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Input/Output/Workflow Scanning, printing, color management, and discussing best practices for control and repeatability


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Old 08-19-2001, 01:34 PM
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DJ Dubovsky DJ Dubovsky is offline
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When color equasions start looking like algebra, I quit. I think I will just stick with my tried and true method...if it looks good you did it right, if it don't, try another color.
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Old 08-19-2001, 06:15 PM
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paulette conlan paulette conlan is offline
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Great thread. I've really been confused on the color stuff. Anyway, I found a link that explains it well.Now I finally understand why in RGB( the visible spectrum) Red+Green =yellow . As I understand it,i t's because the monitor emits light and handles color differently than the traditional way we learned color for painting and printing on paper.Basically, we're talking about two different ways that color is handled. One way where light is reflected and the other way is where light is absorbed.Anyway, Kodak does a great job of explaining it on the link. On to the pixels and vectors!
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Old 08-19-2001, 07:11 PM
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On to the pixels and vectors!
hush yo mouff, honey chile (you speak southern, right? )

onward and upward, thanks for the link paulette
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Old 01-07-2002, 11:07 PM
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Hows this for a thought…
As Doug said earlier “additive” colors R255+G255+B255=White. Referring to your monitor, which is based on light, the absence of any color is Black and the “addition” of color gets you closer to White. Keep in mind that your monitor produces color by shooting Red, Green and Blue guns onto a black screen. (As it turns out the color gamut of monitors does not include a good representation of Cyan, Magenta or Yellow)

Conversely “subtractive” colors C+M+Y=Black. Referring to your Printer, which is based on reflective light, the absence of any color is White (the paper) and the more color you add “subtracted from white” gets you closer to Black. Therefore less ink gives you lighter colors and the addition of Black gives you darker colors. (Unfortunately the color gamut of CKYM printers does not include true Blue, Green, or Red).

Is it any wonder we have a lot of color problems when monitors can’t accurately reproduce printer colors and printers can’t accurately reproduce monitor colors?

For the complete story visit
for a two part “in depth” tutorial on color and color management

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Old 01-08-2002, 01:02 AM
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An excellent explanation.
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Old 01-08-2002, 11:52 PM
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Thanks Doug but I believe I missed the mark a bit. The original question was about color (Red & Green = Yellow)

Given that paint & ink are reflective colors they operate the same way we learned in school. (Blue & Yellow = Green) and (Red & Yellow = Orange).
Color printers set their primary colors as Magenta, Cyan, & Yellow. Why. Because they need a color model that will display as many colors as possible using three ink colors. Combining "White" paper plus "Black" ink gives an incredible color capability to printers. Using normal color theory, printers mix Cyan + Yellow + Black to make Green.
(Using Red, Blue & Yellow inks would not give the same color range capabilities).

The Red, Green, Blue, color model utilized by our monitors however, use a color model we never learned in school. This model starts with a black screen and electrons from three "guns" are targeted on groupings of Red, Green & Blue dots. When these three "guns" fire electrons at all three dots at maximum intensity "white" is created. Varying the "guns" being fired and the intensity at which they are fired create different colors. Maximum "White" = R-255, G-255, & B-255. Maximum "Red" = R-255, G-0, & B-0. Maximum "Black" = R-0, G-0, & B-0. etc… In this color model if we start with "White" = R-255, G-255 & B-255 and remove all the Blue (R-255, G-255 & B-0) we are left with "Yellow".
To see this for yourself open Photoshop and make a new image with a white background. (The "Mode" will be grayscale so change the "Mode" to RGB) Now go to Image\Adjust\Levels. Select the "Red" channel and with "Preview" selected, use your mouse to move the small triangle at the right of the black/white gradient display. This varies the Output Level of the "Red" channel. As you remove the output of the "Red" channel (removing the red) your image will turn "Cyan" in color. [Reset the "Red" Output to 255].
Now change to the "Green" channel and adjust its Output Level from 255 to 0. Now you will see your image turn "Magenta". Doing this in the "Blue" channel will turn your image "Yellow". This demonstrates that "Red" plus "Green" (no "Blue") = "Yellow"

Hope this helps a bit

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