JP4684966B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device such as a digital television broadcast receiver.

  As a conventional image display device, for example, there is a digital television broadcast receiver disclosed in Patent Document 1. In the digital television broadcast receiver described in Patent Document 1, output video characteristics and output audio characteristics are set according to user preference for each genre based on genre information sent from a broadcasting station together with digital broadcast content. .

  A method for characterizing video content is disclosed in Patent Document 2, for example. In the histogram characterization method for video content described in Patent Document 2, a key frame in a video content is identified, a histogram is created from the key frame, and the boundary of the program and video are classified by classifying the histogram. You are searching for content.

Japanese Patent Laid-Open No. 10-322622 Japanese translation of PCT publication No. 2002-520747

  In Patent Document 1, genre information is sent simultaneously with content information in the case of digital broadcasting such as CS broadcasting. In other words, these pieces of content information including genre information are information that is not included in recorded video such as conventional analog broadcasting and DVD. In addition, the genre of the transmitted video is not necessarily correctly divided into the genres classified by the viewer. For example, the determination of whether the content is an animation or a movie is determined based on information sent from a broadcasting station, and may be different from the classification of viewers.

  In Patent Document 2, a genre identifies a key frame, decomposes it into a histogram based on the key frame, determines a genre from the classification of the histogram, and searches for a program boundary and a program in real time. There was a problem that it was not possible to judge by genre.

  In other words, because a key frame is a limited special frame of a predetermined number of frames, if a genre is determined from such a key frame, the video cannot necessarily be determined by genre in real time. There was a point.

  In consideration of the problems of the above-mentioned Patent Document 2, for example, a general feature is that image feature values are extracted in units of frames based on a luminance histogram of an input video signal, and image processing adapted to the feature of the content is performed. Although a technique is conceivable, there is a problem that a feature amount obtained from an image signal for one frame is not easily determined even in the same genre, and a problem may occur when image processing is performed.

  The present invention has been made to solve the above-described problems, and provides an image processing apparatus capable of maintaining real-time characteristics, accurately recognizing the characteristics of content obtained from an image signal, and performing gradation correction. The purpose is to obtain.

The image display device according to any one of claims 1 to 4 receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and obtains a luminance related information value from the histogram. A luminance information detection unit to detect; and a feature determination unit that performs feature determination of video content for the image signal for one frame and obtains a feature determination value based on the luminance-related information value output from the luminance information detection unit; The feature determination value output from the feature determination unit is analyzed based on the equivalent amount for a plurality of frames to obtain a plurality of feature determination values, and a newly obtained 1 based on the plurality of feature determination values A gradation correction unit that performs gradation correction on the image signal for the frame.

The image display device according to any one of claims 5 to 8 receives the image signal, creates a histogram relating to the luminance signal obtained from the image signal for one frame, and obtains the luminance related information value from the histogram. A luminance information detection unit to detect; and a feature determination unit that performs video content feature determination on the image signal for a plurality of frames and obtains a feature determination value based on the luminance-related information value output from the luminance information detection unit; And a gradation correction unit that performs gradation correction on the image signal for one frame that is newly obtained based on the feature determination related value related to the feature determination value.

The multiple feature detection unit in the image display device according to any one of claims 1 to 4 is configured to analyze a plurality of feature determination values by analyzing the feature determination values output from the feature determination unit for a plurality of frames. Therefore, it is possible to accurately determine the characteristics of the content obtained from the image signal.

  Then, the gradation correction unit performs gradation correction on a newly obtained image signal for one frame based on the plurality of feature determination values, so that gradation is automatically performed without performing a separate gradation correction operation. Correction can be performed.

  Furthermore, the feature determination unit can obtain a feature determination value at a relatively high speed by obtaining a feature determination value based on the luminance-related information value in the image signal for one frame.

The feature determination unit of the image display device according to any one of claims 5 to 8 obtains a feature determination value by performing a feature determination of video content with respect to the image signal for a plurality of frames, thereby obtaining a feature determination value with higher accuracy. Can do.

  Then, the gradation correction unit performs gradation correction on the newly obtained image signal for one frame based on the feature determination related value, so that the gradation is automatically adjusted without performing a separate gradation correction operation. Correction can be performed.

<Embodiment 1>
FIG. 1 is a block diagram showing a configuration of an image display apparatus according to Embodiment 1 of the present invention. As shown in the figure, the image display device according to the first embodiment includes an input terminal 1, a receiving unit 2, an image processing device 7, and a display unit 8.

  The input terminal 1 receives an image signal Da of a predetermined format used in a television or a computer. The receiving unit 2 receives the image signal Da via the input terminal 1, converts the image signal Da into a format that can be processed by the image processing device 7, and outputs the image signal Db. For example, the reception unit 2 converts the image signal Da into several digital image signals including the luminance signal Y, and then outputs the image signal Db. The receiving unit 2 that performs the above-described operation is configured by an A / D converter or the like when the image signal Da is an analog signal, and a predetermined signal conforming to the format when the image signal Da is a digital signal. This is composed of a demodulator or the like.

