| 摘要 |
PURPOSE:To obtain an image of invariably high quality by adjusting the quantity of light of a light source so that the readout signal of a line sensor enter the linear response area of the line sensor. CONSTITUTION:The line sensor 30 composed of a CCD is driven by a drive circuit 31 and image information of a microfilm 32 is read by inputting transmitted light from the light souce to the line sensor 30 through a lens system 34. Its readout signal RS is passed through a BPF35 to extract only the image information FS, whose peak value is detected by a peak detecting circuit 36; and exposure EX in the linear response area is calculated from response characteristics of the sensor 30 previously calculated by an arithmetic circuit 37 and the brightness of the light source 33 is adjusted through a light source control circuit 38. Consequently, all frame pictures of the film 32 are read in the linear response area of the sensor 30.
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