How many colors have sRGB, Adobe RGB 1998, ProPhoto and Lab?

[marxoliva]

I didn't found in any site a info about it. Help please.

[davescm]

Hi

They all have an infinite number of colours. They only have a set number, when you divide those colour spaces up using 8 bits, 16 bits or 32 bits per channel.

Using 16 bits in Prophoto will describe a wider set of colours than using 16 bit in sRGB - but the number of colours described will be the same in both cases.

Dave

[marxoliva]

I just know that Adobe RGB 98 have 16,7 million of colors, but I can't find the number of others spectruns.

[D Fosse]

No, it doesn't. That number refers to discrete values at a certain bit depth, like 8 bits or 10 bits, can't remember which. It doesn't have anything to do with color space.

Unfortunately that number is used a lot in monitor marketing. I don't know, maybe some people think it sounds impressive, like "Dynamic Contrast Ratio 300000:1" or some other nonsense. It has no practical relevance whatsoever.

[davescm · Accepted solution]

Hi

I'll try and expand on my earlier post.

The diagram you attached is a demonstration of the range of colours that can be described in those colour spaces i.e. what is the reddest red, the greenest green etc

How many colours those spaces are divided in is dependant on the bit depth.

So using 8 bits for each channel, in RGB, gives 256 values of Red , 256 of blue and 256 of green.256 x 256 x256 = 16777216 . Guess what   :  16.7 million colour values.!

So in sRGB there will be 16.7 million colours available at 8 bits per channel. In ProPhoto there will also be 16.7 million colours available. But the colours described by individual numbers will be different.

Using 16 bits per channel gives 65536 x65536 x65536 = 281 x10^12 = 281 trillion colours. But if that is used in a particular colour space (e.g. sRGB) there are more discreet values but the range of colours (e.g. the greenest green) is still the same.

I hope that helps

Dave

[marxoliva]

The best answer. Thank you!

[c.pfaffenbichler]

And another point about that graphic:

it represents some area for »CMYK« – is that supposed to be one particular CMYK space, all CMYK spaces added together, …?

Even amateurs should be aware that the gamuts of a newspaper and a glossy magazine are different, so pretending like there is one »CMYK« seem to be lazy or worse.

[D Fosse]

c.pfaffenbichler  wrote

is that supposed to be one particular CMYK space

Right.

I think the awareness of this is probably much higher in Europe, because Photoshop's default Web Coated SWOP is definitely and totally unusable everywhere. So a lot of people will have learned the hard way.

In the US you can probably live happily for a while thinking that CMYK is, well, CMYK. Even though other standards like GRACoL are used, I think the same inks basically apply (correct me if I'm wrong), so that even if it doesn't come out quite right, it won't cost you your job or anything. But Web Coated SWOP will probably be accepted by most printers. Not so in Europe.

[sharp_hands16B8]

It's not really more colors as it's a different parameter or range of colors you get in that particular gamut.

For example, in the graphic below. Both ranges go from white on the left to black on the right. But the amount of ways that range is cut up into other shades is how bit depth is used to create a range of values between those colors.

[D Fosse]

To put it simply - marxoliva is confusing color space with bit depth.

But you can't really blame the OP. This is what most monitor manufacturers feed their customers with. Reading monitor spec sheets is a depressing affair - they are so filled with absolute nonsense that it's hard to know where to begin. Most of it sounds impressive, but in reality means absolutely nothing. It's just marketing fluff, and this is one example of that.

At the same time, the parameters that really matter, those that would actually say something meaningful about panel quality, are nowhere to be seen.