JP5903283B2 - Image processing apparatus, image display system, and image display method - Google Patents

Description

  The present invention relates to an image processing device, an image display system, and an image display method, and more particularly to an image processing device, an image display system, and an image display method for displaying one or more images on a plurality of display devices. .

  In recent years, display devices have been increased in size and resolution, and liquid crystal display devices are widely used as information display devices and digital signage display devices that are viewed by many people.

  However, the screen size of the liquid crystal display device is limited by the manufacturing process, and a large-screen liquid crystal display device is generally expensive. Therefore, a so-called multi-display device in which a plurality of liquid crystal display devices are arranged adjacent to each other in a planar shape (in some cases, in a linear shape) may be used. This multi-display device is widely used for digital signage and the like because a large screen can be obtained at low cost.

  Since the liquid crystal display device used for such an application often performs display at all times or for a long time, the power consumption is larger as a result than a general liquid crystal display device. In addition, by using a plurality of liquid crystal display devices, a high-resolution video reproduction and distribution device is also required, and the power consumption as a whole is larger than that of a liquid crystal display device having one large screen. Therefore, a technique for reducing power consumption is required.

  Here, for example, in Japanese Patent Application Laid-Open No. 2004-246099, during the power saving operation, the light amount of the backlight is reduced, and the reduced light amount is compensated by an increase in the pixel value (specifically, light transmittance) of the liquid crystal display element. A configuration of an image processing apparatus that performs enhancement processing on an input image signal is disclosed. With this configuration, it is possible to reduce power consumption without reducing the image quality of the displayed video.

Japanese Patent Laid-Open No. 2004-246099

  However, in the case of a multi-display device, one image is typically divided and displayed by a plurality of liquid crystal display devices. For this reason, when the enhancement correction processing for the input image signal described in Japanese Patent Application Laid-Open No. 2004-246099 is performed as it is in the multi-display device, the correction amount differs for each liquid crystal display, and images having different luminances in the plurality of liquid crystal display devices. May be displayed. In that case, since the luminance distribution becomes uneven in one image, there arises a problem that the display mode is uncomfortable.

  In order to avoid this problem, it is conceivable to perform the correction on the one image displayed on a plurality of liquid crystal display devices. However, since there are cases where a large number (for example, 9 to 25) of liquid crystal display devices are provided, the data amount of all the display images constituting the one image becomes enormous in that case. Therefore, the configuration for correcting this is not realistic because very high-speed processing is required.

  Accordingly, a configuration in which the above correction is performed on input image data that is original data of a displayed image can be considered. However, when generating a plurality of images to be displayed on each liquid crystal display device by enlarging the input image data (increasing the resolution), the edges of the input image are displayed for display on the plurality of display devices. Various image processing based on information and frequency characteristics is often performed. Image processing in such enlargement processing needs to be performed on an input image before correcting the unevenness of the luminance distribution. If the image processing in the enlargement process is applied to the corrected input image, the gradation property of the input image may be lost due to the correction. There is an inconvenience in image processing, which may result in display defects.

  Therefore, an object of the present invention is an image that can reduce the amount of light of a backlight without causing a display defect in a display device configured to display at least one image by a plurality of display devices arranged adjacent to each other. A processing device, an image display system, and an image display method are provided.

The first invention is based on input image data, output image data to be given to display elements arranged on each display screen in a plurality of display devices arranged in a line or a plane, and the plurality of display devices An image processing apparatus that outputs backlight luminance data representing the luminance of each backlight included in the backlight,
An image resolution conversion unit that converts an input image represented by the input image data into a display resolution for display on the display screen and outputs the image as enlarged image data;
An image division output unit that divides an enlarged image represented by the enlarged image data output from the image resolution conversion unit into each image to be displayed on the display screen, and outputs the divided image data as a plurality of divided image data;
Based on the input image data, pixel value correction data corresponding to the image to be displayed on the display screen is calculated so that a pixel value given to the display element to be represented by the output image data is increased. And a correction data calculation unit that calculates and outputs the backlight luminance data so that the emission luminance of the backlight decreases.
An image signal processing unit that outputs output image data obtained by correcting pixel values of an image represented by the divided image data based on the pixel value correction data output from the correction data calculation unit;
The correction data calculation unit
Calculating a value indicating a frequency distribution of pixel values included in the input image data, and calculating the pixel value correction data based on the calculated value;
When the input image includes a plurality of different images, a value indicating a frequency distribution of pixel values in the image is calculated for each of the plurality of images, and each of the images of the plurality of images is calculated. for each, along with calculating and outputting the pixel value correction data so that the pixel values of the image within the enlarged image corresponding increases in the image based on the calculated the value, so that the light emission luminance of the backlight is reduced And calculating and outputting a number of the backlight luminance data corresponding to one or the plurality of divided image data ,
The image signal processing unit, when the input image includes a plurality of different images,
A division including at least a part of one image in the enlarged image corresponding to any one of the plurality of images in the input image among the plurality of divided images represented by the plurality of divided image data. The output image data is generated by correcting the pixel value of the image based on the pixel value correction data calculated by the correction data calculation unit for the one image in the input image,
At least each of two or more images in the enlarged image corresponding to any two or more images in the plurality of divided images in the input image among the plurality of divided images represented by the plurality of divided image data. Based on the two or more pixel value correction data respectively calculated by the correction data calculation unit for the two or more images in the input image, the pixel values of the two or more images in the divided image including a part. By correcting each, the output image data is generated ,
The correction data calculation unit
Based on the value indicating the frequency distribution, when the frequency distribution is biased toward the low luminance side, the gain value is set so that the pixel value of the image to be displayed is increased compared to the case where the frequency distribution is biased toward the high luminance side,
It is determined whether a value obtained by multiplying at least a part of pixel values of the input image represented by the input image data by the set gain value exceeds a maximum pixel value that can be displayed on the display device. If the number or ratio of pixels determined to exceed is less than a predetermined threshold, the set gain value is increased, and the number or ratio of pixels determined to exceed is greater than or equal to the threshold. In this case, the set gain value is determined as the gain value to be multiplied with the pixel value of the image represented by the divided image data,
Output the determined gain value as the pixel value correction data, calculate and output the backlight luminance data based on the determined gain value,
The image signal processing unit outputs the output image data based on a value obtained by multiplying the pixel value of an image represented by the divided image data by the determined gain value. And

According to a second invention, in the first invention,
The correction data calculation unit resets a gain value obtained by increasing the set gain value by a predetermined increase amount as a new gain value, and at least some pixels of the input image represented by the input image data It is determined whether a value obtained by multiplying the value by the reset gain value exceeds a maximum pixel value that can be displayed on the display device, and the number or ratio of pixels determined to exceed the predetermined value is a predetermined value. When the value is less than the threshold, the set gain value is increased by a predetermined amount, and the set gain is increased by the predetermined amount until it is determined to be equal to or greater than the threshold, and the determination is performed. When the number or ratio of pixels determined to exceed the threshold value is equal to or greater than the threshold value, the set gain value is compared with the pixel value of the image represented by the divided image data. And wherein the determining, as the gain value to be multiplied Te.

