matlab normalized pixel Intensities

matlab code:

grayImage = imread('gray.bmp');

originalMinValue = double(min(min(grayImage)))
originalMaxValue = double(max(max(grayImage)))
originalRange = originalMaxValue - originalMinValue;

% Get a double image in the range 0 to +255
desiredMin = 0;
desiredMax = 255;
desiredRange = desiredMax - desiredMin;
dblImageS255 = desiredRange * (double(grayImage) - originalMinValue) /
originalRange + desiredMin;

% Get a double image in the range 0 to +1
desiredMin = 0;
desiredMax = 1;
desiredRange = desiredMax - desiredMin;
dblImageS1 = desiredRange * (double(grayImage) - originalMinValue) /
originalRange + desiredMin;