JP4829905B2 - Display device and method for adjusting optical gradation characteristics - Google Patents

Description

  The present invention relates to a display device and a method for adjusting an optical gradation characteristic, and more particularly to a technique that enables an optical gradation characteristic (gamma characteristic) of an image displayed on a display device to be adjusted by a user operation.

For example, in a display device using a liquid crystal panel such as a liquid crystal television as a display means, gamma correction is performed on input digital image data in order to display an image more naturally or in a quality according to user preference. A gamma correction circuit for performing the above is provided.
In an example of the gamma correction circuit used in such a display device, for example, appropriate conversion data set in accordance with the gamma characteristics of a liquid crystal panel or the like used is converted into a lookup table (LUT) set in a ROM or the like. ) In advance. The gamma correction circuit performs gamma correction by reading conversion data corresponding to the gradation value of the input digital image data from the LUT.

For example, Patent Document 1 discloses an adjustment device for adjusting a gamma curve used in a gamma correction circuit that performs gamma correction. Here, by setting multiple adjustment points on the gamma curve and setting the difference in the input tone values of adjacent adjustment points to be different on the gamma curve, the gamma curve can be adjusted finely and in a short time. A part that can be adjusted with is created.
Japanese Patent Laid-Open No. 8-51557

  As described above, in the configuration in which the gradation value of the input video signal is converted and output using the LUT, an LUT having predetermined conversion data is set in advance in a nonvolatile memory such as a ROM when the display device is manufactured. Gamma correction is performed using conversion data set in the LUT. In other words, the software sets the optical gradation characteristics (gamma characteristics) of the liquid crystal panel or the like by processing the conversion data stored in the LUT.

  However, the display means such as a liquid crystal panel has variations due to the characteristics of the hardware, and the gradation of the output video signal also occurs in the gamma characteristics. For example, due to hardware variations, the black side (low gradation side) gradation of the output video signal sinks (that is, the gradation value of the output video signal becomes relatively low), and black There is a problem in that the gradation on the side cannot be expressed and appears to be crushed.

  In order to deal with such problems, conventionally, for example, a plurality of LUTs having different conversion data are prepared in advance, and an arbitrary LUT can be selected and used. However, even in a configuration in which an LUT that is actually used for gamma adjustment is selected from a plurality of LUTs prepared in advance, it is necessary to select an LUT having limited characteristics, and an output video signal having a desired quality is always selected. There was a case that could not be obtained.

  For example, in the case where the black side gradation in the output video signal sinks as described above and the black image is crushed, in order to solve this, the brightness of the output video signal with respect to the input video signal Therefore, the LUT that increases the output value is selected. However, in this case, although the black side gradation is crushed in the initial output video signal, for example, the video output signal does not sink on the white side, and the level of the maximum gradation value is reached in a constant gradation region on the white side. If the LUT is selected and the luminance level of the entire output video signal is increased, the video quality is improved on the black side, but white perception becomes more noticeable on the white side. There may be a problem that the video quality on the side deteriorates.

  In order to solve the above problem, it is necessary to prepare an LUT so as to raise only the luminance level of the output video signal on the black side. In order to meet the demand for changing only a part of the gamma characteristic in this way, it is necessary to have a large number of complicated pattern LUTs. For this purpose, a large amount of memory resources is required, and the presence of many patterns of LUTs causes the problem of user confusion.

  On the other hand, in the technique of Patent Document 1, the user can adjust the gamma curve by allowing the output gradation value to be increased or decreased at a plurality of adjustment points on the gamma curve. However, in Patent Document 1, the position and number of adjustment points cannot be arbitrarily set by the user, and it is necessary to adjust the gamma curve according to predetermined adjustment points. The degree of freedom is not sufficient, and a desired gamma curve cannot always be set.

  The present invention has been made in view of the above-described circumstances. By allowing the gamma curve to be arbitrarily changed in an arbitrary gradation range, it is possible to easily execute video expression using a freely set gamma curve. It is an object of the present invention to provide a display device and a method for setting optical gradation characteristics.

