Optimizing Printing based on Illuminants

D50 viewing

Standard viewing conditions were re-established including D50 for the Americas and typically D65 for Europe. What is still not well understood is that these illuminants, and specifically D50, are often labeled “daylight” when in fact they are merely an approximation to daylight and produced using fluorescent bulbs typically in standard viewing booths.

Color workflows

Assumptions have been made as to illuminant selection in viewing printed work and also to illuminant selection in color management workflows that on closer examinations have the potential to be optimized.

Let’s explain by using some real world examples. You have just printed a series of posters of people modeling clothes for a large clothing store.

The prints have been evaluated in a D50 viewing booth and they were approved by the print buyer. However, when the prints are mounted and hung up in the store the peoples’ faces appear to be a bit too red.

A second example might be a fine art photographer/printer who is preparing a gallery showing of his works and everything looks good in the D50 viewing booth.

However , once displayed in the museum all the images look a bit cool in appearance. There are reasons for these types of color conflicts. Fortunately there is a solution as well which is available in the Harlequin RIP.

So, if we look at the photographer’s project, regardless of whether he is the printer or he has asked the local print shop to make the prints, his critical eye suggests there is a difference from what he is seeing in the D50 viewing booth verses the gallery wall once the prints are hung. Removing the surround color variable for this discussion we must assume that something else is going on. The mostly likely culprit is an illuminant mismatch. The D50 viewing booth though technically correct for viewing prints in the press environment is different from the museum which is most likely using a different bulb - in many cases a Solux Bulb of either 3500K or 4700K for lighting works of art. The spectral curves therefore of D50 and, say, the Solux 3500K bulb, are going to be quite different and thus different colors are going to reflect color differently throughout the prints. The solution is straightforward though it does require a few engineering steps for color critical work. First, you need to locate, purchase or borrow a measurement device and software combination capable of measuring the spectral curve of the actual illuminant that the work is being viewed under. In our example this could mean two situations the D50 viewing booth and the lighting in the museum. But we will just worry about the museum at this point. This spectral data is than transformed into an XYZ illuminant value (there are spreadsheets and utilities on the internet for this conversion or you can contact Global Graphics technical support) which is then placed in the Harlequin RIP.

Going to the effort to add the actual illuminant into the color chain when using color managed workflows for printing allows one to make use of sound color science principles in order to achieve print color accuracy closer to the intention of the designer/photographer.

So here is one more variable in the color quality matrix that, if understood, can be optimized. It has many applications when printing in any number of situations where the illuminant of the display is known.

Why not offer quality that might be just a bit better than the competition? Using the Harlequin RIP you can!