| 摘要 |
PURPOSE: To increase the difference of density between an extracting object and its background and to attain the separation between them with high precision by increasing the density of the extracting object compared with its background density through the conversion of density and then performing theγconversion and the density gradation conversion. CONSTITUTION: The print pattern read by an image sensor camera 3 is inputted in an image. The look-up table conversion such as inversion, etc., is carried out as the pre-processing so that the density of an extracting object included in a printed matter 7 is increased compared with its background density. Then theγconversion is given to the image that undergone the pre-processing to increase the difference of density between the extracting object and its background. Then the density gradation conversion is performed after the 7 conversion by means of a look-up table consisting of 3 straight lines. As a result, the density of the extracting object included in a high density area is kept as it is. The image that undergone theγconversion is binarized by a certain threshold value of density and the extracting object is separated from its background. When the background noises discontinuous to the extracted binary image are detected, the image processing such as labeling, etc., is carried out to eliminate these noises.
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