# 6026- Color Management & the Corel COLOR MANAGER

Overview
Additive Color Models  combine red, green, and blue light, which the human eye perceives as a
whole spectrum of colors. A red, green, and blue component for each pixel in an image are assigned a
number between 0 and 255. This is suitable for devices that radiate light, such as a monitor. A
computer monitor adds and combines elements of RGB (Red, Green, and Blue) to the black
background of the monitor screen to create the broad gamut (or range) of colors in the display. 

Subtractive Color Models rely on the light reflected from an image. This is determined by the
absorbing properties of the ink on the image. Various percentages of four process color inks are
combined to produce millions of colors. The combination of  pure Cyan, Magenta, and Yellow do not
produce a solid black, but rather a muddy brown. To print a true black, a fourth ink is added to
produce the darker and neutral areas of the image. A printer produces color by masking or subtracting
from the paper's ability to reflect white back to the eye by placing a mixture of CMYK (Cyan,
Magenta, Yellow, and Black) inks onto the paper. Because of this physical limitation, the printer
cannot produce all the colors that are displayed on the monitor screen.

 In fact, the scanner, monitor, graphics software, and printer all have unique color producing and
interpreting characteristics. Each device decodes color information based on the way it reads digital
color data, or interprets the data it is given by other devices in the system. Transforming RGB and
CMYK color data from one device to another is actually the manipulation of that digital data,
subjectively (CIE) or mathematically, in order to produce the correct CMYK color elements required
to produce accurate printed output. This is the Color Space. To maintain color quality control,
hardware and software must be adjusted to enable color data to be translated correctly to the eye, so
that the color on the monitor is the color produced by the output device. This must be achieved within
different color models and different computer systems. It is for this reason that each device must be
calibrated within the color space.

Until recently, digital color prepress, concepts, and techniques for color calibration, color proofing,
image-setting, etc; were the exclusive domain of skilled tradespeople. For this reason,  user's may
determine that their efforts to integrate this specialized technology into the desktop publishing
environment do not produce optimal results. 

A Color Management system calibrates the printer or output device against the software and hardware
devices in the system that are interpreting and performing RGB to CMYK / CMY conversions. This
ensures accurate and predictable color rendition.  The Color Management System is a common
reference color space through which we map the color gamut of one device to the color gamut of
another device. In this way, we obtain predictable color rendering on both devices. In practice, this
means that the image displayed on the monitor will be a close color match to the image that has been
scanned, which in turn will closely resemble the proof from the printer. We say close, because an exact
match is virtually impossible.

Setting Up Your System
When you launch the Corel COLOR MANAGER,  you will be prompted to Create or Edit a color
profile. Start with a baseline profile that includes only the scanner and monitor. Call the profile
"Baseline" and exit the Color Wizard. The file, Baseline.CCM, can then be located in the
COREL\COLOR folder on the hard drive. Make a copy of this file under a new name. This is done so
that the printer target can be scanned with the scanner calibration enabled, and in order to use the
baseline profile to generate dedicated profiles for systems with multiple output devices. Run the Color
Wizard again, and select Edit A System Profile. Add the output device(s) to the copy of the original
baseline to create a complete color profile, and save it with a name that identifies the output device.
Repeat this process for each printer or output device.

Select Automatch for Gamut Mapping when prompted, unless you are creating individual profiles for
CorelDRAW™ and Corel PHOTO-PAINT™.  If you intend to work exclusively with bitmap images,
select Photographic.

Calibrating the Scanner
Scanner calibration is performed by transforming the color values in the scanner target image into
digital information. The colors on the target image are arranged in a grid so that the Color Wizard can
read those values sequentially and match those color values to colors that are also read sequentially in
a file within CorelDRAW 6. The Color Wizard adjusts or corrects the color information that is seen by
the Corel modules (CorelDRAW, Corel PHOTO-PAINT, etc) to compensate for the differences it
detects between the scanned target image and the color information file within the CorelDRAW 6
application. The result is that the digital information sent from the scanner will always be corrected by
the Color Management System before it is introduced to the Color Space of the system itself.

If your scanner is one of the supported devices in the Color Wizard, Corel has calculated the
appropriate color correction information for your scanner.  Select it from the list, and click Next to
proceed to monitor calibration. If your scanner is not supported with a color profile in the Color
Wizard, you can calibrate the scanner manually by scanning the Corel Target that is shipped with the
application, and saving it as a 150 DPI TIF image, or the resolution setting most common in day-to-
day use. 

If you are scanning from within Corel PHOTO-PAINT, remember to click Tools, Options, General,
and disable the Scanner Calibration check box before performing the scan. Store the file in the
COREL\COLOR folder of your hard drive. When you are prompted for an image, Browse to the
COREL\COLOR folder, and select the scanned image.   

To identify the boundaries of the color matrix on the target image, use the Zoom Tool to click on the
corner marks of the target to magnify the corners of the image, then mark them with the cross-hair
cursor. If you do not perform this step, the Color Wizard will not know what you want it to compare
stored values with. This means that extraneous digital information will be included in the calculations,
and calibration will be halted. When the scanner information has been successfully introduced to the
color space, you will prompted to calibrate the monitor. Click Preview and compare the scanned
image to the original. The scanned target image should resemble the actual target image  more closely
than the original target image on the screen.  

