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08/20/2003 08:41:54 PM · #1
Whats the real difference in cameras that shoot in one or the other? Does it affect post production?

I know my Nikon is CGMY but I don't know what to do with that information, if anything.
08/20/2003 09:00:58 PM · #2
As I understand it, RGB is best for web application. CGMY is best for printing. I'm not sure how it affects post production, but professional printers, say of books and brochures and posters, etc. use CGMY because then then know what they are getting, as specific colors are assigned specific numbers that print ink maker, such as Pantone, use.

Of course, it just now occurs to me that I'm confusing CGMY with CMYK. Hmm. Any difference, anyone?
08/20/2003 09:05:34 PM · #3
What's CMYK?
08/20/2003 09:13:03 PM · #4
Let's see . . .

C=cyan
M=Magenta
Y=Green
K=??????

Or am I up in the night--I'm just guessing!
08/20/2003 09:14:25 PM · #5
//www.dpreview.com/learn/key=colour+filter+array

You're both confusing the "color filter array" with "color profile."

To answer your first question, ttreit, it does not effect post processing.
08/20/2003 09:16:45 PM · #6
Originally posted by dsidwell:

Let's see . . .

C=cyan
M=Magenta
Y=Green
K=??????

Or am I up in the night--I'm just guessing!


cyan
magenta
yellow
black

this is not the same as CGMY (cyan green magenta yellow) and is used in a completely different way.
08/20/2003 09:23:05 PM · #7
Originally posted by greenem2:

Originally posted by dsidwell:

Let's see . . .

C=cyan
M=Magenta
Y=Green
K=??????

Or am I up in the night--I'm just guessing!


cyan
magenta
yellow
black

this is not the same as CGMY (cyan green magenta yellow) and is used in a completely different way.


Is the "Y" not really the grey scale or dynamic range of the image? The name "black" does make sense, but I would like to be sure that I understand the issue, can you confirm my assumption?

Also, please explain why CGMY is not the same. Is does sound like the image colour and grey scale information is just being displayed in a different matrix, like Y, R-Y, B-Y and I & Q, please explain more if you can? I am intrigued by CGMY and its application. It sounds like a 4:4:4:4 matrix, is it?

Message edited by author 2003-08-20 21:27:30.
08/20/2003 09:51:18 PM · #8
Cyan, Yellow, and Magenta are the three "subtractive" colors, and are used for "full-color" printing (like photos) where color inks are applied to paper (offset printing, silkscreen, inkjets, color lasers). In theory, those three mixed should make black, but due to impurities in the inks they usually make a dark, muddy brown, so Black ink is added as well for contrast and clarity of detail.

There are also a couple of six-color systems which add either "Light Cyan" and "Light Magenta" or else Orange and Green inks to extend the reproducible color gamut, which is only about 7000 colors in traditional CMYK.

PANTONE(R) colors are specific formulations using a base palette of (usually) eight inks, blended to a color-match before inking the press.
08/20/2003 09:55:10 PM · #9
Originally posted by GeneralE:

Cyan, Yellow, and Magenta are the three "subtractive" colors, and are used for "full-color" printing (like photos) where color inks are applied to paper (offset printing, silkscreen, inkjets, color lasers). In theory, those three mixed should make black, but due to impurities in the inks they usually make a dark, muddy brown, so Black ink is added as well for contrast and clarity of detail.

There are also a couple of six-color systems which add either "Light Cyan" and "Light Magenta" or else Orange and Green inks to extend the reproducible color gamut, which is only about 7000 colors in traditional CMYK.

PANTONE(R) colors are specific formulations using a base palette of (usually) eight inks, blended to a color-match before inking the press.


That's great, but what about CGMY? What is it used for? Green is a primary right? Is the the grey scale colour in this case? It is rather odd to see a additive colour matrixed with three subtractive colours, no?
08/20/2003 09:59:38 PM · #10
I honestly have never heard of that color space. It is possible that it is a variation on the LAB model, where the Y stands for Chrominance or Luminance or something ... I work in offset printing, so I mostly work with CMYK and PANTONE colors ....
08/20/2003 10:26:46 PM · #11
The 'K' in CMYK stands for 'Key' which is a printers term for 'black' ink apparently.

I learned that from the Canon EOS workflow CD this evening...


Are you sure you mean CGMY ? I don't think I've ever heard of that colour space, and neither has google.

Message edited by author 2003-08-20 22:29:27.
08/20/2003 10:54:53 PM · #12
Aha! I knew if I posted false information that someone would correct me! THanks!
08/20/2003 10:59:08 PM · #13
I'm pretty sure the K is used for blacK so that there will be no confusion with a BLue ink, since no other common color starts with K.

For the same reason, at work I always use the spelling GRAy so as to not create a chance of confusion with GREen if I used the more "literarily elegant" spelling.
08/20/2003 11:15:19 PM · #14
Originally posted by GeneralE:

I'm pretty sure the K is used for blacK so that there will be no confusion with a BLue ink, since no other common color starts with K.

For the same reason, at work I always use the spelling GRAy so as to not create a chance of confusion with GREen if I used the more "literarily elegant" spelling.



Yup, its to avoid confusion with the B in RGB, but many places also mention that it is called a 'Key' colour.

//www.hp.com/sbso/advice/articles_printing30.html

'defining color with CMYK
As you just learned, CMYK models each color as a combination of different shades of cyan, magenta, yellow, and a key color. The key color is almost always black (only very special printing instances use something other than black as the key color), so CMYK could be called "CMYB." Color printers (both laser and inkjet) as well as professional printing presses are stocked with inks in these four colors and use unique combinations to create every color on the printed page.'

//wombat.doc.ic.ac.uk/foldoc/foldoc.cgi?CMYK

//www.cknow.com/ckinfo/acro_c/cmyk_1.shtml

A search on the concept of a 'Key plate' for print separations turned up


Key Plate
Definition: In traditional preparation of color separations, the key plate contains the detail in the art. This is normally the black printing plate. Because the black printing plate was often the key plate, the K in CMYK represents the key plate or black. Also see, keyline.'


Also


Keyline:

Definition: In traditional preparation of color separations, a red keyline on the black line art marked the outline of solid or tint color areas. In some cases a black keyline was used when it served as both a color indicator and an outline to be printed in black. Because usually the black plate contained the keyline, the K in CMYK represents the keyline or black plate also sometimes called the key plate.


Message edited by author 2003-08-20 23:18:34.
08/21/2003 11:10:04 PM · #15
It was my dislexic fingers that were the problem. According to DPReview the Nikon has CYGM (Cyan, Yellow, Green, Magenta) color filter array. I didn't know what that meant (good, bad or indifferent) compared to RGB.
08/21/2003 11:26:18 PM · #16

I'm going to guess that CYGM are just different built-in color filters that "translate" your photo to look like it's been shot with a colored filter on front. I don't think it's a color space; rather, I believe they are saying that it can emulate the effects of having four separate colored filters.

My camera does the same thing, although I think it has 7 or 8 colors built-in.

Just a guess.

Rob
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