According to a third aspect of the present invention, there is provided output image data to be given to display elements arranged on each display screen in a plurality of display devices arranged in a line or a plane based on input image data, and the plurality of display devices An image processing apparatus that outputs backlight luminance data representing the luminance of each backlight included in the backlight,
An image resolution conversion unit that converts an input image represented by the input image data into a display resolution for display on the display screen and outputs the image as enlarged image data;
An image division output unit that divides an enlarged image represented by the enlarged image data output from the image resolution conversion unit into each image to be displayed on the display screen, and outputs the divided image data as a plurality of divided image data;
Based on the input image data, pixel value correction data corresponding to the image to be displayed on the display screen is calculated so that a pixel value given to the display element to be represented by the output image data is increased. And a correction data calculation unit that calculates and outputs the backlight luminance data so that the emission luminance of the backlight decreases.
An image signal processing unit that outputs output image data obtained by correcting pixel values of an image represented by the divided image data based on the pixel value correction data output from the correction data calculation unit;
With
The correction data calculation unit
Calculating a value indicating a frequency distribution of pixel values included in the input image data;
Based on the value indicating the frequency distribution, when the frequency distribution is biased toward the low luminance side, the gain value is set so that the pixel value of the image to be displayed is increased compared to the case where the frequency distribution is biased toward the high luminance side,
It is determined whether a value obtained by multiplying at least a part of pixel values of the input image represented by the input image data by the set gain value exceeds a maximum pixel value that can be displayed on the display device. If the number or ratio of pixels determined to exceed is less than a predetermined threshold, the set gain value is increased, and the number or ratio of pixels determined to exceed is greater than or equal to the threshold. In this case, confirm the set gain value,
Output the determined gain value as the pixel value correction data, calculate and output the backlight luminance data based on the determined gain value,
The image signal processing unit outputs the output image data based on a value obtained by multiplying the pixel value of an image represented by the divided image data by the determined gain value. And

According to a fourth invention, in the third invention,
The correction data calculation unit resets a gain value obtained by increasing the set gain value by a predetermined increase amount as a new gain value, and at least some pixels of the input image represented by the input image data It is determined whether a value obtained by multiplying the value by the reset gain value exceeds a maximum pixel value that can be displayed on the display device, and the number or ratio of pixels determined to exceed the predetermined value is a predetermined value. When the value is less than the threshold, the set gain value is increased by a predetermined amount, and the set gain is increased by the predetermined amount until it is determined to be equal to or greater than the threshold, and the determination is performed. When the number or ratio of pixels determined to exceed the threshold value is equal to or greater than the threshold value, the set gain value is compared with the pixel value of the image represented by the divided image data. And wherein the determining, as the gain value to be multiplied Te.

According to the first aspect, the pixel value correction data corresponding to the image is calculated based on the input image data so that the pixel value of the displayed image is increased, and the light emission luminance of the backlight is decreased. As described above, the backlight luminance data is calculated, and based on the pixel value correction data, not the pixel value of the input image, but the output image obtained by correcting the pixel value of the image represented by the divided image data output from the image division output unit Since each data is output, in a plurality of display devices arranged in a line or plane, typically, when one image is displayed, the backlight luminance does not occur without causing a display defect such as video failure. And power consumption can be reduced.
According to the first aspect, when the input image includes a plurality of images, pixel value correction data suitable for each image can be calculated. Accordingly, the brightness can be increased for a dark image, for example, according to the content of the image, so that the display quality of the displayed image can be prevented from further decreasing for each region. In particular, when an image using an OSD having a large difference in luminance (average value) in a plurality of image areas is included, one pixel value correction does not affect the other pixel value correction. Therefore, the display quality of the displayed image can be prevented from further lowering for each region.
Furthermore, according to the first aspect, when the number or ratio of pixels determined to exceed the maximum displayable pixel value is less than a predetermined threshold value, the gain value is set larger, so that the video corruption It is possible to reduce power consumption as much as possible while suppressing display defects such as.

According to the second aspect of the invention, when the number or ratio of the pixels is less than the threshold value, the gain value is continuously set to a large value until the threshold value or more is reached. Power consumption can be reduced as much as possible.

According to the third aspect, the pixel value correction data corresponding to the image is calculated based on the input image data so that the pixel value of the displayed image is increased, and the light emission luminance of the backlight is decreased. As described above, the backlight luminance data is calculated, and based on the pixel value correction data, not the pixel value of the input image, but the output image obtained by correcting the pixel value of the image represented by the divided image data output from the image division output unit Since each data is output, in a plurality of display devices arranged in a line or plane, typically, when one image is displayed, the backlight luminance does not occur without causing a display defect such as video failure. And power consumption can be reduced.
According to the third aspect, when the number or proportion of pixels that are determined to exceed the maximum pixel value that can be displayed is less than the predetermined threshold value, the gain value is set larger, the image collapse It is possible to reduce power consumption as much as possible while suppressing display defects such as.

According to the fourth aspect of the invention, when the number or ratio of the pixels is less than the threshold value, the gain value is continuously set to a large value until the threshold value or more is reached. Power consumption can be reduced as much as possible.

1 is a block diagram illustrating a configuration of a multi-display device according to a first embodiment of the present invention. It is a figure which shows simply the display screen displayed by nine liquid crystal display devices in the said embodiment. It is a figure for demonstrating the correction | amendment aspect of a pixel value when a pixel value distributes to the high gradation side by the histogram analysis in the said embodiment. It is a figure for demonstrating the correction | amendment aspect of a pixel value when a pixel value distributes to the low gradation side by the histogram analysis in the said embodiment. It is a flowchart which shows the flow of the setting process of the gain value in the said embodiment. It is a block diagram which shows the structure of the liquid crystal display device in the said embodiment. It is a figure for demonstrating that display quality can be prevented from falling with the structure of the said embodiment. It is a block diagram which shows the structure of the multi-display apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the liquid crystal display device in the said embodiment. It is a block diagram which shows the structure of the multi-display apparatus which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the flow of the setting process of the gain value in the said embodiment. It is a block diagram which shows the structure of the multi-display apparatus which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the example of the 1st display screen in the said embodiment. It is a figure for demonstrating the 2nd example of a display screen in the said embodiment. It is a figure for demonstrating the example of the 3rd display screen in the said embodiment. It is a block diagram which shows the structure of the multi-display apparatus which concerns on the 5th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<1. First Embodiment>
<1.1 Overall configuration and operation>
FIG. 1 is a block diagram showing a configuration of a multi-display apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the multi-display device 100 is an image display system including an image processing device 10 and nine liquid crystal display devices 61 to 69, and typically displays nine images. Display by one display screen. In the following, the image processing apparatus 10 will be described as an apparatus different from the liquid crystal display apparatuses 61 to 69, but may be incorporated in any of these cases. Further, the number of display devices is not limited, and the arrangement mode is not planar (matrix), but may be arranged linearly according to the shape of the input image and the display application, and there is basically no limitation.

  FIG. 2 is a diagram simply showing a display screen displayed by nine liquid crystal display devices. As shown in FIG. 2, the liquid crystal display devices 61 to 69 are arranged in a planar shape (matrix shape), three in the vertical direction and three in the horizontal direction, and typically one display with nine display screens. Display the screen. With such a configuration, the multi-display device 100 can provide a large screen at a low cost.

  Next, as shown in FIG. 1, the image processing apparatus 10 includes an image resolution conversion unit 11 that converts the image resolution of input image data Dp representing an input image given from the outside, and nine converted images. In order to reduce the backlight luminance based on the gain value G, the image division output unit 13 for dividing, the histogram analysis unit 12 for performing the histogram analysis on the input image data Dp and outputting the gain value G and the backlight luminance data BL And a gain adjusting unit 14 for supplying output image data Da1 to Da9 having increased pixel values (display gradation data values) to the liquid crystal display devices 61 to 69. Here, the backlight luminance data BL is given to the liquid crystal display devices 61 to 69, and the luminance of the backlight incorporated in each liquid crystal display device is determined so as to reduce power consumption, as will be described later.

  Note that the liquid crystal display devices 61 to 69 used in the present embodiment are dedicated display devices whose arrangement positions are predetermined for the multi-display device 100, respectively. A typical liquid crystal display device can also be used. In that case, various kinds of information such as the size of the frame area of the liquid crystal display device to be used are required, but a similar large screen can be obtained if the information can be appropriately input. In this case, the liquid crystal display device needs to be configured to be able to control the light emission luminance of the built-in backlight by receiving the backlight luminance data BL. Furthermore, instead of the liquid crystal display device, a known display device having a backlight capable of displaying the large screen can be used.

