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Better black and white with the ColorMunki
Creating QTR icc profiles for better black and white prints
The ColorMunki from X-Rite allows you to build icc printer profiles with its basic software, but not for specialist black and white printing.
This article covers both specialised monochrome ink sets and using ordinary colour inks with a variety of paper types.
How to get better black and white printing using the ColorMunki and the excellent shareware QuadToneRIP....
Improving B/W printing
See our initial ColorMunki review for more information about basic ColorMunki functionality.
A possible use would be to get better linearity when using third party papers with a printer that supports a specific black and white printing mode (such as the Epson ABW example below)
Using the ColorMunki and QuadToneRIP for better black and white
Note that QuadToneRIP (QTR) is a shareware package - well worth the $50.
It is regularly updated and runs on Windows and Mac OSX.
It is actually a complete B/W print system that gives very good quality B/W prints from a number of colour printers with OEM (manufacturers) colour ink sets and also supports custom black and white ink sets.
I've tried it in the past with replacement inks and although they may take a bit of experimenting, the results can be very impressive too.
I've covered building and using QuadToneRIP icc profiles in several different articles (see the links at the bottom of the article for all the references) but the ColorMunki has slightly different requirements in terms of reading in test patches.
In particular, it works best with bigger patches to measure
I've created a different version of my standard B/W print test image for use with the ColorMunki.
Most of the features of the image are there for particular reasons - I've got an article explaining what they are and how to use it. You can download a zipped JPEG of the file in A4 size (I've also got a slightly different shaped US Letter version)
Note the chevron shaped patches along the bottom of the image - this is for the ColorMunki to measure.
The QTR software contains sample images that you use with the Eye-One spectrophotometer. Whilst you can measure these a patch at a time with a ColorMunki, it's actually more accurate to scan the strip.
I did some experiments with scanning using the ColorMunki and found that the default order in the QTR software did not reliably work, hence my slight change to the patch order. I'll comment more on this when I cover using the scanned data
If you are testing lots of print/media settings I've got a single striped image that will comfortably print several times on a sheet of paper. (Strip image download)
Printing the files
These two files are in the grey Gamma 2.2 colour space.
I use Epson's ABW printing mode for quite a bit of my B/W printing and I believe that the ABW mode currently 'expects' print data to be in a space of Gamma 2.2 (this includes Adobe98 if you were sending a colour image to the printer driver, to print in B/W)
So, in Photoshop, you'd still print either image with 'no colour management' setting and with whatever ABW settings you were using.
Remember that the QTR profiles are for B/W printing, not for files with any colour in them.
Things get a little more complex if you are trying to correct black and white output printed using normal colour printing.
Here you may already have a profile for the paper.
However, trying to correct B/W linearity is potentially a poor alternative to getting a better ICC profile made.
If you were printing to a printer in its normal colour printing mode, then you'd print to the driver using your normal way of printing, that is, printing with an ICC colour profile.
The difficulty comes in using the new QTR profile you have. I recently faced this problem with a third party paper used in an HP z3200 where I'd already created an ICC profile for the paper with the built in profiling kit.
One solution is:
Lets say our image to print is in the Grey Gamma 2.2 space. First convert it to the correcting QTR profile (appearance does not change) then assign a Grey Gamma 2.2 profile to it (image changes appearance). The image is now adjusted to counteract the non linearity of the particular paper/ink/printer I'm using.
This is a bit of a kludge, but by doing the conversion as a Photoshop action I can produce a folder of files specifically for printing. Just make sure you identify the files some way, since if you print them on another printer they will be wrong.
I'm not using the ColorMunki Photo application here, but the Photo ColorPicker application. I've launched this from the 'Create a Color Palette' option in my tray (note I'm doing this on a Mac, but PC use would be similar)
The application launches and detects my ColorMunki.
Before any measurements the ColorMunki must be calibrated by turning the central dial to the calibration setting.
Afterwards I turn the dial to point down and select 'scanning mode' for the measurements
The test strip is scanned in the direction of the chevrons, as shown in the ColorMunki help animation below.
You can scan left to right or right to left as you feel fit.
Just remember to rotate the paper so that you start at the right end of the strip.
Because the 21 patches are slightly closer together than the standard ColorMunki test patch sheet, I scanned slightly slower than usual (3-4 seconds)
Make sure your measurements start and finish on plain paper.
