SPECK EVALUATION DEVICE

• Main Authors: HATA SEIJI, KATSUTA DAISUKE
• Format: Patent
• Language: English
• Published: 04.12.1991
• Subjects: CALCULATING; COMPUTING; CORRECTION OF TYPOGRAPHICAL ERRORS; COUNTING; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; IMAGE DATA PROCESSING OR GENERATION, IN GENERAL; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; LINING MACHINES; MEASURING; PERFORMING OPERATIONS; PHYSICS; PICTORIAL COMMUNICATION, e.g. TELEVISION; PRINTING; SELECTIVE PRINTING MECHANISMS; STAMPS; TESTING; TRANSPORTING; TYPEWRITERS

PURPOSE:To evaluate specks correctly by providing an average value calculation device which calculates the mean value of a difference between a brightness at any spot of an image obtained by a television camera and the brightness of spots around said optional spot. CONSTITUTION:If a recording sheet to be evaluated 1 is illuminated by illumination device 2 and an image of the surface of the sheet 1 is obtained using a television camera 3, the image obtained by the television camera 3 is entered in an image processing device 5, and a mean brightness deflection value M which is the mean value of a difference between the brightness of any pixel and the brightness of pixels at spots around the former pixel is calculated over the entire image using the image processing device 5. If the difference between the brightness of a pixel at a white speck 8 part and the brightness of pixels at the other parts is insignificant, the mean brightness deflection value M of an image at the white speck 8 part differs significantly from the mean brightness deflection value M of pixels at the other parts. Therefore, the white speck 8 part can be easily identified and the white speck 8 can be evaluated correctly.