Contrast ratio results

Black
Contrast ratio	91:1 (edge: 28:1)
Monitor model
Submitted	18 Nov 2016 04:17 CET, by 107.77..
Camera model	Apple iPhone 5s
Processing remarks	Warning: using the flash makes no sense. 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 1: Overexposed. Please decrease the shutter time. Note: image file 1: suggested exposure time: 1/410 s (Set EV to -1.4) 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 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. Note: image file 3: suggested exposure time: 1/73 s (Set EV to -1.3) Warning: Image ISO settings are not the same.
Screen photo	[open image]
Luminance	10 cd/m2
Luminance spread	4 cd/m2 (2 standard deviations)
Exposure value	–1.95 stops (aim for –2 to –3)
Exposure spread	0.58 stops
Area used for calculation	0.419 x 0.419
Camera settings	Exposure time: 1/24 ISO: 250 F-number: 2.2 Focal length: 29 mm (35 mm equivalent) Exposure compensation: 0
White
Screen photo	[open image]
Luminance	938 cd/m2
Luminance spread	868 cd/m2 (2 standard deviations)
Exposure value	–1.14 stops (aim for –2 to –3)
Exposure spread	1.44 stops
Area used for calculation	0.419 x 0.419
Camera settings	Exposure time: 1/160 ISO: 32 F-number: 2.2 Focal length: 29 mm (35 mm equivalent) Exposure compensation: 0
Black at screen edge
Screen photo	[open image]
Luminance	34 cd/m2
Luminance spread	62 cd/m2 (2 standard deviations)
Exposure value	–1.21 stops (aim for –2 to –3)
Exposure spread	4.25 stops
Area used for calculation	0.419 x 0.419
Camera settings	Exposure time: 1/30 ISO: 160 F-number: 2.2 Focal length: 29 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.