JP2003316330A - Video signal processor, its processing method, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dissolve a problem that only color correction is performed since a defective pixel is remained as a luminescent spot when the pixel is the luminescent spot, and as a dark spot when being the dark spot in the case of allowing the luminance of a normal pixel on another display panel to meet that of the defective pixel on one display panel. <P>SOLUTION: In the case of processing a video signal for displaying and driving the display panel as typified by a liquid crystal panel, a position on the time axis of the video signal corresponding to the defective pixel on the display panel is specified by a timing control circuit 15. A correction signal (a correction value) which is set by a correction value arithmetic circuit 14 to correct a luminance difference in the defective pixel with respect to the normal pixel is superimposed by an adder 13 on the video signal corresponding to the defective pixel. Luminance is corrected in the defective pixel to allow the luminance in the defective pixel itself to be equal to that of the normal pixel. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device and a processing method thereof, and a display device, and more particularly to a video signal processing device having a function of correcting the brightness of a defective pixel on a display panel and the brightness of the defective pixel. The present invention relates to a processing method for performing correction processing, and a display device represented by a liquid crystal display device including the video signal processing device.

[0002]

2. Description of the Related Art Conventionally, in a display device such as a liquid crystal display device composed of an aggregate of pixels, there is a defect in a circuit element such as a transistor which constitutes a pixel, and the defective pixel is normally replaced by another defective pixel due to manufacturing variations. When there is a brightness difference with respect to a pixel (hereinafter, simply referred to as “normal pixel”),
Even if the difference in brightness is within the error range of several percent, it is treated as a defective display panel, which is one of the causes of lowering the yield. In this case, since the level of the video signal written in the defective pixel is different from that of the normal pixel,
Usually, it is reflected as a bright spot or a dark spot on the video display screen.

As described above, when a circuit element forming a pixel is defective, the voltage written in the pixel is different between the normal pixel and the defective pixel, so that the luminance level actually written in the pixel is different. Is considered to have occurred. In a normally white mode liquid crystal display device in which the transmittance is maximized when no voltage is applied, what is actually seen as an image is the voltage applied across the liquid crystal cell 31 and the storage capacitor 32 in the pixel circuit of FIG. Although it depends on Vlc, the voltage Vlc is different in the defective pixel from other normal pixels due to the leakage of the pixel transistor 33 and the like.
When lc is low, it appears as a bright spot (see FIG. 11).

FIG. 12 exemplifies a liquid crystal panel having a maximum transmittance when no voltage is applied, and a voltage-transmittance characteristic (VT characteristic) between a pixel which is normally operating (a normal pixel) and a defective pixel. ) Is shown. In FIG. 12, the characteristic indicated by the solid line (a) is the VT characteristic example of the normal pixel, and the characteristic indicated by the broken line (b) is the characteristic example of the defective pixel.

As a system for correcting the brightness of the defective pixel, in a conventional projection type display device having three display panels of R (red), G (green) and B (blue), one display panel has defective pixels. In the case of having a defect pixel, a configuration is known in which correction is performed to reduce the brightness of pixels on the other two display panels having the same coordinates as the defective pixel (Japanese Patent Laid-Open No. 2001-21).
861). In this defective pixel correction system, the defective pixels are inconspicuous in the combined image obtained by combining the images of the three display panels, so that the deterioration of the image can be prevented as much as possible.

[0006]

However, in the defective pixel correction system according to the above conventional example, since the luminance of the normal pixel on another display panel is matched with the luminance of the defective pixel on one display panel, the defective pixel is In the case of a bright spot, it remains as a bright spot, and in the case of a dark spot, it remains as a dark spot, and only color correction is performed. Moreover, since it is the bright spot that is taken up as a more problem, it cannot be said to be a sufficient method for solving the problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a video signal processing apparatus and a video signal processing apparatus capable of effectively making a pixel defect inconspicuous or almost inconspicuous. It is to provide a processing method and a display device using the video signal processing device.

[0008]

In order to achieve the above object, according to the present invention, a video signal corresponding to a defective pixel of the display unit is processed in processing a video signal for driving a display unit composed of an aggregate of pixels. The position on the time axis of is specified, and a correction signal for correcting the luminance difference between the defective pixel and the normal pixel is superimposed on the video signal corresponding to the defective pixel.

