Macbeth color chart question

  • Thread starter Thread starter KenP
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KenP

Does anyone have the color density (CMYK) values for the 24 color
patches on the standard matte Macbeth color chart? I've got a listing
of the RGB values used to create the chart, but nothing on how a
printed chart should measure.

Thanks for any help,
KenP
 
Here you will find a program that permits to compute CMYK to RGB and viceversa
http://www.mick.tilbury.btinternet.co.uk/index.htm?colcal.htm
-Francesc
Click to expand...


You should be aware that there is no one to one mapping between RGB
and CMYK, and that RGB can represent colours not available in CMYK and
vice-versa. To give an example of the former, 10% grey in CMYK can be
represented by equal proportions of C, M and Y and a proportion of K
(black). There are literally hundreds of possibilities - and automatic
conversions don't always choose the "obvious" one of 10%K, 0% CMY!

If you are aiming for a CMYK device, it is better to work in CMYK
values all the way through the process.

Finally, CMYK has a well defined set of colour values for each ink -
defined by industry practise, if by nothing else. However, RGB is far
less well defined, varying with phosphors and LED emitters. So, RGB is
a far less constant thing than CMYK, which is itself less well defined
than more rigorous standards used in high precision colour systems..

Paul Cooper
 
You should be aware that there is no one to one mapping between RGB
and CMYK, and that RGB can represent colours not available in CMYK and
vice-versa. To give an example of the former, 10% grey in CMYK can be
represented by equal proportions of C, M and Y and a proportion of K
(black). There are literally hundreds of possibilities - and automatic
conversions don't always choose the "obvious" one of 10%K, 0% CMY!

If you are aiming for a CMYK device, it is better to work in CMYK
values all the way through the process.

Finally, CMYK has a well defined set of colour values for each ink -
defined by industry practise, if by nothing else. However, RGB is far
less well defined, varying with phosphors and LED emitters. So, RGB is
a far less constant thing than CMYK, which is itself less well defined
than more rigorous standards used in high precision colour systems..

Paul Cooper
Click to expand...

Wheew - guess the answer is to buy a Macbeth chart and measure the
thing myself, doesn't look like there's any other way. I do see your
point, that the "K" term or black ink is used to tone down the other
colors as cheaply as possible-that's what it's for, right? My X-Rite
densitometer measures CMYV, where "V" represents visual density. I'm
not sure how that compares.
 
Wheew - guess the answer is to buy a Macbeth chart and measure the
thing myself, doesn't look like there's any other way. I do see your
point, that the "K" term or black ink is used to tone down the other
colors as cheaply as possible-that's what it's for, right? My X-Rite
densitometer measures CMYV, where "V" represents visual density. I'm
not sure how that compares.
Click to expand...

K is also used to provide a "pure" black - the black obtained by
mixing CMY tends not to be black. As you say, it is also cheaper!

Paul
 
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