JP2010066605A - Image display device and image quality adjustment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device and an image quality adjustment method to display optimal image quality at a user's view angle, taking into consideration the display property of a display and the visual perception properties and visual sensitivity of the user. <P>SOLUTION: The image display device includes a display means on which an image is displayed; a position specifying means 101 which specifies the position of a user 1102 as positional information; a correction table 107 for associating the reference characteristics 106 with a plurality of correction values, corresponding to a plurality of places of the reference properties 106 and the positional information of the user; a post-correction properties calculating part 102 which acquires the plurality of correction values from the correction table 107, based on the positional information of the user specified by the position specifying means 101, corrects the reference characteristics 106 and calculates post-correction property 109; and a display control part 103 which makes the display means 104 display an image, based on the post-correction property 109, calculated by the post-correction properties calculating part 102. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image display apparatus and image quality adjustment method for automatically adjusting display brightness.

  An image display device such as a television receiver has an image quality adjustment parameter that affects the image quality such as brightness and contrast, and an adjustment function that adjusts the image quality displayed based on the parameter. In many image display apparatuses, several image quality adjustment parameters can be changed so that a user can view a desired image.

  On the other hand, when the viewing angle that indicates the angle at which the user views with respect to the surface on which the image of the image display device is displayed changes, the user views before and after the change in viewing angle. You may feel that the image quality of the images to be played is different.

  When it is desired to keep the image quality of the image to be viewed constant, the user may have to adjust the image quality by changing the parameters open to the user each time the viewing angle is changed.

  For example, as an image display device whose image quality changes with viewing angle, an IPS (In Plain Switching) liquid crystal display, a plasma display, a flat panel display such as an organic EL display can be exemplified. As described above, depending on the display method employed in the image display device, as the viewing angle becomes larger than in the case of viewing from the front (viewing angle 0 °), the luminance is lowered as compared with the conventional image display device. There is something that happens prominently. In addition, in the case where an image with a human image that does not differ much in brightness from the background is displayed on an image display device that has a large decrease in luminance due to an increase in viewing angle, the user views the image at a large viewing angle. Then, in particular, the background and the object are assimilated and are difficult to distinguish, and it is difficult to recognize the image.

  FIG. 12 is a graph showing the relationship between the viewing angle of the flat panel display and the overall luminance.

  From the figure, IPS (In Plain Switching) liquid crystal display (IPS), organic EL display (OLED), and plasma display (PDP) are all different in brightness, but the brightness decreases as the viewing angle increases. Is happening.

  FIG. 13 is a diagram conceptually showing a difference in image recognition state due to a difference in viewing angle.

  As shown in the figure, when a user 1102 views an image 1101 with a small luminance difference from the front (FIG. 11A), even if the user 1102 can recognize the contents of the image 1101, When the person 1102 looks at the image display apparatus 100 and looks from an oblique direction (a state where the viewing angle is large) (FIG. 5B), the user 1102 becomes difficult to recognize the contents of the image 1101. This is considered to be due to the fact that the luminance decreases as the viewing angle increases, so that the luminance difference between the object and the background or the object becomes small, making discrimination difficult.

Conventionally, as a means for adjusting the image quality of an image displayed by the image display device in accordance with the viewing angle of the user, a method of determining a voltage to be applied to the liquid crystal panel based on the viewing angle of the viewer has been proposed. Yes. (For example, refer to Patent Document 1). In some cases, following the movement of the user, new brightness and contrast values are calculated based on the brightness and contrast base values and correction values in the table held in the set value storage means ( For example, see Patent Document 2).
JP 11-298828 A JP 2006-267323 A

  However, when the brightness of the entire image display apparatus is changed according to the conventional viewing angle, the brightness difference between the images is the same. Therefore, when the viewing angle is increased, the brightness difference is reduced, and the user eventually has an image. It becomes difficult to recognize. Further, when the overall contrast of the image is changed, the luminance difference between the images increases, so that the image can be easily recognized, but the user feels uncomfortable.