  In order to solve the above-described problems, a first technical means of the present invention is a display device including a gamma correction unit that converts a gradation value of an input video signal so as to obtain a predetermined gamma curve. A display means for displaying a predetermined gamma curve, an operation input means for accepting an operation for changing the gamma curve displayed on the display means, and a gamma adjustment means for adjusting the gamma curve. According to the operation input to the input means, the maximum point that takes the maximum input tone value of the adjustment range on the gamma curve, the minimum point that takes the minimum input tone value of the adjustment range, and the input level between the maximum point and the minimum point The gamma curve is adjusted by setting the adjustment point in the tone value and changing the output tone value of the adjustment point according to the operation input to the operation input means.

  According to a second technical means, in the first technical means, the gamma adjustment means can freely set the input gradation values of the maximum point, the minimum point, and the adjustment point according to the operation input to the operation input means. It is a feature.

  The third technical means is characterized in that, in the second technical means, the gamma adjusting means recalculates the gamma curve by performing curve interpolation on the set maximum point, minimum point, and adjustment point.

  According to a fourth technical means, in the second or third technical means, a plurality of adjustment points can be set between the maximum point and the minimum point on the gamma curve, and each of the plurality of adjustment points is set. On the other hand, the output gradation value can be changed.

  A fifth technical means is a method for adjusting optical gradation characteristics in a display device including a gamma correction unit that converts and outputs a gradation value of an input video signal so that a predetermined gamma curve is obtained. The step of displaying the gamma curve of the image, the step of setting the maximum point for obtaining the maximum input gradation value of the adjustment range on the gamma curve, the step of setting the minimum point for obtaining the minimum input gradation value of the adjustment range, and the maximum and minimum points And a step of setting an adjustment point for an input gradation value between and a step of adjusting a gamma curve by changing an output gradation value of the adjustment point.

  According to the present invention, it is possible to easily change the gamma curve in an arbitrary gradation range, thereby easily performing image expression using a freely set gamma curve, and optical gradation characteristics. A setting method can be provided.

FIG. 1 is a block diagram for explaining a configuration example of an embodiment of a display device according to the present invention, and shows an example in which the display device of the present invention is applied to a liquid crystal television.
The AV selector 13 of the display device 1 receives a broadcast video signal received by the antenna 10 and selected and demodulated by the tuner unit 11 or an external input signal from an external device or the like to the external input terminal 12. The output signal is selected by.
The separation unit 14 separates the signal output from the AV selector 13 into a video signal, a data signal, an audio signal, and the like. The decoder unit 15 performs a decoding process on the separated signal. The data signal includes EPG (electronic program guide) program information, a code signal for OSD (on screen display) display, and the like.

The audio signal decoded by the decoder unit 15 is subjected to audio processing by the audio processing unit 16 and output from the speaker 17 as audio.
The video signal and data signal decoded by the decoder unit 15 are input to the video processor 18. The video processor 18 includes a video signal processing unit 181 and a gamma correction unit 182. The video signal processing unit 181 executes ADC (A / D conversion processing), YC separation processing, IP conversion processing, matrix conversion processing, or other video processing as necessary, and outputs RGB signals.

  The gamma correction unit 182 receives the RGB signal of the video output from the video signal processing unit 181 and executes gamma adjustment processing. The non-volatile memory 19 stores and holds an LUT having conversion data for performing gamma correction. The conversion data of the LUT held in the nonvolatile memory 19 is output by converting the gradation value of the input video signal so that a gamma correction process in the gamma correction unit 182 of the video processor 18, that is, a predetermined gamma curve is obtained. Used for processing.

  Further, the display device 1 has a function of changing the above gamma curve by a user operation. Here, the user makes adjustments by arbitrarily changing the gamma curve of the LUT using an operation input means such as a remote controller (not shown) while checking the adjustment UI (user interface) displayed on the liquid crystal module 20 of the display device 1. It can be performed. When the gamma curve is changed, new conversion data for obtaining the gamma curve is stored in the LUT, and the gamma correction unit 182 uses the new conversion data to convert the gradation value of the input video signal. Do. Further, a gamma curve based on the conversion data stored in the LUT can be further called to adjust the gamma curve. Furthermore, the original conversion data of the LUT is held so that it can be restored to the original conversion data of the LUT according to a predetermined user operation (for example, operation of a reset button, etc.). A specific method for adjusting the gamma curve will be described later.

