Should I consider rgb values of a pixel as one value?
For example if I have r=255, g=255, b=255, can I take pixel value as (in binary), (r&lt;&lt;16)+(g&lt;&lt;8)+b ?


While this number would identify the colour, it would not help with a mean or standard deviation. e.g. pure blue would be 255 but pure red would be 16711680

The paper is unclear so you have a few choices:


Process each channel individually
Convert the image to grayscale, find the mean and std dev, and use this for each channel.


There may be other methods that use different colour spaces.