  As a result of research and experiments, the present inventors have found that there is a need for specific image quality improvement means that takes into account changes in display characteristics depending on viewing angles and the visual characteristics and senses of users. Furthermore, the user of the image display device has also found that the difference in the impression of the image depending on the viewing angle varies depending on the type of image to be displayed.

  The present invention has been made on the basis of such knowledge, and can display the optimum image quality to the user according to the viewing angle in consideration of the display characteristics of the display and the visual characteristics and feeling of the user. An object of the present invention is to provide a possible image display device and image quality adjustment method.

  In order to solve the above-described problems, an image display device according to the present invention includes a display unit that displays an image, a position specifying unit that specifies a user's position with respect to the display unit as position information, and an input luminance signal. And a reference characteristic which is one of luminance input / output characteristics indicating the relationship between the display unit and the luminance value displayed on the display means, and a plurality of correction values for correcting the reference characteristic and user position information are associated with each other. Based on the position information of the user specified by the position specifying means and the storage means for storing the correction table, a plurality of correction values are acquired from the correction table, the reference characteristics are corrected, and the corrected characteristics And a display control unit that causes the display unit to display an image based on the corrected characteristic calculated by the corrected characteristic calculation unit.

  With this configuration, it is possible to automatically perform optimum image quality adjustment for the user according to the viewing angle of the user.

  Further, it is preferable that one of the correction values included in the correction table is a correction value for correcting the luminance input / output characteristics corresponding to the dark part.

  Accordingly, it is possible to perform image quality adjustment that makes it difficult for the user to feel uncomfortable in consideration of the user's senses and visual characteristics.

  Furthermore, when the luminance of the entire display unit that can be observed from the front of the display unit when a predetermined image is displayed on the display unit is set as the reference luminance, the user is located at a position where a luminance decrease of 30% or more from the reference luminance occurs. The display control unit may display an image based on the corrected characteristic when it is determined that the position determination unit is positioned.

  With this configuration, it is possible to avoid unnecessary image quality adjustment in consideration of the user's senses and visual characteristics.

  Further, the image processing apparatus includes a feature specifying unit that specifies a feature of an input image, and a table selection unit that selects one from different correction tables based on the feature of the image specified by the feature specifying unit, It is preferable that the calculation unit calculates the corrected characteristics using the selected correction table.

  With this configuration, it is possible to perform image quality adjustment that makes it difficult for the user to feel uncomfortable in consideration of the characteristics of the displayed image.

  In order to solve the above-described problem, an image quality adjustment method according to the present invention is an image quality adjustment method for an image display apparatus having a display means for displaying an image, and specifies the position of a user with respect to the display means as position information. Based on the position specifying step and the position information of the user specified by the position specifying step, a plurality of correction values are acquired from a correction table held in the image display device, and a reference characteristic held in the image display device And a post-correction characteristic calculation step for calculating the corrected characteristic and a display control step for causing the display means to display an image based on the post-correction characteristic calculated in the post-correction characteristic calculation step. And

  Furthermore, a feature specifying step for specifying the feature of the input image and a table selecting step for selecting one from different correction tables based on the feature of the image specified by the feature specifying step may be included.

The effect by this structure is the same as that of the said image display apparatus.
The present invention includes a program for realizing the above steps by a computer, and also includes a recording medium on which the program is recorded. The present invention also includes an integrated circuit capable of realizing the above steps by signal processing.

  According to the image display device and the image quality adjustment method of the present invention, it is possible to always provide an image with a good image quality at a position where a user exists.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an image display apparatus according to an embodiment of the present invention.

  As shown in the figure, the image display apparatus 100 may display an image based on a signal input from the outside, or may display a moving image (video) by displaying a plurality of images continuously. The display device 104 includes a display unit 104, a position specifying unit 101, a corrected characteristic calculation unit 102, a display control unit 103, a storage unit 105, and a remote operation unit 108.

  The display means 104 is a device that displays an image. The display unit 104 has pixels arranged in a matrix, and allows the user to recognize the image by controlling the color and brightness output to each pixel. .

