Patent ID: 8761518

Claim:
A pattern inspection apparatus comprising: a first inspection data creation section configured to create first inspection data based on an optical image of a pattern formed on a to-be-inspected object; a first reference data creation section configured to create first reference data concerning the pattern; a first gradation conversion section configured to convert an output level so that the output level of the first reference data corresponds to the output level of the first inspection data; a third level difference calculation section configured to calculate a difference between the first inspection data and the first reference data whose output level has been converted; an average level difference calculation section configured to calculate an average of values calculated by the third level difference calculation section, the average in a region of N pixels x N pixels in the first inspection data being calculated; and a distribution collect section configured to collect the averages calculated by the average level difference calculation section over an entire inspection region of the to-be-inspected object.