  The image resolution conversion unit 11 shown in FIG. 1 converts an input image having a predetermined resolution represented by input image data Dp given from the outside into the large screen, that is, the entire display screen of the nine liquid crystal display devices 61 to 69. The process of enlarging it for display at. For example, when the resolution of the input image is the same as the display resolution in each of the liquid crystal display devices 61 to 69, the input image may be enlarged three times in the vertical direction and three times in the horizontal direction. Doubled. When conversion is performed to increase the resolution (that is, when up-conversion is performed), various interpolation methods and correction methods are known so that the quality of the display image is not deteriorated. By using some of the well-known methods, conversion is performed to increase the resolution of the input image (9 times), and the converted enlarged image data Dpu is output.

  The image division output unit 13 provides nine pieces of divided image data that can be supplied to each liquid crystal display device so that the enlarged image data Dpu received from the image resolution conversion unit 11 is suitable for display on the liquid crystal display devices 61 to 69. Ds1 to Ds9 are generated. At this time, the liquid crystal display devices 61 to 69 do not form a seamless single display screen, but in practice, the liquid crystal display devices 61 to 69 are located at the positions of the boundary lines between the liquid crystal display devices 61 to 69 shown in FIG. It has a frame area of the size. Since there is no liquid crystal display element in this frame area, display is impossible. Therefore, if the magnified image represented by the magnified image data Dpu is simply divided into nine without considering the presence of the frame region, the image becomes unnatural as a whole when actually displayed. Therefore, division is performed in consideration of the frame area. Also, since the display brightness of the frame area is 0, an image with a natural brightness distribution as a whole can be obtained by increasing the surrounding brightness. As described above, the image division output unit 13 generates the divided image data Ds1 to Ds9 by cutting out the enlarged image data Dpu at an appropriate position in consideration of the frame area and further performing appropriate correction.

  The liquid crystal display devices 61 to 69 may be configured to be able to display one image seamlessly on nine display screens by arranging optical members such as prisms and fiber plates in the vicinity of the frame region. Also in this case, it is necessary to consider the frame area when generating an image to be displayed on each display screen.

  On the other hand, the histogram analysis unit 12 performs a histogram analysis on the input image data Dp before the image conversion by the image resolution conversion unit 11 is performed, and calculates and outputs a gain value G. Further, the histogram analysis unit 12 calculates backlight luminance data BL with reduced emission luminance in accordance with the histogram analysis result, and supplies it to the liquid crystal display devices 61 to 69 described later.

  As will be described later, the backlight luminance data BL indicates how much the backlight luminance is to be reduced. However, this ratio is not calculated by the histogram analysis unit 12, but is displayed on the liquid crystal display. You may calculate in the apparatuses 61-69. In this case, it can be easily calculated based on the received gain value G. Details will be described later. The histogram analysis is to analyze the distribution state of the luminance (gradation value) of the pixels included in the image, and can be realized by various known methods, so the detailed analysis method will be described. Omitted.

  Here, the histogram analysis unit 12 changes the output gain value G depending on whether the luminance distribution obtained by the analysis is biased toward the high gradation side or the low gradation side. The operation of the histogram analysis unit 12 will be described with reference to FIGS.

<1.2 Operation of Histogram Analysis Unit>
<1.2.1 First Operation Example>
FIG. 3 is a diagram for explaining a correction mode of pixel values in a case where pixel values are distributed on the high gradation side by histogram analysis, and FIG. 4 is a diagram in which pixel values are distributed on the low gradation side by histogram analysis. It is a figure for demonstrating the correction aspect of a pixel value in a case.

  In these drawings, a straight line A indicated by a one-dot chain line indicates a case where the input gradation and the output gradation are equal, that is, a case where correction is not performed. In this case, the gain value G is 1. Here, for convenience of explanation, when correction is not performed, it is assumed that the input gradation and the output gradation are in a correspondence relationship as indicated by a straight line A. Correspondence as shown by a predetermined characteristic curve C in FIG.

  In these drawings, a straight line B indicated by a two-dot chain line indicates a case where the output gradation is larger than the input gradation, that is, a case where correction for increasing the pixel value is performed to reduce backlight luminance. The gain value here is greater than one.

  First, in FIG. 3, when the pixel value distribution (brightness distribution) of the pixels whose input gradation has a peak near 80% is obtained, that is, when the pixel values are distributed on the high gradation side, the backlight luminance is reduced. Therefore, even if it is necessary to correct the pixel value of the image to be large, the image displayed on the liquid crystal display devices 61 to 69 has high luminance as a whole, and thus the backlight luminance cannot be greatly reduced. Therefore, the gain value G is preferably set to be relatively small. In FIG. 3, G = about 1.2.

  On the other hand, in FIG. 4, when most of the pixel values are distributed until the input gradation is close to 20%, that is, when the pixel values are distributed on the low gradation side, Even if the pixel values are corrected so as to increase as a whole, the display quality of the images displayed on the liquid crystal display devices 61 to 69 does not deteriorate significantly. Therefore, it is preferable to set the gain value G to be relatively large. In FIG. 4, G = about 4.

  The luminance distribution shown in FIGS. 3 and 4 is merely an example in which pixel values are distributed on the high gradation side and the low gradation side, respectively, and the value of the gain value G is only an example. It can be determined appropriately according to the characteristics of the liquid crystal display device and the external environment.

  Here, various configurations can be applied to such a method of setting the gain value G. For example, whether the luminance distribution obtained by histogram analysis is biased toward the high gradation side or the low gradation side. A method of determining which case (which is closer) and setting (selecting) a corresponding predetermined gain value is conceivable.

  However, in this case, since there are only two types of gain values G, in order to set a more appropriate gain value G, a feature value such as a peak value or an average value of the luminance distribution is calculated and corresponds to the feature value. The gain value G may be calculated by referring to a predetermined calculation formula or a predetermined correspondence table. Furthermore, the gain value G may be calculated using other parameters.

  Further, instead of uniquely calculating the gain value from the luminance distribution in this way, a configuration in which an appropriate value is calculated according to the content of the input image is also conceivable. That is, when the target gain value is set first and the input gradation is corrected by applying this target gain value, the gradation collapse or video failure caused by excessively correcting the gradation does not occur more than a predetermined number. In addition, a configuration for setting a suitable gain value is also conceivable. An example of the operation of the histogram analysis unit 12 will be described with reference to FIG.

<1.2.2 Second Operation Example>
FIG. 5 is a flowchart showing the flow of gain value setting processing in the present embodiment. In step S10 shown in FIG. 5, the histogram analysis unit 12 sets an initial gain value as a first reference. Here, since the pixel value (liquid crystal light transmittance) of the display element increases as the gain value increases, the backlight luminance can be reduced, so that the gain value G is higher in order to reduce power consumption. Is preferred. However, if the gain value G is set too high, the display quality may deteriorate. Therefore, in step S10, the initial gain value is set small. Then, it becomes easy to obtain the maximum gain value that does not deteriorate the display quality as described below.

  Next, in step S20, the histogram analysis unit 12 multiplies pixel values (gradation values) of all or some of the pixels included in the input image represented by the input image data Dp by the initial gain value. (That is, perform correction) and calculate the number of pixels or the ratio (hereinafter referred to as “error amount”) in which the obtained value exceeds the largest pixel value (for example, 255) that can be displayed on the display device. Process.

  The error amount is configured to be counted equally in all the pixels, but a configuration may be adopted in which a higher weight is applied to a pixel having a gradation value close to the maximum pixel value. That is, the total amount of error amounts corresponding to the difference from the pixel value of each pixel to the maximum pixel value may be calculated.