Note: For optimal results, an IT8 target and corresponding dedicated reference file should be
purchased from a reputable vendor because each target file is individually measured with a
densitometer, and the unique color values for the image are stored in the reference file. Because of
production constraints, the target image and reference file shipped with the CorelDRAW 6 Suite are
generic in nature and may not produce accurate and consistent results under all conditions.    

Monitor Calibration
If your monitor is supported by the Color Wizard, select it from the list of supported monitors. If it is
not supported, you must click Calibrate Monitor. Click Default Characteristics when prompted.
Settings for monitor chromaticity, white point, RGB, etc: are available from the manufacturer. If you
cannot find RGB color values, you can calibrate this visually from the color matching boxes at the
bottom of the Calibrate Monitor dialog box. 

Note:  Do not attempt to guess the proper values for a particular monitor unless you are experienced
at the procedure and certain of the outcome.

Printer Calibration
If your printer is supported by the Color Wizard, select the corresponding profile from the list of
supported printers. If your printer is not supported, and you elect to calibrate it, remember to
determine whether or not the printer is shipped with calibration or color correction built into the printer
driver. If this information is not provided in the owner's manual, contact the manufacturer. Disable
any color matching options in the printer driver. Many Windows® 95 drivers offer the option to Print
in Color Without Image Color Matching.  Enable this check box, or the equivalent option in your
printer properties. If the calibration cannot be disabled, do not attempt to include the printer in the
color profile. It is not possible to apply color correction to a device that has built-in color correction.
Make sure that Scanner Calibration is enabled under Tools, General in Corel PHOTO-PAINT.  Click
Calibrate Printer and click Next.

Note: Determine whether or not the printer is CMYK by performing the steps after clicking on the
Classify button. If you hold the resulting test sheet up to a light, and you can recognize different
shades of black in the shape of a large "C", your printer is CMY or three color. Do not guess what
classification the printer should be. Although output devices are sometimes defined by the
manufacturer as CMYK devices, many produce colors by mixing only CMY color elements in the
printer circuits, then rendering the colors to the paper with a four color ink cartridge. You will then be
prompted to decide between Default Characteristics, or Other Characteristics. Select Default
Characteristics unless you are printing to a specialized device.

The next screen you see will be used to determine what colors your printer is capable of printing. You
may choose between the File method or the Scanner method of color measurement. The File method of
calibration is the most accurate method of calibration, but requires an REF file of color values to be
created for comparison.

Note: The scanner method of printer calibration may be difficult to bring to a successful conclusion
because inconsistencies exist between the color information as interpreted by the scanner and how it is
carried forward to the print calibration process. The technique is included in the Color Wizard because
device-specific files and specialized instruments are often unavailable to the computer user. Other
limiting factors in the process include the texture and shininess of the test target paper, printer ink
characteristics, the accuracy of the scanner calibration, and the general mechanical condition of the
printer itself.

Scanner Method of Printer Calibration 
Print the test pattern file, scan it at 150 DPI, and save it as a TIF to the COREL\COLOR folder of the
hard drive. If your printer is CMY, the test pattern file will contain 270 colors. If your printer is
CMYK, the file will contain 504 colors.

Click Next to retrieve the target from file, and Next again.  Browse to load the target file. Note the
name of the color measurement file name, and click Next. A screen will appear displaying the scanned
target file. Click the Zoom tool, and use the Zoom tool to click on the four corners of the target image.
Clicking on a corner of the image will magnify it, so that you may align the cross hair cursor with the
white corner boxes. Depending on the characteristics of your video driver, you may find it necessary to
align the cross-hair cursor with the inner edges of the outer corners of the white alignment boxes.
Right-angled crop marks should appear at each corner of the target image as they are aligned. 

Note: If the Classify function has been performed incorrectly, the Color Wizard will not complete the
printer calibration process. 

Click Next to initiate the generation of the final profile. If your printer is four-color CMYK, you will
be presented with screens to set up the TAC curve, as well as the curves for the CMYK plates. Adjust
the TAC curve to a value of 260 - 300 according to the media type being used. 
For example, newsprint absorbs ink, so a TAC curve setting of 260 may be appropriate. Vivid blacks
might be best achieved on high quality glossy paper with a TAC curve setting of 300. Click on
Calculate. Click on Next. Click on Finish.

Tips To Remember
Remember to click Tools, Options, General within Corel PHOTO-PAINT, and disable the Scanner
Calibration check box before scanning the target images.  Enable the Scanner Calibration check box
before using the new color profile.

Remember to disable any color matching options in the printer driver. Most Windows 95 drivers offer
the option to Print In Color Without Image Color Matching. Other drivers may have a feature like
ICM which can be disabled.

Remember to disable View, Color Correction, Accurate within the application while using the Color
Wizard, and remember to select it when using your new color profile.

Remember to disable the Printer Color Profile - Generic CMYK check box in the CorelDRAW Print
dialog box when using a color profile. The option to use the new color profile should be available after
the profile has been selected.

If you are unable to use the Zoom tool, or place the cross-hair cursor correctly, you are most likely
experiencing a problem with some aspect of the user interface of your computer. Review the
instructions in Fax on Demand document #6001 to be sure you are not using a 16-bit mouse driver.
This condition may also occur when the video driver or video card is not compatible with Windows
95. Try operating the computer in Standard VGA video mode. Instructions for general Windows 95
troubleshooting can be found in Fax on Demand document #2100, and may also solve this issue.

Depending on the speed of the computer, generation of the final profile may take 15-30 minutes.