When a specific pixel on the display section has a different brightness from other pixels due to manufacturing defects or other defects, first, the position on the time axis of the video signal corresponding to the defective pixel is specified. Then, the correction signal is superimposed on the video signal corresponding to the defective pixel at the timing of the specified position. This correction signal is a signal according to the brightness difference between the defective pixel and the normal pixel. Thereby, the luminance correction of the defective pixel is performed so that the luminance of the defective pixel itself becomes equal to the luminance of the normal pixel.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a video signal processing device according to an embodiment of the present invention. In the present embodiment, it is assumed that the image display device to be driven is an aggregate of pixels, specifically, a liquid crystal panel in which pixels including liquid crystal cells are arranged in a matrix.
As is apparent from FIG. 1, the video signal processing device according to the present embodiment has a white balance adjustment circuit 11, a γ (gamma) correction circuit 12, an adder 13, a correction value calculation circuit 14,
It has a configuration including a timing control circuit 15 and a selector 16.

The white balance adjustment circuit 11 performs white balance adjustment such as gain and brightness on the input video signal. The image signal after the white balance adjustment is input to the γ correction circuit 12. Here, generally, the output with respect to the input signal of the video display device does not appear to change linearly with the human eye. Therefore, in the γ correction circuit 12, the element to be driven with respect to the input video signal, that is, the VT of the liquid crystal in this example.
Γ correction is performed so that the curve has an input / output characteristic that matches the characteristic of the human eye.

The γ-corrected video signal is supplied to the correction value calculation circuit 14 as one addition input of the adder 13. The timing control circuit 15 has a horizontal counter 151 that counts horizontal synchronizing signals, a vertical counter 152 that counts vertical synchronizing signals, and a decoder 153 that decodes the count values of these counters 151 and 152.

In the timing control circuit 15, the horizontal counter 151 counts the master clock corresponding to the horizontal pixel position, and the vertical counter 152 counts the horizontal synchronizing signal. The decoder 153 holds in advance a built-in memory of position (coordinate) information of bright spots (defective pixels) as shown in FIG. 2, and decodes the count values of the horizontal counter 151 and the vertical counter 152 to obtain bright The position on the time axis of the video signal corresponding to the defective pixel requiring bright spot correction is specified at the point position, and the position signal obtained at the specified timing is given to the selector 16 as the select signal.

The correction value calculation circuit 14 sets a correction value for a defective pixel. This correction value is given to the selector 16 as one of its inputs. The selector 16 receives the correction "0" as the other input, selects the correction value given from the correction value calculation circuit 14 when the select signal is given from the timing control circuit 15, and the correction "0" otherwise. Select. The correction value or correction “0” selected by the selector 16 is supplied to the adder 13 as the other addition input.

In the adder 13, a selector 16 is used for a video signal corresponding to a normal pixel which does not require correction.
The correction “0” selected by is added to the γ-corrected video signal, and for the video signal corresponding to the defective pixel requiring the bright spot correction, the correction value selected by the selector 16 is the γ-corrected video signal. It is added to the video signal. It is possible to take both positive and negative values as the correction value at this time.

Here, the setting of the correction value in the correction value calculation circuit 14 will be described. Since the luminance difference between the defective pixel and the normal pixel differs depending on the gradation level of the input video signal, the correction value calculation circuit 14 according to the present example corrects by the signal level of the γ-corrected video signal corresponding to the defective pixel. The value (signal level of the correction signal) is changed. Specifically, for example, as shown in FIG. 3, correction values are set for some specific gradations, and regarding the correction amount in the gradations between them, the correction amounts of the upper and lower correction points are linearly or non-linearly interpolated. A method of calculating by doing is possible.

Next, the circuit operation of the video signal processing device according to the present embodiment having the above-mentioned configuration will be described.

