brightness.m

function brightness()
    I = imread('AtlasMercury.tiff');
    J=I;
    %increase brightness
    [r,c,l] = size(I);
    g = 100;%transformed value
    for i=1:l
      for j =1:r
        for k=1:c
          if(I(j,k,i)+g<256)
            I(j,k,i)=I(j,k,i)+g;
          else
            I(j,k,i)=255;
          end
        end
      end
    end 
    
    %decrease brightness
    for i=1:l
      for j =1:r
        for k=1:c
          if(I(j,k,i)-g<0)
            I(j,k,i)=0;
          else
            I(j,k,i)=I(j,k,i)-g;
          end
        end
      end
    end 
    %imshow(J);
    %imshow(I);
    subplot(1,2,1)
    imhist(J);
    title('Original');
    subplot(1,2,2)
    imhist(I);
    title('Modified');
    saveas(gcf,'histogram.jpg');
   
end