Nec Corporation

Yasuharu Ashida

Fujio Cho

Toshiyuki Shimizu

Shinji Koike

A method of correcting digital NTSC color-television signals in transmission error by substituting the error-included digital color-television signals with those digital color-television signals in the corresponding horizontal scanning periods two frame periods before, stored in memory (12), and an apparatus to work the method. When a transmission error is detected in a specific horizontal scanning period, substitute circuit (13) reads from memory (12) the digital color-television signals in the N horizontal scanning periods two frame periods before corresponding to the specific and subsequent N-1 horizontal scanning periods, and transmits the digital color-television signals read from memory (12) in lieu of those digital color-television signals in the specific and subsequent N-1 horizontal scanning periods.

Method of correcting transmission error in digital color-television

A method for setting the clamp level of a television signal in which the signal is converted by an A/D converter and quantized with a plurality of quantizers, comprises taking into account the quantization characteristics of the various quantizers in addition to the dynamic range of the A/D converter. The television signal is level shifted so that it is within the dynamic range of the A/D converter and is clamped to a level which minimizes the quantization error of that quantizer which has the largest quantization step size of all the quantizers.

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Tokyo, Japan

Fujio Cho