  The image processing apparatus 7 includes a luminance information detection unit 9, a content feature detection unit 10 (feature determination unit), a multiple content feature detection unit 11 (multiple feature detection unit), and a gradation correction unit 6. Includes a correction control unit 4 and a correction execution unit 5. The image signal Db obtained from the reception unit 2 is input to the luminance information detection unit 9 and the correction execution unit 5 in the image processing device 7, respectively.

  The luminance information detection unit 9 detects a luminance information value Yi that is a luminance related information value in each pixel from the luminance signal Y included in the image signal Db, and outputs the luminance information value Yi to the content feature detection unit 10. The content feature detection unit 10 determines the feature of the video content for one frame based on the luminance information value Yi, and outputs the content feature determination information value Ji (feature determination value) to the multiple content feature detection unit 11.

  The multiple content feature detection unit 11 detects video content features for a plurality of frames based on the content feature determination information value Ji, and outputs the multiple content feature determination information value Fi to the correction control unit 4 in the gradation correction unit 6. To do.

  The correction control unit 4 calculates a correction parameter Pi used when the correction execution unit 5 performs gradation correction on the image signal Db based on the multiple content feature information Fi, and outputs the correction parameter Pi to the correction execution unit 5.

  On the other hand, the correction execution unit 5 performs gradation correction on the image signal Db using the input correction parameter Pi, and outputs the signal after gradation correction to the display unit 8 as the image signal Dc. The display unit 8 displays an image based on the input image signal Dc. The display unit 8 may be, for example, a liquid crystal display, a DMD (Digital Micromirror Device) display, an EL (Electro Luminescence) display, or a plasma display, and can be applied to any display means such as a reflective type, a transmissive type, or a self-luminous device. it can.

  FIG. 2 is a block diagram showing in detail an internal configuration example of the luminance information detection unit 9 shown in FIG. As shown in FIG. 2, the luminance information detection unit 9 in the image display apparatus according to the first embodiment includes a histogram generation unit 91, a maximum gradation detection unit 92, an intermediate gradation detection unit 93, a minimum gradation detection unit 94, And an average luminance gradation detection unit 95.

  In the example illustrated in FIG. 2, the image signal Db obtained from the receiving unit 2 and including the luminance signal Y is input to the histogram generating unit 91. The histogram generation unit 91 generates a histogram of the luminance signal Y in the image signal Db for one frame. Hereinafter, information defining the histogram of the luminance signal Y in the image signal Db generated by the histogram generation unit 91 is referred to as luminance histogram information Dby.

  The maximum gradation detection unit 92 detects the luminance signal maximum gradation value in the image signal Db for one frame from the luminance histogram information Dby generated by the histogram generation unit 91, and defines the luminance signal maximum gradation value. The maximum gradation information value Yimax is output.

  The intermediate gradation detection unit 93 detects the luminance signal intermediate gradation value in the image signal Db for one frame from the luminance histogram information Dby generated by the histogram generation unit 91, and defines the luminance signal intermediate gradation value. The intermediate gradation information value Yimid is output.

  The minimum gradation detecting unit 94 detects the luminance signal minimum gradation value in the image signal Db for one frame from the luminance histogram information Dby generated by the histogram generating unit 91, and defines the luminance signal minimum gradation value. The minimum gradation information value Yimin is output.

  The average luminance gradation detection unit 95 detects the luminance signal average gradation value in the image signal Db for one frame from the luminance histogram information Dby generated by the histogram generation unit 91, and determines the luminance signal average gradation value. The specified average gradation information value Yiave is output.

  FIG. 3 is a diagram illustrating an example of the luminance histogram information Dby generated by the histogram generation unit 91. In the figure, the horizontal axis indicates the gradation value (class), and the vertical axis indicates the frequency, that is, the number of pixels with respect to the luminance of the image signal Db for one frame. In the following description, the luminance signal Y of the image signal Db is composed of, for example, 8-bit data, and its gradation value takes a value from “0” to “255”, and the number of gradations is “ 256 ".

  The histogram generation unit 91 according to Embodiment 1 divides, for example, 256 gradations into 32 areas every 8 gradations, and the 32 areas are used as histogram classes. Then, a value near the center value in each class, in this example, an integer value closest to the center value and larger than that is used as the representative value of the class. For example, in a class composed of gradation values “0” to “7”, the central value is “3.5”, so the representative value of the class is “4”. The numbers on the horizontal axis in FIG. 3 indicate the representative values of each class.

  If the center value of the class is an integer, the center value may be used as the representative value of the class. Further, even when the center value of the class is not an integer but a decimal number as in this example, the center value of the class may be adopted as the representative value of the class. When the center value of a class is a decimal, the amount of calculation can be reduced by adopting an integer near the center value of the class as a representative value of the class as in this example.

  As described above, in the histogram generation unit 91 in the image display apparatus according to the first embodiment, an area composed of eight continuous gradation values is set as one class, and therefore each frequency of the histogram shown in FIG. This is the sum of the signals of the distribution. For example, the frequency indicated by the numerical value 4 on the horizontal axis corresponds to the sum of the signals from the gradation value 0 to the gradation value 7 included in the luminance signal Db for one frame.

  Note that, unlike the histogram of FIG. 3, the histogram may be generated by counting the frequency for each gradation value. That is, each class may be configured with one gradation value. In this case, the representative value of each class is the gradation value itself constituting the class. When the number of gradations is divided, the number of divisions may be other than 32. By reducing the number of divisions, the amount of calculation in the histogram generation unit 91 can be reduced. The number of divisions is determined in advance based on the amount of computation that can be processed and the gradation correction accuracy required by the gradation correction unit 6.

