JP2003189125A - Video signal processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video signal processing apparatus that can adjust a black side level without giving the effect on a white side level of an input video signal. <P>SOLUTION: Black level adjustment sections 1, 2 and 3 that vary only the black side level within a setting range as to RGB input video signals but do not change the white side level at the outside of the setting range, and provide an output, are provided for the RGB input video signals, respectively. Further, the setting range in the black level adjustment sections 1 or the like is made to be a black side level range of about 25% or below with respect to 100% white level of the video signal. Moreover, the black level adjustment sections 1 or the like comprise an LUT storing in advance a plurality of kinds of input/ output conversion characteristics. A characteristic setting purpose control signal S1 is used to select the input/output conversion characteristics. <P>COPYRIGHT: (C)2003,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 apparatus, and more particularly to a video signal processing apparatus for adjusting a black level of an input video signal without affecting a white level.

[0002]

2. Description of the Related Art Conventionally, there are brightness adjustment and contrast adjustment as functions for correcting or adjusting the black side level of a video signal. However, each of these functions has a drawback in that when the black side level is adjusted, the white side level including the white peak also changes. For example, when the brightness is lowered, the white peak level is lowered, and conversely, when the brightness is raised, the white peak level is raised. On the other hand, the video signal processing of recent video display devices equipped with a PDP (plasma display panel) or LCD (liquid crystal element) is usually digital processing. However, if the device used for this digital processing has a narrow dynamic range, When the brightness is increased by the function, there is a problem that the white peak is crushed.

[0003]

In view of the above drawbacks or problems, it is an object of the present invention to provide a video signal processing device capable of adjusting the black level of a video signal without affecting the white level. And

[0004]

In order to achieve the above object, the present invention is directed to changing the level of an input video signal only for a video signal in a range set as a black side level, and for changing the level to a white side outside the set range. The present invention provides a video signal processing device including a black level adjusting unit that outputs a level unchanged.

Further, it is assumed that the set range in the black level adjusting section is a black side level range of about 25% or less with respect to 100% white of the video signal.

Alternatively, the setting of the range of the variable black side level in the black level adjusting unit is 100% of the video signal.
The setting may be made by arbitrarily selecting from a plurality of ranges set in the range of the black side level of approximately 25% or less with respect to white.

Further, the black level adjusting section selectively sets a plurality of types of input / output conversion characteristics, which are provided in advance, by a control signal.

In addition, the black level adjusting unit is a LUT (Look Up Ta) that stores a plurality of types of input / output conversion characteristics in advance.
ble).

Further, the black level adjusting section is provided at a stage before gamma correction or white balance correction.

Further, the plurality of types of input / output conversion characteristics are
Each has a linear characteristic. Or non-linear characteristics,
Furthermore, a combination of linear characteristics and non-linear characteristics may be used.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings based on examples. FIG. 1 is a block diagram of a main part showing an embodiment of a video signal processing device according to the present invention, and the input video signal has a form of R (red), G (green), B.
It is assumed to consist of each signal of (blue). FIG. 2 is a block diagram of essential parts showing another embodiment of the video signal processing device according to the present invention. 3A and 3B are block diagrams of a main part of the black level adjusting unit. FIG. 3A corresponds to FIG. 1 and FIG. 3B corresponds to FIG. Further, FIG. 4 is an example of a video signal input / output conversion characteristic diagram for explaining the black level adjusting unit of FIG. 1 or FIG. In FIG. 1, 1 to 3 are R
A black level adjustment unit for each GB signal, 4 to 6 are same / gamma correction units, and 7 to 9 are same / white balance correction units. Also,
In FIG. 2, the same components as those in FIG. 1 are designated by the same reference numerals, and 11 to 13 are black level adjusting units for the respective RGB signals.