  Subsequently, in step S30, the histogram analysis unit 12 determines whether or not the error amount obtained in step S20 is equal to or greater than a predetermined limit amount (for example, 20% of the total number of pixels) that allows an acceptable video failure. If the limit amount is not exceeded (No in step S30), a value obtained by adding a predetermined value from the initial gain value is calculated as a new initial gain value (step S40), and the new initial gain is calculated. The process of calculating the error amount by using the value (S20) is performed, and these processes are repeated until the obtained error amount becomes equal to or greater than the above limit amount (S30 → S40 → S20 → S30).

  As a result of the determination in step S30, if the error amount is greater than or equal to the limit amount (Yes in step S30), the histogram analysis unit 12 performs processing for determining the initial gain value as the gain value G (step S50).

  Next, in step S60, the histogram analysis unit 12 calculates the luminance of the backlight in each liquid crystal display device based on the gain value G determined in step S50, and the backlight luminance for the liquid crystal display devices 61 to 69 is calculated. Output as data BL.

  Here, for example, when the gain value is 1.25, that is, when the pixel value (liquid crystal light transmittance) of the liquid crystal display element is increased by 125%, the backlight luminance is the reciprocal 1 / 1.25 (= 0.8). Do not mean. This is because display devices generally have a so-called gamma characteristic in which the relationship between output gradation and input gradation is not linear.

Therefore, from the gamma value γ and the gain value G in the liquid crystal display devices 61 to 69, the backlight luminance BL indicating the above ratio (here, the same sign as the backlight luminance data BL is used) is expressed by the following equation (1). It is expressed as follows.
BL [%] = 1 / G ^ γ × 100 (1)

  Therefore, for example, when the gamma value γ in the liquid crystal display devices 61 to 69 is 2.2 and the gain value G is 1.25, the backlight luminance BL is about 61.2 [% from the above equation (1). ] (≈1 / 1.25 ^ 2.2 × 100). In this case, the pixel value actually displayed on the display element (corresponding to the display data) is about 163 due to the gamma characteristic except for the portion where the output gradation reaches the maximum in FIG. 3 or FIG. [%] (= 1.25 ^ 2.2 × 100).

  As described above, the histogram analysis unit 12 calculates and outputs the backlight luminance data BL. Since the backlight luminance BL is obtained by substituting the gain value G and the gamma value γ into the above equation (1), It may be configured to output the gain value G. In this case, in the liquid crystal display devices 61 to 69, the backlight luminance BL is calculated based on the above formula (1).

  Further, when the gamma value γ is different in each of the liquid crystal display devices 61 to 69 or different from a predetermined value, all the gamma values of the main display devices are stored, and the product used for the display device The gamma value corresponding to may be used selectively.

  The gain adjustment unit 14 receives the nine divided image data Ds1 to Ds9 generated by the conversion processing in the image division output unit 13 and the gain value G calculated by the above processing in the histogram analysis unit 12 as described above, Correction for multiplying the divided image data Ds1 to Ds9 by a gain value G is performed. Thus, the output image data Da1 to Da9 corrected so that the pixel value is increased based on the gain value G in the gain adjusting unit 14 is provided to the corresponding liquid crystal display devices 61 to 69, respectively.

  The functions of the image processing apparatus 10 as described above are realized by hardware including a predetermined logic circuit corresponding to each of the above components, but a computer having a storage unit such as a CPU (Central Processing Unit) and a semiconductor memory In the above, functions corresponding to the above-described components may be realized by predetermined software.

  As described above, if the gain value is calculated by the process as shown in FIG. 5 and applied to the pixel value of each pixel of the display image, the error amount becomes about the above limit amount, and thus there is a video failure. The degree is suppressed. Therefore, since the maximum gain value G that suppresses the video failure to some extent can be set, the backlight luminance can be reduced while suppressing the video failure to some extent. Next, a specific configuration of a liquid crystal display device that receives a corresponding one of the backlight luminance data BL and the divided image data Ds1 to Ds9 will be described with reference to FIG.

<1.3 Configuration and Operation of Liquid Crystal Display Device>
FIG. 6 is a block diagram showing a configuration of the liquid crystal display device 61. As shown in FIG. 6, the liquid crystal display device 61 receives the corresponding divided image data Ds1 from the image processing device 10 and performs image adjustment, and the backlight luminance received from the image processing device 10. An image control unit 16 that outputs a backlight control signal Cb based on the data BL and user instruction information UC to be described later, a liquid crystal control unit 18 and a liquid crystal display unit 19a for displaying the adjusted image data Dc that has undergone image adjustment, And a backlight unit 19b.

  As shown in FIG. 6, the image signal adjustment unit 15 receives the corresponding divided image data Ds1 from the image processing apparatus 10, and also receives the image from the user (attached to a remote controller or a housing via the image control unit 16). User instruction information UC for image adjustment (by operating a switch or the like) is received. The adjustment mode of the image specified by the user instruction information UC is an adjustment mode set in advance so as to be suitable for the use and display mode of the image tone mode (for example, dynamic, standard, PC, cinema, etc.) as in a general video display device. Mode) setting, brightness adjustment, contrast adjustment, color temperature adjustment, and color balance adjustment. Here, when correction is performed such that the pixel brightness is increased by the above adjustment, even if a suitable gain adjustment is performed, the increase in brightness may actually be too large. In some cases, the user can further adjust the amount of increase in pixel luminance by further adjustment.

  The image control unit 16 functions as an input / output interface with the outside, and the backlight luminance indicated by the backlight luminance data BL received from the image processing device 10 is used as the backlight control signal Cb to the backlight unit 19b. give. Further, the image control unit 16 transmits common control information Cs including user instruction information UC and external environment information so that the liquid crystal display devices 61 to 69 can share the common control information Cs. This point will be described later.

  Here, instead of placing the backlight luminance BL in a state unrelated to the image adjustment result, a configuration in which the image adjustment result is reflected in the backlight luminance BL is also conceivable. In order to realize this configuration, it is difficult to determine the gain value G from the enlarged image as described above, and when it is determined in each display device, the luminance distribution of the image formed (displayed on a large screen) Is uneven and not valid.

  Therefore, in order to uniformly reflect the result of the image adjustment on the backlight luminance BL, the amount of change (for example, change ratio) of the backlight luminance BL corresponding to the aspect of the image adjustment is previously set for each of the liquid crystal display devices 61 to 69. The gain values after the change are set to be the same in all the liquid crystal display devices. This configuration corresponds to a modification of the above embodiment.

  For example, when the adjustment mode of the image specified by the user instruction information UC is “dynamic” in the above-described image adjustment mode, a pixel value that is close to the correction mode based on the gain value for reducing the backlight luminance as a result. It is conceivable that an increasing correction is performed. In this case, for example, an example in which the gain value G is uniformly multiplied by 0.8 can be considered.

  With the configuration of the modified example as described above, it is possible to set the backlight luminance that uniformly reflects the image adjustment result. In particular, when the image adjustment yields the same result as an increase in the gain value, a suitable backlight luminance can be set. And can be displayed in a suitable display mode reflecting the image adjustment result by the user. In this case, since the image adjustment result is uniformly reflected, the image brightness does not become different in each liquid crystal display device, and the display quality can be kept from deteriorating. For this reason, it is not necessary to make further adjustment as in the case of the first embodiment, and the increase amount of the pixel luminance does not become too large, and thus it can be said to be a preferable configuration.