After the white balance adjustment circuit 11 has adjusted the white balance of the input video signal,
In the γ correction circuit 12, γ for adjusting the VT curve of the liquid crystal to the input / output characteristic that matches the characteristic of the human eye
Correction is performed. The timing control circuit 15 operates in parallel with this signal processing. Specifically, the horizontal counter 151 counts the master clock corresponding to the horizontal pixel position, and the vertical counter 152 counts the horizontal synchronization signal. Then, the decoder 153 decodes these count values to specify the position on the time axis of the video signal corresponding to the defective pixel, and gives it to the selector 16 as a select signal at the specified timing.

Here, in order to specify the position on the time axis of the video signal corresponding to the defective pixel, the decoder 153 needs to know the position of the defective pixel on the liquid crystal panel (see FIG. 2). Therefore, the position information is stored in advance in the built-in memory of the decoder 153. The position information of the defective pixel on the liquid crystal panel may be acquired at the inspection stage before the shipment of the liquid crystal panel, and the information may be loaded into the decoder 153. Alternatively, in the present video signal processing device, the correction value is set to an extreme value and a series of correction processes is executed, so that the correction pixel gradually moves as the horizontal scanning and the vertical scanning are performed, and eventually the defective pixel is defective. Since it will pass through the pixel position,
The decode value of the decoder 153 at the timing when the correction pixel is located at the defective pixel may be fetched as position information of the defective pixel on the liquid crystal panel. However, these are merely examples and are not limited to these methods.

On the other hand, in the correction value calculation circuit 14, since the number of defective pixels is not limited to one, the number of correction values corresponding to the number of defective pixels stored in the decoder 153 is set and the position of each defective pixel is set. The correction value for the corresponding defective pixel is output according to the information.

The selector 16 normally selects the correction "0". When the decoder 153 gives a select signal to the selector 16, the selector 16 selects the correction value set by the correction value calculation circuit 14 instead of the correction “0”. As a result, the correction value calculation circuit 14 is applied to the video signal corresponding to the defective pixel requiring the bright spot correction.
The correction value set in 1 is superposed by the adder 13. As a result, as shown in the output conversion table example for the digital input in FIG. 4, the input / output characteristic (b) of the defective pixel in which the difference is shifted by the correction value from the input / output characteristic (a) of the normal pixel.
Can be obtained.

As described above, when processing a video signal for driving a display panel typified by a liquid crystal panel, the position on the time axis of the video signal corresponding to the defective pixel of the display panel is specified and the defective pixel is identified. By superimposing a correction signal (correction value) for correcting the luminance difference of the defective pixel with respect to the normal pixel on the corresponding video signal, the luminance of the defective pixel is corrected so that the luminance of the defective pixel itself becomes equal to the luminance of the normal pixel. Therefore, the pixel defect can be efficiently made inconspicuous. In particular, by changing the signal level of the correction signal according to the signal level of the video signal corresponding to the defective pixel, even if the correction amount required for the defective pixel varies depending on the brightness level, it is more optimal. Since it is possible to set various correction amounts, it becomes possible to make pixel defects almost completely inconspicuous.

In the present embodiment, in order to change the correction value according to the signal level of the video signal, the correction value is set for some specific gradations, and the correction amount for the gradations between those is set up or down. Although the correction amount of the correction point of is interpolated linearly or non-linearly, it is not limited to this,
As a modification thereof, for example, a γ correction table in which correction values are independently set only for bright points for all gradations is provided, and a correction value according to a signal level of a video signal is set using this γ correction table. It is also possible to do so.

Further, if there is a concern that the circuit scale will increase due to the calculation of the correction value in the correction value calculation circuit 14, it is possible to adopt a configuration in which the calculation is not performed. Specifically, a gradation having the best visibility and easily recognized as a difference in luminance level, for example, a luminance difference between a defective pixel and a normal pixel in a halftone that is most visible is set as a fixed correction value,
The bright spots can be improved by superimposing the correction value on all the gradations in the same manner.

Further, from the viewpoint of the visibility of human eyes, since the dark spot is less conspicuous than the bright spot, the display device has the maximum transmittance in the state where no voltage is applied, that is, the normally white liquid crystal display. In the device, it is possible to write a black signal (black level) to a defective pixel that is seen as a bright spot regardless of the signal level of the input video signal. As described above, since the bright spot can be made into the dark spot by writing the black signal, the defective pixel can be made inconspicuous from the viewpoint of visibility of human eyes.