Next, the operation of the present invention will be described. First, FIG. 1 will be described. Each input video signal of RGB is input to each of the black level adjusting units 1, 2 and 3, and the level of the input video signal is adjusted only for the video signal in the range preset as the black side level, The white level outside the set range is output as unchanged. The adjustment is processed according to the input control signal S1 for setting the characteristic. Each black level adjustment unit 1, 2,
Each of the RGB image signals whose black levels have been adjusted by 3 is input to each of the gamma correction units 4, 5 and 6, and P
The level of each of the RGB image signals is corrected so as to match the light emission characteristics of the display device such as DP or LCD. The RGB image signals gamma-corrected by the gamma correction units 4, 5 and 6 are input to the respective white balance correction units 7, 8 and 9 so that an appropriate white display is made on a display element such as a PDP or LCD. Correct the level so that As described above, the black level adjusting units 1, 2, and 3 are provided before the gamma correction and the white balance correction processing. However, this allows proper gamma correction and white balance correction without being affected by the black level adjustment. Done.

Next, FIG. 2 will be described. In the configuration of FIG. 1, the range of the black side level to be adjusted is set in advance, and this range is fixed after the setting. On the other hand, in the configuration of FIG. 2, the range of the black side level to be adjusted can be variably set. For example, 100%
With respect to white, it is possible to select and set from a black side level of approximately 25% or less, a black side level of approximately 20% or less, a black side level of approximately 15% or less, and the like. In this case, the white side level outside the set range is output unchanged.
Is the same as. The setting of the range is processed according to the input range setting control signal S11, and the adjustment of the black side level for each of the RGB image signals after the setting is processed according to the input characteristic setting control signal S12. Gamma correction and white balance correction after black level adjustment are the same as in FIG.

Next, the black level adjusting units 1, 2, 3 in FIG. 1 and the black level adjusting units 11, 12, 13 in FIG.
Will be described with reference to FIGS. 3 and 4. 3A shows the black level adjusting unit 1 of FIG. 1, and FIG. 3B shows the black level adjusting unit 11 of FIG. In addition, RG
The black level adjusting units of the respective Bs have the same configuration.
First, FIG. 3A will be described. In the figure,
The memory unit 1a stores a plurality of types of input / output conversion characteristics in advance, and is a so-called LUT (Look Up Table).
It will be. FIG. 4A shows an example of the plurality of types of input / output conversion characteristics, which is provided with a plurality of types of black-side level input / output conversion characteristics of approximately 25% or less with respect to 100% white. is there. The input / output conversion characteristics include one-to-one conversion characteristics (referred to as reference characteristics), as well as conversion characteristics for increasing the input level with respect to the reference characteristics and lowering the input level. Plural kinds of conversion characteristics to be output are provided.

FIG. 4A shows the above-mentioned conversion characteristics of which the input level is raised and output are m types, and the conversion characteristics of which the input level is lowered and output are n types. The range connecting the input shaft a and the output shaft a in FIG. 4A is the input / output conversion range, which is the black level adjustment range. As can be understood from the figure, the input / output conversion is fixed for the white level outside the adjustment range, and the white level does not change even if the above adjustment is performed. The selection from the plurality of types of input / output conversion characteristics follows the input characteristic setting control signal S1. Therefore, the control signal S1 and each of the plurality of types of input / output conversion characteristics are stored in the memory unit 1a in association with each other. Therefore, when the control signal S1 is input, the control unit 1b reads the input / output conversion characteristic corresponding to the control signal S1 from the memory unit 1a, and outputs the input video signal (R signal in this figure) according to the conversion characteristic. The conversion unit 1c converts the level and outputs it. As described above, the black level can be adjusted within the predetermined range without affecting the white level. The same operation is performed for the other black level adjusting units 2 and 3.

Next, FIG. 3B will be described. Figure 3
As described above, the black level adjusting unit 11 of (B) is capable of variably setting the range of the black level to be adjusted. Therefore, the memory unit 11a includes the memory unit 1a shown in FIG.
A plurality of types of input / output conversion characteristics of the same kind as the storage data of (1) are stored in advance by changing the range of the black side level. An example in which this range is changed is shown in FIG. In FIG. 4A, the black side level of approximately 25% or less with respect to 100% white is set as the adjustment range, whereas in FIG. 4B, the black side level of approximately 20% or less with respect to 100% white is adjusted. It is a range. The point that a plurality of input / output conversion characteristics are provided in this range is similar to the case of FIG. 4A, and FIG.
The black level adjustment range connects the input shaft b and the output shaft b. Further, FIG. 4B shows that there are m types of conversion characteristics for increasing the input level for output, and n types of conversion characteristics for decreasing the input level for output.

