Re: [APML] RGB -> CMYK

[Larry McManus <lmcmanus@clearpointadv.com>]

To print an image on an offset press you have to convert that image from a
RGB to a CMYK. A printed CMYK image is made up of dots. Each dot is one of
the CMYK colors (CYAN MAGENTA YELLOW AND BLACK...CMYK). To print a color
image on an offset press they run four different inks (CYAN MAGENTA YELLOW
AND BLACK...CMYK). These four CMYK colors (depending on how large the dots
are) will virtually reproduce any color.
 
Nowadays there is no reason to worry about press specific CMYK conversions.
There are a some things you will have to know. 1 you will pick up some
contrast in the final image. 2 All offset presses have a tendency to print
on the red side. 3 The dynamic range you will be able to print is around 4 f
stops. When you get something printed, on offset, you supply them with a
color corrected press proof of the image. The press has many fine
adjustments to lay down the correct color using your press proof as a guide.

You must have total faith in the color you see on your monitor so you must
calibrate your monitor when doing color work. We use Mac platforms here and
the best and easiest way we have found to calibrate is: 1 Use the color
calibration that comes with the system to set up the initial calibration. 2
Open up an CMYK image that has a range of colors and grays that has been
printed (on an offset press) and make the final adjustments manually
comparing the screen CMYK image to the Printed CMYK image.

Hope This helps

Larry Mcmanus



on 3/5/03 10:55 AM, Jerry Lodriguss at jerry@astropix.com wrote:

> At 12:41 PM 3/5/2003 -0500, you wrote:
>> When images are published in print, they are usually converted to CMYK
>> color space. Would folks who have experience doing that please share a
>> little bit of practical advice about the steps to perform and in what
>> order? Some detail would be nice, but even a top-level overview would be
>> helpful. Are there any web sites you would recommend for learning about this?
> 
> 
> CMYK conversions are usually press specific and you need the color space
> profile for the individual press that it's going to be printed on.
> 
> If you want to get into CMYK color correction, get Dan Margulis' book
> "Professional Photoshop".
> 
> Jerry
> 
> Astronomical photography: http://www.astropix.com
> 
> 
> 
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