Troubleshooting CMYK color can be a pain, because there are often many places the problem could be lurking, and changes made in one, may inadvertently alter the output based on info from another. So in this five part series, we will look at five important steps to troubleshooting a color managed system, or colorimetric tuning.
As you all know, a color management system is usually broken into five parts:
1. Source color space
2. Media parameter setup
3. Source color space designation
4. Output color profile
5. Output calibration set
One of the first things to be aware of is your own expectations. People often assume that printer profiles should make everything match but a printer profile is just a measurement of what a combination of printer, ink and paper can reproduce.
Different types of printers and ink sets will produce different color gamuts. Different papers and surface textures will influence both color gamut and appearance. Matte papers always look flatter than gloss papers for example. Also the color of the paper white has a big influence. A warmer paper color will give warmer grays and skin tones than a cooler more blue-ish white paper.
Media with Optical Brightening Agents (OBAs) often require custom profiles to account for the fluorescing factor.
The combination of the ICC output profile and the calibration set allow the RIP to adjust for the white point, imaging characteristics and d‐max capability of the output media. For standard color, the output profile may have less effect on color than does the calibration set and other factors described previously. Bypassing conversion always ignores output profiles.
In most cases, the standard Fiery output profiles for Plain, Coated Matte & Coated Gloss may be suitable for most customers on most media. These are based on GRACoL standard, therefore are neutral grey by default.
After machine setup and linearization, the machine should be calibrated on the target media and test prints made using the applicable standard Fiery profile. Only if results appear unacceptable or sub-optimal should the time be spent to create custom output profiles.
If a custom output profile is necessary, the standard 928 patch target seems to provide suitable results on most printer/copiers. I advocate the use of an iSisXL spectrophotometer to reduce the time and effort to read the test patch pages. Otherwise, an ES‐1000 or ES‐2000 can be used within a Fiery RIP, or an XRite spectrophotometer for external software, but of course, using a hand-held device takes more time.
In some cases, the profiles being used in Photoshop may not be the same as the profiles on the RIP controller. One example of this is if the USWebCoatedSWOP profile is being used in Fiery Creative Suite with a newer RIP controller that has the SWOP2006_Coated3 profile installed from the factory. In these cases, you may import the profile you are using for the working space definition in Creative Suite onto the RIP's controller so it is available in Color Setup.
Another example is if you are using a custom press profile for a conventional
press and need to match the RIPs color output to that press.
If your inkjet is driven by RIP software then part of the calibration and profiling process is setting the printer options, ink limiting and linearization and it is with these that the root of most problems can be found. Getting the printer options right for any media can take a while, factors such as the number of passes, resolution, head height and drying times all can have a big influence on the print. Again the media manufacturer should be able to guide you.
The combination of the ICC output profile and the calibration set allow the RIP to adjust for the white point, imaging characteristics and d‐max capability of the output media. For standard color, the output profile may have less effect on color than does the calibration set and other factors described previously. Bypassing conversion always ignores output profiles.
In most cases, the standard Fiery output profiles for Plain, Coated Matte & Coated Gloss may be suitable for most customers on most media. These are based on GRACoL standard, therefore are neutral grey by default.
After machine setup and linearization, the machine should be calibrated on the target media and test prints made using the applicable standard Fiery profile. Only if results appear unacceptable or sub-optimal should the time be spent to create custom output profiles.If a custom output profile is necessary, the standard 928 patch target seems to provide suitable results on most printer/copiers. I advocate the use of an iSisXL spectrophotometer to reduce the time and effort to read the test patch pages. Otherwise, an ES‐1000 or ES‐2000 can be used within a Fiery RIP, or an XRite spectrophotometer for external software, but of course, using a hand-held device takes more time.
In some cases, the profiles being used in Photoshop may not be the same as the profiles on the RIP controller. One example of this is if the USWebCoatedSWOP profile is being used in Fiery Creative Suite with a newer RIP controller that has the SWOP2006_Coated3 profile installed from the factory. In these cases, you may import the profile you are using for the working space definition in Creative Suite onto the RIP's controller so it is available in Color Setup.
Another example is if you are using a custom press profile for a conventional
press and need to match the RIPs color output to that press.If your inkjet is driven by RIP software then part of the calibration and profiling process is setting the printer options, ink limiting and linearization and it is with these that the root of most problems can be found. Getting the printer options right for any media can take a while, factors such as the number of passes, resolution, head height and drying times all can have a big influence on the print. Again the media manufacturer should be able to guide you.
Specific settings that may help:
Optimized: Creates custom calibration d‐max calibration targets as read from the profile test patch page(s).
This setting should generally be left ON, which is the default for most printer/copiers. Only the d‐max endpoint is read from the target. The intermediate curve is calculated using a general formula and does not follow any unique density variations in the printer/copier.
Black Generation: Specifies toner limit and GCR parameters.
Specifying a black toner maximum of 95% instead of the default 100% will provide a smoother tone and gloss generation in the deep shadows. If designated at 95%, TAC reaches a 180‐260% value in the shadows, while designating at 100% usually causes a TAC drop to about 130%. Using the 95% black specification prevents a gloss roll‐off in the shadows on some media, while using the 100% black specification may reduce total toner usage.
Optimized: Creates custom calibration d‐max calibration targets as read from the profile test patch page(s).
This setting should generally be left ON, which is the default for most printer/copiers. Only the d‐max endpoint is read from the target. The intermediate curve is calculated using a general formula and does not follow any unique density variations in the printer/copier.
Black Generation: Specifies toner limit and GCR parameters.
Specifying a black toner maximum of 95% instead of the default 100% will provide a smoother tone and gloss generation in the deep shadows. If designated at 95%, TAC reaches a 180‐260% value in the shadows, while designating at 100% usually causes a TAC drop to about 130%. Using the 95% black specification prevents a gloss roll‐off in the shadows on some media, while using the 100% black specification may reduce total toner usage.
95% is usually recommended for best image quality. A TAC (Toner Limit) value of 260% should be used. Default values for Ricoh printer/copiers in CPS Ver 3 and Ver 4 may default to either 400% or 270% dependent upon the revision.
Very aggressive GCR settings may reduce banding and total toner usage dependent upon the colors found in the source job. Changes to other parameters may be used for specialized purposes.
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Do you have a color management question, horror story or event to share?
Email me at reilley4color@gmail.com
