|There are in fact color spaces that are neither RGB nor CMYK nor luma-derived. Scientific images for example frequently contain data outside the visible spectrum. Given this, I think it's easy to conceive of a palette that's irreducible to RGB values.|
Yes, I understand there are different
color spaces. There is RGB, YCrCb, CMYK, HLS, HLV, XYZ and even more. There is not
just one way to represent colors. But, those color spaces are just different ways to represent the same
information! For example, there are formulars to transform RGB values into the equivalent HSV or CMYK values — and vice versa. Of course, this works with the other aforementioned color spaces just as well. Depending on what kind of processing you do, one color space may be more "convenient" than the other.
But the key point is: A specific color is still the same color, regardless in which color space it is represented in!
See here for an example: https://i.imgur.com/vAC1VoC.png
And yes, there are wave-lengths of light that the human eye can't perceive. In fact, the spectrum that we actually can
perceive is extremely small! But, of course, we are talking about the visible
spectrum (colors) here. Scientific images, recorded, e.g., in the "ultraviolet" or "infrared spectrum", are usually converted
(shifted) into the "visible" spectrum, using pseudo-colors, so that we can actually see them.
|Pantone is a separate color space that's not necessarily translatable to any of those.|
If you pick a specific color — and yes, I mean a color in the normal "human visible" spectrum — put that color into your fancy color book and give it an elaborate name like "Pantone color #42"
, then that's simply yet another
(obscure) way to refer to the same, plain old color! It's still the same color that — just as well — could be referred to by the equivalent RGB or equivalent HSV or equivalent CMYK value.
|No. You are wrong. I can easily show how it can be done:|
Sure, if you store an image using indexed colors
, then — at least in theory — some of the colors in your color table
may be defined by their RGB value, while others are defined by their CMYK, HSV, XYZ or whatever color space value. And, yes, some of the colors in your color table may even be defined by their fancy "Pantone" identifier. But: Why would anybody want to have this unnecessary over-complication? Why "mixing" different color spaces (or Pantone id's) in your color table? Keep in mind: All1
the colors that you want to have in your color table can be transformed
into the desired target color space (e.g. RGB) once
. And then we only have to deal with a single
In fact, this is what real-world image formats, such as PNG do: If indexed-colors
are used, then each pixel in the PNG image is stored as a palette index
(in the range from 0 to 255), and the palette
itself is stored as a sequence of 256 RGB
triplets (three bytes each).
1 in the normal "human visible" spectrum of colors
|Have you looked at the drivers of professional publishing printers in order to make this assertion?|
No, I haven't. But I don't have to. I know that a "professional" printer probably is capable of reproducing the specified colors (in the source image file) much more accurately than my "$99" printer at home — because the "professional" printer is more accurately calibrated, has better/more inks available, and so on. Still:
All this does not
change the fact that the same color is still is the same color, regardless of what color space it is represented in, or what fancy name we assign to it! In the end, we send the color to be printed — encoded in one way or another — to the printer. And then it's up to the printer (driver) to reproduce that color in the best way that it is capable of.