A palette window will open containing your measurements.
Check carefully that there are 21 measurements. Any more or less means your scanning was faulty and you should delete the measurements and try again. To delete patches just select them all and hit delete.
For this quick test I'm using PermaJet Smooth Art Silk paper on an Epson 7880 with photo black (Pk) ink and ABW (advanced black and white) print mode. [See a past review of using textured and smooth versions of this paper]
Now I know in advance that this combination is unlikely to give the best results, since I normally use this very nice warm paper on my Epson 9600 with matt black (Mk) ink.
In fact, just looking at the measured patches above shows that the Pk Ink isn't giving very black blacks. You can also see the warmth of the paper.
Next you export the measurement data as a comma separated (CSV) file. I'm going to alter this in MS Excel before using it, but any spreadsheet application can do this simple task.
Note the CSV option may not be available when doing this on a PC - see the Addendum below for how to get an XML file into Excel
I've used a name that will hopefully remind me of some of the settings I was using (it's best to write this down too)
The ColorMunki is a full UV Cut spectrophotometer, so the data file contains masses of measurements, including the suggested names for the patch colours.
The data is in the order that the patches were measured
I created a simple empty data file that needs just the LAB values for the measurements.
You can download it (it's a simple csv test file)
I've added numbers describing the true (0% to 100%) order of the measurements and their values (percent black)
You can see the data I need in the exported file below if you move your mouse over the image.
Save this new file (meaningful name again!)
The QuadToneRIP package comes with an 'Eye One' folder that contains the scripts for building black and white ICC profiles (and some notes that you should read)
I just dropped the data file on the script file and it ran, producing the output below. It handles the out of order data with no problem.
You can see that while the line of 'L's is fairly straight (showing pretty good linearity) the 100% point is just not that far over to the left.
The blackest black of this particular print setting, just isn't very black on this paper (it's most likely due to the Pk ink choice).
As you can see a linearising profile has been created. You need to put this into wherever your profiles live on your system.
I've opened up the test image again and gone to the Photoshop CS3 print dialogue.
Note that with the 'match print colours' box ticked, the profile is being used to give a simulation (or 'soft proof') of what the print will look like.
I don't use soft proofing much for black and white but you can see the effects of the rather poor black in the screen shot below.
Note that although I'm going to print using the Epson ABW mode, I'm still applying colour management in Photoshop.
The profile will correct any slight non linearity that I'm getting from using from using a third party paper (see the links to other articles below for more on this)
In the print dialogue, I've selected a particular paper media type to print.
For this example I made a fairly arbitrary choice, but if I was going to be using this paper in this printer a lot, I'd do comparison prints using all kinds of setting variations.
Getting the right media settings at this stage makes a big difference - I've written an article about media settings choices, covering this sometimes neglected aspect of profiling.
I'm told that the export function is different on the PC version of the ColorMunki software and that you can import the .CxF file into Excel 2007 (I still use Excel 2004 on the Mac so have not been able to test this)
Thanks to Marco Brambilla for sending me a screenshot of the import process and a sample Excel file for the import process.
You right-click on one of the title cells, then choose xml|import, then browse to the xml file you've exported.
Seems to work well - since the ColorMunki is still new I'd appreciate any comments from people trying it out.
In the QTR Eye One folder there are various test patch images you can use, including a 51 patch image and a set of four copies of the 21 patch image, for averaging readings.
Whilst they are useful when building your own QTR printer Ink Curves, I've always found them overkill for the kind of linearization I'm looking at here.
In my own opinion you don't need any more than the 21 patches to improve a typical Epson ABW print.
If the original curve is so uneven that 21 patches isn't enough to sort it out, then change your print settings or change your paper or even ditch the printer.
Buying the ColorMunki
We make a specific point of not selling hardware, but if you found the review of help please consider buying the ColorMunki, or any other items at all, via our links with Amazon or B&H
It won't cost any more (nor less we're afraid) but will contribute towards the running costs of our site.
I've come across too many people getting into colour management, that have tried to fix problems with repeated profiling that I'd have quickly given up on and moved to another paper or printer. The technique I've described is for fine tuning print output, not setting it up in the first place.
The ColorMunki is a useful package, but uses like this show that it can be used for more advanced work too.
The views in this article represent those of Keith Cooper.
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