Debugging Profiled Inkjet Printing
By Edmund Ronald, Ph.D.
The vendor color workflow is a valuable tool for debugging profiled printing by comparison,
rather than by absolute judgement.
Profiled inkjet printing should just work, and all too often it just doesn't. When faces turn bright green the malfunction is obvious, however more often one will have nagging but uncertain doubts about the colors, As a color management specialist I see a lot of "issues" occurring with profiled printing, and have heard quite a few cries for help. Over the years, I have learnt to deal with these problems methodically, and I've summarized my approach in this article.
This article is about diagnosis, not treatment. I'm going to show you a quick way to figure out whether you have a hardware problem, or whether software issues are corrupting your profiled printing workflow. The key step is to get some original vendor paper and make a print with the vendor workflow aka. "Printer Manages Colors". This print then acts as a reference baseline for debugging. By creating a reference, the process of finding issues becomes a matter of comparison rather than requiring absolute judgement.
">The debugging process I detail below leads you through three steps. First you get some of the printer manufacturer's paper, and make a print with vendor settings. Then you make a print with the manufacturer's own profile; finally you make your own profile and print with the same vendor paper. The condensed set of steps, is followed by some explanations about vendor color and canned profiles.
Diagnosing Profiled Printing Issues: The Procedure
1. Set up the vendor workflow with "Printer Manages Colors" and make a nice colorful test print on vendor paper, making sure to choose the right paper type in the print driver dialog. If the print made with the vendor workflow looks ok, then your hardware is working well. If the print is bad then you might have a hardware issue eg. a clog, or you might have inappropriately chosen, fiddled with or otherwise corrupted the paper and color settings, so you need to clean the printheads and need to reset the default values for the print system and then make another test print.
2. If the print from (1) looks ok, then set up your usual profiled workflow, and make a test print using the same vendor paper, the paper settings validated in (1), and the vendor's canned profile. If this print does not match the print made in (1) then your profiled printing workflow is compromised by inappropriate settings or some other software issue —vendor profiles should always match vendor color.
3. If the print made in (2) with the vendor's profile looks ok, then your hardware and profiled printing workflow is good. Now it's time to focus on your own profiling technique. Make a profile of the vendor paper yourself to compare with the vendor's profile. To print the profiling testchart the safest thing to do now is to make use of Adobe's ACPU utility, using the same paper settings as in (2), and then scan the print with your favorite spectro and software to create a new profile. Now make a new print with the profiled workflow. If this matches the vendor color print in (1) you are done, just go ahead and profile your own media. However if your own profiled print on vendor paper does not roughly match the print in (1) then you probably have an issue with the profiling process itself —hardware or software— and should call the profile tool vendor for support.
Making profiles and printing with them is a fussy business, and many of us would prefer that "it just works". The good news is that Epson, Canon etc realize users want an easy solution, and they provide one: If you have a decent modern printer you will obtain decent color from any app —and Photoshop —by just selecting "Printer Manages Colors" in the print dialog. However you need to correctly specify the paper you have loaded. This is sometimes called Vendor Color mode.
The nice thing about Vendor Color is that it is almost foolproof. To make it work correctly you just need to reset the printing system, make sure you have the right paper type selected, and make sure that there are no leftover color bias settings hidden away in your print dialog.
Of course there is a price for the simplicity of this workflow: you must use the manufacturer's paper, and for neutrals to stay neutral and color prints to be really spot on, you should have one of the more expensive printers which have several gray inks, and whose manufacturing tolerance is so good that it closely matches the canned profile. Incidentally, the printer driver's Black and White Mode works great on these models.
Vendor mode is also a great debugging tool, because on their own papers Epson delivers very closely matched results by using vendor mode and by using their own canned profiles. So to see whether your color-management printing setup is working, you just need to locate the canned profile for your paper and print with it using color management - this is called printing in Application Color Mode.
And how do you find the canned profiles for your printer? Well, on Macs at least, the profiles should already be there in your color management dialogs. Otherwise, if you open the Colorsync utility, and select the printer, the installed printer's profile paths will be displayed for you.
Printing an image in Vendor mode should show you whether your printer is set up correctly and working ok. Printing in Application mode and comparing with the vendor mode should tell you whether color management is working ok. Your last problem if you do wish to profile your printer is to print a testchart with no color management - to do this it might be best to download Adobe's dedicated ACPU utility which excels at printing charts. I have seen every other method of printing charts fail at some point.
PS. I like Thomas Holm's 2009 Pixl test image which can be downloaded at (http://www.pixl.dk/download/).
Edmund Ronald was a member of the ICC's late Digital Photography Workgroup. He lives in Paris and has a color management blog which can be found at http://photofeedback.blogspot.fr/