command input of the memory 39 the falling edge detector 34 is adapted to output a signal at logic 34 1 34 when the output of the threshold comparator 32 changes from logic 34 1 34 to logic 34 0 34 the output of the falling edge detector 34 is connected to the write command inputs of the memories 36 and 40 using this circuit for each defect 2 or 3 and for each fiber 4 appearing on a line on the film 1 inspected by the opto electronic sensor 6 the memory 36 holds information on continuity of defects between the two consecutive line signals previously output by the opto electronic sensor 6 the memory 40 holds the last number of a point on the line corresponding to this defect or fiber and the memory 39 holds the first number of a point on the line corresponding to this defect or fiber the memories 36 39 and 40 can be 34 first in first out 34 fifo memories the memory 39 is adapted to output a partial or total filling signal to the transfer signal output 37 when it receives this signal the computer 44 reads the memories 36 39 and 40 via the multiplexer 41 using known procedures and devices the information received by the computer 44 at its defect information input 42 is simple to process.