In this blog I’ll be looking at CMYK printer profiling in the new i1 Profiler software, including the Printer Linearization, Printer QA and Data Analysis workflows. The new i1 Prism color engine in i1 Profiler seems to make exceptionally good CMYK profiles, although as with other parts of the software there are functions included that I think few people will use and some that don’t seem to have much effect, there are also a couple of features of ProfileMaker that I will miss.
Let’s start with the Printer Linearization workflow. Linearizing a printer ensures that each colour channel is printing in a defined linear fashion so that 50% of a colour is half as strong as 100%, for example. The software won’t let you linearize a RGB printer since most printers being profiled as RGB are only virtual RGB devices and are really printing with CMYK inks. Not all CMYK printers need linearizing in profiling software since most RIPs have a linearization function within the media calibration wizard and you’ll get better results linearizing there. If, however, you are profiling something like a simple colour laser without a RIP then you may get better results doing a linearization before you profile. You start by defining the number of patches per channel, 40 is more than enough, and then go on to set page size and print the chart. You then measure and save the linearization result. It would be nice to be able to see the curves at this point, as you could in Monaco Profiler.
When you start the CMYK Printer Profiling workflow you can then load your Linearization file and it will be applied to the colour patches you generate for the profiling and also embedded in the profile at the end of the process. Linearizing a printer profiling will get you a better profile because the colour patches will be more evenly distributed across the colour gamut of the printer.
When you generate patches for a CMYK profile you have additional options to the ones you had for an RGB profile. You can set the total ink coverage for the patches. If you’ve ink limited in your RIP then you can leave that to 400 but otherwise you can set it to lower amounts if the media you are profiling won’t take that much ink and you get drying or spreading problems. You can also set a slider for Patch weighting (dark/light), the theory behind this feature is that if you know you are going to be generating a profile with high level of black (more about this further down) then you can choose to have more dark patches. I haven’t had time to fully explore this option but I guess it might come into its own with some of the trickier types of media I profile such as cloth or leather.
The Test Chart, Measurement and Lighting pages are the same as for RGB profiling so I’ll skip over them and get to Profile Settings. It’s here that you set the black generation options. I haven’t got space to explain black generation in detail so I suggest if you are new to the concept that you go to the CMYK Printer chapter in Practical Colour Management, which you can download for free from our websites.
You can control the total ink coverage, how soon black ink or toner begins to be used in the tonal range and the maximum level of black. The Black curve control sets how much black is generated at any tonal level. Some devices suit quite a light black curve and with others you’ll get better results and save ink with heavier curves. You can view the K%/Lightness curve by clicking on the button on the control bar above the test image (more about that in minute). It would be good to be ale to view all the gradation curves as you can in Measure Tool. The black width control determines the range of colours affected by the black generation, a setting of zero means that only neutral colours are affected, 100 would mean all colours might be.
The Full black separation check box will produce very heavy black generation, and the Use intelligent black check box will stop the Black curve you’ve selected from compromising the total gamut of your profile, it is best to leave this on unless you have problems and need to force the behavior of the black curve.
The affect of any setting can be viewed by looking at the channels of the test images supplied, or indeed by loading your own. There are test images for high key, low key, mid tone and various colours so you can get a good idea how the profile will generate black before you do any test prints. Once you have made your black generation choices you can then go to the next page and create your profile. ProfileMaker had some pre-set black generation settings and I think it would be good for novice users if i1 Profiler adopted this approach as well, there is one fairly hidden offset printing preset you can use but there should be more. The Perceptual, Tables and Advanced options are the same as for RGB profiling.
Once you have built and tested your CMYK profile you can go to the Printer QA workflow to measure a control strip to see how well your device conforms to an international printing standard, or you can use this workflow to monitor the consistency of your printer over time. The software supports the popular IDEAlliance and FOGRA test wedges, which are fine for those familiar with proofing and press standards but it would have been nice if X-Rite had included the option of creating your own test wedge. Once you’ve measured your wedge you can compare it to an industry standard reference, or if you’ve previously saved the page data from a Printer QA measurement page you can use that as a reference to judge your own devices against each other or against themselves over time. At the end of the workflow you get a Pass/Fail result and details of the delta e values (colour differences) and you can save out a QA report. The Printer QA workflow could be useful for monitoring printer behaviour, although I think most users needing to use it would have the functionality built into their RIPs. The Data Analysis workflow allows you to get a similar report to the Printer QA workflow but allows you to compare any two sets of measurement data as long as they have the same number of patches. This could be useful for comparing results across different media on the same printer, the same media over time or the same media on two different printers.
I’ve been really impressed with the CMYK profiles I’ve made using the software so far, our first customer using the software was a a very demanding fine art printer and he is getting excellent results on a wide range of canvas and fine art media.
The next and final blog in this series will be on Display and Projector profiling.
