha blending in linear colour space

Just turning the comments into a fully-fledged answer as it may prove useful to others. IMHO, the alpha channel should always be linear and treated as such. You described blending a black quad over ...
• 4,261
Accepted

### Does CIE XYZ preserve spectral accuracy when used for progressive rendering?

The choice of various tristimulus color spaces or spectral rendering matters when you're doing multiplicative color operations, like multiplying a light source color by a material reflectance. For ...
• 25k
Accepted

### Why is there a difference between the CIE XYZ colour gamut vs CIE RGB?

Correct, the missing curvy section in the green-cyan-blue area represents where the red component would have to go negative to express those colors in CIE RGB coordinates. RGB and XYZ are, at one ...
• 25k
Accepted

### How to convert from XYZ or sRGB to ACEScg/AP1

The discrepancy comes from chromatic adaptation, which is included in the matrix from shadertoy. If you combine XYZ->AP1 with D65->D60 from the aces page you end up with the same matrix that I got by ...
• 203

### Interpolating HSV color with black

If you are interpolating in HSV you will need to handle a few special cases. If the value of a colour is 0, you should calculate as though the hue and saturation of that colour is the same as the ...
Accepted

### How do I calculate average hue, since the numbers loop around?

How do I calculate average hue, since the numbers loop around? I will get silly answers sometimes. For example, in HSB/HSL, the average of hue=10 (slightly orange red) and hue=350 (slightly blue red) ...
• 256

### Does CIE XYZ preserve spectral accuracy when used for progressive rendering?

How accurate it is to estimate rendering equation using wavelengths This is probably as accurate as it gets if you are using with the full form of Fresnel equation. then convert result to CIE XYZ ...
• 461

### What is the name of this moving color pixels effect, for animating a painting?

This effect is called Color Cycling (or Palette Shifting). Mark Ferrari has a great GDC talk where he demonstrates and explains the entire technique. You can view a bunch of his artwork based on this ...
• 222

### How do I plot tristimulus curves?

You can certainly convert the wavelengths of the visible spectrum into the XYZ colour space with some extra considerations. Converting wavelengths of the visible spectrum into RGB will present some ...
1 vote
Accepted

### What are the exact math steps to convert sRGB (D65) to Lab (D50) colorspace?

convert sRGB to RGB by first removing gamma (colors must be in linear color space for the conversions to be accurate) The Fujiwaratko site is confusing since it lists sRGB in its table but the ...
• 3,219
1 vote
Accepted

### How to visualize color synthesis in HSL diagram

The first thing to say is that the line and triangle in the chromaticity diagram show the result of mixing coloured lights, so the triangle works for the additive RGB model which is mixing emitted ...
1 vote
Accepted

### Luminace, RGB, and SMPT ST 2084 EOTF

I fully understand the confusion (I was also a bit confused when I saw it). So, I decided to look at the ACES implementation of the ST 2084 EOTF. https://github.com/ampas/aces-dev/blob/v1.0.3/...
• 1,605
1 vote

### What is the relation between colour spaces and what is actually displayed on our screens?

The real story here is actually very interesting and can be enlightening. So I offer this alternate answer to help better answer this question. Also, my answer below is a very specific to this ...
• 3,219
1 vote
Accepted

### What is the relation between colour spaces and what is actually displayed on our screens?

Several reasons. Im listing them in random order There are entire industries that do other things than display things on computer screens. If you were to print a booklet, make a package, movie ...

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