Wednesday, November 14, 2012

Extending the printer gamut upwards

Full color printing started with cyan, magenta, and yellow. Then black was added to extend the gamut down in the shadows. Later spot colors were added to make the gamut wider (Hexachrome, Indichrome, etc.). Now Romain Rossier & Roger David Hersch are adding light fluorescent magenta and yellow to extend the gamut up in the light colors. They are presenting their work at the CIC 20th Conference in Hollywood in the Friday afternoon session on Printing chaired by Jan Allebach. Of course, the slides are limited by the projector's gamut, so you need to be there and look at the actual prints.

Gamut at L*=80


  1. Interesting. But fluorescents seem to present a problem: they emit light rather than modulate a reflection of light. That means that images will have vastly different appearances under different illuminants. It also means that some portions of an image might have a higher brightness than other portions. i.e., I can imagine a yellow car that appears brighter than a white one. This is OK if the "real" car is fluorescent too. It will be interesting to see if the authors have a means to compensate for these effects.

  2. Actually, fluorescent inks re-emit photons at a different energy level, there still is modulation (no energy is created). As you will see in the presentation, the excitation is not just in the UV range, but mostly in the blue respectively green range. There are commercial fluorescent inks that do not need UV at all. With such inks you can achieve good colorimetric matches under the standard illuminants and even preserve decent illumination metamerism even with such light sources as LED lights.