Contrast ratio results

Black
Contrast ratio	770:1
Monitor model
Submitted	19 Sep 2012 17:37 CEST, by 78.92..
Camera model	Canon PowerShot A75
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. Note: image file 1: suggested exposure time: 4.9 s (Set EV to +1.3) Warning: image file 2: automatic white balance can cause inaccuracies.
Screen photo	[open image]
Luminance	0.24 cd/m2
Luminance spread	0.03 cd/m2 (2 standard deviations)
Exposure value	–3.78 stops (aim for –2 to –3)
Exposure spread	0.19 stops
Area used for calculation	0.5 x 0.5
Camera settings	Exposure time: 2 ISO: 100 F-number: 2.8 Focal length: 34.6 mm (35 mm equivalent) Exposure compensation: 0
White
Screen photo	[open image]
Luminance	187 cd/m2
Luminance spread	14 cd/m2 (2 standard deviations)
Exposure value	–1.85 stops (aim for –2 to –3)
Exposure spread	0.11 stops
Area used for calculation	0.5 x 0.5
Camera settings	Exposure time: 1/101 ISO: 100 F-number: 2.8 Focal length: 34.6 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.