<1.4 Information sharing operation between liquid crystal display devices>
Further, as described above, the image control unit 16 transmits the common control information Cs including the user instruction information UC and the external environment information so as to be shared by the liquid crystal display devices 61 to 69. For example, when user instruction information UC is received in one of the liquid crystal display devices 61 to 69, the same user instruction is transmitted by transmitting the common control information Cs including the information to all the liquid crystal display devices 61 to 69. Share information UC. When a plurality of items are received, by predefining the priority relationship (for example, by defining the last user instruction information UC), one user instruction information UC is shared.

  In order to share the user instruction information UC among such liquid crystal display devices 61 to 69, each needs to be connected by a signal line capable of transmitting the information, and the configuration is typically the simplest. It is preferable that they are connected by a daisy chain method. Then, information can be easily shared with a small number of signal lines. Here, the image processing apparatus 10 is also preferably connected to the liquid crystal display devices 61 to 69 in a daisy chain manner. Then, the backlight brightness BL can be similarly transmitted to the liquid crystal display devices 661 to 69 with a simple configuration. Note that the above connection method is an example, and a known signal transmission network such as a wireless LAN method may be used.

  Here, when the correction using the gain value G as described above is performed, the correction amount in the vicinity of the low gradation is relatively small (that is, the gradation is not greatly increased), so that the display quality is lowered. It seems to be. Therefore, the effect of this embodiment will be described with reference to FIG.

<1.5 Effects of this embodiment>
FIG. 7 is a diagram for explaining that the display quality can be prevented from being deteriorated by the configuration of the present embodiment. According to the characteristic curve E indicating the relationship between the input gradation and the output luminance in the normal display state in the liquid crystal display device shown in FIG. 7, an easy-to-see normal display screen can be provided, but the backlight luminance is high. Not reduced. Here, if only the backlight output is reduced to 60%, the relationship between the input gradation and the output luminance becomes the characteristic curve C, so that the display state is insufficient as a whole. Therefore, in order to reduce the backlight luminance while maintaining the necessary display luminance, it is necessary to increase the output gradation corresponding to the pixel value.

  However, the display luminance (pixel value) in the liquid crystal display device cannot exceed the output gradation 100% (for example, gradation value 255) which is the display limit. Therefore, when the backlight luminance is reduced, it is not actually possible to provide the same display screen as the characteristic curve E. Therefore, by multiplying the characteristic curve C by the gain value G as described above, the portion corresponding to the display limit on the high gradation side becomes the same gradation, but as described above, the display quality is reduced as much as possible in the histogram analysis unit 12. Since the suppressed gain value G and backlight luminance BL are calculated, a characteristic curve D with reduced backlight luminance can be obtained without degrading the display quality in the present embodiment.

  As described above, the image processing apparatus 10 included in the multi-display device 100 according to the present embodiment typically displays one image on the liquid crystal display devices 61 to 69 arranged so as to be adjacent in a matrix. The backlight luminance can be further reduced without causing display defects such as video failure.

  In addition, by calculating the gain value using the frequency distribution of pixel values such as histogram analysis and performing pixel value correction, the display quality is not deteriorated in an average or statistically suitable manner as the entire pixel. Can be.

<2. Second Embodiment>
<2.1 Overall configuration and operation>
FIG. 8 is a block diagram showing a configuration of a multi-display apparatus according to the second embodiment of the present invention. As shown in FIG. 8, the multi-display device 200 is similar to the multi-display device 100 according to the first embodiment shown in FIG. 1, and includes an image processing device 20 and nine liquid crystal display devices 71 to 79. The image display system includes: typically, one image is displayed on nine display screens.

  However, unlike the image processing apparatus 10 according to the first embodiment, the image processing apparatus 20 according to the present embodiment does not include a gain adjustment unit, and the gain adjustment unit is included in the liquid crystal display devices 71 to 79. Each is provided.

  That is, as illustrated in FIG. 8, the image processing apparatus 20 includes an image resolution conversion unit 21 that performs the same operation as the image resolution conversion unit 11 in the first embodiment, and an image division similar to the image division output unit 13. Although the output unit 23 and the histogram analysis unit 22 similar to the histogram analysis unit 12 are provided, the components corresponding to the gain adjustment unit 14 in the first embodiment are provided in the liquid crystal display devices 71 to 79, respectively. . Hereinafter, the configuration of the liquid crystal display device 71 will be described in detail with reference to FIG. 9 as an example. In the following, the image processing device 20 will be described as a device different from the liquid crystal display devices 71 to 79, but may be incorporated in any of these cases.

<2.2 Configuration and operation of liquid crystal display device>
FIG. 9 is a block diagram showing a configuration of the liquid crystal display device 71. As shown in FIG. 9, the liquid crystal display device 71 receives the corresponding divided image data Ds1 from the image processing device 20 and performs image adjustment, and the adjusted image data Dc adjusted thereby. On the other hand, a gain adjusting unit 27 that performs gain adjustment based on the corresponding gain value G received from the image processing device 20, a liquid crystal control unit 18 and a liquid crystal display unit 19a for displaying the output image data Dv that has been gain adjusted. And a backlight unit 19b.

  As can be seen from a comparison of the configuration of the liquid crystal display device 71 shown in FIG. 9 with the configuration of the liquid crystal display device 61 shown in FIG. Except for being different from the above, since they have similar components and operate in the same manner, detailed description of these components will be omitted. However, in the present embodiment, unlike the first embodiment, the backlight luminance data BL is not given to the image control unit 26. However, as described above, it can be easily calculated from the above equation (1). It is. Of course, the image control unit 26 may be provided with backlight luminance data BL.

  Here, in the first embodiment, the image adjustment performed in the image signal adjustment unit 25 is performed on the image after the gain adjustment in the gain adjustment unit 14. Finally, the gain cannot be adjusted for the image. On the other hand, in the configuration of the present embodiment, gain adjustment can be performed finally (finally), so that suitable gain adjustment can be performed so as not to affect the adjustment result.

  Here, instead of placing the gain value G in a state unrelated to the image adjustment result, a configuration in which the image adjustment result is reflected in the gain value G is also conceivable. In order to realize this configuration, it is difficult to determine the gain value G from the enlarged image as described above, and it is formed when the gain value is determined in each display device (the gain adjusting unit 27 thereof) (large The luminance distribution of the image (displayed on the screen) becomes uneven and is not appropriate.

  Therefore, in order to uniformly reflect the result of the image adjustment with respect to the change of the gain value G, the change amount (for example, change ratio) of the gain value G corresponding to the image adjustment mode is set in advance to each of the liquid crystal display devices 71 to 79. The gain values after the change are set to be the same in all the liquid crystal display devices. This configuration corresponds to a modification of the above embodiment.

  For example, when the image adjustment mode specified by the user instruction information UC is “dynamic” in the above-described image adjustment mode, correction that increases the pixel value is performed, which is close to the correction mode based on the gain value that increases the pixel value. It is possible that Therefore, for example, an example in which the gain value G is uniformly multiplied by 0.8 can be considered.

  With the configuration of the modified example as described above, it is possible to set a gain value that uniformly reflects the image adjustment result. In particular, when the image adjustment yields a result similar to the setting of the gain value for increasing the pixel value. Therefore, it is possible to set a suitable gain value and perform display in a suitable display mode reflecting the image adjustment result by the user. In this case, since the image adjustment result is uniformly reflected (with respect to the gain value), the display quality can be maintained without different image brightness in each liquid crystal display device.

<2.3 Effects of this embodiment>
As described above, in the present embodiment, in addition to the effects of the first embodiment, the gain adjustment unit 27 can finally (finally) perform gain adjustment, and is thus specified by the user instruction information UC. Since the result of the image adjustment is not affected, a suitable gain adjustment can be performed. Therefore, the display quality can be prevented from being lowered by the gain adjustment.

