Using the examples presented for displaying an image in Matlab together with those for accessing pixel locations, investigate adding and subtracting a scalar value from an individual location, i.e. I(i, j)=I(i, j) 25 or I(i, j)=I(i, j)-25. Start by using the grey-scale 'cell.tif' example image and pixel location (100,20). What is the effect on the greyscale colour of adding and subtracting? Expand your technique to RGB colour images by adding and subtracting to all three of the colour channels i