Wikipedia talk:WikiProject Color/Archive 6

June 2009--May 2010

National Flag Blue and Pantone references

I looked for a page for National Flag Blue - the particular color used in the US National flag. I didn't find one, so I considered created one. However, I see the article blue, so perhaps it would be better as a section of that article.

However, I note that article claiming "blue" is the color of the US flag and Greece and UK, but those are three different colors, none of which correspond to the blue in the article with color #0000FF.

Before I boldly create a separate section for National Flag Blue and rewrite the reference to the US Flag in the national colours section, am I missing something?

On a related note, some sources define their color using the Pantone numbers. I realize it is proprietary, but it is ubiquitous - is there a reason the color templates do not include the Pantone number? Is there an unwritten (or written) rule to avoid Pantone number references? --SPhilbrickT 17:16, 15 June 2009 (UTC)

The blue in the US Flag is specified to be Cable No. 70075. What that color is precisely is unclear (I don’t have access to the “Cable” color spec). But it’s supposed to be close to the Pantone PMS 282. This is described on the page Flag of the United States. –jacobolus (t) 22:16, 12 February 2010 (UTC)

In case anyone is still interested, I found a source for the cable colors, and started up a discussion over at talk:Flag of the United States. –jacobolus (t) 02:04, 30 May 2010 (UTC)

History of color printing

Is there an article about the history of color printing? I want to link to some relevant content from International Cloud Atlas, which was published in 1896 with color plates prepared from photographs. --Una Smith (talk) 17:12, 14 July 2009 (UTC)

I don’t think there’s a good article about the history of color printing, but it sounds like an urgently useful thing to work on. Go for it! –jacobolus (t) 22:11, 12 February 2010 (UTC)

The Jacob Christoph Le Blon article would be a good starting point for material on 3-color and 4-color printing. Dicklyon (talk) 05:22, 4 August 2010 (UTC)

Several incorrect chromaticity diagrams

Several chromaticity diagrams with incorrect coloring are currently being used. See Talk:Chromaticity#Chromaticity_diagram_colors_are_wrong.

For instance, compare (flip between) these. Note the difference in white-point location.

bogus white-point

more plausible

The incorrect white-point then results in incorrect blackbody colors (yellows and such).

Fixing all this will be a lot of work. Even just tagging it all. So, fyi. 98.216.110.149 (talk) 00:45, 4 September 2009 (UTC)

I left a message on the original uploader's page linking to your concerns. I can definitely see a difference between the position of the white point between the two diagrams. Image:CIExy1931.png looks to have a white point close to D65 which is what I would expect, but my technical level concerning the science of color is just enough to be dangerous. Might need to check out Image:PlanckianLocusWithYellowComplements.png also if there is a problem. P.S. I edited the thumbnails to be on the right side in your comment so that discussions can flow better, hope you don't mind. PaleAqua (talk) 06:49, 4 September 2009 (UTC)

Hi - There are a number of chromaticity diagrams that I generated, all derived from the original one at http://en.wikipedia.org/wiki/File:CIExy1931.png. This particular one has an explanation of how the diagram was generated and it reads:

The colors for this diagram were generated using the RGB color space in en:Adobe photoshop. The transformation from xy chromaticity coordinates was done using the en:sRGB color space specification on the [X,Y,Z]=[x,y,1-x-y] tristimulus values, then multiplying by a constant so that one of the R, G, or B values was maximized. Assuming that one's monitor converts Adobe photoshop RGB according to the sRGB color space (probably a good assumption) then, within the sRGB gamut, the chromaticities are correct, but are incorrect outside the gamut. (See the sRGB article for a description of the sRGB gamut). The process of maximizing the value of R, G, or B results in a distinct 3-pointed star in the diagram, centered at the D65 white point. This is because, although the chromaticities are correct, the luminosities (brightness values) are not equal across the diagram. If the luminosities were all made equal, then the entire diagram would be rather dark, since pure blue has a low luminosity. Any attempt to equalize luminosity to remove the star will reduce the overall luminosity of the diagram, and the star will not completely disappear until the diagram is very dark. Alternatively, we could blur the colors to get rid of the star, which would give incorrect chromaticities. I have opted for correct chromaticities at maximum brightness, thus the presence of the star.

Now, this may not be the absolute best way to do things. For example, someone has made the very good suggestion that rather than have the out-of-gamut colors be the same as the nearest in-gamut-color that lies on a line between the point and the D65 white point, one should have it equal to the color of the nearest in-gamut point based on a distance measured in a good chromaticity metric, like the Lab color space. At any rate, PLEASE, if anyone decides to change things, give a very detailed description of how the diagram was generated, and try to make it have some connection to reality. PAR (talk) 11:48, 9 September 2009 (UTC)

Template:Shades of color

I've been playing sandbox for {{Shades of color}} to see if I can figure out a way to eliminate most uses of the article##= parameter. From watching the various shades of templates seems like that parameter is the one most commonly missed when adding or deleting colors resulting in links to the wrong articles. Any input or suggestions would be helpful. PaleAqua (talk) 21:41, 12 May 2010 (UTC)