HW048
Math 2984 - Fall 2017
Intro to Mathematical Problem Solving

TASK: Read a PNG file containing a grayscale image of a scene from the movie "Casablanca"; copy Ingrid Bergman's head and use it to replace the heads of Humphrey Bogart and Dooley Wilson; save the image as "bergman3.jpg".

COMMENT: A forger can try to manipulate photographic evidence by cutting and pasting bits of a picture. We will try a very simple version of such an exercise by locating Ingrid Bergman's head, copying it into a submatrix, and then using that to replace the heads of Humphrey Bogart and Dooley Wilson.

The tricky part of this exercise is deciding the coordinates of the heads. I will suggest that you look for Ingrid Bergman's head as a 100x100 block of pixels. Once you know M and N, the size of the image, you can make a rough guess for where to look, and you can check by using the imshow() command:

        imshow ( I(101:200,301:400) )
      

Now you can use imshow() to search for a 100x100 box around the heads of each of the two male actors. I don't know of any better way than to look at the picture and guess, and then try imshow.

After your investigations, you should have something like this information:

      Ingrid Bergman head: (a:b,c:d)
      Humphrey Bogart head: (e:f,g:h)
      Dooley Wilson head: (i:j,l:m)
      

Now you can try to replace heads:

      ingrid = I(a:b,c:d);
      I(e:f,g:h) = ingrid;
      I(i:j,l:m) = ingrid;
      

INSTRUCTIONS: Copy the file 'casablanca.png' from the Canvas homework site.

        I = (read the file into MATLAB)
        view the image I
        do your experiments to get the coordinates.
        ingrid = I(a:b,c:d);
        I2 = I;  <- Work on a copy of I.
        I2(e:f,g:h) = ingrid;
        I2(i:j,l:m) = ingrid;
        view the image I2
        save I2 to 'bergman3.jpg'
      

CHECK: You might get something like this:

SUBMIT: Your script file should be named "hw048.m", and begin with:

        % hw048.m
        % YOUR NAME
        % This script (describe what it does)