Computing Science 320

CSC320 Visual Computing
Assignment 3

Due:	Monday March 15 at 9AM.
Late penalty:	15% /day to a maximum of 4 days, not accepted after that.
Hand in:	Submit submit electronically here
Marking:	See the syllabus
Groups:	Groups of 2
Environment:	Java 1.4, under linux in 1158

Announcements

Please read the Questions and Answers Section at the bottom!!
More tiles have been added (thanks Mike).

Requirements

You will add a Tiling painterly effect to the supplied supplied code
Modify the Menu so that the Effects/Tiling menu brings up a dialog. The dialog accepts parameters which allow the specification of the tiling to be done. An alternative is to add a collection of sub menu items, allowing the user to choose a category of tiling (ie Uniform, Haar) and then an appropriate dialog appears.
Uniform tiling: User chooses a single tile size (ie ONE OF 2x2, 4x4, 8x8 etc.). Each tile has exactly one color, the average of the color over that region. I have implemented uniform, sampled tiling for a fixed tile size.
Haar tiling: User chooses a range of tile sizes (ie 4x4 to 16x16). Your system uses a Haar transform (see the image compression note in week 04) to define the tiles. Again, each tile consists of a single color. You should crop the image to an appropriate size to allow Haar wavelet processing.
Add the option of giving each tile a realistic effect. This includes a border as well as texture. You can see how one individual added texture to create a 'coin'. One approach is to take a picture of a tile and then set the alpha channel at each point appropriately. Another approach is to simply add appropriate imges. You will of course have to scale these tiles. A not so good collection of tile images Some tiles with a bit of texture/effect Here is a set of tiles with good lighting effect, little texture though
Up to this point, you have 8/10 if your submission works, is simple, efficient and well documented. For the rest of the marks add in one of the following below... For these remaining marks, we will rank your assignments against other students based on difficulty, success as well as clarity of code and documentation. If you have another idea, please speak with me. Make sure the additional features are accessable in the menu or one of the dialogs.
Use another tiling algorithm to tile the image. Explore use of different size tiles, rectangular tiles etc. Start off simple and then improve. You can break tiles near the border, but see if you can avoid it.
Add in edge detection and break tiles across edges. Try breaking tiles in a straight line to keep things simple. You will need to figure out how to still make the tiles look real.
Allow the user to specify a directory of images and use these images to tile the target image. You will need to figure out the average color for each of the tiling images.
- here is an example
- A large collection of images.
- Another photomosaic example.
- Gimp photomosaic plugin/
- Opensource Mosaic software.
- Someone actually sells software to create mosaics here
- More mosaic software
Add a completely different painterly effect, for example oil painting or stained glass (tiling with arbitrary shaped pieces, with border and a glass effect).
Allow the user to choose a number (ie 16) of different colors to use. You will tile the image with the specified number of colors. You will have to do this based on some measure of success, that is, choose the best set of colors to achieve the goal. This feature can be added to all of the original tiling approaches. Another option is allow the user to choose a specific set of colors to use.

Documentation

Please document your code, describing any interesting algorithms. Describe any interesting features you have added.

My development notes

Use these at your own risk. These are notes I am making while working on the solution. The structure of the program will necessarily change as I learn about the problem. This is the reality of software development.

Student samples

References

Questions and Answers

Question:

Can I have some more images of tiles?

Answer:

OK, here are some...

Question:

How should I approach this problem?

Answer:

I will be maintaining a set of development notes. You are welcome to follow along or not as you wish.

Question:

arbitrary number of channels I read the "Development Notes" but don't quite understand the structure of the design.
bit shift operators: can you please explain how it works and where and when do we need them?
why does Haar transform need to be recursive? please expalin.

Answer:

Well you will need at least 3 channels, one corresponding to each of red, green, blue. You will be performing the Harr transform on each channel.
Bit shift operators can be found here See the sample code at the top of the PixelGrabber documentation in the Java API (careful, I am sure I saw one version of this sample code that was incorrect).
Well it does not have to be recursive, a simple, obviously correct implementation is recursive. There is another approach which yields a simple transform. See the development notes.

Question:

Can you give us a example of how to use bitwise in oder to calculate the pixel. Thank you.

Answer:

OK, here is a snipet from my code. In it, I separate out the three channels. int pixel=bimg.getRGB(x,y); c[2][x][y]=(short)(pixel & 0xff); // blue pixel=pixel >> 8; c[1][x][y]=(short)(pixel & 0xff); // green pixel=pixel >> 8; c[0][x][y]=(short)(pixel & 0xff); // red

Question:

Why can't I load files from other directories using the supplied code?

Answer:

There is an error in the handler for the File/Open Image menu item. I have included the fix below. The issue is that I previously only extracted the file name from the instance of File returned by the fileChooser. I need to extract the full pathname for the file. menuItem = new JMenuItem("Open Image"); menuItem.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e){ int returnValue=fileChooser.showOpenDialog(AppFrame.this); if (returnValue == JFileChooser.APPROVE_OPTION) { String fileName=fileChooser.getSelectedFile().getAbsolutePath(); if(imagePanel.setImage(fileName))pack(); } } }); menu.add(menuItem);

Question:

It takes a long time to tile my image!!

Answer:

If you are creating lots of instances of any class (PixelGrabber comes to mind) then Your system may be swapping or you may be garbage collecting a lot. Maybe don't do that (ie create many instances of the PixelGrabber). I did not actually use PixelGrabber in my code so far.

Question:

For Haar tiling, the users can specify tiles only in the range 4x4-16x16 right?

Answer:

When I said User chooses a range of tile sizes (ie 4x4 to 16x16). I was giving an example of what the user actually chose. You should provide a range of choices (min size and max size). You can make this picture dependent.

CSC320 Visual Computing Assignment 3

Announcements

Requirements

Documentation

My development notes

Student samples

References

Questions and Answers

CSC320 Visual Computing
Assignment 3