Host: The Institute of Image Electronics Engineers of Japan
There are various techniques to decide the threshold for binarization of the image. But in the image which was taken under the bad condition, selection of threshold is very difficult. So we proposed the threshold equation to decide the threshold. In this dissertation threshold equation was derived by the correlation of the optimum threshold values and the average density of the background part which illuminated uniformly under various lighting conditions. But, with just decision of the optimum threshold is not obtained the satisfactory result. Then the image was divided, threshold was set to each territory where it divided. As a result, we could obtain the satisfactory result from the decision of appropriate division and optimum threshold value. Moreover, comparision with the other techniques was able to be performed and validity of our technique was checked.
