c - How can I measure the level of ambient light from an image? -

I'm looking to create an app that uses a camera while using an image

I think this would be a very bad measure, some conditional behavior is based on how light it is - that is, "the message sleeps like sleeping". The real amount of light exists and is due to such things, but it does not need to be very accurate.

I have no experience with image processing, so I do not even know what to ask, or what is possible. Is this possible? Is there a C library to do something like this?

A very rough estimate can be done by converting each one using the camera's known or eclipse Color value for the intensity of the color intensity of each pixel. Then use the intensity of the whole image.

If you want the level to be an estimate, you will reduce the intensity of the green channel and the blue channel (because our eyes are particularly sensitive to the green and blue colors Insensitive).