  The remote operation means 108 is a device for remotely controlling each function of the image display device 100, and is a small portable device called a so-called remote controller. For example, the remote control unit 108 can turn on / off the power of the image display apparatus 100 and move the cursor displayed on the display unit 104.

  The position specifying means 101 is an apparatus that can specify the position of the user with respect to the display means 104 as position information. In the present embodiment, the user display means 104 is operated by the user's operation of the remote operation means 108. The position information can be specified by detecting the position with respect to.

  In addition to the above, the position specifying unit 101 may be an apparatus using position detection by an interpersonal position detection infrared sensor or an apparatus that acquires position information input by a user.

  FIG. 2 is a diagram schematically showing a specific state of the position information when the user operates the remote control means.

  The method for the position specifying means 101 to specify the position information of the user 1102 using the remote operation means 108 is as shown in FIG. That is, in the case of the present embodiment, the position specifying unit 101 specifies the viewing angle θ as position information. The position specifying means 101 includes a first distance specifying means 121 at the center in the width direction, which is a frame of the image display device 100. When the user 1102 operates the remote operation unit 108, the position specifying unit 101 specifies the distance L (first distance) between the remote operation unit 108 and the first distance specifying unit 121. The distance L is regarded as a distance between the user 1102 and the first distance specifying unit 121.

  The position specifying unit 101 includes a second distance specifying unit 122. When the user 1102 operates the remote operation means 108, the position specifying means 101 causes the second distance specifying means 122 to drop the perpendicular foot and the first distance specifying means on the display surface of the display means 104 from the remote operation means 108. A distance W (second distance) from 121 is specified.

  The viewing angle θ is an angle formed by a line of sight when the user looks at the center of the display unit 104 and a plane perpendicular to the display surface of the display unit 104. Therefore, when the user 1102 is located in front of the display unit 104, the viewing angle θ as position information is 0 °. Further, the viewing angle θ is 90 degrees at the maximum on one side (maximum of 180 degrees on both sides).

  A specific method for specifying the first distance and the second distance is as follows. The remote operation means 108 includes infrared light emitting means used for normal viewing operations (volume adjustment, channel change, etc.) of the image display device 100. Further, the remote control means 108 includes a distance measurement signal transmission means capable of transmitting a signal simultaneously with the first infrared light emitting means. The ranging signal transmission means may be a signal that transmits infrared light of a different type from the infrared light transmitted by the infrared light emitting means, such as those that transmit ultrasonic waves, those that transmit high frequencies, etc. It is a device that can send signals for distance measurement by radio. The first distance specifying means 121 receives the infrared light transmitted by the infrared light emitting means and the signal transmitted by the ranging signal transmitting means, and specifies the first distance between the infrared light and the ranging signal. The distance L between the user 1102 and the display means 104 (image display device 100) is specified from the arrival time difference to the means 121.

  The second distance specifying unit 122 includes an element for receiving infrared light arranged in a straight line over the entire width of the image display device 100, and has a strong reception directivity in a direction perpendicular to the display unit 104. I have. Then, when any one of the elements receives the infrared light transmitted from the remote control means 108, it is possible to substantially specify W as the second distance.

  The position specifying unit 101 derives the viewing angle θ of the user 1102 from the following formula (1) based on the specified distance L and distance W.

  θ = sin-1 (W / L) (1)

  The position information of the user 1102 specified by the position specifying unit 101 is sent to the corrected characteristic calculation unit 102.

  The storage unit 105 is a device that stores information such as the reference characteristics 106 and the correction table 107, and is, for example, a hard disk, RAM, ROM, or the like.

  The corrected characteristic calculation unit 102 acquires a plurality of correction values by referring to the correction table held in the storage unit 105 based on the position information of the user 1102 specified by the position specifying unit 101, and stores the storage unit A processing unit that corrects the reference characteristic held in 105 using the correction value and calculates a corrected characteristic.

  The display control unit 103 processes the input image signal based on the corrected characteristics calculated by the corrected characteristic calculation unit 102 and displays an image suitable for the characteristics of the display unit 104 and the position of the user 1102. It is a processing part for displaying.

