1. Performs Vsg adjustment to correct TD sensor output.
  2. Creates a MUSIC pattern on the transfer belt with each color toner.
  3. Reads the MUSIC pattern on the belt, and measures the positions of the lines on the pattern.
  4. Calculates the color skew amount from the position data.
  5. Calculates the tolerance/deviation for main scan magnification, and the main/scan registration skew amount. Then determines the amount of color skew adjustment.