Talk:Prussian blue

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[edit] Unqualified use of color coordinates

As any formally trained color scientist would confirm, it is inappropriate to use unqualified color coordinates to specify a color appearance. In the Prussian Blue article, as I would guess all the other color-related articles, there is a box on the upper-right of the page that pretends to state the color coordinates of the color in RGB, CMYK, HSV and Hex values. This is wholly incorrect. RGB values in themselves cannot depict color appearance. In order to do so, the RGB triplet has to be connected to physical reality through, at the minimum, the definition of the RGB color space used, the white point of the illuminant, and in certain cases, the gamma function. The ICC specifications can help one understand what these requirements are. If Prussian Blue has such and such color coordinates, they have to be qualified as, for example, in AdobeRGB color space. Better still, linear XYZ color coordinates should be used. Furthermore the conversion of RGB to CMYK is wholly dependent on the particular transfer functions used for a specific set of inks and paper combination - the idea of posting the CMYK color coordinates for a physical color appearance is naïve at best and mostly preposterous.

As such the article runs contrary to the most basic precepts of color science, and is wholly misleading to uninformed readers. Trying to digitally reproduce the appearance of Prussian Blue using the information contained herein will not work at all.

Then please conduct a series of independent tests with all the information needed, publish it, cite it here, and change the Color Composition section. In the meantime, it will do as an approximation. -Toptomcat 22:40, 24 November 2006 (UTC)