CS21 Spring 2006
Homework 7
Due: Monday, March 27 before 11:30 pm

Assignment Description
Documentation on Classes with starting point code
Required Features
Extra Credit Features
Using your own image files
Examples of Most of the Image Manipulation Features


You may work with one partner on this assignment. If you do so, either you or your partner should submit your joint solution using cs21handin (please do not both submit it).

You should start by copying over my starting point code into your hw07 subdirectory:

	% cd ~/cs21/hw07
	% cp ~newhall/public/cs21/hw07/* .
	% ls

For this assignment, you will implement a program that manipulates jpeg images. A jpeg image is encoded as a 2 dimensional grid of pixel values. Each pixel has a Red, Green, and Blue component, each of which can have a value ranging from 0 to 255. For example, the color white is represented by the value 255 for R, G, and B components of the pixel, and the color black by 0 for all three. All other permutations correspond to color and grey values (when a pixel has the same value for all of its R, B, and G components, it is a greyscale color).

You can think of the image as being stored as a 2-dimensional grid of Pixel objects. However, unlike 2-D array accesses using row and column indices, pixels are accessed using their (x,y) coordinate value in the grid, where (0,0) is the pixel in the upper left corner, and the x and y values are increasing to the right and down:

                     3     x-axis 
   (0,0)  *----------|------------------------>
y-axis    |          _
        2 -  	    | | Pixel (3, 2)
          |          -

For example, to set the pixel in the upper left corner to WHITE I'd do the following:

	Pixel pix = picture.getPixel(0,0);

Features should be cumulative, so that if the user first clicks on the rotate 90 degrees button twice, you first rotate it 90 degrees and then rotate the rotated image 90 more degrees (it is now upside down). The Revert button, which is already implemented for you, restores the image to its initial form. Some features can be done in place on the image, and others require that you make a temporary copy of the image from which you can get the "before the modification" pixel values.

You will add code only in the Image.java file, and you should use the examples to guide your adding new features. You will implement each image manipulation feature as the actionPerformed method of a feature-specific ActionListener class. For each image manipulation feature you need to add two things to the code:

  1. Add a new SimpleButton object to the buttons array in the createButtons method. With this button you will associate a call-back object whose actionPerformed method will be invoked when the button is "pushed". Here is how I would add a button for the Vertical Scroll feature:
     buttons[counter++] = new SimpleButton("Vertical Scroll", new VScroll());
  2. Add a new clss that implements ActionListener and has an actionPerformed method that contains your code to implement the image manipulation. For example, here is how the VScroll class and its actionPerformed method would be defined (minus the implementation of modifying the image):
    class VScroll implements ActionListener {
        public void actionPerformed (ActionEvent e) {
             // here is where you add code to implement
    	 // scrolling the image vertically

I strongly suggest that you implement one feature, then compile and test it, then implement the next feature, compile and test it, and so on. Start with easier features like Negative, Lighten, and Darken before trying some of the more difficult features, like zoom, sort, tile and rotate 90 degrees. Also, for some features it may be easier to see if they are correctly implemented if you try them out on a greyscale image.

Class Documentation

Here is some documentation for the classes that I'm giving you with the starting point code (the Pixel and Picture will be the most useful for this assignment):
Pixel Class
Picture Class
SimpleButton Class

Required Features

The Restore and Quit options are already implemented. Also, there there are two additional features fully implemented for you (the RemoveRed and the Crop features). You should use these as a guide for how to implement other image manipulation features.

You must implement the following features (see below for examples of most of these features):

  1. Make Negative
  2. Convert to Greyscale
  3. Flip Horizontally
  4. Flip Vertically
  5. Flip Corners (swap upper left with lower right)
  6. Lighten the image by some amount
  7. Darken the image by some amount
  8. Polarize
  9. Scroll Vertically
  10. Scroll Horizontally
  11. Zoom UpperLeft
  12. Zoom LowerLeft
  13. Zoom UpperRight
  14. Zoom LowerRight
  15. Zoom Center
  16. Blur the image
  17. Sort Each Row by Pixel values (by the average of each Pixel's R,G, and B component)
  18. Rotate the image by 90 degrees
  19. A Tiling Effect

Discussion of some features

Extra Credit Features

In addition, you are welcome to try adding extra features for extra credit. More difficult features will be worth more extra credit points. Some suggests are adding edge detection, the 8 puzzle effect, a histogram of R, G, and B components of pixel values (you need to handle the case when for a particular pixel value, there are more than the image height instances of it), arbitrary rotate (this one is hard). However, feel free to come up with your own effects. Here is a link with some information about image processing that may give you some ideas to try out.

Using your own image files

You can download and save image files from firebird by clicking the right mouse button on the image and choosing the "Save Image" option.

If the image file is too large, or you want to crop it, you can run either xv or gimp to edit it. Here is how to use xv:

% xv image.jpg

* right click on the image to get the xv controls menu.

* ImageSize menu to make it larger, smaller, or of specified dimention
  (note: gimp does much better scaling than xv, but it is a bit more
   complicated to use)

* Drag left mouse button and choose Crop to crop picture

* Save button: to save your changes and choose image format (gif or jpg is good)

Examples of most of the features

(these are shown approximately in order of easier to more more difficult features to implement)

Example Menu of Buttons: Original Image:
Darken: Lighten:
Negative: Polarize:
Flip Vertically: Scroll Horizontally:
Zoom (upper left): Switch the top left and bottom right corners:
Greyscale: Sort Each Row (I converted to greyscale before sorting):
Blur: Tile (the 4 sub-image version):
Rotate 90 Degrees: The 16 sub-image Tile Version (not required):
8 squares puzzle:
(randomly reassigns 9 squares of image to 8 slots)
Infinite Split:
(make the image square before splitting)
EdgeDetect: Histogram of R, G, and B pixel values: