by Mike McNamee Published 01/04/2009
You might be forgiven for thinking that making a bespoke profile using thousands of pounds worth of equipment, auditing the profile to demonstrate it was really top-notch and then using it to make a print, would result in a near perfect black and white print onto matt paper. How wrong you would be!
This exercise began when we were proofing the pages for Trevor and Faye Yerbury's feature on the mono nude, and trying, at the same time, to link it to the Paper Chase feature on matt, Sugar Cane paper. The image in question relies heavily on the dark background surroundings to create the mood. However, the detail in the shadows is vital and if it were to disappear altogether the message of the image would be lost. We tried to make a print onto Hahnemuhle PhotoRag UltraSmooth paper using matt black ink. The profile had audited particularly well with an average error of just 2.19?E 2000, compared with an overall average, across all tests, of around 3.3?E 2000 (smaller is better).
The audit data include spectacular skin tone error values of just 1.2?E 2000 average. So where did it all go wrong and why was our printed image using the colour profile so lacking?
The plot of residual lightness error for the entire tone range of the test target reveals the problem. As will all statistics the devil is in the detail. Although the bulk of the data are very accurate, the high-error outliers are all the deep tones. In trying to get the best average error across the gamut, the profile-building mathematics has sacrificed the deep tones, the ones it cannot achieve because of the restricted Dmax of the matt paper.
This shows as the bulk of the data points lying on or close to the red line (zero error) but the deep blacks, rich browns and the deep blue rendered much too light, ie below the line. What is showing here is the inability of the paper/ink combination to achieve the correct density. What actually happens then is the shadows are all massively compressed and what you see with a 'print in-hand' is a swath of blocked shadow information, ie large areas of solid black.
As our next move we tried printing a test target specifically designed to isolate the point at which the shadows blocked up. We used the fullcolour profile (printing in full colour) at both 'Relative Colorimetric' and 'Perceptual' rendering intents and three tone setting using the Advanced Black and White driver (Light, Dark and Darkest). We then examined the test prints and assessed where the shadow blocking occurred in both Northern Daylight (ie the office with the blinds open!) and a viewing booth set for the ISO standard of 2,000 lux and D50.
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