The Voronoi Paper

This is a report about the Voronoi Project, by Chad Brewbaker of Drake University and Daniel Wengerhoff of the University of Iowa.

You can get a LaTeX version of the paper.

You can view or download a PDF version of the paper.

One experiment described compression of a gray scale image. The original image was stored in ASCII PGM format. The gray scale format uses 256 gray scales. CVT techniques were used to choose a reduced set of gray scales, and Encapsulated PostScript (EPS) files were made of the images. You can copy:

• balloons.pgma, the original image file.
• balloons.eps, an EPS version of the image;
• balloons04.eps, an EPS version of the image, compressed to 4 grays;
• balloons16.eps, an EPS version of the image, compressed to 16 grays;
• balloons32.eps, an EPS version of the image, compressed to 32 grays;
• balloons64.eps, an EPS version of the image, compressed to 64 grays;

Another experiment took stock market data for 256 stocks, and tried to group them into a small number of clusters based on their performance over 250 trading data. For the data presented here, the experimenters chose to group the data into 15 clusters. The last cluster contains a single stock, which had split in value, and hence wasn't handled very well by the clustering algorithm.

• cluster201.eps, cluster #1.
• cluster205.eps, cluster #5.
• cluster206.eps, cluster #6.
• cluster215.eps, cluster #15.

One of the experiments described in the paper involves compressing a WAV sound file of a Homer Simpson quote. The MATLAB program includes a very handy function called wavread which can extract the information encoded in a WAV file, allowing you to modify it. You can then use the wavwrite function to write your revised information back to a WAV file. You can copy the various binary WAV files and listen to them on a PC:

• thermo.wav, the original sound file.
• thermo_004.wav, compressed to 4 amplitudes;
• thermo_008.wav, compressed to 8 amplitudes;
• thermo_016.wav, compressed to 16 amplitudes;
• thermo_032.wav, compressed to 32 amplitudes;
• thermo_064.wav, compressed to 64 amplitudes;
• thermo_128.wav, compressed to 128 amplitudes;

One of the experiments described in the paper involves compressing the opening bars of "American Woman". You can copy the various binary WAV files and listen to them on a PC:

• woman.wav, the original sound file.
• woman_002.wav, compressed to 2 amplitudes.
• woman_004.wav, compressed to 4 amplitudes;
• woman_008.wav, compressed to 8 amplitudes;
• woman_016.wav, compressed to 16 amplitudes;
• woman_032.wav, compressed to 32 amplitudes;
• woman_064.wav, compressed to 64 amplitudes;
• woman_128.wav, compressed to 128 amplitudes;