Contrast ratio results

Contrast ratio 4:1
Monitor model
Submitted 25 Nov 2013 18:02 CET, by 59.126.*.*
Camera model Nokia Lumia 620
Processing remarks

Warning: image file 1: could not determine angle of view; assuming 38 mm lens (35 mm equivalent).
Warning: image file 1: automatic white balance can cause inaccuracies.
image file 1: Warning: image includes screen edges or something that's not a monitor. Hold the camera close to the screen.
Warning: image file 2: could not determine angle of view; assuming 38 mm lens (35 mm equivalent).
Warning: image file 2: automatic white balance can cause inaccuracies.
image file 2: Warning: image includes screen edges or something that's not a monitor. Hold the camera close to the screen.
Warning: image file 2: Underexposed. Please increase the shutter time.
Note: image file 2: suggested exposure time: 1/12 s (Set EV to +1.8)
Warning: image file 3: could not determine angle of view; assuming 38 mm lens (35 mm equivalent).
Warning: image file 3: automatic white balance can cause inaccuracies.
image file 3: Warning: image includes screen edges or something that's not a monitor. Hold the camera close to the screen.
Warning: image file 3 is too bright to be a dark photo. Maybe you mixed up the files?

Black
Screen photo
Luminance 2.58 cd/m2
Luminance spread 6.33 cd/m2 (2 standard deviations)
Exposure value –4.26 stops   (aim for –2 to –3)
Exposure spread 4.25 stops
Area used for calculation 0.528 x 0.222
Camera settings Exposure time: 1/40   ISO: 400   F-number: 2.4
Focal length: 0 mm   (35 mm equivalent)
Exposure compensation: 0
White
Screen photo
Luminance 11 cd/m2
Luminance spread 12 cd/m2 (2 standard deviations)
Exposure value –1.64 stops   (aim for –2 to –3)
Exposure spread 1.69 stops
Area used for calculation 0.528 x 0.222
Camera settings Exposure time: 1/29   ISO: 400   F-number: 2.4
Focal length: 0 mm   (35 mm equivalent)
Exposure compensation: 0
Black at screen edge
Screen photo
Luminance 11 cd/m2
Luminance spread 12 cd/m2 (2 standard deviations)
Exposure value –1.64 stops   (aim for –2 to –3)
Exposure spread 1.69 stops
Area used for calculation 0.528 x 0.222
Camera settings Exposure time: 1/29   ISO: 400   F-number: 2.4
Focal length: 0 mm   (35 mm equivalent)
Exposure compensation: 0

The luminance values in cd/m2 are not very reliable, since camera sensitivities can easily differ up to 50% from their nominal value. Typically, the real luminance is 30% lower than this number. The area used for calculation is chosen such that it corresponds to a viewing angle of ±14° horizontally and ±10.5° vertically, which is equivalent to viewing the screen from a distance of about 1.5 times the diagonal size.

Unfortunately, there is a lot of variation in how cameras use EXIF settings. If photos from your camera your produce unusable results, try coming back in a few days. I review submitted pictures regularly and try to fix problems.