  Next, a method for adjusting the image quality so as to obtain an image suitable for the position of the user 1102 using the image display device 100 according to the present embodiment will be described.

  FIG. 3 is a flowchart for explaining the operation of determining the optimum corrected characteristic of the image display apparatus.

  The position specifying means 101 specifies position information (viewing angle θ) at the timing when the user 1102 operates the remote control means 108 (S31: position specifying step).

  Next, the corrected characteristic calculation unit 102 acquires position information from the position specifying unit 101, and whether the position information is different from the previously acquired position information, that is, the viewing position of the user 1102 is the previous remote operation unit 108. It is determined whether or not the operation time is different (S32). When the position information is different (S32: YES), the correction table 107 is acquired from the storage unit 105, and a correction value suitable for the viewing angle θ is acquired from the correction table 107 based on the latest position information (S33: correction value). Acquisition step).

FIG. 4 is a graph showing luminance input / output characteristics.
The graph shown in the figure shows what value of luminance value is output (displayed) for a luminance signal input as one of image signals (hereinafter referred to as “input luminance signal”) (hereinafter referred to as “output luminance value”). It is a graph showing the relationship. In the figure, a dotted line indicates a reference characteristic 106 which is a reference luminance input / output characteristic. A solid line indicates a corrected characteristic 109 which is a luminance input / output characteristic calculated by the corrected characteristic calculation unit 102.

  As shown in the figure, the luminance input / output characteristic is a simple increase graph determined by the characteristic of the display means 104, the position of the user 1102, etc. For example, when the reference characteristic 106 is employed, the input luminance signal is A. In this case, the output luminance value is A ′.

  In the present embodiment, the reference characteristic 106 indicates the relationship between the output luminance value and the input luminance signal when the user 1102 views an image from the front of the display unit 104, that is, when the viewing angle θ is 0 °. It is a thing.

FIG. 5 is a diagram conceptually showing the correction table held in the storage means.
As shown in the figure, in the correction table 107, the position information (viewing angle θ) of the user 1102 is held in a plurality of stages, and two correction values are stored in each stage of the viewing angle θ. It is associated. The correction value stored in association with the A column is changed from the output luminance value A ′ obtained from the reference characteristic 106 to the output luminance value A ″ when the input luminance signal is A shown in the graph of FIG. This is a value for changing the luminance input / output characteristics. The correction value stored in association with the B column is a value corresponding to the input luminance signal B.

Returning to FIG.
The corrected characteristic calculation unit 102 corrects the reference characteristic 106 based on the acquired correction value, and calculates a corrected characteristic 109 which is a final luminance input / output characteristic (S34: corrected characteristic calculation step).

  Next, the display control unit 103 uses the previous luminance input / output characteristic when the viewing angle θ is not different (S32: NO), and the corrected characteristic when the viewing angle θ is different (S32: YES). An image is displayed on the display unit 104 using the latest corrected characteristic calculated by the calculation unit 102 (S35: display control step).

Here, a detailed correction method will be described.
The storage means 105 of the image display apparatus 100 covers from the darkest input luminance signal to the brightest input luminance signal, for example, when the luminance signal is digitized, from the input luminance signal (0) to the input luminance signal (255). The entire reference characteristic 106 is stored. On the other hand, there are two correction values acquired by the corrected characteristic calculation unit 102. Therefore, it is necessary to correct a wide range of the reference characteristic 106 using two correction values. The corrected characteristic calculation unit 102 uses a smoothing curve with excellent continuity and approximation such as spline interpolation and Bezier interpolation so as to satisfy the result of correcting the reference characteristic 106 with two correction values, and maintains a simple increase. The corrected characteristic 109 is calculated by performing smoothing as it is.

  If an image is displayed by the above configuration and method, the user 1102 who is viewing the image display device 100 at a predetermined viewing angle can recognize the displayed image satisfactorily without feeling uncomfortable. Become.

