JP2010197656A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device which stably displays an image with an appropriate image quality in accordance with a viewing environment and the color of viewer's eyes without troubling the viewer about setting. <P>SOLUTION: The image display device includes: a face region detection part 102 which detects a region of a viewer's face from an image picked up by a camera 101 provided in the device; an eye region detection part 103 which detects a region of his or her eyes from the region of his or her face; an image analysis part 106 which analyses image data of the eye region to generate a brightness histogram and a hue histogram and acquires environmental feature quantities such as the brightness and tone of external light and the color of viewer's eyes from features of the distributions; and an image quality correction part 107 which corrects the image quality of a display image in accordance with the acquired environmental feature quantities. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a video display device that appropriately controls the image quality of a video to be displayed in accordance with a viewing environment and the color of a viewer's eyes.

  2. Description of the Related Art In recent years, various video display devices such as television devices have been proposed for adjusting the image quality of an image to be displayed according to a viewing environment such as ambient brightness and hue (color temperature) in order to improve image quality. In addition to these viewing environments, it has been proposed to adjust the image quality so that it is easy to see in consideration of differences in sensitivity to colors depending on the color of the viewer's (user) eye (for example, Patent Documents). 1). The color of the eye depends on the amount of melanin pigment in the iris that regulates the amount of light entering the eye. If there is a lot of melanin, the color of the eye will be brown or black, and if there is little melanin, it will be blue or green. There is a difference in visual value between black eyes and blue eyes. Generally, black eyes prefer high color temperature, and blue eyes are said to have high color difference visual acuity.

JP 2007-264124 A

  The display device described in Patent Document 1 adjusts the displayed image so that it is easy for the user to see according to the difference in the color of the eyes of the user and the change in the color temperature of the ambient light. Specifically, for the user's eye color, the user's eye color information is set in advance for the display device and stored in the storage unit. The color temperature of the external light is estimated by measuring the chromaticity of the skin in the vicinity of the user's eyes from the image data taken by the camera.

  In this case, the user's eye color information is set on the setting screen by the user himself / herself. Therefore, when a user with a different eye color uses it, the eye color information must be reset. Further, the brightness of external light and the color temperature are estimated by analyzing an image of the user's skin. At that time, since the color of the skin is different for each user, a reference value for the user must be set in advance. Further, since the skin color may change even for the same user, the reference value must be corrected. When a plurality of viewers (users) use it like a television device, these settings and changes are troublesome and inconvenient for the user. Therefore, it seems difficult to stably perform appropriate image quality adjustment.

  An object of the present invention is to provide an image display device that stably displays an image with appropriate image quality according to the viewing environment and the color of the viewer's eyes without bothering the user's settings.

  The video display device of the present invention includes a camera that captures a viewer around the device, a face region detection unit that detects a region of the viewer's face from an image captured by the camera, and the detected face. An eye region detection unit that further detects an eye region from the region, and an image analysis unit that analyzes the eye region image data output from the eye region detection unit and acquires an environmental feature including the eye color of the viewer And an image quality correction unit that corrects the image quality including the color temperature of the video to be displayed according to the environmental feature value acquired by the image analysis unit.

  Here, the environmental feature amount includes brightness and color of outside light. The image analysis unit analyzes the eye area image data to create a luminance histogram and a hue histogram, and acquires the environment feature amount from the characteristics of the distribution.

  Further, when the eye area detection unit detects an eye area from the face area, the eye area detection unit removes an image other than the eye area from the eye area image data by zooming in on the detected eye area.

  ADVANTAGE OF THE INVENTION According to this invention, the video display apparatus which displays stably the image | video of a suitable image quality according to viewing environment or a viewer can be implement | achieved without bothering a user's setting.

The block diagram which shows one Example of the video display apparatus concerning this invention. The block diagram which shows the other Example of the video display apparatus concerning this invention. 6 is a flowchart showing a flow of image quality correction in the video display apparatus of the present embodiment. The figure which shows the relationship between an environmental feature-value and a brightness | luminance histogram. The figure which shows the relationship between an environmental feature-value and a hue histogram. The figure which shows the relationship between the hue of external light, a brightness | luminance, and a hue histogram. An example of an image quality control matrix table used for image quality correction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a video display apparatus according to the present invention. In this embodiment, a case where a liquid crystal display (LCD display unit) 109 is used for video display is shown. The LCD display unit 109 includes a backlight 111 for illuminating the liquid crystal panel.