  In the histogram generated as described above, the maximum gradation detecting unit 92 accumulates the frequencies from the maximum to the minimum of the classes, and the accumulated frequency HYW obtained thereby becomes a class that becomes larger than the predetermined threshold YA for the first time. The representative value of is extracted. The maximum gradation detection unit 92 outputs the extracted value as the maximum gradation information value Yimax.

  On the other hand, the minimum gradation detection unit 94 accumulates the frequencies from the minimum to the maximum in the histogram generated by the histogram generation unit 91, and the accumulated frequency HYB obtained thereby becomes larger than the predetermined threshold YB for the first time. The representative value of the class is extracted. Then, the minimum gradation detection unit 94 outputs the extracted representative value as the minimum gradation information value Yimin.

  Further, in the histogram generated as described above, the intermediate gradation detection unit 93 accumulates the frequencies from the minimum to the maximum of the class, and the accumulated frequency HYB obtained thereby becomes a predetermined threshold YC (for example, the number of pixels). The representative value of the class that becomes larger than the first half) is extracted. Then, the intermediate gradation detecting unit 93 outputs the extracted representative value as an intermediate luminance gradation Yimid. It should be noted that halftone detection may be performed using the cumulative frequency HYW.

  In the example of the histogram shown in FIG. 3, since the representative value of the class in which the cumulative frequency HYW becomes larger than the threshold value YA for the first time is “188”, this “188” is the maximum gradation information value Yimax. This maximum gradation information value Yimax is not the maximum gradation value in the image signal Db for one frame but a value according to the maximum gradation value detected using the cumulative frequency HYW and the threshold value YA.

  In the example of FIG. 3, the representative value of the class in which the cumulative frequency HYB becomes larger than the threshold value YB for the first time is “20”, so “20” is the minimum gradation information value Yimin. This minimum gradation information value Yimin is not the minimum gradation value in the image signal Db for one frame, but a value according to the minimum gradation value detected using the cumulative frequency HYB and the threshold value YB.

  Since the representative value of the class in which the cumulative frequency HYB becomes larger than the threshold value YC for the first time is “76”, this “76” becomes the intermediate gradation information value Ymid. Normally, this intermediate gradation information value Yimid is a gradation value when it reaches half (50%) of the total number of pixels in the image signal Db for one frame.

The average luminance gradation detection unit 95 calculates an average luminance gradation information value in the luminance signal Dby for one frame from the luminance histogram information Dby obtained from the image signal Db for one frame, and calculates this as the luminance signal average gradation. Output as information value Yiave. Specifically, the following equation (1) is calculated, assuming that the number of luminance signal gradations is “Yi” and the number of pixels of the luminance signal gradations is “nYi”.
Luminance signal average = Σ (Y × nYi) / ΣnYi (1)
The average luminance signal gradation number including the luminance signal average of the above formula (1) is output as the luminance signal average gradation information value Yiave.

  In the above example, the cumulative frequencies HYW, HYB, and the like are generated by the histogram generation unit 91, but the maximum gradation detection unit 92, the intermediate gradation detection unit 93, the minimum gradation detection unit 94, the average luminance scale, and the like. Each may be generated in the key detection unit 95.

  As described above, since it includes information values such as the luminance information value Yi and the maximum gradation information value Yimax that is statistically classified from the luminance histogram information Dby, the luminance information that is statistically classified for each frame is highly accurate. A value can be obtained.

  Further, the luminance information value Yi further includes an average average gradation information value Yiave indicating an average gradation value of the luminance signal Y in the image signal Db, whereby a more accurate luminance information value Yi can be obtained.

  In the above example, the histogram generation unit 91 divides the histogram evenly. However, the histogram is divided unequally so that the range of gradation values to be counted can be freely set. It may be configured. Thereby, the amount of calculation can be reduced, and the minimum luminance information value and the maximum luminance information value condition can be set finely.

  For example, it is assumed that the minimum luminance information value condition is set to 16 gradations and the maximum luminance information value condition is set to 160 gradations. In the case of equal division, it is possible to divide into 16 areas by dividing every 16 gradations so as to meet the minimum luminance information value condition. On the other hand, if it is possible to divide unevenly, the number of divisions while satisfying the minimum luminance information value condition and the maximum luminance information value condition described above with at least three area divisions of 0 to 16, 16 to 160, and 160 to 255. It is possible to greatly reduce the amount of calculation associated with the reduction.

  The gradation range of the histogram created here may be a small gradation step of only the minimum luminance information value, a small gradation step of only the intermediate luminance information value, or a maximum The gradation increment of only the luminance information value may be reduced. The step value may be selected according to the characteristics of the content to be detected.

  The configuration shown in FIG. 2 is an example of the configuration of the luminance information detection unit 9, and the luminance information detection unit 9 can output the luminance information value Yi based on the luminance signal Y included in the image signal Db. Anything can be used.

