Screen and Printer Colour Matching ---------------------------------- Why do I need Colour Matching ? ------------------------------- As more and more people use Colour monitors and introduce colour images into their work a problem getting hardcopies is created. When a hardcopy of an image on the screen is produced the colours have to be converted from the Red, Green and Blue (RGB) colourspace to the Cyan, Magenta, Yellow and Black (CMYK) colourspace. This conversion is usually done by the printer itself, but does not take account of the different colours a printer and screen can display. Since the conversion is not done correctly the images produced on the colour printer differ greatly from the original image on the screen. Algorithms exist for doing a better conversion from RGB to CMYK, but they usually need the user to be an expert in colour theory and spend a large amount of time tweaking the images. Quite often the equipment needed to take the necessary measurements for these algorithms is expensive to hire/buy and so people put up with inferior images. What does the package do ? -------------------------- This colour matching package gives a simple method of matching images on monitors and printers. The user does not need to know anything about the underlying algorithms, and does not need any specialist equipment. The only equipment required is a Kodak Reflection Density Guide (Kodak Publication Q-16) which can be found in most reprographics departments. The package is made up of a number of programs each performing a specific task in the colour matching process. In order to start the colour matching process please read the following documents that accompany this package. The documents can be found in the 'doc' directory once the package has been unpacked. (see below) ralcolour_match - Provides an overview of the whole colour matching process. ralcol_match - Manual page for the program used in taking measurements. 16shades - Manual page for the program used to calibrate the monitor. midtone - Manual page for the program used to take monitor measurements charts - Manual page for the printer test charts. ralmatch - Manual page for the command line version of the colour matching program. ralmatchx - Manual page for the Motif version of the colour matching program. Before attempting to use the colour matching package please read the above documents. How to unpack the Colour Matching package ----------------------------------------- Once the tar file has been retrieved you can unpack it as follows :- First cd to where you want the colour matching package to be located and then type the following. % uncompress ralcol_match.tar.Z % tar xvf ralcol_match.tar This will create a number of files and directories taking up approximately 160 KBytes of disk space. Instructions on how to build the package can be found in the INSTALL file.
