Method for the correction of television signals at transmission, and implementation device
AssigneeLaboratoire Europeen de Recherches Electroniques Avancees Societe en Nom Collectif
InventorMichel Leduc
Life of this patent
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Abstract
According to the disclosed method, a reference line is caused to be transmitted during the non-visible part of the image, the transmissions are received with a calibrated receiver, this reference line is sampled, an error signal is produced from the difference between this line and its theoretical value, a correction coefficient is deduced therefrom for each of the samples of the line, and this correction coefficient is applied to the lines of the following frames.
Claims9
A method for correction of defects occurring in a video signal during transmission comprising the steps of:
- (a) transmitting, in a portion of the video signal corresponding to a portion of frames of the video signal not visible on a display screen, at least one reference line having defects included therein;
- (b) sampling said at least one reference line at a plurality of points along said line;
- (c) calculating an error signal resulting from a difference between the reference line having defects and a line representing an ideal reference line having no defects;
- (d) calculating a correction coefficient from the error signal for each of said plurality of samples;
- (e) applying said correction coefficient to portions of the video signal during frames following said portion of the frames of the video signal not visible on the display screen;
- and
- (f) receiving, at a transmission station which includes a calibrated receiver, said transmitted video signal;
- said step of calculating said correction coefficient including applying a weighting function to said error signal based on a luminance level of said video signal.
A device for the correction, during transmission, of a video signal having defects included therein, comprising:
- (a) an analog-to-digital converter;
- (b) a memory device, connected in series with said analog-to-digital converter, for receiving an output from said analog-to-digital converter;
- (c) a logic correction circuit, connected to said memory device, for receiving an output from said memory device;
- (d) a luminance detection circuit, having an output connected to said logic correction circuit, for detecting a luminance level of said video signal;
- and
- (e) a digital-to-analog converter, connected to said logic correction circuit, for receiving an output from said logic correction circuit;
- said analog-to-digital converter, said memory device, said logic correction circuit, said luminance detection circuit and said digital-to-analog converter being connected between a video signal source and a transmission portion of said correction device and being included in a plurality of receivers for applying said correction of defects occurring in the video signals;
- said logic correction circuit receiving a luminance level from said luminance detection circuit and calculating a weighting function to be applied to an error signal which represents a difference between an actual reference video signal having defects included therein and an ideal reference video signal without defects in order to thereby compute a correction coefficient.
Dependencies are inferred from the claim text.