How to calculate the pixels occured by white color in binary image?

To find the white and black pixels:

numWhitePixels = sum(binaryImage(:));
numBlackPixels = sum(~binaryImage(:));

To get the number of perimeter pixels of the white regions

perimImage = bwperim(binaryImage);
numPerimeterPixels = sum(perimImage(:));

An alternate way to get the area of the white is to use bwarea():

% A weighted sum of white pixels that depends on shape of perimeter.
area = bwarea(binaryImage);