Dye Transfer Done Digitally


Here is the text of my article in the May/June 2007 issue of PHOTO TECHNICQUES:

Digital printing has matured. With the latest generation of pigments and printers available it is possible with little experience or training to produce a print whose quality can approach that of, dare I say it, Dye Transfer.

The digital work flow, starting with digital capture or scan, through manipulation and color management leaves few choices however when ready to print. Aside from print size the only other real choice is the media you chose to print on. There are many papers to chose from but the differences are subtle. You can select a glossy, satin, or mat finishes, smooth or textured. There are also a few more unusual media such as canvas and transparency materials that can be used in a digital printer. Tri-Trans printing presents another method for producing a different look for your Prints.

I came to this process indirectly. Alternative Photographic Processes have been of interest to me for a long time. I recall making salt and gum-dichromate �SUN PRINTS� following the instructions in the chemistry set that I had as a child. So I began tooling up and getting educated to start doing tri-color gum-dichromate printing. I found that I had a problem in producing gray scale transparencies because of the mat black K3 ink in my printer. It seems that the mat ink does not have the chemistry to allow it to adhere to transparency material. The ink would smudge and rub off on handling. At first I thought of lamination to protect each separation but I feared this might result in less sharpness during contact printing due to the additional thickness. I then thought of using a protective photo spray but could not find one that did not include UV filtering. UV light is a necessary component for gum-dichromate printing, as it is this part of the spectrum that hardens the gum. Not wanting the expense of changing to the glossy ink I next thought why not print another color? That led me to figure out how I could use PhotoShop to make gray scale separations that were not gray. I discovered how to do this and how to maintain the pure colors used in dye transfer printing.

In dye transfer, separations are made for the yellow, magenta, cyan and black layers. From each of these separations a matrix is made, the matrix is used to carry a color dye, each in turn, that is transferred to the print media in a manner similar to silk-screening. This is how Technicolor movies are made.
By making grayscale separations and applying the correct color pigment to each it is possible to make a Print layering multiple transparencies in registration and reproducing the original color.

Making a printer profile for transparencies is a bit tricky. I use Monaco EZColor and have both reflective and transmission ITT test targets. I tried various ways to make a transparency profile. The most workable method I found was to print the test patches onto the transparency material and attach the reflective target. This is placed in the scanner with a piece of bright white photo grade paper on top, I used Moab Kayenta. This is then scanned normally as a reflective source and used to produce the resulting profile. Trying to scan as a transmission with the transmission target simply would not work due to the low densities inherent in the hi-light colors. A good working profile is important to insure that the primary colors will print as pure as possible.

Prepare your selected image for size, color balance, and other chosen manipulations. You may want to enlarge the canvas a bit to add some registration marks that will make alignment easier when making the stack.
When ready, select:
Image > Mode > CMYK color
On the channels pallet right click on and delete the black, yellow, and magenta channels leaving only cyan.
Next select: Image > Mode > grayscale
And then:
Image > Mode > duo-tone and select monotone
At the color picker select a pure cyan using the table below. Cyan is: RED = 0     GREEN = 255 BLUE = 255 Magenta is: RED = 255 GREEN = 0     BLUE = 255 Yellow is: RED = 255 GREEN = 255 BLUE = 0 Black is: RED = 0     GREEN = 0     BLUE = 0
Close the dialog and save the image as a copy adding a C to the file name, revert to the original and repeat the process for each of the other channels adding M, Y, and K to each file name respectively.

Note that in each of the colors the complementary is equal to 0 while the other two are at full saturation. There is really no need to apply a duo-tone to the black as it is already there. Changing the opacity of each separation when printing can control color balance.

Each image is then printed using your transparency profile. The Prints are then layered in registration on a light table and then float mounted on a foam core mounting board with a piece of the same Moab Kayenta behind them for reflective viewing. Transmission viewing works well also, with lighting from behind. Due to the low absorbency of transparency materials there is a limit to the amount of pigment that can be applied. Because each of the layers is printed at full density the overall result is a transparency Print with a higher saturation than can be achieved when printing all colors on a single piece of material.

Another reason I wanted to do this was to try and settle an issue with tri-color gum dichromate printing. The question is which color should be printed first? By having all three layers I was able to experiment with how the appearance changed dependant on the order of the layers. The answer became obvious quickly. The layers should be ordered by density with the highest density on the bottom. In my experience, the order is:
Bottom = Yellow    Center = Magenta   Top = Cyan

Allowing the Prints to float means that they are not in tight contact with one another. As the viewing angle changes slight changes in color occur due to chromatic aberration. This effect can be amplified by placing spacers between each of the layers when mounting. You can use clear Mylar or transparency material between the layers, or make a stack with each Print attached to some two or four ply mat board. Another option is to print the black layer (or any other layer) onto the white backing paper to create another effect.

The constraints of digital printing have brought us to a time when Prints are tending to look alike. There was a time when an educated eye could immediately tell if a color Print was made using a negative or a positive process. Of course, content is the most important part of any Photograph. The choice of printing method can enhance or subtract from the content. Tri-Trans printing offers another choice for making the most of your images.