Printer calibration only gets you so far

I have a fairly nice calibrated setup (previous post) but sometimes I encounter an image that still leaves me scratching my head when I go to print. These tend to be dark images such as this one.



The problem with such images are twofold. First, the printer (at least my mid-level Epson R1800) is not designed to handle the concentrated dark tones. This is one of those images that makes me long for the newer printers with multiple gray-level inks included with the color ink sets. The second problem is that even with the brightness level turned all the way down on my monitor the LCD screen is still much brighter than any white paper you can print on, making it difficult to predict how the print will turn out.

Recent version of Photoshop have a "Proof Setup" viewing option that does a nice job of simulating on-screen what your printed image will look like. In the case of the image above it let me know that the darkest shadows would print as black - areas under the dash and just under the steering column. Sure enough, a first test print came out utterly black in these areas and other parts. Brighter areas of the image came out as revealed on-screen with correct colors.

So how does one solve this problem? Remembering from a digital printing class I took years ago that most printers cut off (move to black) shadow areas, and push to white highlight areas, I created this chart:



I found a previous version of this chart from another website discussion of this problem but examination of the CMYK numbers revealed that the values were significantly off. Mine is a chart I created from scratch. I print it on papers I want to use with the color profiles I have already established. The resulting print tells me where extremes shadows and highlights become indistinguishable. On Epson's Premium Luster photo paper, for example, the test chart reveals that everything below 92% black is pure black. On the highlights, detail is lost between 2% and 4%. The color bars reveal similar results for the color levels but I am not as interested in them for near b&w work such as this image.

How do I make use of this info? I add a curves adjustment layer to the image to squeeze the original range of 0-255 brightness levels into the range I know I can print. Each level represents a change of ~2.6% In this case level 0 (black) in the image has to be remapped to level 21 (92% on the scale). A Levels adjustment will make this a linear change with a large reduction in contrast. Using a nonlinear curve adjustment I can reduce some of the loss in contrast. The adjustment is a layer meaning it is non-permanent. I can create one for various paper types if I wish without effecting the underlying image.