FIG. 4B is an example. In addition to this, a plurality of types of adjustment ranges having different ratios are set, and these adjustment ranges are associated with the range setting control signal S11 and the memory section is set.
It is stored in 11a in advance. In addition to this, FIG. 4 shows that a plurality of types of input / output conversion characteristics associated with the characteristic setting control signal S12 are stored in the memory section 11a.
It is similar to the case of (A). The subsequent operation is basically the same as in the case of FIG. 3 (A), and the control signals S11, S
When there are 12 inputs, the control unit 11b sends the control signal S11,
The input / output conversion characteristic in the range corresponding to S12 is read from the memory unit 11a, the input video signal (R signal in the figure) is level-converted by the conversion unit 11c according to the conversion characteristic, and output. As described above, the black level can be adjusted within the set range without affecting the white level. The same operation is performed for the other black level adjusting units 12 and 13. Further, in FIGS. 4A and 4B, the input / output conversion characteristics are drawn as linear (linear) characteristics for proportional conversion, but in addition to this, non-linear (non-linear) characteristics may be used, or both may be used. The conversion characteristics may be combined appropriately.

[0018]

As described above, according to the present invention, it is possible to adjust the black side level without affecting the white side level, and the black level adjustment becomes easier than ever. Further, since the white side level is not affected, the problem that the white peak is crushed by the black level adjustment does not occur even when the dynamic range of the device used for digital image processing such as PDP is narrow. Further, since the black level adjusting unit is provided before the gamma correction and the white balance correction processing, proper gamma correction and white balance correction processing can be performed without being affected by the black level adjustment.

[Brief description of drawings]

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

FIG. 2 is a block diagram of essential parts showing another embodiment of the video signal processing device according to the present invention.

3A and 3B are block diagrams of a main part showing an embodiment of a black level adjusting unit, FIG. 3A corresponds to FIG. 1, and FIG.
It corresponds to.

FIG. 4 is an example of a video signal input / output conversion characteristic diagram for explaining the black level adjustment unit of FIG. 1 or FIG. 2 respectively.

[Explanation of symbols]

1, 2, 3, 11, 12, 13 Black level adjuster 4, 5, 6 gamma correction section 7, 8, 9 White balance correction section 1a, 11a Memory section 1b, 11b Control unit 1c, 11c converter S1, S11, S12 control signals

Claims (8)

[Claims] 1. A black level adjusting unit for varying the level of an input video signal only for a video signal in a range set as a black side level, and outputting a white level outside the set range as unchanged. A video signal processing device characterized by the following. 2. The video signal processing device according to claim 1, wherein the set range in the black level adjusting unit is a range of a black side level of about 25% or less with respect to 100% white of the video signal. . 3. The setting of the range of the variable black side level in the black level adjusting unit is arbitrary from a plurality of ranges set in a range of the black side level of about 25% or less with respect to 100% white of a video signal. 2. The video signal processing apparatus according to claim 1, wherein the video signal processing apparatus can be selected and set. 4. The black level adjusting unit is configured to selectively set a plurality of types of input / output conversion characteristics, which are provided in advance, by a control signal.
The video signal processing device according to any one of claims. 5. The LUT (Look Up Table) in which the black level adjusting unit stores a plurality of types of input / output conversion characteristics in advance.
5. The video signal processing device according to claim 4, comprising: 6. The video signal processing apparatus according to claim 1, wherein the black level adjusting unit is provided in a stage before gamma correction or white balance correction. 7. The video signal processing device according to claim 4, wherein each of the plurality of types of input / output conversion characteristics is a linear characteristic. 8. The video signal processing apparatus according to claim 4, wherein the plurality of types of input / output conversion characteristics are non-linear characteristics or a combination of linear characteristics and non-linear characteristics.