Compare two images( Gold standard black vs regular black) using RGB?

I have two images. I am comparing one to a gold standard pure black image from edmunds. I'm not sure how I would go about comparing them. I think I want a sort of correction factor that can say how dark a specific pigment is in relation to another.

Here is the code for 12 images that we at the lab are using now.

str = 'C:\Users\Jake\Desktop\MATLAB IMAGES\IMAGES\Edmund-polymer comparison_ABR\'; % Purpose??? 
imagefiles = dir('C:\Users\Jake\Desktop\MATLAB IMAGES\IMAGES\Edmund-polymer comparison_ABR\*.jpg'); % accesses folder     
nfiles = length(imagefiles);    % Number of files found
for i = 1:nfiles
   currentfilename = [str imagefiles(i).name]; % sets file name with string
   currentimage = imread(currentfilename); % reads image 
   subplot(2,nfiles,i); % plots image with (?) and (?)

     imshow(currentfilename); % shows image
     subplot(2,nfiles,i+12); % plots below (?) and (i +12?)
     imshow(currentimage(:,:,3)); %shows the image at the plot location

     % YOLO TOTALLY WORKED AND I JUST WINGED IT, TIME TO CELEBRATE

     % 1      next step needs each pic to have name 
     % 2     ENLARGE
     % 3     How to compare mathematically?? (correction factor that patil
     % discussed for noise??) 
     % 4      format axes? somehow

     %Split into RGB Channels
      Red = currentimage(:,:,1);
      Green = currentimage(:,:,2);
      Blue = currentimage(:,:,3);
      %Get histValues for each channel
      [yRed, x] = imhist(Red);
      [yGreen, x] = imhist(Green);
      [yBlue, x] = imhist(Blue);
      %Plot them together in one plot
      plot(x, yRed, 'Red', x, yGreen, 'Green', x, yBlue, 'Blue');
      title_text = imagefiles(i).name;
      title(title_text, 'Fontsize', 6, 'Position', [120,2.7*10^6]);
      xlim([0,255]);
      ylim([0,2.5*10^6]);
      xlabel('Color'); % how to autoformat
      ylabel('# of Pixels'); % how to autoformat

end;

    if true
      % code
    end

[Image Analyst]

If you still need help, attach your two images so we can visualize what you are talking about.

Answer 1

[Prasad Mendu]

The MATLAB function "immse" compares two images using the color values (RGB) to calculate the Mean Squared Error (MSE) of two images.

For example it is executed as:

err = immse(X,Y)

Refer to the link below for more information on this:

http://www.mathworks.com/help/images/ref/immse.html