Patent ID: 7787144

Claim:
A storage medium readable by a computer, the storage medium storing a program of instructions executable by the computer to perform a function for executing an image processing on an image defined by vector data containing a plurality of lines having different line widths, the function comprising: calculating the line widths of the plurality of lines so as to maintain the number of types of line widths of the plurality of lines and a thinner-or-thicker relation among the line widths of the plurality of lines before executing the image processing; and setting the line widths calculated by the calculating step as line widths of the plurality of lines after the image processing, wherein the line widths of the plurality of lines are calculated so as to maintain the number of types of line widths of the plurality of lines before executing the image processing, by increasing or reducing the line width of either one of the lines that will become the same line width by the image processing.