Correcting vertical resolution in television color images

Claim 3

A method according to claim 1 wherein the deriving step comprises taking the correction signal from the chrominance signal by band limiting.

Claim 4

A method in accordance with claim 2 for use with color signals according to NTSC system, further comprising the step of deriving the difference between an undelayed chrominance signal and a color signal which is delayed by one line period to obtain thereby a difference signal which is a chrominance signal, said correction signal being derived from the difference signal.

Claim 5

A method in accordance with claim 2 for use with color signals according to a PAL system, further comprising the step of deriving the difference between a color signal which is delayed by one line period and a color signal which is delayed by two line periods to obtain thereby a difference signal which is said chrominance signal component, said correction signal being derived from the difference signal.

Claim 6

A method in accordance with claim 1, for use with color signals according to a PAL system, further comprising the step of deriving, as a first difference signal, the difference between a color signal which is delayed by one line period and an undelayed color signal, adding the first difference signal and a second difference signal which is delayed by one line period with respect to the first difference signal for obtaining a chrominance signal, summing an undelayed color signal and said color signal which is delayed by one line period to derive a summation signal, deriving a third difference signal representing the difference between the summation signal and the second difference signal for use as the luminance signal, wherein the correction signal is derived by the additional step of subtracting the first difference signal from the second difference signal.

Claim 7

The method in accordance with claim 1 for color signals in accordance with a PAL system, comprising the steps of adding and subtracting a color signal which is delayed by two line periods and an undelayed color signal to obtain respectively the luminance signal component and the chrominance signal component, forming differences between a color signal which is delayed by one line period and an undelayed color signal, forming differences between a color signal which is delayed by two line periods and a color signal which is delayed by one period, summing the two said differences, and taking a correction signal from a summation signal resulting from the summing of the two differences.

Claim 8

The method in accordance with claim 1, comprising the further step of adjusting amplitude of the correction signal.

Claim 9

Apparatus for correcting vertical resolution in television color images comprising a source of color signals, a delay line connected to the source, a first adder connected to the source and tO the delay line, subtracting means connected to the source and to the delay lines for forming a difference between an undelayed color signal and a delayed color signal, chrominance signal output means connected to the subtracting means for yielding a chrominance signal, a low pass filter connected to the subtracting means, and a second adder connected to the first adder and to the low pass filter for adding signals from the low pass filter and the first adder, thereby producing corrected luminance signals.

Claim 10

Apparatus for correcting vertical resolution in television color images comprising a source of color signals, a delay line connected to the source, a first adder connected to the source and tO the delay line, subtracting means connected to the source and to the delay lines for forming a difference between an undelayed color signal and a delayed color signal, chrominance signal output means connected to the subtracting means for yielding a chrominance signal, a low pass filter connected to the subtracting means, and a second adder connected to the first adder and to the low pass filter for adding signals from the low pass filter and the first adder, thereby producing corrected luminance signals.

Claim 11

The apparatus of claim 8 wherein the subtracting means comprises a first subtractor, a second delay connected thereto and a third adder connected to the first subtractor, to the second delay and to the chrominance output for adding a difference of a delayed and undelayed signal and a delayed signal of the difference, and thereby producing a chrominance signal and further comprising a second subtractor connected to the second delay and to the first adder and a third time delay connected between the second subtractor and the second adder.

Claim 12

The apparatus of claim 9 wherein the low pass filter is connected between the third adder and the second adder.

Claim 13

The apparatus of claim 9 wherein the subtracting means further comprises a third subtractor connected in parallel between the second delay and the third adder, and wherein the low pass filter is connected between an output of the third subtractor and the second adder.

Claim 14

The apparatus of claim 11 further comprising a variable amplitude control between the filter and second adder.

Claim 15

The apparatus of claim 8 wherein the delay line comprises first and second series-connected delays wherein the subtracting means comprises a first subtractor having inputs connected to an output of the delay line and to the source, and having an output connected to the chrominance signal output, second and third subtractors having inputs respectively connected in parallel to the first and second delays, a third adder connected to outputs of the second and third subtractors, wherein the low pass filter is connected between an output of the third adder and an input of the second adder, and further comprising a third delay connected between the first and second adders.

Claim 16

The apparatus of claim 13 further comprising an amplitude control connected between the low pass filter and the second adder.