Talk:Subtractive color

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Article Grading: The following comments were left by the quality and importance raters: (edit history refresh watch) The article does not reflect the significant variation in the colors of subtractive primaries -- both in CMYK inks and in artists' paints. There is no mention of the importance of color management in converting source images to the color space of the specific colorants that are being used (or of artists' adaptation to the particular paints they are using). The previous article assessment here was completely confused about CMYK (calling it an additive color space, which is certainly wrong), and tried to argue that red, blue and yellow are "the true" primaries. Actually there is no such thing: the names "magenta", "cyan" and "yellow" or "red", "blue" and "yellow" are conventional names for whatever primaries are being used in a three-primary system -- the former by the printing/reprographic industry, and the latter by artists. "Cyan" as used in CMYK printers is often very blueish, for example. In fact any vaguely similar colorants will work as a three-primary system, although some combinations are better than others in maximizing color gamut. The "Limitations" section of the article, besides being poorly titled, fails to mention several other reasons for using black ink (e.g. ink economy, more accurate alignment), and the reason it does give is confused: there's no reason why equal densities of CMY (or RYB) would need to be used to produce a rich black. There is no discussion of the role of white (i.e. white ink, paint, or the white of the unmarked substrate) when using subtractive color spaces.

Contents 1 Yikes, Wikipedia sure has gone downhill 2 Subtractive? 3 Silver and Gold aren't "colors" per se. 4 Lack of information? 5 Article too technical 6 Article Grading wildly innaccurate 7 article too focused on cmyk color model

[edit] Yikes, Wikipedia sure has gone downhill

Yikes, I've not seen these definitions for 2 years. They have been through an evolution to perfection through the words of many people (in the fields of color science, etc.) when I left in 2004. Now the pages on color terms have come full circle back to horrible, confusing, bad grammar, inorrect info, info in the wrong place. I gotta give up. Good luck to you all, I'm sure you will all figure it out and the pages relating to color will be good again someday...until the next generation of "Wiki's" comes along... ha ha.

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It's not "Subtractive color space" It's just Subtractive color--[[User:Dkroll2|Dkroll2]] 08:38, Dec 24, 2004 (UTC)

Where is a description of the attention needed? Notinasnaid 16:34, 26 Dec 2004 (UTC)

[edit] Subtractive?

It's logically multiplicative colour, isn't it? After all, the proportion of light that one filter ir pigment layer lets through is multiplied by the proportion of light that another filter lets through. —Ashley Y 23:40, 2005 Jun 2 (UTC)

"Subtractive" because the object that you view only subtracts light; the opposite, additive color, is used where the object that you view adds light. Notinasnaid 12:41, 3 Jun 2005 (UTC)

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From the article: "except the imperfect system resulting from mixing real pigments, something that is very confusing nowadays." Could this be explained or a link provided that does explain it? How is this confusing and how is it neither additive nor subtractive? Threepounds 06:44, 8 December 2005 (UTC)

I have to agree. I've deleted it. If this really is outside additive/subtractive color that is both interesting and useful, but it isn't really either unless it is explained. Notinasnaid 09:44, 8 December 2005 (UTC)

It seems to me that mixing oil paints is mathematically equivalent to adding the RGB values in the proportions mixed. So if I start with green paint and add white, it gets brighter, but if I add black it gets darker, so is this additive or subtractive? Neodymion 04:50, 20 September 2006 (UTC) Actually, it seems the Kubelka-Munk Theory is the actual science for this link title but doesn't appear to apply to translucent things like inks. Neodymion 10:57, 1 October 2006 (UTC)

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It seemed necessary for me to extend this article with "For those who want to know more ..." section and an image of layers of coloured glass. As I work on Faculty of Graphic Arts, University of Zagreb, I may be able to get expert opinions on the subject from Department chiefs. I currently work on a project in enhancing of teaching material in this area (reproduction of photography department). Somewhere it should be said about use of actual pigments. Although I might agree that my wording on the subject may not be the luckiest.

I have an additional Image:Color-additive-mixing.png picture that is three-dimensional and may catch the eye, for other pages. This subject is IMHO the oprotunity to visually enhance Wikipedia, isn't it? If you have an idea of simple animation showing better how this color system works, I may be able to do it in POV-Ray, as this could fit into my project. Mtodorov 69 22:17, 24 February 2006 (UTC)

[edit] Silver and Gold aren't "colors" per se.

Ideas For your point you are trying to make, use monitor green (vivid chartruse you see on a computer monitor.) And make 2 images that domonstrate how the green turns to deep evergreen in CMYK. Or read color printing and add to that.

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[edit] Lack of information?

I'm curious why no one has yet to mention the fact that colors are multiplied. If you want to get all upity (not a real word, I know) you could say that it's "subtractive color" because there is less light than when you started, and I'll buy that for the title of the page, however there is no good reason why we shouldn't explain how light is multiplied, not subtracted.

