How to check light intensity using iPhone camera

Question

Is there any way to check the light intensity using iPhone? Does API allows to do this?

Answer 1

Obtaining Luminosity from an iOS Camera

Answer 2

I suppose you can easily do this yourself:

1. take a still => UIImage.
2. convert the UIImage to a CGImageRef (UIImage.CGImage).
3. Now, read every pixel's color and perform such code: x += (red + green + blue) / 3.f;
4. Calculate the average brightness: avg = x / numberOfPixels;.

avg will now give you a float indicating the average brightness of the still. Most of the time (if not always), this will be identical to the light intensity.