calculating light intensity using image

How to measure light intensity of an image (white in color) using matlab? is it possible to get steps to do it ? Thank you

Answer 1

[Image Analyst]

The image already is a measure of the intensity of the scene. If you read the image in with imread() or similar, then you have the light intensity.

[Stew]

Is this intensity measurement an average of each pixel's intensity, or is it based on the most intense pixel?

Also, is there a way to have MATLAB automatically produce the image intensity calculation after each image, so that previous images can be compared and flagged for changes in intensity?

Thank you.