  The camera 101 is attached to the video display device, and photographs viewers around the device. The face area detection unit 102 detects the face part of the viewer from the captured image, and the eye area detection unit 103 further detects and extracts the eye part from the face area. The face is detected by using, for example, skin color information or detecting feature points such as eyes, mouth, and nose. Details of such face detection are disclosed in various documents such as Japanese Patent Application Laid-Open No. 2004-259215, Japanese Patent Application Laid-Open No. 2006-72770, Japanese Patent Application Laid-Open No. 2005-71344, and the description thereof is omitted here.

  In the eye detection, the eye region is specified based on the feature points detected by the face detection. Details of such eye detection are disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-216515 other than the patent document cited as an example of the face detection, and the description thereof is also omitted here. At that time, by zooming in on the specified area, unnecessary images other than the eyes can be removed, and the resolution of the eye area image can be improved. Furthermore, since there are individual differences in eye size, the size of the extracted eye region is normalized to a standard size. The eye area detection unit 103 outputs the extracted image data in the eye area (eye area image data) to the CPU 106.

  The CPU (image analysis unit) 106 analyzes the eye region image data output from the eye region detection unit 103, and determines the brightness (illuminance) and hue (illumination color) of external light and the color of the viewer's eyes (hereinafter referred to as the eye color). These are collectively referred to as “environment feature quantity”). As will be described later, in the analysis of image data, a luminance histogram and a hue histogram are created, and environmental feature amounts such as brightness of external light, hue, and eye color of the viewer are acquired from the characteristics of the distribution. As described above, all the environmental feature amounts are acquired from the eye region image data. Also, the accuracy of acquiring the environmental feature amount can be increased by zooming in on the camera to improve the resolution of the eye area image.

  On the other hand, a video signal is input to the video input unit 104 from a tuner or the like (not shown), and the video feature detection unit 105 determines the brightness and hue of the video from the input video signal (hereinafter referred to as “video feature amount”). To detect. The detected video feature amount is output to the CPU 106.

  A CPU (image analysis unit) 106 controls image quality correction for the image quality correction unit 107 and the backlight drive unit 110 according to the video feature amount output from the video feature detection unit 105 and the acquired environmental feature amount. Send a signal. In other words, the image quality is corrected to the image quality suitable for the feature amount (image feature amount) of the video itself, and is also corrected to the image quality suitable for the viewing environment and the viewer condition (environment feature amount). For correction, for example, an image quality control matrix table (FIG. 7) described later is prepared, and control is performed with reference to this. The image quality correction unit 107 corrects image quality parameters such as contrast, brightness, gamma, color temperature, sharpness, and saturation for the input video signal in accordance with a control signal from the CPU 106. The video output unit 108 outputs the corrected video signal to the LCD display unit 109. In addition, the backlight driving unit 110 adjusts the power supplied to the light source of the backlight 111 to correct the brightness of the light source.

  As described above, in the video display device according to the present embodiment, environmental feature amounts (brightness and hue of external light, color of the viewer's eyes) are collectively acquired from the image of the viewer's eyes captured by the camera 101. The video image quality suitable for this is displayed. Therefore, even when a user with a different eye color uses the user's eye color, the user's hand is not bothered. In addition, when acquiring the shade of external light, the user's skin color is easy to change, but the eye color is stable, so the shade is accurately acquired without setting a reference value for each user, As a result, image quality adjustment can be performed stably.

  FIG. 2 is a block diagram showing another embodiment of the video display apparatus according to the present invention. In this embodiment, a case where a plasma display panel (PDP display unit) 209 is used for video display is shown. The configuration of the apparatus is the same as that in FIG. 1, and the elements 201 to 208 are the same as the elements 101 to 108 in FIG. Since the PDP display unit 209 is self-luminous, a backlight and its driving unit are not required.

Also in the video display apparatus according to the present embodiment, environmental features (brightness and hue of external light, color of the viewer's eyes) are collectively obtained from the viewer's eyes image captured by the camera 101, and suitable for this. The image quality is displayed.
The video display device shown in FIG. 1 and FIG. 2 may have an integrated configuration including a tuner that receives a television broadcast and a recording device that records the received broadcast program on an HDD or an optical disk.

