Contrast ratio results

Contrast ratio 21:1
Monitor model
Submitted 01 Sep 2012 22:36 CEST, by 24.52.*.*
Camera model Canon PowerShot A530
Processing remarks

Warning: image file 1: automatic white balance can cause inaccuracies.
image file 1: Note: image seems to be noisy. Try reducing the ISO setting or increasing the exposure time.
Warning: image file 1: Underexposed. Please increase the shutter time.
Note: image file 1: suggested exposure time: 1/22 s (Set EV to +4.2)
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.

Black
Screen photo
Luminance 6 cd/m2
Luminance spread 7 cd/m2 (2 standard deviations)
Exposure value –6.68 stops   (aim for –2 to –3)
Exposure spread 2.05 stops
Area used for calculation 0.497 x 0.497
Camera settings Exposure time: 1/403   ISO: 400   F-number: 2.6
Focal length: 34.4 mm   (35 mm equivalent)
Exposure compensation: 0
White
Screen photo
Luminance 121 cd/m2
Luminance spread 58 cd/m2 (2 standard deviations)
Exposure value –2.27 stops   (aim for –2 to –3)
Exposure spread 0.71 stops
Area used for calculation 0.497 x 0.497
Camera settings Exposure time: 1/403   ISO: 400   F-number: 2.6
Focal length: 34.4 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.