1. A vector data processor for processing vector data before the vector data is converted into raster data for image recording, comprising: a thinning part that processes target vector data indicating an outline of a target figure that includes a linear figure having a thickness, to acquire thinned data that is vector data indicating a thinned figure obtained by thinning said target figure; a central line acquiring part that processes said target vector data to acquire central line data that is vector data indicating at least part of a central line of said target figure; and a superimposing part that generates data that includes an instruction to record a combined figure obtained by superimposing said thinned figure and said central line one on the other.