Question

Pick some jpeg/jpg images (Note that the images must not be offensive. If you choose to submit images that are offensive to course staff it may be pursued as a violation of our academic integrity policy. Use your imagination but I trust you to act responsibly.) and for each one;

• Apply compress_image with various tolerances to try to find values corresponding to compression rates of 50%, 80%, and 95%.

• Plot the original image, and the three ”compressed” images, on a single page (use MATLAB’s subplot command). Clearly label the compression rate associated with each image on your plot.

  Start with the provided function plotImages that should assist you with this process. Include your version of plotImages with your solution in addition to the plots.

  function [ ] = plotImages( image_file)
  % plotImages plots the image in image_file with various levels
  

%   of compression
%
% Consumed value:
% image_file is the name of a jpg/jpeg file in the current

5

• %     folder that will be displayed with approximately 50, 80, and 95%
  

•   %     compression
  

    orient landscape;
  

    % Experiment with the values of tol50, tol80, tol95
    % to achieve compressions rates close to 50%, 80%, and 95%
  

    P = imread(image_file);
    subplot(2,2,1);
    image(P);
    title(’Original Image’);
    axis off;
  

    subplot(2,2,2);
    tol50 = 29; % You have to adjust this value
    [cP50, comp50] = compress_image(P, tol50);
    image(cP50);
    title(strcat(’Compression Rate: ’,num2str(comp50)));
    axis off;
  

    subplot(2,2,3);
    tol80 = 116; % You have to adjust this value
    [cP80, comp80] = compress_image(P, tol80);
    image(cP80);
    title(strcat(’Compression Rate: ’,num2str(comp80)));
    axis off;
  

    subplot(2,2,4);
    tol95 = 2000; % You have to adjust this value
    [cP95, comp95] = compress_image(P, tol95);
    image(cP95);
    title(strcat(’Compression Rate: ’,num2str(comp95)));
    axis off;
    end
  

Answer 1

load mask

image(X)

axis square

colormap(pink(255))

title('Original Image: mask')

2) compressed:

subplot(1,2,1); image(X);

axis square;

title('Original Image')

subplot(1,2,2); image(Xc);

axis square;

title('Compressed Image')

xlabel({['Compression Ratio: ' num2str(CR,'%1.2f %%')], ...

['BPP: ' num2str(BPP,'%3.2f')]})

1,