| 摘要 |
PURPOSE:To accurately recognize a divided pattern by finding a threshold value which is a specific quantity less than the maximum value of an image signal and finding picture elements having signal values larger than the threshold value on a recording medium. CONSTITUTION:A histogram analysis part generates a histogram of a preread image signal Sp. Namely, a mountain part H which is a set of signals carrying a high-density radiation absent part is formed nearby the image signal maximum value Smax. The histogram analysis part finds the signal value at the border part between the mountain part H and an image signal carrying a subject part mainly as the threshold value T and inputs a signal ST which indicates the threshold value T to a binary coding processing part. Thus, the threshold value which is the specific quantity less than the maximum value of the image signal is found, picture elements having signal values larger than the threshold value are found, and the image divided pattern on the recording medium is correctly recognized according to the distribution pattern of the set of those picture elements. |
