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Polycolor, a professional photo lab in Essen, Germany has developed a unique CRT based digital enlarger, the Variochromat. This machine is capable of exposing onto all photographic materials, including traditional fiber-based paper for black and white prints.

The Variochromat is based on a high resolution cathode ray tube (CRT) which has a resolution of over 30 mega pixels with an 8-bit grayscale. The Variochromat software is said to provide optimal tonal reproduction of grayscale digital images, creating a profile for each size and material. Before actual production starts, a stepwedge is processed and measured to guarantee consistent reproduction of tonal values.

Due to the widely varying density ranges of the B&W papers used (RC and FB, matte, pearl and glossy), a different gamma value for each of the material types is applied. The gamma is incorporated in the Variochromat material profile and describes the relation between the numerical value in a pixel and its density on the print. For example, a matt RC paper has a density range of D 1.7 log, compared to a glossy fiber-based paper, which reaches D 2,4 log - nearly double the range of matte materials. The Variochromat software adjusts the exposure selectively so that the midtones of an image are always placed within the same region of the D 0,7 log range.

Polycolor offers a test chart and a downloadable Photoshop profile which enables customers to adjust their monitor to give an excellent preview of the final print.

The Variochromat system is also capable of emulating other output systems - including inkjet printers. This is a useful option if files have already been optimized for a specific printer. Further tonal corrections, which can spoil a file, can therefore be avoided. In the lab, all exposure is done digitally and the paper wet processed in the traditional way. After developing, fixing and washing to archival standard , the prints are carefully dried and pressed for optimum flatness.

Contact:
www.polycolor.de
www.variochromat.de
(Note: English language version is available on these sites)