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What are OKLCH colors?

jakub.kr

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Re: What are OKLCH colors?

#121

Post by the_af »

layer8 wrote: post #97
the_af wrote: post #90

Earlier quoted context omitted.

Is gray perceived as "just another color" or where all colors go when desaturated? I assumed the latter, which would explain why to avoid it if one isn't playing with saturation.

Think of fashion, of smartphone colors, pen and pencil colors and the like. Gray, white, black, are just color choices among all the available colors. A gray T-shirt isn’t a desaturated colored T-shirt. It’s its own color.

Oh, I understand what you say. But in color spaces, isn't gray the "sink" towards which desaturated colors shift? This would make it a location to avoid (unless you're purposefully desaturating).

Re: What are OKLCH colors?

#122

Post by cruffle_duffle »

layer8 wrote: post #97
the_af wrote: post #90

Earlier quoted context omitted.

Is gray perceived as "just another color" or where all colors go when desaturated? I assumed the latter, which would explain why to avoid it if one isn't playing with saturation.

Think of fashion, of smartphone colors, pen and pencil colors and the like. Gray, white, black, are just color choices among all the available colors. A gray T-shirt isn’t a desaturated colored T-shirt. It’s its own color.

Color is weird like. Gray is “all the visible spectrum in equal proportions”, which is white… just less white than the whitest thing visible but more white than the darkest (blackest) thing visible.

It’s a “color” because it’s useful to describe such a thing. If you had monitor entirely filled with 50% white you’d call it white. Only by comparing it to something brighter do you call it gray. Brown is the same thing. In a dark room if you looked at a monitor filled with red and green pixels you’d call it orange. Only when you start adding in clues like whites and brighter colors would you call it brown.

Anyway, yes grey is a color. But it is not quite the same as other colors. Other colors occupy only parts of the visible electromagnetic spectrum. Whites are the whole thing.

There is actually several very good technology connections videos about this stuff. Color is very cool!

Re: What are OKLCH colors?

#123

Post by AnimalMuppet »

layer8 wrote: post #85
cubefox wrote: post #80

Earlier quoted context omitted.

One could also argue that the detour through other hues is necessary in this case to avoid going through grey.

Gray is arguably just another color, it’s not clear why you’d want to avoid it. How is going via red and yellow better than going via gray? Varying hue is often perceived as a larger change than varying saturation or lightness. A path going through several distinct hues is visually less uniform than one going through gray once.

It depends on how you think about your spread. If, as someone else said, you're trying to represent a tunable laser going from red to blue, going through gray is completely wrong. That is not what a laser will do, ever. It will always be a fully saturated color.

So, depending on what you're doing, you want different things. You may want to view your color space as an RGB cube, and go through gray. Or you may want to view your color space as something more like HLS or OKLCH, and not go through gray.

Re: What are OKLCH colors?

#124

Post by xg15 »

pavlov wrote: post #75
xg15 wrote: post #66

Earlier quoted context omitted.

In the spirit of "Oll Korrekt", "Otto's Kolors"? How do you pronounce it, btw? "Oklich"? "okay L.C.H."?

Lich is an old word for a corpse (or in D&D mythology an undead magician). An okay lich is like a chill corpse, maybe?

Was more thinking of a single word like "Oxford", but that works as well!

Re: What are OKLCH colors?

#125

Post by Sharlin »

spoiler wrote: post #105
Diggsey wrote: post #57

Earlier quoted context omitted.

Also, isn't the way browsers interpolate colors in sRGB just a bug that I assume is retained for backwards compatibility? sRGB is a logarithmic encoding, you were never supposed to interpolate between colors directly in that encoding - the spec says you're suppose to convert to linear RGB first and do the interpolation there...

It's not a bug, its a property of the colour space. Which is partially tied to how the colour is represented (RGB). When doing linear interpolation through the RGB cube (for eg a gradient), you normally pick the shortest path. It just so happens that sometimes that path passes thorough some shade of gray as different colour components are scaled. Usually you fix it by moving your point through a different colour spac…

I think GP is referring to the difference between "normal" (gamma-encoded) sRGB and linear sRGB. Though it's not logarithmic but a power law. In any case linear interpolation done in non-linear sRGB gives you intermediate colors that are darker than they should (though historically it's been so common in computer graphics that people are accustomed to it).

Re: What are OKLCH colors?

#126

Post by ximm »

cb321 wrote: post #102
seanwilson wrote: post #74

Earlier quoted context omitted.