  FIG. 4 is a block diagram showing in detail a configuration example of the content feature detection unit 10. As shown in the figure, the content feature detection unit 10 in the image display apparatus according to the first embodiment includes a maximum luminance determination unit 101, an intermediate luminance determination unit 102, a minimum luminance determination unit 103, an average luminance determination unit 104, and a content And a feature determination unit 105.

  Regarding the maximum gradation information value Yimax, intermediate gradation information value Yimid, minimum gradation information value Yimin, and average gradation information value Yiave output from the luminance information detection unit 9, the maximum gradation information value Yimax is the maximum luminance determination unit 101. The intermediate gradation information value Yimid is input to the intermediate luminance determination unit 102, the minimum gradation information value Yimin is input to the minimum luminance determination unit 103, and the average gradation information value Yiave is input to the average luminance determination unit 104. Is done.

  The maximum brightness determination unit 101 classifies the magnitude of the maximum brightness from the maximum gradation information value Yimax, and generates a maximum brightness information value D101 (Yimax information value) that defines the classification information. The intermediate luminance determining unit 102 classifies the intermediate luminance level from the intermediate gradation information value Yimid, and generates an intermediate luminance information value D102 (Yimid information value) that defines the classification information. The minimum luminance determination unit 103 classifies the minimum luminance magnitude from the minimum gradation information value Yimin, and generates a minimum luminance information value D103 (Yimin information value) that defines the classification information. The average luminance determination unit 104 classifies the average luminance magnitude from the average gradation information value Yiave, and generates an average luminance information value D104 (Yiave information value) that defines the classification information.

  The maximum brightness determination unit 101 determines whether the maximum gradation information value Yimax is a value smaller than a predetermined maximum brightness determination threshold Ymaxa or a predetermined threshold greater than a predetermined threshold Ymaxa and a threshold Ymaxa. Maximum brightness information indicating whether it is a value between the maximum brightness determination threshold value Ymaxb and indicating any one of the three classification information values Yimax low, Yimax medium, and Yimax high The value D101 is output to the content feature determination unit 105.

  FIG. 5 is an explanatory diagram showing an example of generation of the maximum luminance information value D101 by the maximum luminance determination unit 101. As shown in the figure, the maximum gradation information value Yimax is a value between a predetermined threshold Ymaxa value and a Ymaxb value that is a predetermined threshold larger than the threshold Ymaxa. The luminance information value D101 is output and input to the content feature determination unit 105.

  Returning to FIG. 4, the intermediate luminance determination unit 102 determines whether the value of the intermediate gradation information value Yimid is smaller than a predetermined intermediate luminance determination threshold Ymida or a predetermined threshold Ymida value and a predetermined threshold larger than that. It is determined whether it is a value between a certain Ymidb value or a value greater than the intermediate luminance determination threshold Ymidb, and an intermediate value defining any one of three classification information values (Yimid low, Ymid mid, Ymid high) The luminance information value D102 is output to the content feature determination unit 105.

  FIG. 6 is an explanatory diagram illustrating an example of generation of the intermediate luminance information value D102 by the intermediate luminance determining unit 102. As shown in the figure, the intermediate gradation information value Yimid is a value between a predetermined threshold value Ymida value and a Ymidb value that is a predetermined threshold value larger than the predetermined threshold value Ymida. The value D102 is input to the content feature determination unit 105.

  Returning to FIG. 4, the minimum luminance determination unit 103 determines whether the minimum gradation information value Yimin is smaller than a predetermined minimum luminance determination threshold Ymina or a predetermined threshold Ymina value and a predetermined threshold larger than that. It is determined whether it is a value between a certain Yminb value or a value greater than the minimum luminance determination threshold Yminb, and the minimum indicating one of the three classification information values (Yimin low, Yimin high, Yimin high) The luminance information value D103 is output to the content feature determination unit 105.

  FIG. 7 is an explanatory diagram showing an example of generation of the minimum luminance information value D103 by the minimum luminance determination unit 103. As shown in the figure, since the minimum gradation information value Yimin is smaller than a predetermined threshold value Yimina value, a minimum luminance information value D103 indicating “Yimin low” is output and input to the content feature determination unit 105. Is done.

  Returning to FIG. 4, the average luminance determination unit 104 determines whether the average gradation information value Yiave calculated by the equation (1) is smaller than a predetermined average luminance determination threshold Yavea or a predetermined threshold Yavea value. It is determined whether the value is between the value Yaveb and the predetermined threshold value Yaveb that is greater than the threshold value or larger than the average luminance determination threshold value Yaveb. Three classification information values (Yiave low, Yiave medium, Yiave high) Is output to the content feature determination unit 105.

  The content feature determination unit 105 determines the content feature determination information value Ji based on the combination content of the four luminance information values D101 to D104, and outputs the content feature determination information value Ji to the multiple content feature detection unit 11.

  FIG. 8 is an explanatory diagram showing the determination details of the content feature determination information value Ji by the content feature determination unit 105 in a table format. As shown in the figure, 81 types of content feature determination information values Ji are determined by 81 (3 × 3 × 3 × 3) combinations of luminance information values D101 to D104.

  Note that the content feature determination combination by the content feature determination unit 105 can be arbitrarily created based on the viewer's preference and the video database. In the example of FIG. 8, the average luminance determination value Yiave is “low”, the minimum gradation information value Yimin is “low”, the intermediate gradation information value Yimid is “low”, and the maximum gradation information value Yimax is “low”. If so, the content feature determination information value Ji indicating the content feature J1 as the determination type is output to the multiple content feature detection unit 11.

