Brightness histogram of a video

Question

I want an histogram of the brightness of a video.

I define brightness of an image as the sum of RGB values of all its pixels, divided by 3, divided by the number of pixels.

The program would calculate this brightness value for each frame of the video, then draw an histogram that could look like this:

Brightness                 __
 ^                 _      /
 |                / \    /      
 |__             /   \__/           
 |  \___        /                 
 |      \______/                     
 |                           
 +---------------------------> Time
 Start                      End

Free, or at least free trial, ideally open source.

Answer 1

Step 1: Split video into frames

Step 2: As you know, there are many definitions of brightness:

• https://stackoverflow.com/q/596216/395857
• http://www.nbdtech.com/Blog/archive/2008/04/27/Calculating-the-Perceived-Brightness-of-a-Color.aspx

You can compute the brightness in any language e.g. in Matlab:

[X,map] = imread('corn.tif'); % Read image
Im = ind2rgb(X,map); % convert the data in X to RGB.
brightness = mean2(Im); % using your formula.