US 6,674,488 B1Granted

Luminance and color difference signal separator for adaptively selecting color difference signals output from comb and line filters

AssigneeOki Electric Industry Co., Ltd.

InventorYasunori Satoh

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Abstract

A luminance (Y) and a color difference (C) signal separator switches filters according to an image and separates a Y signal and a C signal included in a composite color picture signal to eliminate a degradation which would otherwise be involved at a transition point because of the characteristics of the filters. A first weighting circuit calculates the weighted average of the C signals extracted from the composite signal by a comb filter and a three-line comb filter. A second weighting circuit calculates the weighted average of the C signals extracted by the three-line comb filter and a two-line comb filter. When the motion level of the image exceeds a predetermined threshold, a selector selects, as the final C signal, the signal output from the second weighting circuit. When the motion level is equal to or lower than the predetermined threshold, the selector selects, as the final C signal, the signal output from the first weighting circuit.

Claims8

Dependent claims

A luminance and color difference signal separator circuit for separating a luminance signal and a color difference signal which are included in a composite color picture signal representing an image, said circuit comprising:

a motion detector for detecting a motion of the image and determining a motion level of the detected motion;
a line correlation detector for detecting a correlation level of lines of the image;
a first filter having first filtering characteristics for extracting the color difference signal from the composite color picture signal according to the first filtering characteristics;
a second filter having second filtering characteristics, different from the first filtering characteristics, for extracting the color difference signal from the composite color picture signal according to the second filtering characteristics;
a first weighting circuit operative in response to the motion level determined for calculating a weighted average of the color difference signals extracted by said first and second filters;
a third filter having third filtering characteristics, different from the first and second filtering characteristics, for extracting the color difference signal from the composite color picture signal according to the third characteristics;
a second weighting circuit operative in response to the correlation level detected for calculating a weighted average of the color difference signals extracted by said second and third filters;
a selector for selecting the weighted average calculated by said first weighting circuit if said motion detector determines that the motion level of the image is below a predetermined threshold, and selecting, if the motion level of the image exceeds the predetermined threshold, the weight average calculated by said second weighting circuit, and developing the selected weighted average as an ultimate color difference signal;
and
a subtracter for subtracting the ultimate color difference signal from the composite color picture signal to produce an ultimate luminance signal.

7 more elements

a motion detector for detecting a motion level of the image;
a line correlation detector for detecting a correlation level of lines of the image;
a color difference signal extractor having at least three filtering characteristics, different from each other, for extracting at least three color difference signals from the composite color picture signal in accordance with the at least three filtering characteristics to produce at least three color difference signals;
a weighting circuit for calculating weighted averages between two of the at least three color difference signals;
a selector for selecting either one of the weighted averages output from said weighting circuit as an ultimate color difference signal according to the motion level detected;
and
a subtracter for subtracting the ultimate color difference signal from the composite color picture signal to produce an ultimate luminance signal.

4 more elements

Dependencies are inferred from the claim text.