  Further, the content feature determination unit 105 may perform determination using only three or less pieces of information among the four luminance information values D101 to D104. For example, it is possible to select information values such as classifying content features based only on the average luminance information value D104, or classifying the feature based on two combinations of the average luminance information value D104 and the maximum luminance information value D101. Thus, by reducing the amount of information in the luminance information values D101 to D104, the speed of feature detection can be increased and the required memory capacity can be reduced.

  The content feature detection unit 10 illustrated in FIG. 4 is merely an example, and the content feature detection unit 10 may have any configuration as long as the content feature information value Ji can be determined based on the luminance information value Yi.

  As an example of a method for outputting the content feature information value Ji based on the brightness information values D101 to D104, the likelihood of the brightness information values D101 to D104 is calculated, and the content feature information value Ji is output from statistical processing. And so on.

  The multiple content feature detection unit 11 performs an arithmetic operation based on the input content feature information value Ji, and analyzes the content feature information value Ji for a plurality of frames based on first to third determination criteria described later. Processing is performed to obtain a plurality of content feature information values Fi reflecting the plurality of content feature determination information values Ji. Thereby, compared with the content feature information value Ji of a plurality of frames, more accurate and stable content determination can be performed.

  As one of the arithmetic operations in the multiple content feature detection unit 11, the multiple content feature detection unit 11 determines the feature determination value Ji (determination type) for one frame based on the sequentially input content feature determination information value Ji. And a method (first determination criterion) of determining as a plurality of feature determination values Fi when the same feature determination value (determination type) reaches a certain determination number N (predetermined appearance).

  Specifically, for example, when the fixed determination number N is “10”, the content feature determination information value Ji for each frame is added for a plurality of frames as shown in FIG. In this example, since the content feature determination value type that has reached the fixed determination number “10” earliest is “J3”, the multiple content feature determination value Fi is detected as “J3”, and the feature determination value J3 Is output to the correction control unit 4 in the gradation correction unit 6.

  As described above, the multiple content feature detection unit 11 according to the first embodiment counts the determination types indicated by the sequentially obtained content feature determination information values Ji, and recognizes the type whose count result reaches the fixed determination number N earliest. In addition, by having the first determination criterion for obtaining the multiple content feature information value Fi instructing the type, the multiple content feature information value Fi with relatively high accuracy can be obtained relatively early.

  As another method, the multiple content feature detection unit 11 adds the feature determination value Ji for one frame to the sequentially input content feature determination information value Ji, and the same feature determination value continues. In this case, there is a technique (second determination criterion) for determining as the multiple feature determination value Fi when the predetermined determination number M (predetermined number of consecutive appearances) is reached.

  Specifically, for example, when the fixed determination number M is “10”, the content feature determination information value Ji for each frame is added for a plurality of frames as shown in FIG. In this example, the content feature determination value is “J3” continuously from the fourth frame to the thirteenth frame. Therefore, the content feature determination value type that has reached the fixed determination number 10 in the earliest manner is “J3”. The multiple content feature determination value Fi is determined to be the feature determination value J3, and the multiple content feature information value Fi instructing the feature determination value J3 is output to the correction control unit 4.

  As described above, the multiple content feature detection unit 11 of the image display device according to the first embodiment counts the types indicated by the sequentially obtained content feature determination information values Ji, and the count result is the earliest and the number of constant determinations continuously. By having a second criterion for recognizing a type that has reached M and obtaining a multi-content feature information value Fi that indicates the type, a multi-feature feature determination value that is more accurate than the first criterion can be obtained. .

  As another method, the multiple content feature detection unit 11 adds the feature determination value Ji for one frame to the input content feature determination information value Ji so that the same feature determination value is a fixed determination frame. A method (third determination criterion) for determining as the multiple feature determination value Fi when the maximum appearance degree is within a few K (within a predetermined period).

Specifically, for example, when the fixed determination frame number K is “15”, the content feature determination information value Ji for each frame is added for 15 frames which is the fixed determination frame number as shown in FIG. In this example, the appearance level of each content feature determination information value in 15 frames is 0 for J1, 7 for J2, 6 for J3, and 1 for J4 and J5. The feature determination value having the maximum appearance degree is “J2” as the feature determination value type for which the determination is performed seven times. Therefore, the multiple content characteristic information values Fi instructing FEATURES determination value J2 is output to the correction controller 4.

  As described above, the multiple feature determination unit of the image display device according to the first embodiment counts the types indicated by the sequentially obtained content feature determination information values Ji, and recognizes the type having the largest count value within a certain number of determination frames. In addition, it is possible to always obtain a relatively high-precision multi-feature determination value within a certain number of determination frames, which has the third determination criterion for obtaining the multi-content feature information value Fi indicating the type.

  The multiple content feature detection unit 11 according to Embodiment 1 may output the content feature determination information value Ji itself as the multiple content feature determination value Fi. That is, it is possible to employ a configuration in which the content feature determination information value Ji output from the content feature detection unit 10 is directly taken into the correction control unit 4 without the multiple content feature detection unit 11.