<3. Third Embodiment>
<3.1 Overall configuration and operation>
FIG. 10 is a block diagram showing a configuration of a multi-display apparatus according to the third embodiment of the present invention. As shown in FIG. 10, the multi-display device 300 is similar to the multi-display device 100 according to the first embodiment shown in FIG. 1, and includes an image processing device 30 and nine liquid crystal display devices 61 to 69. The image display system includes: typically, one image is displayed on nine display screens.

  That is, as illustrated in FIG. 10, the image processing apparatus 30 includes an image resolution conversion unit 31 that performs the same operation as the image resolution conversion unit 11 in the first embodiment, and an image division similar to the image division output unit 13. An output unit 33 and a gain adjustment unit 34 similar to the gain adjustment unit 14 are provided, but unlike the histogram analysis unit 12, the histogram analysis unit 32 in the present embodiment receives external information from various sensors and input devices not shown. Is is received, and the gain value Gc is determined based on the external information Is. Hereinafter, the contents of the external information Is and the operation of the gain adjusting unit 34 will be described in detail. In the following, the image processing device 30 will be described as a device different from the liquid crystal display devices 61 to 69, but may be built in any of these cases, and the same applies to the following embodiments. And

<3.2 Operation of Histogram Analysis Unit>
The determination method of the gain value Gc in the histogram analysis unit 32 shown in FIG. 10 is almost the same as the determination method of the gain value G in the histogram analysis unit 12 described in the first embodiment and the point of using the external information Is. Although the content is the same, the setting mode of the target gain value corresponding to the initial gain value is different from the setting mode of the backlight luminance. Hereinafter, the setting of the gain value and the backlight luminance will be described with reference to FIG.

  FIG. 11 is a flowchart showing the flow of gain value setting processing in the present embodiment. In step S5 shown in FIG. 11, the histogram analysis unit 12 determines the backlight brightness BL based on the external information Is. Here, the external information Is refers to information that should influence power consumption reduction and image display, including external environment information and user instruction information UC in the first embodiment. For example, external light information indicating ambient brightness acquired by a light sensor (not shown), luminance setting information specified by a user's operation input (for a remote controller, etc.), power consumption reduction given via an internal timer or the Internet Examples include time, date, and weather information for predicting the necessity of data, and data indicating power consumption in the surrounding area. For example, since power consumption is closely related to time, date, and weather, the above backlight is used to reduce power consumption as much as possible at the peak of power consumption or shift the peak of power consumption. The brightness BL is determined. Further, the backlight luminance BL is similarly determined with reference to data indicating the power consumption in the surrounding area in the next generation power transmission network.

  Further, for example, whether or not the power consumption may be reduced may be detected by a human sensor that detects whether or not a person is present in the vicinity, and the backlight luminance BL may be set according to the detection result. For example, when it is detected that there is no person, the backlight brightness BL is set to be small in order to greatly reduce the power consumption, and when it is detected that there is a person, the power consumption is greatly reduced. Even if it cannot be performed, it is also conceivable that the histogram analyzer 32 performs an operation such that the display quality is not lowered as much as possible by setting the backlight luminance BL to be large. In this way, the backlight brightness BL can be suitably set according to the external situation (for example, the presence or absence of a person who sees the display).

  In step S <b> 10 shown in FIG. 11, unlike the case of the first embodiment, the histogram analysis unit 12 sets a target gain value as a first reference based on the backlight luminance BL. That is, a gain value corresponding to the determined backlight brightness is calculated based on the above formula (1) and set as a target gain value.

  For example, when the value of the backlight brightness BL is set to 50 [%] in order to reduce power consumption as much as possible at the time of peak power consumption or the like, calculation is performed by substituting the value corresponding to the above equation (1). The target gain value G = 1.37 (= (100/50) ^ (1 / 2.2)).

  When the target gain value is determined in this way, the error amount is calculated in the same manner as in the first embodiment (step S20). Subsequently, in step S35, the histogram analysis unit 12 determines whether or not the error amount obtained in step S20 is equal to or less than the allowable limit amount for the predetermined video failure (step S35). In the case of No), a value obtained by subtracting a predetermined value from the target gain value is calculated as a new target gain value (step S45), and an error amount is calculated by using the new target gain value. (S20) is performed, and these processes are repeated until the obtained error amount does not exceed the above limit amount (S35 → S45 → S20 → S35).

  As a result of the determination in step S35, when the error amount is equal to or smaller than the limit amount (in the case of Yes in step S35), the histogram analysis unit 12 performs processing for determining the target gain value as the gain value G (step S50). Note that step S60 shown in FIG. 5 is omitted because it is naturally unnecessary in FIG.

<3.3 Effects of this embodiment>
As described above, in the present embodiment, in addition to the effects of the first embodiment, the histogram analysis unit 32 can set a suitable gain value G according to the external situation, particularly the necessity of reducing power consumption. it can. This makes it possible to reduce the luminance of the backlight and reduce the power consumption at an appropriate time when there is a great need for power consumption reduction.

<4. Fourth Embodiment>
<4.1 Overall configuration and operation>
FIG. 12 is a block diagram showing a configuration of a multi-display apparatus according to the fourth embodiment of the present invention. As shown in FIG. 12, the multi-display device 400 is similar to the multi-display device 100 according to the first embodiment shown in FIG. 1, and includes an image processing device 40 and nine liquid crystal display devices 61 to 69. In this case, a plurality of images are displayed on a large screen composed of nine display screens.

  That is, as illustrated in FIG. 12, the image processing device 40 includes an image resolution conversion unit 41 that performs the same operation as the image resolution conversion unit 11 in the first embodiment, and an image division similar to the image division output unit 13. And an output unit 43.

  However, unlike the gain adjustment unit 14, the gain adjustment unit 44 of the present embodiment uses a plurality of gain values Ga that are individually set corresponding to a plurality of input image areas. Unlike the histogram analysis unit 12, the area-specific histogram analysis unit 42 outputs a gain value Ga for each area in the first embodiment. This is greatly different from the configuration of the first embodiment. Hereinafter, the operations of the area-specific histogram analysis unit 42 and the gain adjustment unit 44 will be described in detail.

<4.2 Operation of Histogram Analysis Unit by Area>
In the present embodiment, as described above, a plurality of images corresponding to a plurality of image areas are included in the input image represented by the input image data Dp. For example, the following first to third examples can be considered for the arrangement of the images. Hereinafter, each will be described with reference to FIGS. 13 to 15. In addition to the following examples, various display modes are conceivable, and in this embodiment, a mode in which a plurality of image areas are arranged may be used.

  FIG. 13 is a diagram for explaining a first display screen example in the embodiment. As shown in FIG. 13, the configuration of the large screen formed by the display screens of the liquid crystal display devices 61 to 69 is the same as the screen shown in FIG. 2 described in the first embodiment. In FIG. 1, the first to fourth divided display images 601 to 604 are displayed instead of one image. The divided display images 601 to 604 are images having different contents, and four images are synthesized at appropriate positions by an input image data generation device (not shown). Since the divided display images 601 to 604 are not related to the contents, the display luminances of the divided display images 601 to 604 are different from each other, but to some extent (as one image) in one divided display image. Uniform luminance distribution. Therefore, in order to increase the pixel value of each image, it is preferable to perform a histogram analysis for each image and calculate a gain value for each image.

  FIG. 14 is a diagram for explaining a second display screen example in the embodiment. As shown in FIG. 14, the configuration itself of the large screen formed by the display screens of the liquid crystal display devices 61 to 69 is the same, but this large screen is not a single image but an entire large image. Are displayed so as to include a small insertion image 605. Such a display mode is also called PinP (Picture in Picture). The inserted image 605 is an image having a content different from that of the entire image including the inserted image 605 and is synthesized so as to be inserted at an appropriate position of the entire image by an input image data generation device (not shown). Since the inserted image 605 is not related to the content of the entire image, the display luminance is different, but the luminance distribution is uniform to some extent (as one image) in each image. . Therefore, in order to increase the pixel value of each image, it is preferable to perform a histogram analysis for each image and calculate a gain value for each image.