In the present embodiment, the case of correcting defective pixels that appear as bright spots has been described as an example. However, from the method of correction, it goes without saying that defective pixels that appear as dark spots can also be corrected. Clearly applicable.

The video signal processing device according to the above-described embodiment can be used, for example, as a signal processing system of a three-panel liquid crystal projection video display device. FIG. 5 shows a schematic configuration of a three-panel liquid crystal projection image display device.

This three-plate type liquid crystal projection image display device includes liquid crystal panel modules 21R, 21G and 21B, liquid crystal drivers 22R, 22G and 22B for driving these panel modules 21R, 21G and 21B, and liquid crystal panel modules 21R and 21G, 21B for generating various timing pulses for driving 21B
And a video signal processing circuit 24 for processing each of the R, G and B video signals.

Liquid crystal panel modules 21R, 21G, 2
1B is manufactured by enclosing a liquid crystal material between two transparent insulating substrates (for example, glass substrates), and the R, G, and B color filters are arranged on each unit pixel arranged in a matrix. It has been configured. The liquid crystal panel modules 21R, 21G and 21B have a built-in shift register that constitutes a scanning system.

FIG. 6 shows a configuration example of the peripheral circuit of the unit pixel. As is clear from the figure, the unit pixels are connected in parallel to each other, and the liquid crystal cell 31 whose counter electrode is connected to the Cs line 34, and the storage capacitor 32 which is connected in parallel to this liquid crystal cell 31, The pixel electrode of the liquid crystal cell 31 has a drain electrode, a data line (signal line) 35 has a source electrode, and a gate line 36 has a pixel transistor 33 to which a gate electrode is connected.

FIG. 7 shows the structure of the optical system of the three-panel liquid crystal projection image display device. In FIG. 7, white light emitted from a light source 41 such as a white lamp is a dichroic mirror 4.
2, only a specific color component, for example, the R light component is reflected,
The remaining color light components pass through the dichroic mirror 42. The optical path of the R light component reflected by the first dichroic mirror 42 is changed by the dichroic mirror 43, and enters the R liquid crystal panel module 21R through the polarizing plate 44R.

Regarding the light component transmitted through the dichroic mirror 42, for example, the G light component is reflected by the dichroic mirror 45, and the B light component is transmitted through the dichroic mirror 45. The G light component reflected by the dichroic mirror 45 enters the G liquid crystal panel module 21G through the polarizing plate 44G. The optical path of the B light component transmitted through the dichroic mirror 45 is polarized by the dichroic mirrors 46 and 47, and passes through the polarizing plate 44B to B light.
It enters the liquid crystal panel module 21B.

Liquid crystal panel modules 21R, 21G, 2
The respective light components of R, G, B which have passed through 1B respectively enter the dichroic prism 49 through the polarizing plates 48R, 48G, 48B and are combined by the dichroic prism 49. And this dichroic prism 49
The combined light emitted from is projected onto a screen (not shown) by the projection lens 50.

In the three-panel liquid crystal projection image display device having the above-mentioned configuration, the image signal processing device according to the above-described embodiment is used as the image signal processing circuit 24. This allows
For each R, G, B video signal input from the outside,
Γ that matches the VT curve of the liquid crystal in the video signal processing circuit 24
It is corrected and output. The R, G, and B video signals that have passed through the video signal processing circuit 24 are supplied to the liquid crystal drive 22R,
At 22G and 22B, the liquid crystal is converted into a drive waveform that causes AC inversion.

The AC-driven video signal is input to the liquid crystal panel modules 21R, 21G and 21B, and the timing pulse output from the timing generator 23 matches the display area of each panel. The voltage is being written to. These processes are performed for each of the three primary colors R, G, B of light, and the three colors are combined and projected according to the optical system shown in FIG.

At this time, the liquid crystal panel module 21R,
In a specific pixel of 21G and 21B, for example, when the ON current characteristic of the pixel transistor is lower than the characteristic of the transistor of the normal pixel and the resistance at ON is large,
A voltage cannot be written sufficiently to other normal pixels, and as a result, in the case of a normally white liquid crystal panel, defective pixels appear as bright spots. This is because the characteristics of the transmittance of the defective pixel with respect to the voltage from the outside are different from those of the normal pixel as described above.

