Before you Start

• Be sure that your Lighting Booths meet ISO3664 Criteria - make and audit with Lighting Inspector
• Be sure that your display is capable of confidently rendering colors according to your specification
• The ambient light meets ISO 3664 specification
• The walls and operator clothes are neutral gray - so no vivid color  reflections can affect on the visual appearance of the samples

The first rule is that Display Luminance should correspond to Light Booth

The formula is simple:

White Display Luminance [cd/m2] x Pi constant [3.14]  = Light Booth Illuminance [lx]

ISO 3664 Part 2 “practical appraisal” specifies a lower light intensity (500 lux) for tone reproduction evaluation with tolerance ±125 lx which defines the acceptable range of 375 - 625 lx.

500 lx / Pi = 159.2 cd/m2, however, some users prefer a lower value of 440 where corresponding Luminance = 140 cd/m2

Paperwhite Simulation

Then a sheet of white paper is inserted into Lighting Booth should look very similar to the paper with the same Lab coordinates on the screen.  Be sure to use a setting where paperwhite is simulated. ( Adobe Acrobat, Photoshop, or InDesign have such function build-in) In normal mode, paper white is 100/0/0 which is a relative mode -  we need absolute as the paper real paper is never 100/0/0

Adopt White Point

Due to Observer Metamerism, everybody can see differently. In the next step, an individual White Point correction has to be applied to compensate for the White Point hue. Some Industry guidelines ( e.g. UGRA) say about corrected temperature and mentioned practical range is reported as 5000-6400 with an average for the most of tested population pick value about 5700°K, but RIT research shows that one-dimension White Point is not enough and two-dimensions corrections might be required.

For White Point Editing display grayscale pictures that have details in all regions from highlights through mid-tones to deep shadows.

The whole procedure is extremely person related and requires hours of individual tests. This time is not wasted as the Operator will get personal experience that is key for visual judgenet