For critical evaluation of an image in print against the same image displayed on a computer screen, the lighting that is used to illuminate the print must be in sync with the display, in terms of brightness and colour temperature, etc. You might say, “Wait a minute, when the print is hung in my home it won’t be illuminated by anything but my living room lights.” This may be true, but neither will your print be evaluated for accuracy in your living room. It is irrelevant to the process of critical evaluation of the print against the same image displayed on a colour critical monitor.
When an image is translated from an emissive medium (a screen display) to a reflective one (paper, for example), it’s success in print becomes entirely dependant upon ambient lighting. The luminance and purity of an RGB image can only be simulated on paper using relatively impure CMYK inks to create a print that is viewed under lighting which is usually far from ideal. The quality of the ambient light, its brightness and colour temperature have dramatic effects on the appearance of the print. Subdued lighting darkens tonality. Shadow detail may seem to be lost altogether. This is the primary reason for one to conclude that their print is too dark.
Therefore, to effectively evaluate a print against the digital image, the illumination on the print must be in line with the display. The surrounding evaluation area must also be free from distracting elements and should be painted in a neutral light to mid-gray in accordance with the ISO3664 standard. Only then can an accurate evaluation and predictive image adjustments be made.
Even then, the chances of a first print not being somewhat disappointing are slim unless some informed forethought is invested toward making print related adjustments to the image tonality, colour and sharpness as well as the viewing environment in which the print will be critically evaluated. This would include adjusting room lighting and clearing any surrounding clutter in order to avoid distraction and to facilitate an effective presentation. The goal, of course, is to achieve a successful translation in print.
A black & white print may appear to be perfectly neutral under one lighting condition, yet greenish or pinkish under another. A cool toned image when displayed under warm illumination may look slightly more grey. Conversely, a warm toned image under cooler lighting can appear stark. In general, image colour and neutral balance may appear to be off. In effect, all of the effort invested by photographers to white balance the shoot and maintain balance throughout the editing and printing processes can easily appear to be lost in the ambient illumination.
The calibration and profiling of displays, cameras and printers are effective and necessary requirements for the achievement of predictable results in print. But, when we then evaluate the print under common room lighting, all bets are off. The illumination under which the print will be critically evaluated must also be calibrated to a condition which aligns with the display and visa versa. Otherwise, accurate evaluation of the image in print is simply not possible.
The correct standard illuminant for this kind of evaluation is D50 (similar in spectral characteristics to daylight near sunrise or sunset). D65 which is slightly cooler is also used by some photographers for their viewing illumination. The latter is also the best colour temperature to use for display calibration. When camera, display and viewing environment are all calibrated in alignment as a cohesive group, the image will be viewed in a consistent condition, throughout the process of critical evaluation.
As mentioned earlier, the standard by which all the viewing illumination is measured in terms of its accuracy for critical image evaluation is ISO 3664. This standard specifies level of brightness, colour temperature, colour rendering index (CRI), spectral distribution and evenness of the illumination used for critical evaluation of a print against a calibrated display. The standard applies to viewing illumination in the same way as calibration specifications exist for our displays (ISO 12646). In short, if the two viewing conditions are not ‘on the same page,’ as it were, an effective comparison of an image on screen versus the same image in print is not possible.
Of course, one could run out and purchase a professional viewing booth from GTI or Judge at a cost of thousands of dollars. Ours function extremely well. Alternatively, a much more affordable route which can be equally effective (when set up properly) can be created by setting aside an area in your home or office, painting its walls in a medium – light, neutral grey (or Standard Grey Neutral 8 from GTI), placing a table or counter against one light grey wall, installing above the table a 3 foot track lighting rail with 8 to 10 MR-16 fixtures and installing D50 Solux bulbs.
Rest assured, we have no relationship with Solux or their vendor, Tailored Lighting, aside from the fact that I use Solux bulbs for my own viewing area in one of my studios. Nor do we receive any compensation from them whatsoever. The product works. That’s compensation enough.
In the viewing area of our other studio, we use large GTI viewing booths. Both systems are equally effective. But, the viewing area which I created using Solux Bulbs as described above was comparatively quite inexpensive and complies in every way with the aforementioned standard. It has a colour rendering index of 98 which is extremely good as is the uniformity of the illumination.
While there are inexpensive bulbs available on the market some of which are named Cool White, Daylight or even D-50 or D65, these bulbs do not come close to complying with the ISO 3664 standard. They may appear to be balanced. But, they will not have the correct Colour Rendering Index (may be as low as 70) and the overall quality of illumination emitted by these fluorescent bulbs will likely have severe “spikes” in the blue or green regions of the spectrum. This will negatively effect the balance of your prints particularly with respect to B&W images which may appear to have a green or magenta cast.
In that case, corrective colour gels (filters) may help. If that were to work, it certainly would not be an elegant solution. But, the goal is to tune the viewing illumination and whatever achieves that is acceptable.
The bottom line is that viewing conditions are critically important to your review process. If you feel that you really don’t have a need for this degree of accuracy, that’s fine, provided you can live with your prints not appearing to match your screen display in a critical evaluation. But, if you make your own prints and do care about the accuracy of the result, you will soon decide to balance your illumination. Otherwise, in terms of making adjustments to try to compensate for the effects of inaccurate ambient lighting, you’ll be chasing your tail.
Colour Systems Inc. – CSi Print Studio