  Further, the plurality of content feature detection units 11 according to the first embodiment may be implemented in combination of a plurality of arithmetic operations represented by the above three methods (first to third determination criteria).

  For example, the feature judgment value Ji for one frame is added as the constant judgment number Na, and after the same feature judgment value reaches the constant judgment number Na, the feature judgment value Ji for one frame is added as the constant judgment number Nb. Then, when the same feature judgment value continuously reaches a certain judgment number Nb, a combination such as judgment as the multiple content feature judgment value Fi is conceivable.

  As another combination method, the feature determination value Ji for one frame is added as the fixed determination number Na to obtain the multiple content feature determination value Fai, and then the multiple content feature determination value Fai is added to obtain the multiple content feature. The determination value Fi may be obtained. In this example, the combination is two times, but two or more combinations may be performed.

  Specifically, when the constant determination number Na is “10” and Nb is “3” as shown in FIG. 12, first, the feature determination value Ji for one frame is added, and the same feature determination value is the fixed determination number. The multi-feature determination value Fai that has reached 10 times is determined. Next, the same method is used to determine from the feature determination value Ji to the multiple content feature determination value Fai, the earliest fixed determination number of 3 times. In this example, the multiple content feature determination values Fai are J3, J3, J2, and J3 in order. For this reason, the multiple content feature determination value Fai reaches J3 the earliest at J3, and the multiple content feature determination value Fi is determined to be the feature determination value J3, and the multiple content feature information value indicating the feature determination value J3 Fi is output to the correction control unit 4.

  As described above, the plurality of contents can be obtained by obtaining the plurality of content feature information values Fi by a plurality of combinations including at least one judgment criterion in the first to third judgment criteria based on the content feature judgment information value Ji. When the feature information value Fi is determined, it is possible to adjust the speed and accuracy until the feature information value Fi is determined, and the gradation correction unit 6 can perform gradation correction rich in adaptability.

  Even when the content of the content changes significantly in one frame by the multiple content feature detection unit 11 according to the first embodiment, the determination type of the content feature information value Ji in the frame is analyzed by the multiple content feature detection unit 11 Since it is automatically removed by the processing, it is possible to prevent extreme gradation correction. Also. Since gradation correction is not performed based on the content feature determination information value Ji that may change for each frame, the frequency of gradation correction is reduced and the processing speed is improved.

  In addition, the content feature detection unit 11 can be used not only for image display devices but also in other fields related to video as a method for more accurately determining the feature amount of video content from the luminance information value.

  For example, video storage devices including HD and various video recorders can be used as other fields. When recording data, a method of determining a genre by using content detection of a plurality of frames and storing the determination result in a storage medium is conceivable. In addition, it may be used as a mark when searching as a keyword.

  The correction control unit 4 selects a correction parameter Pi corresponding to the content feature based on the input multiple content feature determination information value Fi, and outputs the correction parameter Pi to the correction execution unit 5. FIG. 13 is a diagram for explaining the operation of the correction control unit 4. As shown in FIG. 13, in the xy coordinate system, the correction control unit 4 represents the gradation value of the input signal (image signal Db) on the x axis and the gradation value (image signal Dc) to be output on the y axis. Then, the conversion formula (correction parameter Pi) corresponding to the content feature determination information value Ji indicated by the plural content feature information value Fi is selected. Specifically, when the multiple content feature information value Fi indicates the feature determination value J1 by the combination of the luminance information values D101 to D104 shown in FIG. 8, the correction parameter Pi corresponding to the feature determination value J1 is selected. The The correction parameter Pi in FIG. 13 is merely shown as an example, and the feature determination values J1 to J81 shown in FIG. 8 and the correction parameters P1 to P81 shown in FIG. Absent. That is, FIG. 13 merely shows an example in which 81 kinds of correction parameters Pi are provided to correspond to 81 kinds of content feature determination information values Ji on a one-to-one basis.

  For example, for a genre with a large overall dark screen such as a movie, an image with a low overall brightness (dark) such as a feature determination value J1 is obtained. For this reason, by using the correction parameter Pi having a characteristic that increases the luminance of the low gradation part as the correction parameter Pi corresponding to the feature determination value J1, the dark and hard-to-see part can be seen. It is possible to perform processing. Therefore, the correction parameter Pi corresponding to the feature determination value J1 is preferably a correction parameter Pi that has a steep slope near the origin and becomes gentle as the x-axis increases, like the correction parameter P81 in FIG.

  As described above, the image correction unit 6 of the image display apparatus according to the first embodiment performs tone correction using the correction parameter Pi corresponding to the type indicated by the plurality of content feature information values Fi on a one-to-one basis. High-accuracy gradation correction adapted to the characteristics of the signal Db can be performed.

  Here, the correction parameters Pi to be prepared may be provided as many as the number of combinations based on the luminance information value (81 in this example), or may be the same as the number of types of content features.

  The correction execution unit 5 performs gradation correction based on the correction parameter Pi. This gradation correction is performed for each frame. In addition, the correction control unit 4 according to the first embodiment may output other parameters corresponding to the content features to the correction execution unit 5 based on the input multiple content feature information values Fi. Examples of other parameters include parameters such as sharpness, color adjustment, and noise processing.

