| 摘要 |
PURPOSE:To accurately extract an object from a background by finding out a mean value of luminance and its standard deviation and finding out a threshold based on an operation formula by using the obtained values and a parameter. CONSTITUTION:The mean value X of the luminance of an image and its standard deviation alpha are found based on image date in an image memory, the threshold Th is determined by using the obtained values X, sigma and a previously set parameter K based on the operation formula of X+Ksigma and the image data read out from the image memory are binarized on the basis of the threshold Th. Even when the background luminance of an image is changed due to the change of illuminating conditions or a measuring object, when there is no object, or when the area of an object is unclear, the threshold is automatically set up to a proper value and the extracting accuracy of the object from the background can be improved.
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