  In particular, when there are a plurality of correction values (two in this embodiment), the correction width can be adjusted with different input luminance signals. As a result, a corrected characteristic 109 having a complicated curve different from the reference characteristic 106 can be obtained, and the output luminance can appeal to the sense of the user 1102.

  In particular, it is desirable that at least one of the correction values is a correction value for a dark part. As a result, the user 1102 can recognize the image without any discomfort from any viewing angle.

  In the position information stage in the correction table 107, the viewing angle of the user is divided by 15 degrees, but the present invention is not limited to this. For example, the viewing angle may be finer or coarser. In addition, for example, the angular interval may not be equal, such as setting the angular interval according to the luminance reduction rate for each image display device.

Further, the correction values may be three points or more as shown in FIG.
In order to increase the visibility of an image when the user 1102 at a position where the viewing angle is large looks at the image display apparatus 100, generally, the difference in output luminance value between the dark side and the bright side. May be corrected in the direction of enlarging. In the case of the present invention, for the input luminance signal on the dark side, as shown in FIG. 5, the correction value becomes the same output luminance value as the reference characteristic 106 or the correction value that becomes slightly brighter, and the bright portion For the input luminance signal on the side, the luminance difference can be expanded as a correction value that is significantly brighter than the reference characteristic 106. Further, as shown in FIG. 8, the input luminance signal on the dark side has a correction value that makes the output luminance value darker than the reference characteristic 106, and the input luminance signal on the bright side has the reference characteristic. As a correction value that is brighter than 106, the luminance difference can be enlarged. In any case, it is sufficient that the corrected characteristic 109 simply increases as shown in FIGS.

  Furthermore, the correction value that is the same as the reference characteristic 106, that is, the correction value may be 1.0.

  The dark portion indicates a range from the central value of the luminance signal indicating the darkest state and the brightest luminance signal to the luminance signal indicating the darkest state among the input luminance signals. The dark part side indicates a luminance signal that is darker than the target luminance signal.

(Embodiment 2)
Next, another embodiment according to the present invention will be described.

FIG. 9 is a block diagram showing the configuration of the image display apparatus according to the embodiment of the present invention.
As shown in the figure, the image display device 100 displays an image based on an image signal input from the outside, or displays a moving image (video) by continuously displaying a plurality of images. Display means 104, position specifying means 101, corrected characteristic calculation section 102, display control section 103, storage means 105, feature specifying section 112, table selection section 113, position determination Means (not shown) are provided.

  In the following description, description of components having the same functions and functions as those described in the first embodiment will be omitted.

  The feature specifying unit 112 is a processing unit that can specify the features of a video signal composed of a plurality of image signals sent to the image display apparatus 100. Specifically, a plurality of image signals transmitted sequentially are acquired for a predetermined time, a luminance histogram is created from the acquired image signals, and the plurality of luminance histograms are statistically processed to obtain a luminance histogram as a feature of the video signal The brightness histogram is compared with a plurality of genre brightness histograms stored in advance, and the genre linked to the closest genre brightness histogram is specified as the feature of the video signal. The case can be illustrated. Further, the characteristics of the video signal may be specified based on meta information added to the image signal or the video signal. In addition, the feature specifying unit 112 is designated by the user 1102 operating the image display device 100 and designating a feature from a plurality of types of features displayed on the user 1102 by the image display device 100. May be specified as a feature of the video signal.

  The feature of the image signal specified by the feature specifying unit 112 may be the background of the scene and the average brightness and brightness distribution of the object, or a program genre such as a movie or drama.

  The table selection unit 113 is based on the characteristics of the image specified by the feature specifying unit 112 and the characteristics of a plurality of continuous images (videos), and stores a plurality of correction tables (hereinafter, “ This is a processing unit that selects one correction table 107 from “correction table group 111”.

  The position specifying means 101 according to the second embodiment includes infrared sensors arranged radially, and by specifying an infrared sensor that reacts to infrared rays emitted from the user 1102, the viewing angle θ that is position information is obtained. It is a device that can be identified.

