Patent ID: 7331025

Claim:
A data storage method which stores pattern data for manufacturing a semiconductor device, comprising the steps of: dividing input data having a monochrome pattern into a plurality of fields; calculating a first number of rectangles contained in each of the plurality of fields of an original image of the monochrome pattern by dividing each field of the original image into one or plurality of rectangles; calculating a second number of rectangles contained in each of the plurality of fields of an inverted image of the monochrome pattern by dividing each field of the inverted image into one or plurality of rectangles; selecting, for each field, one of pattern data of the original image and pattern data of the inverted image which has a smaller number of rectangles, by comparing the first number of the rectangles constituting a corresponding field in the original image with the second number of the rectangles constituting a corresponding field in the inverted image; and storing the pattern data selected for each field in a recording medium.