| 摘要 |
PURPOSE:To enhance a contrast for an original with a low contrast and to improve picture quality by converting density so as to indicate density distribution so that a picture signal may be uniform for all density levels, based upon a histogram concerning density of respective picture elements of the original. CONSTITUTION:A picture signal read by a reading part 1 is converted to a digital signal indicating a gradation of density by an analog/digital converter 2, and data for one page are stored to a page memory 3. The digital signal is inputted to a histogenerator 4 and a histogram of density of an original is prepared. At a distribution function generating circuit 5, a distribution function indicating density distribution is calculated from the histogram. At a density converting circuit 6, a conversion function to obtain an output signal indicating uniform density distribution is calculated from a distribution function, the picture signal to be read successively from the page memory 3 is converted by the function and sent to a recording part 7. |
