| 摘要 |
PURPOSE:To discriminate whether a picture is a negative picture or a positive picture without intervention of the operator by reading photoelectrically a picture recorded on a film and comparing the ratio of white and black picture signals to discriminate whether the film is the negative picture or the positive picture. CONSTITUTION:A linear array sensor 11 reads a picture of a microfilm on a prescribed read position at each line. An output signal of the linear array sensor 11 is amplified by an amplifier 16, a comparator 17 compares its amplified output with a predetermined threshold voltage Vth and the result is subjected to binary coding. Then integration devices 20, 21 integrate separately periods of '1' and '0' of the comparator output at each main scanning line, the operation is repeated with respect to all main scanning lines, and each period of '1' and '0' is integrated totally with respect to a picture of a frame. The total integration of the '1', '0' periods is subjected to quantity discrimination by a comparator 22, and when the film is the positive film, the integrated value of the period of '1' exceeds the integrated value of that of '0', a Q output of a flip-flop 23 is logical 1, a transistor 24 is turned on to light an LED25.
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