Methods of collecting photometric image data and determining light exposure by extracting feature image data from an original image

摘要

A method of determining light exposure is provided to read information in relation to a color original image and dividing the color original image into many picture elements to analyze the respective picture elements into three color light of red light, green light and blue light for photometry, find a histogram in relation to hue value depending upon data obtained by the photometry and divide the found histogram for each crest. Further, the method is provided to decide to which of the divided crests the respective picture elements of the color original image belong so as to distribute the picture element into a corresponding cluster, and divide the color original image for each cluster, select the most adaptable region to information in relation to the color original image which is read from the divided region as a feature image region. The method is still further provided to determine the light exposure to copy material depending upon image data in the feature image region. Therefore, the image data of the feature image region is extracted as the feature image data, and the light exposure is determined depending upon the extracted data to create a printed image. As a result, a feature image portion can be printed in proper density, or in proper density and color.