  The position determination means is a position where a luminance drop of 30% or more occurs from the reference brightness when the brightness of the entire display means 104 that can be observed from the front of the display means 104 when a predetermined image is displayed on the display means 104 is used as the reference brightness. It is an apparatus or a processing unit for determining whether or not the user 1102 is located in the area.

  Here, the position where the luminance decrease of 30% or more from the reference luminance may be obtained as follows. That is, an image having the highest luminance of the entire display unit 104 is displayed on the display unit 104, and the luminance value obtained from the luminance measuring device placed in front of the display unit 104 is set as the reference luminance and normalized as 100. With the same image displayed, the viewing angle of the luminance measuring device is gradually shifted, and the luminance value is measured each time. The viewing angle at which the luminance value is 70 or less is a position where the luminance is reduced by 30% or more from the reference luminance. For example, the range of + 35 ° to + 90 ° and the range of −35 ° to −90 ° from the front of the display unit 104 may be positions where the luminance decreases by 30% or more from the reference luminance.

  Specifically, with respect to a range of, for example, + 35 ° to −35 ° from the front of the display unit 104, the infrared sensor included in the position specifying unit 101 may not be disposed, and the position determination unit may be used. When the user 1102 exists in the range of + 35 ° to −35 ° from the front of the display unit 104, the position specifying unit 101 cannot acquire the presence / absence of the user 1102, but this state is determined by the position determination unit. It can be considered that it is determined that the user 1102 is not located at a position where the luminance is reduced by 30% or more from the luminance. In this case, the display control unit 103 causes the display unit 104 to display an image based on the reference characteristic 106.

  Specifically, the position determination unit may be configured by setting the correction value corresponding to the range of + 35 ° to −35 ° in the correction table 107 to 1.0. Also in this case, the display control unit 103 causes the display unit 104 to display an image based on the reference characteristic 106.

  Whether the post-correction characteristic 109 is used or not is determined depending on whether or not it is determined that the luminance is reduced by 30% or more from the reference luminance for the following reason. That is, it is a numerical value based on an experiment for obtaining a viewing angle at which the user notices image quality deterioration. Specifically, users with different ages and genders are extracted randomly. The user views the image while gradually changing the viewing angle from the front of the display unit 104, and obtains the viewing angle that the user feels that the image quality has deteriorated. The acquired viewing angle is statistically processed. This experiment is performed on flat panel displays of different display methods such as an IPS (In Plain Switching) liquid crystal display, a plasma display, and an organic EL display. As a result of the above experiment, the image quality degradation viewing angle of each display almost coincided with the viewing angle at which the luminance was reduced by 30% or more from the reference luminance.

  Therefore, it is preferable to change the image quality of the image displayed on the display unit 104 at a viewing angle at which a luminance reduction of 30% or more from the reference luminance occurs, and a viewing angle at which a luminance reduction of less than 30% from the reference luminance occurs. In this case, it is less likely that the user 1102 feels uncomfortable when the image is displayed with the reference characteristic 106.

Hereinafter, the image quality adjustment method according to the second embodiment will be described.
In the second embodiment, as the display means 104 of the image display apparatus 100, an IPS (In Plain Switching) liquid crystal display, in which the luminance reduction due to the viewing angle is particularly remarkable, is assumed as a result of experiments. .

  FIG. 10 is a flowchart for explaining the operation of determining the optimum corrected characteristic of the image display apparatus. In the figure, the same reference numerals are used for the same steps as those in FIG. 3, and the description thereof may be omitted.

  When the viewing angle θ which is the position information of the user 1102 identified by the position identifying unit 101 is different from the viewing angle θ identified last time (S32: YES), the luminance is reduced by 30% or more from the reference luminance. It is determined whether or not the viewing angle is occurring (S71: position determination step).

  Next, the feature specifying unit 112 specifies the feature of the image based on the input signal (S72: feature specifying step). The table selection unit 113 selects one optimal correction table 107 from the correction table group 111 based on the specified image characteristics (S73: selection step).