  As described above, in the image display device according to the first embodiment, based on the content feature determination information value Ji for one frame determined from the luminance information values D101 to D104, the feature of the content is based on the feature amount for a plurality of frames. Is determined as the multiple content feature information value Fi, the content characteristics can be determined more accurately. Further, since gradation correction is performed on the image signal Db based on the determination result, gradation correction is not frequently performed, and optimal contrast adjustment is possible.

  On the other hand, when the content feature determination is performed using the technique described in Patent Document 2 described above, the key frame for characterizing the content is identified, and the key frame is identified based on the information. The associated frame number needs to be preserved during processing.

  However, in the image processing apparatus according to the first embodiment, the feature is extracted for each frame, the content feature is determined, and the tone correction is performed on the image signal Db. Optimal contrast adjustment is possible every time.

  As described above, the multiple content feature detection unit 11 in the image display apparatus according to the first embodiment analyzes the content feature determination information value Ji output from the content feature detection unit 10 by a corresponding amount for a plurality of frames. Since the content feature information value Fi is obtained, the characteristics of the content obtained from the image signal Db can be accurately determined.

  The gradation correction unit 6 performs gradation correction on the newly obtained image signal Db for one frame based on the plurality of content feature information values Fi. Therefore, the gradation correction unit 6 automatically performs the gradation correction operation without performing a separate gradation correction operation. Gradation correction can be performed.

  Furthermore, the content feature detection unit 10 can obtain the content feature determination information value Ji at a relatively high speed by obtaining the content feature determination information value Ji based on the luminance information value Yi in the image signal Db for one frame.

<Embodiment 2>
FIG. 14 is a block diagram showing a configuration of an image display apparatus according to Embodiment 2 of the present invention. The image display device according to the second embodiment includes an image processing device 17 instead of the image processing device 7 in the image processing device according to the first embodiment described above.

  The image processing device 17 in the image display device according to the second embodiment includes a luminance information detection unit 9, a multiple luminance information detection unit 12, a content feature detection unit 20, a multiple content feature detection unit 11, and a gradation correction unit 6. Yes.

  The image signal Db output from the reception unit 2 is input to the luminance information detection unit 9 and the correction execution unit 5 of the image processing device 17. The luminance information detection unit 9 detects the luminance information value Yi in each pixel from the luminance signal Y included in the input image signal Db and outputs it to the multiple luminance information detection unit 12.

  The multiple luminance information detection unit 12 calculates the integration and average for multiple frames based on the luminance information value Yi, and outputs the calculation result to the content feature detection unit 20 as the multiple luminance information value Yical.

  The content feature detection unit 20 determines the feature Ji of the video content based on the multiple luminance information value Yical, and outputs the content feature determination information value JMi to the multiple content feature detection unit 11. As described above, the multi-luminance information detection unit 12 and the content feature detection unit 20 constitute a feature determination unit that performs feature determination of video content on the image signal Db for a plurality of frames and obtains a content feature determination information value JMi.

  The multiple content feature detection unit 11 determines the feature of video content for a plurality of frames based on the content feature determination information value JMi, and outputs the multiple content feature determination information value Fi, which is a feature determination related value, to the correction control unit 4. .

  The correction control unit 4 calculates a correction parameter Pi used when the correction execution unit 5 performs gradation correction on the image signal Db based on the multiple content feature information Fi, and outputs the correction parameter Pi to the correction execution unit 5.

  Since the luminance information detection unit 9 in the image display apparatus according to the second embodiment has the same configuration as that of the first embodiment and the operation thereof is the same, detailed operation description regarding the luminance information detection unit 9 is omitted.

  The multiple luminance information detection unit 12 calculates the integration and average for multiple frames based on the luminance information value Yi, and outputs the calculation result to the content feature detection unit 20 as the multiple luminance information value Yical. As a specific example, the maximum gradation information value Yimax output from the luminance information detection unit 9 is calculated for a certain number of frames m to obtain an average, and is output to the content feature detection unit 20 as Yicmax. Further, the intermediate gradation information value Yimid is calculated for a certain number of frames m to obtain an average, and is output to the content feature detection unit 20 as Yicmid. Further, the minimum gradation information value Yimin is calculated for a certain number of frames m to obtain an average, and is output to the content feature detection unit 20 as Yicmin. In addition, the average gradation information value Yiave is calculated for a certain number of frames m to obtain an average, and is output to the content feature detection unit 20 as Yicave.

  In addition, after the luminance information value Yi of the fixed number of frames m is input, the plural luminance information detection unit 12 sets the plural luminance information values Yical for each frame by setting the luminance information value Yi for the latest m frames as a calculation target. Can be output sequentially.

  Note that the maximum gradation information value Yimax, the intermediate gradation information value Yimid, the minimum gradation information value Yimin, the average gradation information value Yiave, and some information values are not obtained by performing all calculations. The average value may be obtained by performing only the calculation for.

  Further, in the multiple luminance information detection unit 12 in the image display device of the second embodiment, the maximum gradation information value Yicmax, the intermediate gradation information value Yicmid, the minimum gradation information value Yicmin, and the average gradation information are obtained by obtaining the average value. Although the value Yicave is obtained, it is not limited to an average value as long as an arithmetic operation is performed using a plurality of frames and the result is output to the content feature detection unit 20. As an example, a method of using an intermediate value instead of an average value can be considered.