  Further, FIG. 15 is a diagram for explaining a third display screen example in the embodiment. As shown in FIG. 15, the configuration itself of the large screen formed by the display screens of the liquid crystal display devices 61 to 69 is the same, but this large screen is not a single image but a single image. The item display image 606 is displayed so as to be included in such a manner that it is superimposed on the image. Such a display mode is also called OSD (On Screen Display). This item display image 606 is an image having a content different from that of the entire image including the item display image 606. The input image data generation device or the present image processing device 40 (not shown) displays the item display image 606 as a display image for the user interface. It is overwritten and synthesized at an appropriate position. The item display image 606 is not related to the contents of the entire image and is basically a computer composite image, and thus the display brightness differs greatly. As a uniform image). Therefore, in order to increase the pixel value of each image, it is preferable to perform a histogram analysis for each image and calculate a gain value for each image.

  As described above, when a plurality of images with different luminance distribution states are included in the input image, the area-specific histogram analysis unit 42 increases the pixel value of each image. An analysis is performed to calculate a plurality of gain values Ga corresponding to each. The histogram analysis method and the gain value calculation method are the same as those in the first embodiment, and are different only in that they are performed separately for each image. Therefore, description of the calculation method is omitted.

  The backlight luminance BLa is calculated based on the above equation (1) as well as in the case of the first embodiment, in addition to the method for calculating the backlight luminance BLa. When the backlight brightness BLa is calculated for each area and given to the corresponding liquid crystal display device, the liquid crystal display device adopts an area active drive method (or local dimming drive method) that controls the backlight brightness for each area. Need to be. However, even if such a driving method is not employed, the backlight luminance of each of the liquid crystal display devices 61 to 69 can be calculated differently. By appropriately setting the value Ga, the backlight luminance can be determined so that the power consumption is further reduced.

  Here, the area-specific histogram analysis unit 42 also calculates which area (position) of the input image represented by the input image data Dp is a plurality of image areas that are to be subjected to histogram analysis. Output as position information Ia.

  Here, since the display positions of the divided display images 601 to 604 shown in FIG. 13 are determined in advance, the area-specific histogram analysis unit 42 does not need to particularly calculate and output the positions. In addition, when the item display image 606 shown in FIG. 15 is output by an image synthesis output unit (not shown) in the image processing apparatus 40, the area-specific histogram analysis unit 42 can receive the position, so if it is output as it is. Good. Furthermore, if the insertion position of the insertion image 605 shown in FIG. 14 can be received from an external device, it may be output as it is. However, if the position information cannot be received, the area-specific histogram analysis unit 42 detects the boundary portion of each image with a known differential filter or the like, and calculates the position of each image area in the entire input image. For such image position detection or region detection, any method such as well-known pattern recognition analysis may be applied in addition to the method of detecting the boundary portion.

  Note that the area-specific histogram analysis unit 42 does not perform histogram analysis on the enlarged image represented by the enlarged image data Dpu converted by the image resolution conversion unit 41, but here is the target of the histogram analysis. The position of each image area in the magnified image is calculated (typically, a three-fold coordinate value according to the magnification) and is output as area position information Ia. The plurality of gain values Ga and area position information Ia calculated as described above are given to the gain adjusting unit 44. The operation of the gain adjusting unit 44 will be described.

<4.3 Operation of gain adjustment unit>
The gain adjusting unit 44 multiplies the pixel value (gradation value) in the area by the gain value Ga calculated for each area of the input image corresponding to the plurality of images, thereby obtaining the pixel value. Make corrections to increase. This correction content is the same as that of the first embodiment, and is different from that of the first embodiment only in that the target is limited to the corresponding image area.

  Here, it is rare that the image area includes only one image area on the display screen of each of the liquid crystal display devices 61 to 69, and usually includes a plurality of image areas. That is, in a normal case, one image area is displayed over a plurality of display screens. Therefore, a plurality of gain values may be required for one display screen among the liquid crystal display devices 61 to 69. For example, the gain adjustment unit 44 is one image represented by the divided image data Ds, and one of the two image areas (for example, the first image) included in the image displayed on the one display screen. The pixel value in the area) is multiplied by the first gain value, and the pixel value in the other image area (for example, the second image area) is multiplied by the second gain value.

  Specifically, when the divided display images 601 to 604 shown in FIG. 13 are displayed on each display screen, since the display screen of the liquid crystal display device 61 includes only the divided display image 601, the corresponding gain value is Although the display screen of the liquid crystal display device 62 includes the divided display images 601 and 602, the corresponding gain value is two.

  In this way, in the image represented by the divided image data Ds, which part of the pixel value is multiplied by which gain value can be easily calculated from the area position information Ia. That is, for example, since the image represented by the divided image data Ds1 is determined in advance to be disposed at the upper left position shown in FIG. 13, the arrangement of the image with respect to the enlarged image represented by the enlarged image data Dpu. The position is predetermined. Therefore, it is easy to calculate which part of the pixel value is multiplied by which gain value in each image indicated by the divided image data Ds1 to Ds9 from the position in the enlarged image of each image area indicated by the area position information Ia. Can do.

<4.4 Effects of the present embodiment>
As described above, in the present embodiment, in addition to the effects of the first embodiment, when an input image includes a plurality of images, a gain value suitable for each image can be set. Accordingly, the brightness can be increased for a dark image, for example, according to the content of the image, so that the display quality of the displayed image can be prevented from further decreasing for each region.

  Further, in the case of an image using OSD as shown in FIG. 15, since the difference in luminance (average value) in a plurality of image areas is large, one pixel value correction affects the other pixel value correction. In particular, it is possible to prevent the display quality of the displayed image from being deteriorated for each region by the configuration that is performed individually so as not to give the image.

<5. Fifth Embodiment>
<5.1 Overall configuration and operation>
FIG. 16 is a block diagram showing a configuration of a multi-display apparatus according to the fifth embodiment of the present invention. As shown in FIG. 16, this multi-display device 500 is similar to the multi-display device 400 according to the fourth embodiment shown in FIG. 12, and includes an image processing device 50, nine liquid crystal display devices 61 to 69, and The image display system includes a plurality of input image data provided to the image processing apparatus 50.

  That is, as shown in FIG. 16, the image processing apparatus 50 includes an image resolution conversion unit 51, an area-specific histogram analysis unit 52, an image division output unit 53, and a gain adjustment unit 54 similar to those in the fourth embodiment. However, one input image does not include a plurality of image areas, but differs in that one display image is formed by four images corresponding to the four input image data Dp1 to Dp4.

  In addition, the image resolution conversion unit 51 outputs enlarged image data Dpu1 to Dpu4 representing four enlarged images obtained by enlarging the input images represented by the input image data Dp1 to Dp4, respectively, in the fourth embodiment. It is different from the case of form.

  That is, the image resolution conversion unit 51 displays four input images having a predetermined resolution represented by the input image data Dp1 to Dp4 on the large screen, that is, the entire display screens of the nine liquid crystal display devices 61 to 69. Perform the process of enlarging. Of course, by simply compositing four input images, if the size is suitable for display on the entire display screen, enlargement processing is not necessary, but here, appropriate enlargement processing is performed. And

  Here, it is not necessary to perform the process of combining the images into one enlarged image. The image division output unit 53 easily divides the divided images represented by the divided image data Ds1 to Ds9 by synthesizing a plurality of corresponding regions at appropriate positions from the four enlarged images appropriately enlarged. It is because it can produce | generate.