FIG. 3 is a flowchart showing the flow of image quality correction in the video display apparatus of the present embodiment. Although the case of the configuration of the video display device of FIG. 1 will be described, the same applies to the case of FIG.
In step S <b> 301, the surroundings of the apparatus are photographed by the camera 101.
In S302, the face area detection unit 102 detects the viewer's face area from the captured image. If the face area is not detected, the process proceeds to S307, and standard image quality correction (correction according to the video feature amount) is performed. If there are a plurality of detected faces, the average of these is taken (the average of the subsequent image data is taken).

In S303, the eye area detection unit 103 detects an eye area from the face area and acquires eye area image data. At that time, the camera 101 zooms in and normalizes the detected eye area size.
In S304, the CPU 106 analyzes the eye area image data. Specifically, the eye area is divided into a plurality of areas, and a luminance distribution (histogram) and a hue distribution (histogram) are created from the image data of each area.
In S305, environmental feature quantities such as the brightness of external light, hue, and eye color of the viewer are acquired from the created luminance histogram and hue histogram based on the characteristics of the distribution.

In S <b> 306, the CPU 106 controls the image quality correction unit 107 and the backlight drive unit 110 in accordance with the acquired environmental feature amount to correct the image quality of the video. For correction, an image quality control matrix table (FIG. 7) showing the relationship between the environmental feature amount and the image quality setting is referred to. At this time, an optimum image quality is realized by combining correction according to the video feature amount.
In S <b> 308, an image with corrected image quality is displayed by the LCD display unit 109 and the backlight 111.

  Next, how to acquire the environmental feature amount from the eye area image data will be described. In this embodiment, a luminance histogram and a hue histogram are created from eye area image data, and environmental feature amounts such as brightness of external light, hue, and eye color of the viewer are acquired from the characteristics of the distribution. These will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating the relationship between the environmental feature amount and the luminance histogram. The luminance histogram is obtained by dividing the eye area into about 20 meshes, obtaining the luminance value in each divided area from the eye area image data, and showing the frequency distribution. As environmental parameters, the brightness of external light is changed in three stages (bright (1000 lx), standard (150 lx), dark (30 lx)), and the eye color of the viewer is compared between brown and blue. The shade of outside light is a daylight color (color temperature 6500K).

  The distribution of each histogram is separated into three parts (reference numerals 401 ′, 402 ′, 403 ′), and these correspond to the pupil 401, iris 402, and sclera (white eye) 403 constituting the eye region. Yes. The pupil 401 has low brightness, the iris 402 has medium brightness, and the white eye 403 has high brightness.

  When the outside light is bright (a1, a2), the pupil 401 is small, and the reflected light from the white eye 403 is strong, so that the distribution is enhanced with high luminance components. When the outside light is dark (a5, a6), the pupil 401 is large, and the reflected light from the white eye 403 is weak, so that the distribution is enhanced with low luminance components. There is no significant difference in eye color (brown or blue). Therefore, the environmental feature amount regarding the brightness of outside light can be acquired from the distribution of the luminance histogram.

  FIG. 5 is a diagram illustrating the relationship between the environmental feature amount and the hue histogram. Also in this case, the eye area is divided into about 20 meshes, the hue value in each divided area is obtained from the eye area image data, and the frequency is shown. As an environmental parameter, the brightness of external light is changed in three levels (bright, standard, dark), and the eye color of the viewer is compared between brown and blue. The color of outside light is daylight (color temperature 6500K).

  The distribution of each histogram is concentrated in one place (reference numeral 502 ′), because most of the hue component is generated from the portion of the iris 502 constituting the eye region. Since the pupil 501 and the white eye 503 are black or white, they have almost no hue component and are not counted as histogram frequencies. Therefore, the frequency displayed on the histogram is smaller than the number of divisions of the eye area.

  When the eye color is brown (b1, b3, b5), the red (R) and orange (YR) components from the iris 502 are emphasized. When the eye color is blue (b2, b4, b6), the blue-green (BG) and blue (B) components of the iris 502 are emphasized. Note that the frequency of the histogram changes with respect to the brightness of external light, but the distribution position of the hue component does not change. Therefore, the environmental feature amount for the color of the viewer's eyes can be acquired from the distribution of the hue histogram.

  FIG. 6 is a diagram illustrating the relationship between the hue of external light, luminance, and hue histogram. A luminance histogram and a hue histogram are created under the illumination of daylight color (color temperature 6500K) and light bulb color (2800K) as the shade of external light. The brightness of outside light is standard, and the viewer's eyes are brown.

