Step 3: Calibrate your CD-Rs
Each brand (or maybe even set) of CD-Rs has slightly different properties such as track pitch or linear scanning velocity. Before successfully drawing a picture, it is necessary to determine what these values are. To do this, create a data file which represents a radial line. Draw this to the CD-R, and you may get a spiral. Now it's time for the guesswork. Try to change the values, to convert this spiral back into a radial line.