A format storage unit stores a predetermined geometric property format. A chart data creating unit creates chart data based upon the geometric property format, and a printing unit creates a test chart by printing mark groups on a recording medium such as a paper sheet based upon the chart data. An image pickup unit outputs a chart image by scanning the test chart, and a mark center calculating unit calculates the center of each mark based upon the chart image. A fitting unit performs a fitting calculation comparing calculation results output from the mark center calculating unit and the chart based upon the geometric property format such that the squared difference therebetween becomes minimum for each mark position.
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