Patent ID: 6526154
Filing Date: 2003-02-25
Classification: B27L,G01N

Abstract:
A method for defining the amount of wood material present in a bark flow coming out from a debarking process and for controlling the debarking process on the basis of said data for reducing wood losses in the debarking process, in which method the bark flow is measured optically for its whiteness and the measuring result is used as a basis for determining programmatically by means of a data processing unit the amount of wood material in the bark flow, and the debarking process being controlled on the basis of the amount of wood material determined from the bark flow, wherein an image taken of a bark flow is analyzed for whitenesses and the method for defining the amount of wood material comprises the steps of:dividing the image into picture elements; defining the whiteness of each picture element of the image in terms of at least a three-way split numerical scale, whose end points are m and n, one end point being applied to represent bark and the other to represent wood; setting predetermined threshold values a and b wherein asetting the value of a picture element to m, when the picture element has a whiteness within the range from m to a; setting the value of a picture element to n, when the picture element has a whiteness within the range of from b to n; maintaining the value of a picture element when the picture element has a whiteness within the range from a to b; employing a mean value filter to process the image in image sections by means of a mean-value filter, each said image section consisting of a predetermined number of picture elements, the mean-value filter defining a whiteness mean value for each picture element of a particular image section and the obtained mean values are used as a basis for classifying all picture elements the particular image section with the same value m or n or with an unchanged value, if within the range from a to b; repeating the foregoing steps until all picture elements are classified or until a predetermined number of iterations is achieved; calculating the ratio of a number of picture elements representing wood to the total number of picture elements in an image for expressing the amount of wood present in the bark flow.