  As described above, the operations of the image resolution conversion unit 51 and the image division output unit 53 are slightly different from those in the fourth embodiment, but the image displayed on the entire display screen is the same as the example shown in FIG. Therefore, the histogram analysis processing and gain value calculation processing in the area-specific histogram analysis unit 52, the gain value multiplication processing in the gain adjustment unit 54, and the like are the same as in the fourth embodiment. As described above, since the display positions of the divided display images 601 to 604 shown in FIG. 13 are determined in advance, the area-specific histogram analysis unit 52 determines the position in the same manner as the area-specific histogram analysis unit 42. It is not necessary to calculate and output the area position information Ia.

<5.2 Effects of this embodiment>
As described above, in the present embodiment, the same effects as in the first and fourth embodiments can be achieved. That is, the display quality of the displayed image can be prevented from further decreasing for each region.

10, 20, 30, 40, 50 ... image processing apparatus 11, 21, 31, 41, 51 ... image resolution conversion unit 12, 22, 32 ... histogram analysis unit 13, 23, 33, 43, 53 ... image division output unit 14, 27, 34, 44, 54... Gain adjustment unit 15, 25... Image signal adjustment unit 16, 26... Image control unit 18... Liquid crystal control unit 19a. Analysis unit 61-69, 71-79 ... Liquid crystal display device 100-500 ... Multi-display device

Claims (4)

Based on input image data, output image data to be given to display elements arranged on each display screen in a plurality of display devices arranged in a line or a plane, and each backlight provided in the plurality of display devices An image processing apparatus that outputs backlight luminance data representing the emission luminance of
An image resolution conversion unit that converts an input image represented by the input image data into a display resolution for display on the display screen and outputs the image as enlarged image data;
An image division output unit that divides an enlarged image represented by the enlarged image data output from the image resolution conversion unit into each image to be displayed on the display screen, and outputs the divided image data as a plurality of divided image data;
Based on the input image data, pixel value correction data corresponding to the image to be displayed on the display screen is calculated so that a pixel value given to the display element to be represented by the output image data is increased. And a correction data calculation unit that calculates and outputs the backlight luminance data so that the emission luminance of the backlight decreases.
An image signal processing unit that outputs output image data obtained by correcting pixel values of an image represented by the divided image data based on the pixel value correction data output from the correction data calculation unit;
The correction data calculation unit
Calculating a value indicating a frequency distribution of pixel values included in the input image data, and calculating the pixel value correction data based on the calculated value;
When the input image includes a plurality of different images, a value indicating a frequency distribution of pixel values in the image is calculated for each of the plurality of images, and each of the images of the plurality of images is calculated. for each, along with calculating and outputting the pixel value correction data so that the pixel values of the image within the enlarged image corresponding increases in the image based on the calculated the value, so that the light emission luminance of the backlight is reduced And calculating and outputting a number of the backlight luminance data corresponding to one or the plurality of divided image data ,
The image signal processing unit, when the input image includes a plurality of different images,
A division including at least a part of one image in the enlarged image corresponding to any one of the plurality of images in the input image among the plurality of divided images represented by the plurality of divided image data. The output image data is generated by correcting the pixel value of the image based on the pixel value correction data calculated by the correction data calculation unit for the one image in the input image,
At least each of two or more images in the enlarged image corresponding to any two or more images in the plurality of divided images in the input image among the plurality of divided images represented by the plurality of divided image data. Based on the two or more pixel value correction data respectively calculated by the correction data calculation unit for the two or more images in the input image, the pixel values of the two or more images in the divided image including a part. By correcting each, the output image data is generated ,
The correction data calculation unit
Based on the value indicating the frequency distribution, when the frequency distribution is biased toward the low luminance side, the gain value is set so that the pixel value of the image to be displayed is increased compared to the case where the frequency distribution is biased toward the high luminance side,
It is determined whether a value obtained by multiplying at least a part of pixel values of the input image represented by the input image data by the set gain value exceeds a maximum pixel value that can be displayed on the display device. If the number or ratio of pixels determined to exceed is less than a predetermined threshold, the set gain value is increased, and the number or ratio of pixels determined to exceed is greater than or equal to the threshold. In this case, the set gain value is determined as the gain value to be multiplied with the pixel value of the image represented by the divided image data,
Output the determined gain value as the pixel value correction data, calculate and output the backlight luminance data based on the determined gain value,
The image signal processing unit outputs the output image data based on a value obtained by multiplying the pixel value of an image represented by the divided image data by the determined gain value. An image processing apparatus. The correction data calculation unit resets a gain value obtained by increasing the set gain value by a predetermined increase amount as a new gain value, and at least some pixels of the input image represented by the input image data It is determined whether a value obtained by multiplying the value by the reset gain value exceeds a maximum pixel value that can be displayed on the display device, and the number or ratio of pixels determined to exceed the predetermined value is a predetermined value. When the value is less than the threshold, the set gain value is increased by a predetermined amount, and the set gain is increased by the predetermined amount until it is determined to be equal to or greater than the threshold, and the determination is performed. When the number or ratio of pixels determined to exceed the threshold value is equal to or greater than the threshold value, the set gain value is compared with the pixel value of the image represented by the divided image data. And wherein the determining, as the gain value to be multiplied Te, the image processing apparatus according to claim 1. Based on input image data, output image data to be given to display elements arranged on each display screen in a plurality of display devices arranged in a line or a plane, and each backlight provided in the plurality of display devices An image processing apparatus that outputs backlight luminance data representing the emission luminance of
An image resolution conversion unit that converts an input image represented by the input image data into a display resolution for display on the display screen and outputs the image as enlarged image data;
An image division output unit that divides an enlarged image represented by the enlarged image data output from the image resolution conversion unit into each image to be displayed on the display screen, and outputs the divided image data as a plurality of divided image data;
Based on the input image data, pixel value correction data corresponding to the image to be displayed on the display screen is calculated so that a pixel value given to the display element to be represented by the output image data is increased. And a correction data calculation unit that calculates and outputs the backlight luminance data so that the emission luminance of the backlight decreases.
An image signal processing unit that outputs output image data obtained by correcting pixel values of an image represented by the divided image data based on the pixel value correction data output from the correction data calculation unit;
The correction data calculation unit
Calculating a value indicating a frequency distribution of pixel values included in the input image data;
Based on the value indicating the frequency distribution, when the frequency distribution is biased toward the low luminance side, the gain value is set so that the pixel value of the image to be displayed is increased compared to the case where the frequency distribution is biased toward the high luminance side,
It is determined whether a value obtained by multiplying at least a part of pixel values of the input image represented by the input image data by the set gain value exceeds a maximum pixel value that can be displayed on the display device. If the number or ratio of pixels determined to exceed is less than a predetermined threshold, the set gain value is increased, and the number or ratio of pixels determined to exceed is greater than or equal to the threshold. In this case, confirm the set gain value,
Output the determined gain value as the pixel value correction data, calculate and output the backlight luminance data based on the determined gain value,
The image signal processing unit outputs the output image data based on a value obtained by multiplying the pixel value of an image represented by the divided image data by the determined gain value. An image processing apparatus. The correction data calculation unit resets a gain value obtained by increasing the set gain value by a predetermined increase amount as a new gain value, and at least some pixels of the input image represented by the input image data It is determined whether a value obtained by multiplying the value by the reset gain value exceeds a maximum pixel value that can be displayed on the display device, and the number or ratio of pixels determined to exceed the predetermined value is a predetermined value. When the value is less than the threshold, the set gain value is increased by a predetermined amount, and the set gain is increased by the predetermined amount until it is determined to be equal to or greater than the threshold, and the determination is performed. When the number or ratio of pixels determined to exceed the threshold value is equal to or greater than the threshold value, the set gain value is compared with the pixel value of the image represented by the divided image data. And wherein the determining, as the gain value to be multiplied Te, the image processing apparatus according to claim 3.

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