  The display device 1 includes a liquid crystal module 20 as display means. The liquid crystal module 20 includes a display device using a liquid crystal panel and a backlight. The liquid crystal panel displays an image by driving the liquid crystal according to the image signal output from the gamma correction unit 182. The backlight includes a drive circuit and a light emitter, and the light emitter is driven by the drive circuit. As the illuminant, a general fluorescent tube (CCFL) or LED, or a hybrid type using both the fluorescent tube and the LED is applied.

  In the above configuration, the operation input means for accepting an operation for changing the displayed gamma curve recognizes and processes an operation input button provided on a remote controller or a display device (not shown) and an operation signal generated by the operation input. This is realized by a microcomputer (not shown) that performs the above. A gamma adjustment unit that calculates a gamma curve in accordance with an operation input for changing the gamma curve is also realized by a control unit such as a microcomputer (not shown).

  FIG. 2 is a diagram for explaining an example of gamma curve adjustment that can be executed by the display device according to the present invention. When the user adjusts the gamma curve, the gamma curve based on the LUT conversion data stored in the non-volatile memory 19 is displayed on the liquid crystal module, and the gamma curve can be arbitrarily selected using operation input means such as a remote controller. Adjustments can be made. Then, conversion data corresponding to the adjusted gamma curve is stored in the LUT.

  Here, first, the user uses an operation input means such as a remote controller to call a predetermined adjustment UI (user interface) screen to display an adjustment gamma curve as shown in FIG. When a remote controller is used as an operation input means for calling and adjusting a gamma curve and storing the adjusted gamma curve, for example, a pointer movement or a determination operation using a cross key or a determination key provided in the remote control is used.

Here, the user sets an arbitrary minimum point (Min) 101 and maximum point (Max) 102 on the displayed gamma curve. The minimum point 101 and the maximum point 102 define a range for adjusting the gamma curve. The minimum point 101 takes the minimum input tone value of the adjustment range, and the maximum point 102 takes the maximum input tone value of the adjustment range. . Thereby, it is possible to arbitrarily set the input gradation range that the user wants to adjust.
After setting the arbitrary minimum point 101 and the maximum point 102, the user sets an arbitrary adjustment point 103 on the gamma curve within the adjustment range from the minimum point 101 to the maximum point 102. The adjustment point 103 is set as a point for changing the output gradation value for the input gradation value. In the present embodiment, the input gradation value for setting the minimum point 101, the adjustment point 103, and the maximum point 102 can be freely set according to a user operation.

  Then, the user raises or lowers the output gradation value of the adjustment point 103 using an operation input unit such as a remote controller, and generates an arbitrary gamma curve. For example, the adjustment point 103 ′ is set by raising the output gradation value of the adjustment point 103. Or similarly, the adjustment point 103 ″ can be set by lowering the output gradation value of the adjustment point 103. At this time, the display device 1 raises or lowers the output gradation value of the adjustment point 103 according to the user operation, and at the same time, the minimum point 101, the adjustment point 103 (103 ′, 103 ″), and the maximum point 102. Interpolate the curve to generate a smooth curve. The interpolation theory used for the three-point curve interpolation is not limited to a specific interpolation theory, and a known interpolation theory can be appropriately applied.

The converted data corresponding to the gamma curve is stored in the LUT of the nonvolatile memory 19 and displayed in the generated gamma curve. Then, the gradation of the input video signal is converted and output using the stored conversion data and reflected on the display screen.
In this case, for example, when an image of a received broadcast program or an image input from an external device is displayed on the display device, the adjustment UI screen is displayed by the OSD, and the adjustment result of the gamma curve is displayed on the display screen. Reflect it. As a result, the user can confirm the adjustment result of the gamma curve based on the video being viewed.

  FIG. 3 is a diagram for explaining another adjustment example of the gamma curve that can be executed by the display device according to the present invention. In the adjustment example of FIG. 2 described above, one adjustment point 103 is set in accordance with a user operation, and the output tone value of the adjustment point 103 is raised or lowered to adjust the gamma curve. On the other hand, in the present example, a plurality of adjustment points 103 are set, and an output gamma value is raised or lowered for each adjustment point 103 so that an arbitrary gamma curve can be generated by the user.