For those of you who don't understand it, there is one big problem with subtractive color (other than the fact that you can visibly see that it's being multiplied, not subtracted), and that is negative color. There is no such thing as negative color, yet if you subtracted one color from another it seems like you could produce negative color very easily.

Light is measured in values between 0 and 1, including both 0 and 1. 0 is black and 1 is white. When you multiply two decimal numbers less than 1 you get a smaller number, which is why when you multiply two pigments together you get a darker color.

For example, if you combine magenta (RGB decimal values 1,0,1) and yellow (RGB decimal values 1,1,0) then you multiply each of their values. 1 * 1 = 1, so the R decimal value is 1. 0 * 1 = 0, so the G decimal value is 0. 1 * 0 = 0, so the B decimal value is 0. Thus, when you multiply magenta and yellow you get Red (RGB decimal value 1,0,0).

This needs to be explained in detail by someone at some point. —The preceding unsigned comment was added by Vjasper (talk • contribs).

I agree with the principle of this, although the details are a bit off. Light is not measured in values in the range [0,1] since there is no upper limit on brightness, but it's a good model for a filter. It might be more useful to think of a grey filter that reduces the light by 0.5. Two of these will reduce it to 0.25 and so on. A pure cyan filter stops nearly all the red light so it's harder to see the difference between using one or two of them. It's less easy to see with ink since there's a limit to how much ink you can put on one spot. Neodymion 04:34, 20 September 2006 (UTC)

Now I have to disagree. When talking about color, RGB (light) values are indeed measured in the range 0 to 1. See RGB color space and other articles about RGB. I understand what you're saying about an upper limit on brightness, but that hasn't stopped color scientists. Notinasnaid 08:06, 20 September 2006 (UTC)

But you agree with the principle? It seems rather important to get the science right in an encyclopedia. I would support creating a new article 'Color Mixing', especially since everything else I've seen on the net claims subtraction (and half of them still use RYB instead of CMY).Neodymion 06:43, 30 September 2006 (UTC)

[edit] Article too technical

This article spends too much time focusing on printing, and does not spend enough time really fleshing out the details of subtractive color. This article needs to be rewritten for a more general audience, and quite a bit of the content here needs to be moved to a more appropriate article. This article is about subtractive color, and nothing else. Stack 00:00, 15 March 2007 (UTC)

What kind of details are you looking for? The article’s content seems fairly reasonable to me, though much of it could be reorganized and maybe fleshed out a bit more. I think it would be good to have more (even very condensed) historical discussion of the uses of pigments and dyes, with some discussion of the associated changes in color theory, for instance changing the colors considered "primary" from red, yellow, and blue, to magenta, yellow, and cyan, as improved cyan and magenta pigments were created through technological advance. Not to mention a bit more discussion of color photography. It would also maybe be good to have some images showing spectral power distributions, and demonstrating the "subtraction" obtained from mixing of multiple pigments which absorb different spectra. But I don't see anything here which should obviously be removed. --jacobolus (t) 08:04, 16 May 2007 (UTC)

Most "too technical" complaints can be dealt with by proper use of the lead section. This article, like most, does not have one. The lead section should be a summary of the entire article, with no unique information. That is to say, removing the lead section would leave a complete technical article, and the lead section alone would tell a less technical summary. Notinasnaid 12:20, 16 May 2007 (UTC)

[edit] Article Grading wildly innaccurate

Much of the data for subtractive color is wrong. first of all, the CMYK scheme is for additive color. The true primaries of subtractive color and of the world of art are, red, yellow, and blue ...

CMYK is not additive color. Black would never appear in an additive color system. Both CMYK and RYB are correctly referred to as subtractive color schemes (setting aside that multiplication is the actual arithmetic operation).

There are no "true primaries of subtractive color," to say that there are reflects a profound misunderstanding of the science of color.

It's possible to transform color coordinates between CMYK, RGB, and RYB. The fact that someone might use RGB colors as the source for CMYK, or vice versa, does not mean that they both belong to the same (additive or subtractive) color scheme.

(the previous unsigned comments were left by 69.134.236.134)

Um, I'm not sure what you mean here… of course there are no "true primaries" (does the article say that there are? if so it should be amended), but CMYK and RGB are definitely different types of color models. In one, colors of pigment (which absorb particular wavelengths) mix to near black, while in the other, colored lights (which emit particular wavelengths) mix to white. One of these is "subtractive," and the other is "additive." That you can transform colors from one space to another (approximately; process printing and RGB displays have very different gamuts), doesn't imply anything about the color models. --jacobolus (t) 05:36, 16 May 2007 (UTC)

I do agree that the article is far from great though, and I downgraded it to “start” class. --jacobolus (t) 00:24, 29 July 2007 (UTC)

[edit] article too focused on cmyk color model

We already have an article for the CMYK color model, which is easily linked from this article (and is recently improved enough that I feel comfortable doing that :) ). But there are many other subtractive models, including those used in photographic processes, painting, etc. This article should be more of an overview of what subtractive color means, and leave describing CMYK in detail to the relevant article. --jacobolus (t) 00:26, 29 July 2007 (UTC)