Patent Document ID: 5393378
Application ID: 08025726
Patent Flag: 1

Claim One:
1. A method for generating a paper quality membership function to be used in an apparatus for controlling the degree of fiber variance in paper sheet, comprising the steps of: (a) picking up an image of transmitted light from a light source on an area of paper by a plurality of cameras with different visual fields, the cameras being arranged so that images of the transmitted light are picked up by the cameras concurrently in comparatively wide and narrow visual fields and are introduced to a display unit of an image processing computing element, there being means provided for changing the visual field introduced to the display unit; (b) dividing the image of the transmitted light on the display unit into a predetermined size and number of windows, the windows comprising pixels; (c) measuring the tone density of each pixel, and the tone density of each window from the tone density of the pixels comprising the window; (d) calculating values chosen from at least one of the following: an average value of tone density and a primary variance of tone density of each window from the tone density of each pixel, an average value of the primary variance of the tone density for all of the windows, a secondary variance of tone density for all of the windows, and a variance of average values of tone density of each window; and (e) using one of or at least two in combination of said values as a formation factor; (f) changing the visual field transmitted to said display unit by said plurality of cameras; (g) repeating steps (a)-(e) one or more times to obtain different formation factors; (h) generating a paper quality membership function from the different formation factors obtained: and (i) using said paper quality membership function to control the degree of fiber variance in said apparatus.