For example, in the example of FIG. 3, the gamma curve is adjusted by setting two arbitrary adjustment points 103 within the adjustment range between the arbitrary minimum point 101 and the maximum point 102. Here, as in the example of FIG. 2, the user first sets a minimum point (Min) 101 and a maximum point (Max) 102 that define an adjustment range, and then sets two adjustment points 103 within the adjustment range. At each adjustment point 103, the output tone value is raised or lowered to set an arbitrary output tone value. On the other hand, in the display device 1, the minimum point 101, the maximum point 102, and the two adjustment points 103 (103 ′, 103 ″) are subjected to curve interpolation, and the obtained gamma curve is reflected on the display screen to the user. Let me check.
In this example, two adjustment points 103 are set to adjust the gamma curve, but three or more adjustment points may be set.

FIG. 4 is a diagram illustrating an example of a user interface screen for adjusting the gamma curve. The display device 1 can display a video adjustment setting screen 100 as shown in FIG. 4 as a user interface screen according to the menu selection by the user.
Here, when “gamma adjustment” 111 is selected from the selection items 110 displayed on the setting screen 100 by a user operation, an arbitrary point selection screen 120 is displayed. The arbitrary point selection screen 120 displays an adjustment point selection menu 121 including items for selecting movement of an adjustment range (minimum point, maximum point), addition and movement of an adjustment point, and a currently used gamma curve 122. Is done.

Then, the user performs adjustment point setting processing using operation input means such as a remote controller. For example, when “adjustment range Min point movement” 131 is selected, movement adjustment of the minimum point (Min) 101 on the gamma curve 122 becomes possible. The user can move the position of the minimum point 101 to an arbitrary position on the gamma curve by operating a cross key or the like on the remote controller.
Similarly, when the user selects “adjustment range Max point shift” 132, the maximum point (Max) 102 can be moved to an arbitrary position on the gamma curve 122.

When “add new adjustment point” 133 is selected, a new adjustment point can be added in addition to the adjustment point 103 currently set. In the example of FIG. 4, one adjustment point 103 is set, but one additional adjustment point can be added by selecting “add new adjustment point” 133. If the same operation is repeated, a plurality of adjustment points can be added.
Also, by selecting “Move Adjustment Point” 134, the position of the currently set adjustment point 103 on the gamma curve can be moved. When a plurality of adjustment points 103 are set, the position of each adjustment point 103 on the gamma curve can be moved.

  When “selection complete” 134 is selected, the setting of the adjustment range and the adjustment point is completed, and the screen shifts to an adjustment screen shown in FIG. In addition, by selecting “reset” 136, it is possible to reset the conversion data of the gamma curve changed by the user and return to the conversion data of the gamma curve held by the display device 1 as an initial value.

  FIG. 5 is a diagram showing another example of a user interface screen for adjusting the gamma curve. When the selection of the adjustment point is completed on the screen of FIG. 4, an adjustment screen 140 as shown in FIG. 5 is displayed. On the adjustment screen 140, an adjustment menu 151 including an item for adjusting the output gradation value of the adjustment point is displayed, and the gamma curve 122 is also displayed at the same time. Here, the user can arbitrarily move the output gradation value of the adjustment point 103 set on the gamma curve 122 in the vertical direction by selecting “Adjustment” 161.

  Then, the display device 1 interpolates the minimum point (Min) 101, the adjustment point 103, and the maximum point (Max) 102 in accordance with the adjustment of the adjustment point 103 by the user, and displays the obtained gamma curve. When the user selects “Adjustment Complete” 162, the display device 1 stores conversion data corresponding to the adjusted gamma curve in the LUT, and uses the conversion data of the LUT for subsequent video adjustments. Here, as described above, the setting screen 100 and the adjustment screen 140 are OSD-displayed with respect to the normal display screen, and the gamma curve after the adjustment is reflected and displayed, so that the user confirms the adjustment result on the screen. be able to.

FIG. 6 is a flowchart for explaining an embodiment of an optical gradation characteristic adjusting method according to the present invention. Here, an example of the processing will be described using the display device 1 of FIG. 1 as an example. First, in the display device 1, when gamma adjustment is selected by a user operation (step S1-YES), an arbitrary point adjustment screen as shown in FIG. 4 is displayed (step S2).
When the user's operation of selecting arbitrary points (maximum point, minimum point, adjustment point) on the arbitrary point adjustment screen is completed (step S3-YES), an adjustment screen as shown in FIG. 5 is displayed (step S4). ). The gamma curve for adjustment is displayed on the adjustment screen.

