| 摘要 |
PURPOSE:To make an automatic negative/positive polarity decision over a wide decision range regardless of the kind of a film by photodetecting an image of a microfilm by plural photodetecting elements, and comparing their detected values with a threshold value. CONSTITUTION:The image of the microfilm is photodetected by plural photodetecting elements, whose outputs are inputted to a selector SE, the output of which is inputted to a CPU through an operational amplifier Amp2, AD converter AD1, and I/O(1). Other signals are inputted to the CPU through an I/O(2). The CPU performs arithmetic processing according to a program written in ROM. Density values obtained by the photodetecting elements are compared with a specific mean value in the 1st judgment J1, and the number mHt of elememts which obtain high density values and the number nL of elements which measure low density values are compared with each other in judgment J2; and the results are ANDed 1 and the both are inverted and ANDed 2 to decide on a negative film when nh>nL or a positive film when not. |
