KR930005188B1 - Peaking correction circuit for digital video signal - Google Patents

Abstract

The peaking correction circuit compensates the brightness during peaking in improved or extended definition televisions. The circuit comprises a noise eliminating section (20) for eliminating the noise component from an input signal, a gain control section (30) for controlling the gain of the noise eliminated signal, a white limiter section (40) for limiting the gain controlled signal to suppress the over-peaking to the white level direction, an adder (7) for adding the output of the white limiter section and the original signal, a peaking correction section (50) for correcting the brightness when the output of the gain control is applicable to the white limit. A brightness controller (13) selectively receives the outputs of a code discriminator (9) and a low pass filter (11).

Description

Peaking correction circuit for digital video signal processing

1 is a circuit diagram showing a peaking brightness correction circuit according to the present invention.

2A and 2B are signal waveform diagrams when there is no white limiter and when the white limiter is set.

* Explanation of symbols for main parts of the drawings

1: Band Pass Filter (BPF) 2: Noise Reduction Coring

3 multiplier 4 gain control data feeder

5: white limiter 6: limiter data feeder

7: adder 8: subtractor

9: code determiner 10: 2 divider

11: low pass filter (LPF) 12: switch

13: brightness adjuster 20: noise removal unit

30: gain adjusting unit 40: white limiter

50: peaking correction unit

The present invention relates to an ID (Improved Definition) television and an ED (Extended Definition) television that perform digital video signal processing, and more particularly, a peaking correction for digital video signal processing that compensates for the lowering of brightness during peaking. It is about a circuit.

In general, the peaking circuit (Peaking Circuit) is limited to prevent the excessive picking in the back-level direction through the noise removal coring (Coring) for removing noise and the white limiter (White Limtter) after gain adjustment. However, in this case, since the peaking is not performed in the direction of the black level, the DC level is lowered, resulting in a dark screen.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a peaking correction circuit for processing digital video signals to compensate for the brightness when white limiting is applied so that the phenomenon of darkening even when a lot of peaking is applied can be eliminated. .

The feature of the picking correction circuit for digital video signal processing according to the present invention for achieving the above object is a noise removing unit for removing noise components from an input signal applied from the outside, and applying a signal removed by the noise removing unit A gain adjuster that receives the signal and adjusts it to a predetermined gain value, a white limiter that receives the signal adjusted by the gain adjuster and restricts the signal from being excessively picked in the back level direction, a signal limited by the white limiter, A peaking circuit for processing digital video signals by adding original signals to adjust brightness of a screen; A peaking correction unit is further connected to an output terminal of the gain adjusting unit and an intermediate node point of the white limiting unit. The peaking correction unit further corrects brightness when the white limit corresponds to a white limit. The peaking correction unit outputs the data value and the limiter in the white limiter unit. A subtractor for generating a difference signal with respect to the data value output from the data supplier, a code determiner for determining the sign for the data value output from the subtractor, a two-division cycle for generating a frequency signal obtained by dividing the data value by two; And a low pass filter for passing only a DC component of data to be compensated according to the frequency signal output from the two-division period, and a switch for selectively applying an output of the low pass filter and an output of a code determiner to a brightness controller. Is in point.

