An image processing apparatus processes vector image data in units of blocks. The first garment portion and the second garment portion are discontinuously affixed to each other at defined intervals along a surface of each portion proximate to the first side and the vent side creating a vent seam having a plurality of ductsscalloped vents for directing air towards a body of a wearer. The pattern generating section repeatedly executes an instruction stream within the repeated interval in the test instruction stream when the repeated interval is stored on the interval register.