I'm not following. These examples are using the WCAG2 contrast algorithm which is well known to be flawed for people interested in this stuff, especially for dark themes so there should be lots of bad examples here? APCA is supposed to improve on this (see the example graphic comparing WCAG2 and APCA): https://git.apcacontrast.com/documentation/WhyAPCA.html > But as @c-blake has rightly pointed out, this doesn't take…

I don't think you & I have much disagreement here as I like the way you write about approximations and edge cases and things involving human judgement calls and "both not either" kinds of testing. The WhyAPCA document you link to also includes language to such effect with sliding scales over regions & such. Me - I'm mostly asking questions not offering answers. That said, to correct the record.. >These examples are u…

There is no real difference between ratio and difference. It is just scaled with a logarithm. See https://blog.ce9e.org/posts/2022-09-10-contrast-algorithms/ for details.

Re: What are OKLCH colors?

#127

Post by Sharlin »

brulard wrote: post #116
layer8 wrote: post #85

Earlier quoted context omitted.

Gray is arguably just another color, it’s not clear why you’d want to avoid it. How is going via red and yellow better than going via gray? Varying hue is often perceived as a larger change than varying saturation or lightness. A path going through several distinct hues is visually less uniform than one going through gray once.

Let's say you continuously change wavelength of a laser from blue (~480nm) to red (~630nm), you are going through green, not through gray. If in your use case going through gray makes sense, that's ok, there may be many paths from one color to another.

In general people don't really think of color in terms of the spectral progression (or the hue wheel), and I don't think that most people intuitively expect a gradient between two colors to pass through another "unrelated" primary or secondary color. The point is somewhat moot though, given that such gradients (like yellow to blue or red to green) are very unnatural anyway.

Re: What are OKLCH colors?

#128

Post by hansvm »

guenthert wrote: post #84
adrian_b wrote: post #71

Earlier quoted context omitted.

For any really bigger color space, you would have to use more than 3 primary colors, which would increase a lot the cost. Moving the monochromatic BT.2020 colors from 630 nm, 532 nm and 467 nm could get a little increase in color space coverage, but at the expense of a lower efficiency in power consumption to brightness conversion. 467 nm is not a very pure blue, but the sensitivity of the eye drops very quickly in t…

> For any really bigger color space, you would have to use more than 3 primary colors, which would increase a lot the cost. Unless you want to make displays for the bees and birds (and the tiny alleged minority of human tetrachromats) that seems rather pointless. People with three color receptors are your customers, so that's driving the market. I rather predict, future displays will further improve on contrast, incl…

That's not the issue. Take pure blue wavelengths as an example. They also activate your green cones a little. Increasing the frequency activates the blue cones less and the green cones much less, yielding a higher ratio of blue to green activation, and a new color (violet) that you can't represent with mixed color output exactly aligning with mode receptor wavelengths.

Re: What are OKLCH colors?

#129

Post by nkrisc »

chrismorgan wrote: post #7

The “Better Gradients” thing is dodgy. OKLCH is a polar coordinate space. Hue is angle in this space. So to interpolate hue from one angle to another, to get from one side of a circle to the other, you go round the edge. This leads to extreme examples like the one shown: linear-gradient(in oklch, #f0f, #0f0) You can also go round the circle the other way, which will take you via blue–aqua instead of via red–yellow: l…

IMO in pretty much all cases if the two colors at the end of your gradient are not already very close, you will always get the best results by manually specifying the colors at one or more steps between the two original colors.

Which brings me to point at the crux of the matter: avoid gradients between two dissimilar colors in the first place.

Re: What are OKLCH colors?

#130

Post by Diggsey »

spoiler wrote: post #105
Diggsey wrote: post #57

Earlier quoted context omitted.

Also, isn't the way browsers interpolate colors in sRGB just a bug that I assume is retained for backwards compatibility? sRGB is a logarithmic encoding, you were never supposed to interpolate between colors directly in that encoding - the spec says you're suppose to convert to linear RGB first and do the interpolation there...

It's not a bug, its a property of the colour space. Which is partially tied to how the colour is represented (RGB). When doing linear interpolation through the RGB cube (for eg a gradient), you normally pick the shortest path. It just so happens that sometimes that path passes thorough some shade of gray as different colour components are scaled. Usually you fix it by moving your point through a different colour spac…

No, sRGB refers to both a colour space and an encoding of that colour space. The encoding is non-linear to make best use of the 256 levels available per channel, but you were never supposed to interpolate sRGB by linearly interpolating the encoded components: you're supposed to apply the transfer function, perform the linear interpolation at higher precision, and then convert back down into the non-linear encoding.

Failure to do this conversion is what leads to the bad results when interpolating: going from red to green will still go through grey but it should go through a much lighter grey compared to what happens if you get the interpolation wrong.

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