JPS5614934A - Signal processing method for hot flaw detection - Google Patents

Abstract

PURPOSE: To detect a flaw automatically and reliably by differentiating an image signal from a television camera, subjecting the differentiated signal to automatic gain control, and processing the resulting signal while comparing the same with a reference judgement level signal.

CONSTITUTION: An image signal stored in a video memory 3 is applied to a differentiator 42 through a synchronizing signal separator 41 to be differentiated. The differentiated signal is subjected to gain control automatically in an automatic gain controller 43 to be thereafter applied to a comparator 44, in which the signal is compared with a reference judgement level signal α. A signal from the comparator 44 is applied to a synchronizing signal superposer 45 and an adder 46. A synchronizing signal β from the synchronizing signal separator 41 is subjected to superposition in the synchronizing signal superposer 45, and then applied to a flaw position detector 5 to detect the position of a flaw. At the same time, an image signal from the video memory is added in the adder 46, and a signal from the adder 46 is sent to a monitor 8 to form an image thereon. Thus, a reference judgement level regulation is carried out automatically, and a noise signal and a flaw signal can be discriminated from each other clearly, so that the overlooking of a flaw can be prevented.

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