Q: What is the KPG CFM? How is it different from other CMM's?
A: The KPG CFM is an intelligent, ICC compliant conversion engine. Instead of requiring many profiles for each printing condition to permit many conversion options (such as GCR, TAC, etc.), the KPG CFM requires only one accurate profile for each printing condition. The user defines all options, such as GCR, for any profile used for conversion via the CFM Control Panel.
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Q: What else is different about the KPG CFM?
A: Since the CFM automatically creates and stores device links for all conversions; the CFM can perform many tasks, which were formerly only possible by using third party device link tools.
Only a few devices, such as certain RIPs driving platesetters or proofers, could perform these tasks since most applications do not support device links. By contrast, all ICC compliant applications (e.g., Adobe PhotoShop and MatchFlow Composer) can use the KPG CFM.
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Q: What type of special tasks require the CFM?
A: Since all standard ICC conversions involve converting to and from L*a*b*, four-color specific information (CMYK) is lost during normal conversions (e.g., converting between different CMYK printing conditions). Device links allow many possibilities that are needed by graphic arts professionals, such as:
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Preserving the visual appearance of both the individual CMYK inks and the final combined CMYK inks.
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Converting CMYK images without contaminating pure CMYK colors (e.g., Y=100% or M=50%, Y=100% with highlight dots such as cyan or black).
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Preserving black-and-white (B/W) images as B/W while recalculating a much higher GCR for non-B/W CMYK images.
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Q: Are there any other differences in quality by converting images using the KPG CFM?
A: Yes. Along with all the CMYK-specific needs of the graphic arts, which are addressed by the CFM, there is one other benefit. Since the CFM "knows" the gamut of the source RGB or CMYK profile and the gamut of the destination CMYK profile, the CFM can determine the optimal color mapping to ensure the best preservation of color appearance and color information. In addition, users can customize the technology used by the CFM for these conversions to open up shadows, open up saturated areas of images, as well as to modify the trade-offs between hue, chroma, and lightness when converting between profiles with very different gamut sizes and shapes.
Note: The CFM takes several minutes to build an optimized device link, with new settings, for the first time. However, the CFM performs subsequent conversions by calling the device link from the cache so normal production operations are extremely efficient.
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Q: How do I use the KPG CFM in MatchFlow Composer or in other ICC compliant applications?
A: After installation, simply select the KPG CFM as the default CMM in the Apple ColorSync Utility.
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Q: How do I define GCR and other key options for converting colors to CMYK?
A: Launch the CFM Control Panel and select Black Generation. This window allows you to define UCR, GCR, TAC, and to enable/disable the unique Retain Integrity of CMYK to CMYK option. After changing the settings, be sure to save them (click on the Add button adjacent to the Current Settings list box, name the settings, and then click the Save button).
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Q: How do I enable the advanced options such as "Preserve Black as Black Only" and "Do Not Contaminate CMYK"?
A: The instructions for enabling these options are in the CFM Advanced Application Guide which is provided with your MatchFlow Composer Installer.
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Q: How do I apply color management to files converted by MatchFlow Composer?
A: In the template window for the conversion you have selected (for example, "Convert to High Quality PDF") enable Color Matching and click on the ColorSync Profiles Setup button. In the ColorSync Profiles Setup window, select the appropriate ICC profile for Input, Printer, Proofer, and the appropriate Rendering Intent. The "Input Profile" indicates the CMYK printing condition for which the input file was optimized (for example "KPG_SWOP"). The "Printer Profile" indicates the printing condition for the destination printing press that will print the job (for example "KPG_SNAP"). Leave Proofer Profile to None unless you are planning to create a file for printing on an ink jet or other proofer (see FAQ below).
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Q: What rendering intent should I use for converting files?
A: The most common rendering intent for nearly all conversions is Perceptual. This rendering intent will ensure the best conversion between systems with very different color gamuts.