  Next, the selected correction table 107 is acquired from the storage unit 105, and a correction value suitable for the viewing angle θ is acquired from the correction table 107 based on the latest position information (S33: correction value acquisition step). The corrected characteristic calculation unit 102 corrects the reference characteristic 106 based on the acquired correction value, and calculates a corrected characteristic 109 which is a final luminance input / output characteristic (S34: corrected characteristic calculation step). When the viewing angle θ is not different (S32: NO), or when the viewing angle θ is in a range that is less than 30% of the luminance reduction rate (S71: NO), the display control unit 103 displays the previous luminance input / output characteristics and reference characteristics 106. In other cases, the image is displayed on the display unit 104 using the latest corrected characteristic calculated by the corrected characteristic calculation unit 102 (S35: display control step).

  As described above, by selecting the optimal correction table 107 based on the characteristics of the input image, it is possible to obtain an optimal image that does not cause a sense of incompatibility regardless of the viewing angle of the user 1102. It can be displayed on the display means 104.

FIG. 11 is a diagram showing the concept of the characteristic change after correction in the present embodiment.
As shown in FIG. 5A, when the image displayed on the display unit 104 is an image in which the object image 902 exists in the dark background image 901, the feature specifying unit 112 sets the feature of the image as a horror movie. Identify. In this case, the table selection unit 113 selects the correction table 107 suitable for the horror movie. For example, the correction table 107 suitable for a horror movie is, as shown in FIG. 5B, a brightness signal portion B that is well suited to the background image 901 is brightened to some extent, and a brightness signal that is well suited to the object image 902. Is a correction table 107 in which correction values for brightening the portion A are held. By selecting such a correction table 107, the object image 902 can be recognized while allowing the user 1102 to recognize the background image 901, and the user 1102 viewing from a viewing angle with a luminance reduction rate of 30% or more. Even if the post-correction characteristics are changed, the brightness difference between the background image 901 and the object image 902 is increased even when the overall brightness is reduced. Therefore, the same visibility as when viewed from the front is obtained. can get.

  According to such a configuration, in addition to the effects of using the first embodiment, for a display with a large decrease in luminance, the luminance reduction in a dark image associated with the viewing angle is a major factor in image quality degradation. Image quality can be adjusted in consideration of sensation and visual characteristics. Accordingly, since it is not necessary to make adjustments for portions that are not important to the user or are unaware of image quality deterioration, it is possible to perform image quality adjustment with fewer side effects and high practicality.

  In particular, when there is a high-luminance part in the screen, humans have a characteristic that the brightness adapts to the brightest part and the discrimination ability of the low-luminance part decreases. Therefore, according to the present embodiment, when the low-luminance discrimination capability is high, for example, in the case of a uniformly dark image having no high-luminance portion in the screen, the correction table 107 suitable for this is selected and low When the luminance discrimination capability is low, for example, in the case of an image having a high luminance portion in the screen, the correction table 107 including a correction value that darkens the dark portion can be selected to assist the discrimination.

  In the present embodiment, the image quality adjustment of an IPS (In Plain Switching) liquid crystal display has been described as an example. However, the present invention is not limited to this, and the present invention can be applied to a display in which luminance decreases depending on the viewing angle. it can.

  In the first and second embodiments, the post-correction characteristics are changed by selecting the post-correction characteristic table. However, a digital signal processor (digital signal processor) that is a microprocessor specialized in processing of audio, images, etc. A signal processor (DSP) may be used.

  Furthermore, in the first embodiment and the second embodiment, the visibility of the object can be further increased by linking the corrected characteristic calculation unit and the contour correcting unit.

  Note that it may be determined whether or not there are a plurality of users 1102, and in the case of a plurality of users, which position to employ may be set.

  The image display device and the image quality adjustment method according to the present invention can automatically obtain the optimum image quality depending on the position where the user exists and the characteristics of the image. Useful as.

