Due to numerous requests I am posting this is a quick and dirty program that I wrote for visualizing 
the Discrete Cosine Transform (DCT) while writing the book "Compressed Graphics File Formats" from 
Addision-Wesley-Longman.

The way the program works is you enter the 8 values you want to perform the DCT on in the text boxes below
graph. When you change an input value, it is displayed on the graph using a black circle and the DCT 
coefficients are updated to the right. Use values in the range -128 to 127 in order to keep the graph 
from going outside the edges.

The graph also shows the Inverse DCT as a thin line among the points. The "Show All" check box controls 
whether the segements are drawn as a straight line or as a curve showing the IDCT values between the data
points.

At the lower left, the edit box with a spin control selects the number of coefficients (1-8) to use in the 
IDCT  calculations. With 8 coefficients, the IDCT line will go straight through the middle of all the data 
points on the graph. With 1 coefficient, you get a horizontal line going through the middle of the data points. 
By changing this value you can get an idea of how the quality of the IDCT approximation is affected by the 
number of DCT coefficients.


John M. Miano
miano@colosseumbuilders.com