| 摘要 |
PURPOSE:To obtain density data with high accuracy by generating correction data based on an error between a characteristic used when a logarithmic transformation circuit of the unit applies logarithmic transformation to a known waveform signal and an ideal logarithmic transformation characteristic of the waveform signal so as to correct the logarithmic transformation characteristic of a photoelectric conversion signal thereby attaining ideal logarithmic transformation. CONSTITUTION:At first a switch 13b is closed and a ramp waveform signal outputted from a ramp generating circuit 12 is subjected to logarithmic transformation at a logarithmic amplifier LOG 14, A/D-converted and the result is inputted to a line buffer memory LBM 20 via a lookup table LUT 19 whose conversion coefficient is 1. A CPU 17 obtains an error of data stored in the LBM 20 and ideal logarithmic transformation data of a ramp waveform signal stored in a memory 16 to generate correction data, which are set to the LUT 19. Then a switch 13a is closed to input a photoelectric conversion signal from a photoelectric conversion means 11 to the LOG 14, and the characteristic is converted into an ideal logarithmic transformation characteristic by using the correction data of the LUT 19. |