It is the block diagram which showed the structure of the image display apparatus in embodiment of this invention. It is a figure which shows roughly the specific state of the positional information by a user operating a remote control means. It is a flowchart explaining the operation | movement which determines the optimal characteristic after correction | amendment of an image display apparatus. It is a graph which shows a luminance input / output characteristic. It is a figure which shows notionally the correction table currently hold | maintained at the memory | storage means. It is a figure which shows notionally the correction table currently hold | maintained at the memory | storage means. It is a graph which shows a luminance input / output characteristic. It is a figure which shows notionally the correction table currently hold | maintained at the memory | storage means. It is the block diagram which showed the structure of the image display apparatus in embodiment of this invention. It is a flowchart explaining the operation | movement which determines the optimal characteristic after correction | amendment of an image display apparatus. In this Embodiment, it is the figure which showed the concept of the characteristic change after correction | amendment. It is a graph which shows the relationship between the viewing angle of a flat panel display, and the whole brightness | luminance. It is a figure which shows notionally the difference in the recognition state of the image in the difference in viewing angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image display apparatus 101 Position specification means 102 Corrected characteristic calculation part 103 Display control part 104 Display means 105 Storage means 106 Reference characteristic 107 Correction table 108 Remote operation means 109 Corrected characteristic 111 Correction table group 112 Feature specification part 113 Table selection part 121 First distance specifying unit 122 Second distance specifying unit 901 Background image 902 Object image 1102 User

Claims (9)

Display means for displaying an image;
Position specifying means for specifying the position of the user with respect to the display means as position information;
A reference characteristic that is one of the luminance input / output characteristics indicating the relationship between the input luminance signal and the luminance value displayed on the display means, a plurality of correction values for correcting the reference characteristic, and user position information Storage means for storing a correction table associated with
Based on the position information of the user specified by the position specifying means, obtain a plurality of correction values from the correction table, correct the reference characteristics and calculate the corrected characteristics;
An image display apparatus comprising: a display control unit that causes the display unit to display an image based on the corrected characteristic calculated by the corrected characteristic calculation unit.   The image display apparatus according to claim 1, wherein the calculation by the corrected characteristic calculation unit is applied to a dark part input signal.   The image display apparatus according to claim 1, wherein one of the correction values included in the correction table is a correction value for correcting a luminance input / output characteristic corresponding to a dark part.   The image display apparatus according to claim 1, wherein the calculation by the corrected characteristic calculation unit is applied when a luminance decrease of 30% or more occurs from the front. further,
When the luminance of the entire display unit that can be observed from the front of the display unit when a predetermined image is displayed on the display unit is set as the reference luminance, the user is positioned at a position where a luminance decrease of 30% or more from the reference luminance occurs. A position determination means for determining whether or not
The image display apparatus according to claim 1, wherein the display control unit causes the display unit to display an image based on a corrected characteristic when it is determined that the position determination unit is located. further,
Remote control means capable of operating the image display device,
The position specifying means includes
First distance specifying means for specifying a first distance between the remote control means and the center of the display surface of the display means;
2. The image according to claim 1, further comprising: a second distance specifying unit that specifies a second distance between a foot of a perpendicular line dropped from the remote operation unit to the display surface of the display unit and a center portion of the display surface of the display unit. Display device. further,
A feature identifying unit that identifies the features of the input image;
A table selection unit for selecting one from different correction tables based on the features of the image specified by the feature specifying unit;
The image display device according to claim 1, wherein the corrected characteristic calculation unit calculates the corrected characteristic using the selected correction table. An image quality adjustment method for an image display device having display means for displaying an image,
A position specifying step for specifying the position of the user with respect to the display means as position information;
Based on the position information of the user specified in the position specifying step, a plurality of correction values are acquired from the correction table held in the image display device, and the reference characteristic held in the image display device is corrected and corrected. A corrected characteristic calculating step for calculating a post characteristic;
A display control step of causing the display means to display an image based on the corrected characteristic calculated in the corrected characteristic calculating step. further,
A feature identification step for identifying features of the input image;
The image quality adjustment method according to claim 8, further comprising a table selection step of selecting one from different correction tables based on the feature of the image specified by the feature specification step.