  If the output gradation value of an arbitrary adjustment point is changed on the adjustment screen (step S5-YES), the display device 1 calculates curve interpolation between arbitrary points (step S6). Here, curve interpolation is performed for the set minimum point, maximum point, and adjustment point, and the gamma curve is recalculated. When the end of the arbitrary point adjustment work is instructed by the user operation (step S7—YES), the process is ended, and the conversion data corresponding to the adjusted gamma curve is stored in the nonvolatile memory as the conversion data used for the gradation value conversion. Remember. If the arbitrary point adjustment operation has not been completed, and if the adjustment point has not been changed in step S5, the adjustment screen display in step S4 is maintained.

  Through the processing as described above, the user can further arbitrarily adjust a preset gamma curve. In this case, the output gradation value of the user arbitrary adjustment point can be set for the user arbitrary gradation range, and the user desired gamma curve can be easily set.

It is a block diagram for demonstrating the structural example of one Embodiment of the display apparatus which concerns on this invention. It is a figure for demonstrating the adjustment example of the gamma curve which can be performed by the display apparatus which concerns on this invention. It is a figure for demonstrating the other adjustment example of the gamma curve which can be performed by the display apparatus which concerns on this invention. It is a figure which shows an example of the user interface screen for adjusting a gamma curve. It is a figure which shows the other example of the user interface screen for adjusting a gamma curve. It is a flowchart for demonstrating embodiment of the adjustment method of the optical gradation characteristic which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 10 ... Antenna, 11 ... Tuner part, 12 ... External input terminal, 13 ... AV selector, 14 ... Separation part, 15 ... Decoder part, 16 ... Sound processing part, 17 ... Speaker, 18 ... Video processor, DESCRIPTION OF SYMBOLS 19 ... Nonvolatile memory, 20 ... Liquid crystal module, 100 ... Setting screen, 101 ... Minimum point, 102 ... Maximum point, 103 ... Adjustment point, 110 ... Selection item, 120 ... Arbitrary point selection screen, 121 ... Adjustment point selection menu, 122: Gamma curve, 140: Adjustment screen, 151: Adjustment menu, 181: Video signal processing unit, 182: Gamma correction unit.

Claims (5)

A display device including a gamma correction unit that converts and outputs a gradation value of an input video signal so as to obtain a predetermined gamma curve,
Display means for displaying the predetermined gamma curve;
An operation input means for accepting an operation for changing the gamma curve displayed on the display means;
Gamma adjustment means for adjusting the gamma curve,
The gamma adjustment means, according to an operation input to the operation input means, a maximum point that takes the maximum input gradation value of the adjustment range on the gamma curve, a minimum point that takes the minimum input gradation value of the adjustment range, Set the adjustment point for the input tone value between the maximum and minimum points,
A display device, wherein the gamma curve is adjusted by changing an output gradation value of the adjustment point according to an operation input to the operation input means.   The display device according to claim 1, wherein the gamma adjustment unit can freely set input gradation values of the maximum point, the minimum point, and the adjustment point according to an operation input to the operation input unit. A display device.   3. The display device according to claim 2, wherein the gamma adjustment unit recalculates the gamma curve by performing curve interpolation on the set maximum point, the minimum point, and the adjustment point.   4. The display device according to claim 2, wherein a plurality of adjustment points can be set between the maximum point and the minimum point on the gamma curve, and each of the plurality of adjustment points set is set. A display device characterized in that the output gradation value can be changed for a point. A method for adjusting optical gradation characteristics in a display device including a gamma correction unit that converts and outputs a gradation value of an input video signal so as to obtain a predetermined gamma curve,
Displaying the predetermined gamma curve;
Setting a maximum point that takes the maximum input tone value of the adjustment range on the gamma curve and a minimum point that takes the minimum input tone value of the adjustment range;
Setting an adjustment point in an input gradation value between the maximum point and the minimum point;
Adjusting the gamma curve by changing the output tone value of the adjustment point.

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