The most notable exception is when converting from one output color space to another. Since the image has already been converted to CMYK, it is best to use the Relative Colorimetric intent, or Absolute Colorimetric if you want to preserve the appearance of a paper such as Newsprint on a brighter proofing stock. Note that the Absolute Colorimetric intent will lay down some greying dots on a 4/C 0%, such as the page background, which some users find objectionable. In this case, Relative Colorimetric is a good choice since the white remains white and the shadows are not tonally compressed a second time (which would occur with the Perceptual intent.
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Q: I converted my files in the manner described above using Perceptual, but still see some plugging in shadows and saturated colors. Is there anything else I can do?
A: Yes. By adjusting the value of PerBPC (Perceptual Black Point Compensation) from 1.0 to 2.0, you can generally obtain the optimal conversion of dark and saturated colors from one system to another. Refer to the Color Fidelity Module (CFM) Advanced Application Guide for instructions on how to adjust the PerBPC parameter.
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Q: My dark and saturated colors have about the right amount of detail, but the saturated colors are not exactly converted in the manner I would prefer. What can I do to change this?
A: There is no one perfect method when converting from very large gamut, saturated colors to much more limited forms of color printing such as newsprint, because of the limitations of the final destination where the image is printed. In order to account for this, the KPG CFM allows you to determine the trade-offs when performing such conversions. By increasing the weighting factors for PerL (achromatic image detail), PerH (the hues of saturated colors), or PerC (the chroma or saturation of colors) you can obtain the optimal color conversion for your particular situation. To modify the CFM default values for these weighting factors, please refer to the Color Fidelity Module (CFM) Advanced Application Guide.
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Q: How can I use previously saved CFM Settings?
A: Launch the CFM Control Panel and select Black Generation. Select the previously saved settings in the Current Settings list box.
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Q: How can I set up multiple CFM Settings automatically in my workflow?
A: In the ColorSync Profiles Setup window in the Composer templates, enable the Load CFM Settings Before Processing Job feature at the bottom of the window. In the adjacent field, type in the name of the CFM saved setting you wish to use. Any time you convert files with that template, Composer will ensure that the correct CFM setting is used.
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Q: I get an error when I try to set up my workflow for automatic setting of the CFM -- what could be wrong?
A: Check to make sure that 1) the setting does actually exist and is listed in the Black Generation Window of the CFM Control Panel and that 2) the spelling is exactly correct for that CFM Setting in the Composer Template.
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Q: How can I create a "Proof Only" file with Composer?
A: Referring to the answer above for applying color management to files, select the profile for your ink jet or other device in the Proofer Profile menu list. The converted file generated by Composer can be printed on that proofing device in order to give an accurate simulation of the final printed job.
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Q: My proof file described above printed on my ink jet doesn't seem to match my job printed on the press -- what do I do?
A: Check the following:
1.
Did I print my proof file on my ink jet with EXACTLY the same setup conditions as the test chart that was used to create the ICC profile?
2.
Are the papers on my proofer similar in color to papers on my press?
3.
Did I check the accuracy of my proofer profile?
4.
Is the profile I am using for the destination printing press an accurate representation of the printing condition?
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Q: How can I check the accuracy of my Proofer Profile or Printer Profile?
A: The simplest check is to identify a particular color that appears to be wrong on your proof or press and confirm if the measured color agrees with the profile for that proofer or press. To determine this, open the proof file or printer file in PhotoShop, set Color Settings to Absolute Rendering, set the first color readout in eyedropper tool Palette Options to Actual Color, second color readout to Lab Color. Be sure to set the CMYK profile in Color Settings to the profile being evaluated. Be sure also to assign the same profile to the image using Image>Mode>Assign Profile. If you place the mouse over the color in the image being studied, PhotoShop will give you both the CMYK value as well as the expected Lab value you should measure on that color using the measurement device used to create the profile. If expected Lab value is within 1 or 2 delta E of the actual measured value, the profile is probably not the source of your problem. If the two values differ significantly (i.e., 3 or more delta E), your profile may not be sufficiently accurate for use in your workflow. At this point, your options are either to improve the accuracy of your proofer or press via linearization or other adjustment, or to create a more accurate profile.
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