THE EFFECT OF SAMPLE-SIZE ON THE CONFIDENCE-INTERVAL FOR IMAGE-ANALYSIS OF IMPURITIES IN PULP AND PAPER

It has been shown that the random distribution of impurities significa ntly affects the error in image analysis. Charts presented here provid e guidelines to estimate the area to be scanned for a given confidence interval if an estimation of the level of impurities and the average size of the spots is made. With the same charts, and estimate of the c onfidence interval can be made given the scanned area, average spot si ze, and level of impurities. These methods can be used to plan scannin g routines in the mill environment and to investigate the performance of existing routines.