Week 1 of the Advanced Printing Module was primarily concerned with light and colour in a lecture titled “A Critical Appraisal of Colour”.
One of the most important lessons to take away from this lecture was values of light known as “D50” and “D65”. D50 is light to the value of 5000K and takes into account the full gamut of colour throughout the daylight period. It includes the warmth of sunrise and sunset in its value and can be described as a “warmish white”. The colour graph of D50 has more red tones and less blue. D65, however, is a more ‘pure white’. We may think of D65 as noon on an overcast day. For evaluating photographs, we use D65 for monitor and screens and D50 for a print since technology allows a value closer to D50. Also discussed was a concept of “colour constancy” which we may think of as an auto white balance for the eyes.
Conditions for viewing photographs both on screen and in print were laid out. The use of a “dim light” source (valued: 32-64 lux), is necessary while bulbs should be valued around 5000K, as close to D50 as is possible. In the field of view there should be no bright lights or strong colours as this will affect proper appraisal of work.
The calibrating of monitors and screens was given great importance. Colour temperature of monitor screens should be 6500K (close to D65). Gamma requires a value of 2.2 while Luminance should be 100 cd/m2 for desktop screens and 90 cd/m2 for laptop screens. The different values for cd/m2 here is due to power differences between types of computers. Recalibrating is recommended quarterly with monthly checks being better.
The use of ProPhoto RGB is essential for working with photographs. Developed by Kodak in 1998, this colour profile offers the widest gamut of colours. While no device can capture or display in ProPhoto, its use is recommended as a way of ‘future proofing’. The recommended settings are ProPhoto, 16-bit files, never in jpg. RAW and TIF files must always be used. This information was extremely useful in how to set up a camera and editing software in order to achieve the highest quality.
Finally, the ‘myth’ of screen resolution of 72ppi was discussed. 72ppi related only to the first mac screens in use. Screens are sized in various ppi values and it was important to use a ruler on a photoshop file in order to find out the correct value. The value of the sreens in DIT print room for example are 102-103ppi.
I include some reminders that I photographed for setting required when printing from Photoshop.