Measuring light intensity with a smart phone

[withoutid]

Hi everyone,
I am new member to the forum (but not that new to orchid ). I just figured out that there are 2 apps for android phone that can measure the light intensity: beeCam lightmeter and Light meter. Has anyone tried to compare the accuracy of these apps to a professional light meter? Using the galaxy S4 with these apps, I came up with some number:
Outdoor, under direct sunlight: 58~60k lux
Indoor, through a black window glass: 20~24k lux
Indoor, toward the sky, no sunlight: ~2k lux
It would be wonderful if our smartphones can give us number close to that from a professional device, that's why I 'd like to ask. Thanks