JPS5446560A - Automatic texture blot compensating device - Google Patents

Abstract

PURPOSE: To automaticaly eliminate the texture blot whthout any substantial reduction in image density by allowing the lower component of an image reading signal than a preset voltage to pass through a limiter circuit, by integrating the same in an integrating circuit in accordance with the size of the image and by erasing the same from the reading signal with the use of a detecting circuit.

CONSTITUTION: An image reading signal, in which the noises and image signals from a reading section 13 overlapped, has its component higher than a preset voltage level cut through a switch S₂ by a liitter circuit 16 whereas the lower component is allowed to pass therethrough. The output signal has its time constant determined in an integrating circuit 12 by interchanging selecting switches S₄₁ in accordance with the size of the image and is integrated with the time constant according to the size of an original so that the scale of the noises due to the texture blot can be detected. In response to the signal of a control section 11, the switch S₂ is interchanged so that the image on the original 14 is read out by the resding section 13. The output signal of the integrating circuit 12 is subtracted by a detecting circuit 17 so as to detect the image signal. This signal is fed to a writing sectin 15 so as to effect the writing operation

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