by Mike McNamee Published 01/01/2005
We examine the implications of choosing either the Matte Black or Photo Black option for the Epson Ultrachrome ink set and then see how the decison affects the analysis of a new canvas material from Epson, PremierArt Water Resitant Canvas.
Ultrachrome™ Matte or Photo Black?
This is a relevant question for users of the Epson Ultrachrome ink sets on the 2100/7600/9600 series of printers.The ink is a seven-colour set with two black options, Photo Black and Matte Black, hereafter called PK and MK. The MK is preferred for all matte and art papers, indeed the Epson 4000, which carries both types by default, chooses the ink according to which media is selected.There are a number of conflicting issues to be resolved as you make the choice of which ink set to use on the 2100/7600/9600 printers.
1. Longevity data is based on MK for art papers and PK on all others. If you choose to stray outside this set of combinations you lose touch with the database.
2. Changing ink on the 7600 and 9600 results in a loss of about £45 worth of ink, dumped into the sump to flush the system. Quick changes on a daily basis are thus out of the question.
3. Dmax is improved on art papers by the use of MK.
4. MK cannot be used on gloss and lustre papers as it smudges and rubs off.
5. Metamerism can be different between the two inks, the pigment based MK has a higher metameric index on some papers.
6. There is a poor database on the effect of the two inks and print quality.
7. Some RIPs, notably the original Ilford Studio do not recognise the MK set up on the printer and hang the system.
Setting out to measure the differences between the two ink sets is not for the faint-hearted. If the differences are subtle then the test must be carefully designed, including using the same ink cartridge set, the same paper batch and the same printer settings (e.g. media type, resolution, rendering intent).
This particular Paper Chase was timely in that we were in the middle of an ink change and we had abundant supplies of the test materials.We have chosen to compare Permajet Portrait and Epson PremierArt Water Resistant Canvas.The former is our standard fine art media for which we have lots of data, the latter was the subject of this review - we got side tracked onto the MK v PK issue! Our findings are described here and summarised in graphical form acorss the following two pages.
The most apparent difference between an MK and a PK audit image is the Dmax i.e. the maximum black density achieved. We have available a number of different materials from a number of different printers using different profiles.The data are summarised in the table below.
In summary, the main difference is in the Dmax and depends mostly on the ink set rather than any other factor such as printer, profile or paper batch/type. It amounts to a loss of about 0.2 in Dmax when using the PK ink set compared to the Mk ink set, equivalent to about 4½% in Lab Brightness terms.The difference in Dmax was unaffected by the rendering intent.When viewing the prints in a controlled light booth it was just possible to detect the difference between the two types of print but only in the deep blacks and the very deep brown landscape tone. It was necessary to have both prints present to detect the difference and it is highly unlikely that an unskilled viewer could detect the difference without the benefit of comparing the prints side by side.We found no detectable difference in the metameric index between the two prints.
PremierArt Canvas for Epson
The differences between the two inks on the PremierArt canvas are considered in more detail as part of the review of that material.However the main findings for the PK versus MK issue are as follows.
The difference in density was about 0.2 Dmax units. The difference in the metameric index was more pronounced being 1.5 for PK and 2.5 for MK. The difference was detectable by eye, the prints matched in the viewing booth but the MK biased more green in overcast daylight.
The difference in the colour values was less pronounced on the PremierArt for the hue and saturation values especially in the skin tones.T his was s lightly surprising result but it was sustained over a number of tests and is assumed to be a real effect.
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