Monday, 14 December 2009

My prints don't match my display!

A common problem I see on forums is that prints come out too dark compared to what is seen on the monitor. This occurs most commonly when editing photos on an uncalibrated monitor and viewing prints in lower lighting conditions.

A common problem with LCD displays is that they are often by default too bright, sometimes 300 cd/m^2. The recommended brightness of an LCD display should be around 120 cd/m^2 or less. The reason for this is so that pure white on the screen should be about the same brightness as a plain white sheet of paper under good lighting. By editing your photos with your LCD set at this much lower brightness, you should now adjust the dark areas of the photo to match the printed output.

The second part of the problem is when viewing prints. The ability of the human eye to pick out detail depends strongly on the ambient lighting conditions since one of the effects is to change pupil size. The ideal pupil size is around 2-3mm, larger than this, aberrations dominate, and below this diffraction takes over. For getting the print and screen to look similar, the print brightness should match that of your on-screen version. This usually means quite bright light illuminating the print. If you know where the print will be viewed, you may try to optimise the print density for those conditions.

To set the brightness of your monitor, a hardware calibrator is usually required. However, you may be able to use a light meter instead, like the one in your camera. An approximate reading for 120 cd/m^2 is f/4 and 1/30th at ISO100. Alternatively, get the monitor brightness and a blank piece of paper under the bright viewing illumination to match by comparing the metered exposure.

A useful link.

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