I am using an Xrite ColorMunki Display to profile my displays. As part of the calibration process, I need to choose the White Luminace for my display (an iMac Retina 5K). I can either ask the ColorMunki to measure the ambient lighting and automatically set the whitepoint for best screen-to-print matching:
I would like ColorMunki to automatically determine the optimum luminance level fro my display based on my ambient light conditions where I view my printed output. (Recommended for display to print matching.)
Or I can choose from a series of predefined display luminace values (cd/m2).
I understand that I can place the ColorMunki in my print viewing area with my viewing light on and have it measure the light there and build the profile accordingly. However what about when I know the image will be viewed on a screen? I can understand that measuring the ambient lighting in my room could help tweak the profile so that the way I perceive the image is minimally effected by the strength of light in my room, but obviously every screen / device and every environment in which they are used will be different (compare someone viewing using an iPad on the beach to someone on a laptop in a dark bar). The auto option even says 'Recommended for display to print matching', so I'm assuming I should instead choose one of the fixed values.
So what should my display luminance be set to if I want to preview images destined to be viewed on screens / devices?
Note: I'm setting my Whitepoint to D65