METHOD FOR MEASURING IMAGE NOISE OF IMAGE READER, RESOLUTION MEASURING APPARATUS AND RESOLUTION MEASURING METHOD, AND RECORDING MEDIUM THEREFOR

摘要

In measuring image noise of an image reader, image data obtained as a result of reading a read region of a test chart having a constant density are analyzed by an image analyzing program of a computer, so that an anomalous portion of the image data is extracted and is judged whether the anomalous portion is noise, on the basis of a predetermined standard. Further, in measuring the resolution of an image reader, a test chart having white/black line pair patterns, which are formed at a pitch slightly different from the read pixel pitch of the image reader, is read over a region which is large enough to include a location where coincidence occurs between patterns and pixels. A necessary portion is cut out from the read image, and a gradation difference for each pixel of the read image over the entirety of the cut-out region is calculated in order to detect the maximum gradation difference. When the maximum gradation difference exceeds a value for defective/non-defective judgment, the image reader is judged to have passed a resolution test. IMAGE