Hereinafter, an embodiment of the peaking correction for digital image signal processing according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a circuit diagram showing a peaking brightness correction circuit according to the present invention. In the circuit, the noise removing unit 20 for removing noise from a signal input from the outside is connected to the band pass filter 1 with a noise removing coring 2 so as to pass only a frequency component to be picked. A gain adjusting unit 30 for adjusting gain is connected to the noise removing unit 20, and the gain adjusting unit 30 multiplies the multiplied signal 3 to remove the noise removed through the noise removing unit 20, and A gain adjusting data supply 4 connected to the input of the multiplier 3 is provided. In addition, the gain adjuster 30 is connected to a white limiter 40 that restricts excessive picking in the back level direction. The white limiter portion 40 includes a white limiter 5 and a limiter data supply 6. Also, an adder 7 is connected to an output terminal of the white limiter 40 to add two signals, which are an original input signal and an output signal of the white limiter 5. On the other hand, the peaking correction unit 50 connected to the gain adjusting unit 30 operates to increase the brightness when white limiting is applied. The brightness compensator 50 is connected to an output terminal of the subtractor 8 and a subtractor 8 for generating a difference between the two signals of the output signal of the noise removing unit 20 and the limiter data supply. The determiner 9 is connected, and the signal output from the divider 10 and the divider 10 for bringing down the output signal of the subtractor 8 in half (1/2) is below a predetermined signal level. A low pass filter 11 for passing only the value of is connected in parallel with the code determiner 9. In addition, the switch 12 which is in the "on" state is connected only when a limit is applied to the sign determiner 9 and the low pass filter 11. In addition, a brightness controller 13 for adjusting the brightness of the screen is connected to the output terminal of the adder 7 and one terminal of the switch 12.

In more detail, the high frequency components to be picked by the band pass filter 1 are picked out, and the noise components are removed by the noise removing coring 2. Then, the data is supplied from the gain adjustment data supplier 4 and multiplied in the multiplier 3 to perform the picking operation. On the other hand, the white limiter 5 receives the signal output from the multiplier 3 and the data from the limiter data supply 6 to limit the frequency to the upper side, and adds this frequency to the input signal from the adder 7 Try to pick. If the input signal is the solid line waveform of Fig. 2a, the DC level of this signal is at (A), and if the white limiter 5 is not present, it can be seen that it appears as a dotted line waveform. However, if the white limiter is set at point (B), the direct current level is also at point (A), i.e. assuming that the data of the limiter data supply 6 of FIG. The final output of the picking in the degree adder 7 is shown in figure 2b. In this case, the DC point becomes (A '), which is different from the point (A) in FIG. 2A. That is, according to the present invention, the data that is limited in the data before the white limiter is subtracted by the subtractor B, the level is halved in the divider 10, and is generated as a DC component by the low pass filter 11. This results in the generation of direct current components by the difference between (A) and (A ') shown in FIG. Therefore, only such a DC component is applied to the brightness controller 13 by the switching operation of the switch 12 to level up the point (A ') of FIG. In this case, when the output of the subtractor 8 is positive, that is, when the limiting is detected, the brightness is adjusted only when the white limiting is applied by turning on the switch 12 only in this case.

As described above, the peaking correction circuit for digital video signal processing according to the present invention has the effect of compensating the brightness only when white limiting is applied, thereby eliminating the phenomenon of peaking.

Claims (1)

A noise removing unit 20 for removing noise components from an input signal applied from the outside, a gain adjusting unit 30 for receiving a signal removed by the noise removing unit 20 and adjusting the signal to a predetermined gain value; A white limiter 40 for limiting the signal to prevent excessive picking in the back level direction by receiving the signal adjusted by the gain adjuster 30, and a signal limited by the white limiter 40 and the original signal. A peaking circuit for processing digital video signals by adding a digital signal; A peaking correction unit 50 is further connected to an output terminal of the gain adjusting unit 30 and an intermediate node point of the white limiter unit 40 to correct brightness when the white limiter corresponds to the white limiter. The peaking correction unit 50 is further included. Is a subtractor (8) for generating a difference signal between the data value output from the gain adjusting section (30) and the data value output from the limiter data supply (6) in the white limiter section (40), and the subtractor (8). A code determiner 9 for determining a sign for a data value outputted from the signal generator; a dividing frequency generator 10 for generating a frequency signal obtained by dividing the data value into two; and a frequency signal output from the two frequency divider 10. And a switch for selectively applying the output of the low pass filter 11 and the output of the code determiner 9 to the brightness adjuster 13. Characterized by consisting of 12 Peaking correction circuit for digital video signal processing.

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