In order to correct the luminance of this defective pixel,
In the video signal processing device according to the above-described embodiment, when the same video signal level is input, it is possible to obtain the same transmittance as that in the case where a signal is written in a normal pixel even for a defective pixel. The correction signal is superimposed on the video signal corresponding to the defective pixel. The operation seen from the external drive voltage of the defective pixel is V-
It seems that the T characteristics are different, so the γ correction is changed only for this defective pixel from that for other pixels,
It suffices to make a correction such that the same input signal has the same transmittance as that of a normal pixel.

In this way, for example, in the three-panel liquid crystal projection image display device, the image signal processing device according to the above-described embodiment is used as the image signal processing circuit 24, whereby the liquid crystal panel and the module 21 are also used in the image signal processing device.
For each of R, 21G, and 21B, the luminance correction is performed so that the luminance of the defective pixel itself becomes equal to the luminance of the normal pixel. As it is, if it is a dark spot, it remains as a dark spot,
Only the color correction is not performed, and the pixel defect can be more surely made inconspicuous.

FIG. 8 shows the waveform of the liquid crystal drive video signal converted into an alternating current. As is clear from the figure, even if the correction value (correction signal) is changed according to the signal level of the video signal, the defective pixel signal (b) is within the operating range X of the normal pixel signal (a). It will change. However, in this way, in the bright spot correction in which the defective pixel signal (b) is changed within the operating range of the normal pixel signal (a), a voltage larger than that of a normal black level signal cannot be applied. Correction at the black level is impossible.

Therefore, a signal exceeding the driving range of a normal pixel can be input to a defective pixel whose luminance level is different in a normal pixel driving state. In particular,
The output conversion table for the digital input is made to have the characteristics shown in FIG. 9, and a voltage larger than a normal black level signal is applied to the pixel serving as the bright spot. FIG. 10 shows the waveform of the liquid crystal drive video signal converted into an alternating current in this case. As is clear from the figure, the operating range Y of the defective pixel signal (b) is wider than the operating range X of the normal pixel signal (a).

In this way, by applying the black signal for the defective pixel larger than the black signal for the normal pixel,
It is possible to correct even when a black signal is input. That is, a pixel that is no longer displayed as black due to a pixel defect can be displayed as original black.

Here, the case where the present invention is applied to the liquid crystal projection image display device has been described as an example, but the present invention is not limited to the projection type general liquid crystal display device, and further not limited to the liquid crystal display device. , EL (electroluminescence) elements used as display elements
The present invention can be applied to general display devices including elements for controlling pixels, such as L display devices.

[0044]

As described above, according to the present invention,
When processing a video signal for driving a display panel typified by a liquid crystal panel, the position on the time axis of the video signal corresponding to the defective pixel of the display panel is specified, and the normal signal is added to the video signal corresponding to the defective pixel. By superimposing the correction signal for correcting the difference in brightness of the defective pixel, the brightness of the defective pixel is corrected so that the brightness of the defective pixel becomes equal to the brightness of the normal pixel. It can be completely unobtrusive.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video signal processing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a position (coordinates) relationship of bright points with respect to a display panel.

FIG. 3 is a characteristic diagram showing a change in correction amount depending on gradation.

FIG. 4 is a diagram showing an example (part 1) of an output conversion table for digital input.

FIG. 5 is a block diagram showing a schematic configuration of a three-panel liquid crystal projection image display device.

FIG. 6 is a circuit diagram showing an example of a configuration of a unit pixel.

FIG. 7 is a configuration diagram showing an optical system of a three-plate type liquid crystal projection image display device.

FIG. 8 is a waveform diagram showing an alternating liquid crystal drive video signal (No. 1).

FIG. 9 is a diagram showing an example (part 2) of an output conversion table for digital input.

FIG. 10 is a waveform diagram showing an alternating liquid crystal drive video signal (part 2).

FIG. 11 is a diagram showing a state of bright spots due to a pixel defect.

FIG. 12 is a characteristic diagram of voltage-transmittance (VT) of a liquid crystal panel.

