| 摘要 |
PURPOSE:To eliminate the need for using a D/A converter and to sharply shorten a measuring time by controlling the quantity of irradiating light so that the mean value of sample data for all picture elements in a reflected light measuring range coincides with the objective quantity of reflected light. CONSTITUTION:A halogen lamp 8 is lighted up by a lighting voltage to be a reference and a reflected light quantity measuring means 2 samples original reflecting density for all picture elements in the reflected light quantity measuring range and successively stores the sampled data in a memory. Then, information such as the maximum value, minimum value, mean value, and reflected light frequency distribution of the data is calculated from the sampled data by an objective reflected light quantity computing means 3 and the feature of an original is extracted. Since all the picture elements in the reflected light quantity measuring range are scanned only once, the succeeding scanning is executed only by plural proper points in the measuring range and the reflected light quantity data of the residual picture elements are identified by the reflected light quantity data of these points, the use of a D/A converter is eliminated and the measuring time can sharply be shortened. |