The shade of outside light is reflected in the hue histogram. In the case of the light bulb color (c4), since there are many red, orange and yellow components, they are added to the hue distribution of the eye color. As a result, compared to the daylight color (c2), the frequencies of red and orange are increased, and the distribution width is expanded to the yellow component. Therefore, the environmental feature amount regarding the shade of external light can be acquired from the distribution of the hue histogram. At that time, by analyzing the distribution width and intensity of the histogram, it is possible to obtain the image separately from the environmental feature amount of the viewer's eye color.
In addition, there are daytime white (5000K) and white (4200K) as other light shades. These can also be identified by using a high-resolution camera.

  FIG. 7 is an example of an image quality control matrix table used for image quality correction. Here, contrast, brightness, backlight (in the case of LCD), gamma, color temperature, sharpness, and saturation are taken up as image quality parameters. As environmental feature amounts, (a) takes up the brightness of the outside light and the color of the viewer's eyes, and (b) takes up the shade of the outside light. The numerical value in the table is the setting level of each image quality parameter, and the maximum level is represented by “10”. The color temperature is set to a bluish color when the level is high and a reddish color when the level is low. In this figure, the relationship between the environmental feature amount and the image quality setting is set as follows.

(1) Regarding the brightness of external light, the setting level of each parameter is increased as the external light is brighter. As a result, it is possible to realize a more easily viewable image quality adapted to the brightness of outside light.
(2) Regarding the color of the viewer's eyes, blue eyes lower the setting level of each parameter than brown eyes. This is adapted to the property that brown eyes prefer a high color temperature and blue eyes have a large color difference visual acuity.
(3) Regarding the color of the outside light, the setting level of the color temperature parameter is lowered in the case of the light bulb color than in the case of the daylight color. Thereby, a more natural image quality is realized as a color tone suitable for the illumination color.

  In this way, the optimum image quality can be set according to a plurality of environmental feature amounts such as the brightness of external light, the hue, and the color of the viewer's eyes. The content of the image quality control shown in FIG. 7 is an example, and the setting value of the image quality parameter for the environmental feature amount can be changed as appropriate.

  As described above, in the video display device according to the present embodiment, environmental feature amounts such as the brightness of the external light, the hue, and the color of the viewer's eyes are collectively obtained from the viewer's eye area image, thereby improving the image quality. It is something to control. Therefore, when a plurality of viewers use, it is possible to stably display an image with an appropriate image quality according to the viewing environment and the color of the viewer's eyes without bothering the viewer.

  As another effect, by using the image information of the viewer's eyes (specifically, the luminance histogram and the hue histogram of the eyes), the viewer's eyes are actually affected by the color of the eyes and the external light. It is possible to grasp how the image is perceived. By using this, it is possible to realize image quality settings that are more suitable for the visual characteristics of the eyes.

101, 201 ... camera,
102, 202 ... face area detection unit,
103, 203 ... eye area detection unit,
104, 204 ... Video input section,
105, 205 ... image feature detection unit,
106, 206 ... CPU (image analysis unit),
107, 207 ... an image quality correction unit,
108, 208 ... Video output section,
109 ... LCD display,
110: Backlight drive unit,
111 ... Backlight,
209: PDP display unit.

Claims (4)

In the video display device that corrects the image quality of the input video and displays it on the display unit,
A camera that captures viewers around the device;
A face area detection unit for detecting a face area of the viewer from an image captured by the camera;
An eye area detection unit for detecting an eye area from the detected face area;
Analyzing the eye area image data output from the eye area detection unit, and obtaining an environmental feature including the color of the viewer's eyes; and
An image quality correction unit that corrects the image quality including the color temperature of the image to be displayed according to the environmental feature amount acquired by the image analysis unit;
A video display device comprising: The video display device according to claim 1,
The image display device characterized in that the environmental feature amount includes brightness and hue of outside light. The video display device according to claim 1 or 2,
The image analysis device, wherein the image analysis unit analyzes the eye area image data to create a luminance histogram and a hue histogram, and acquires the environmental feature amount from the characteristics of the distribution. In the video display device according to any one of claims 1 to 3,
When the eye area detecting unit detects an eye area from a face area, the eye area detecting unit removes an image other than the eye area from the eye area image data by zooming in on the detected eye area. A video display device.

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