[Explanation of symbols]

11 ... White balance adjustment circuit, 12 ... γ (gamma)
Correction circuit, 14 ... Correction value calculation circuit, 15 ... Timing control circuit, 16 ... Selector, 21R, 21G, 2
1B ... Liquid crystal panel module, 22R, 22G, 22B
... LCD driver, 23 ... Timing generator, 24
... Video signal processing circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 641 G09G 3/20 641P 642 642A 670 670A H04N 5/66 102 H04N 5/66 102B F term ( (Reference) 2H092 JA24 JB13 JB61 JB77 NA25 NA29 NA30 PA06 RA05 2H093 NA16 NA21 NA79 NC13 NC27 NC34 NC35 NC68 NC90 NG02 5C006 AA22 AF12 AF45 AF46 BB16 BC11 BF01 BF22 BF24 BF28 BF24 BF28 BF28 BB28A05 BA10 BA05 BA10 BA13 BA05 BA13 BA05 BA13 BA05 BA13 BA05 DD28 EE28 FF11 GG12 JJ01 JJ02 JJ04 JJ05 JJ06 KK43

Claims (11)

[Claims] 1. A video signal processing device for displaying and driving a display unit comprising a group of pixels, the detection unit detecting a position on a time axis of a video signal corresponding to a defective pixel of the display unit, A video signal, comprising: a correction means for responding to a detection output of the detection means, for superimposing a correction signal for correcting the luminance difference between the defective pixel and the normal pixel on the video signal corresponding to the defective pixel. Processing equipment. 2. The video signal processing device according to claim 1, wherein the correction means controls the signal level of the correction signal in accordance with the signal level of the video signal corresponding to the defective pixel. 3. When the display unit is a liquid crystal panel in which the display unit has a maximum transmittance in a state in which a voltage is not applied to the pixel, the defective pixel has a bright spot higher than the luminance of a normal pixel. 2. The video signal processing device according to claim 1, wherein a black signal is superimposed as the correction signal on a video signal corresponding to a defective pixel that becomes a bright spot. 4. The video signal processing apparatus according to claim 1, wherein the correction means provides the defective pixel with a video signal having a signal level exceeding a drive range of a normal pixel. 5. When the display unit is a liquid crystal panel in which the display unit has a maximum transmittance in a state in which a voltage is not applied to the pixel, the defective pixel has a bright spot higher than that of a normal pixel. 5. The video signal processing device according to claim 4, wherein a black signal having a signal level exceeding the drive range is superimposed as the correction signal on the video signal corresponding to the defective pixel which becomes the bright spot. 6. When processing a video signal for driving display of a display unit made up of a group of pixels, a position on the time axis of the video signal corresponding to the defective pixel of the display unit is specified to correspond to the defective pixel. A video signal processing method comprising: superimposing a correction signal for correcting a brightness difference between the defective pixel and a normal pixel on the video signal. 7. A display unit comprising an aggregate of pixels, a position on a time axis of a video signal corresponding to a defective pixel of the display unit is specified, and a video signal corresponding to the defective pixel is identified as the defective pixel. A display device, comprising: a signal processing unit that superimposes a correction signal that corrects a brightness difference with a pixel. 8. The display device according to claim 7, wherein the signal processing means controls the signal level of the correction signal in accordance with the signal level of the video signal corresponding to the defective pixel. 9. The display unit is a liquid crystal panel that has a maximum transmittance in a state in which a voltage is not applied to the pixel, and the signal processing unit causes the defective pixel to have a bright spot higher than the luminance of a normal pixel. The display device according to claim 7, wherein the black signal is superimposed as the correction signal on the video signal corresponding to the defective pixel that becomes the bright spot. 10. The display device according to claim 7, wherein the signal processing means provides a video signal having a signal level exceeding a drive range of a normal pixel to the defective pixel. 11. The display unit is a liquid crystal panel that has a maximum transmittance in a state in which a voltage is not applied to the pixel, and the signal processing unit causes the defective pixel to have a bright spot higher than the luminance of a normal pixel. 11. The display device according to claim 10, wherein the black signal having a signal level exceeding the drive range is superimposed as the correction signal on the video signal corresponding to the defective pixel serving as the bright spot.