  FIG. 15 is an example of a block diagram illustrating a detailed configuration of the content feature detection unit 20. As shown in FIG. 15, the content feature detection unit 20 according to the second embodiment includes a maximum luminance determination unit 201, an intermediate luminance determination unit 202, a minimum luminance determination unit 203, an average luminance determination unit 204, and a content feature determination unit. 205.

  The maximum luminance information value Yicmax output from the multiple luminance information detection unit 12 is input to the maximum luminance determination unit 201, the intermediate luminance information value Yicmid is input to the intermediate luminance determination unit 202, and the minimum luminance information value Yicmin is the minimum luminance determination unit. The average luminance information value Yicave is input to the average luminance determination unit 204.

  The maximum luminance determination 201 classifies the magnitude of the maximum luminance from the maximum luminance information value Yicmax, and generates a maximum luminance information value D201 (Yicmax information value) that defines the classification information. The intermediate luminance determination unit 202 classifies the size of the intermediate luminance from the intermediate luminance information value Yicmid, and generates an intermediate luminance information value D202 (Yicmid information value) that defines the classification information. The minimum luminance determining unit 203 classifies the magnitude of the minimum luminance from the minimum luminance information value Yicmin, and generates a minimum luminance information value D203 (Yicmin information value) that defines the classification information. The average luminance determination unit 204 classifies the average luminance from the average luminance information value Yicave, and generates an average luminance information value D204 (Yicave information value) that defines the classification information.

  The maximum luminance determination unit 201, the intermediate luminance determination unit 202, the minimum luminance determination unit 203, and the average luminance determination unit 204 are respectively the maximum luminance determination unit 101, the intermediate luminance determination unit 102, the minimum luminance determination unit 103, and the like. Since the same operation as that of the average luminance determination unit 104 is performed, detailed operation description of each of the determination units 201 to 204 is omitted.

  The configuration shown in FIG. 15 is a configuration example of the content feature detection unit 20, and the content feature detection unit 20 may output the content feature information value Ji based on the plurality of luminance information values Yical. Various configurations are possible. As an example of a method of outputting the content feature information value Ji based on the brightness information value Yical, a method of calculating the likelihood of the brightness information value Yical and outputting the content feature information value Ji from statistical processing is considered. It is done.

  The multiple content feature detection unit 11 according to the second embodiment has the same configuration as the multiple content feature detection unit 11 according to the first embodiment, and the operation thereof is the same. Omitted.

  As in the first embodiment, also in the second embodiment, the content feature determination information value JMi output from the content feature detection unit 20 with the multiple content feature detection unit 11 omitted is taken into the correction control unit 4 as it is. A configuration can be employed.

  When the multiple content feature detection unit 11 is omitted, the content feature determination information value JMi itself obtained from the content feature detection unit 20 is used as a feature determination related value, and the gradation correction unit 6 performs image processing based on the content feature determination information value JMi. Since gradation correction can be performed on the signal Db, the image display apparatus can be configured with a relatively simple circuit configuration by omitting the multiple content feature detection unit 11. At this time, the content feature determination information value JMi is a value obtained by statistical processing for a plurality of frames by the multiple luminance information detection unit 12 and the content feature detection unit 20, and thus the multiple content feature detection unit 11 is omitted. It is possible to minimize the degradation of the determination accuracy associated with.

  Similar to the tone correction unit 6 of the first embodiment, the tone correction unit 6 includes a correction control unit 4 and a correction execution unit 5. The correction control unit 4 in the second embodiment is the same as the correction control unit 4 in the first embodiment, and the gradation correction unit 6 and the display unit 8 perform the same operations as those described in the first embodiment. Therefore, the detailed operation description thereof is omitted. However, the content feature determination information value JMi is used instead of the content feature determination information value JMi shown in FIG.

  As described above, in the image display device according to the second embodiment, the features of the content are determined from the feature amounts of the plurality of frames by performing integration for a plurality of frames from the luminance information value and obtaining an average. Therefore, it is possible to more accurately determine content characteristics at the content feature determination information value JMi stage. Further, since the tone correction is performed on the image signal Db based on the detection result (multiple content feature information value Fi) of the multiple content feature detection unit 11 based on the content feature determination information value JMi, the tone correction is frequently performed. This eliminates the need to perform optimal contrast adjustment.

  In order to perform content feature determination using the technique described in Patent Document 2 described above in order to correspond to the image display device according to the second embodiment, a key frame for characterizing content is identified and a key is determined based on the information. The frame number associated with the frame needs to be preserved during processing.

  However, in the image processing apparatus according to the second embodiment, after the multiple luminance information value Yical is obtained once by the multiple luminance information detection unit 12, the content feature determination information value JMi is obtained from the content feature detection unit 20 for each frame. Since output is possible, the detection time of the multiple content feature information value Fi by the multiple content feature detection unit 11 based on the content feature determination information value JMi is not significantly different from that of the first embodiment. Therefore, as in the first embodiment, by performing gradation correction on the image signal Db of the gradation correction unit 6, optimum contrast adjustment can be performed for each frame while performing content feature determination while maintaining real-time characteristics. is there.

  That is, after the content feature detection unit 10 first obtains the content feature determination information value JMi, the content feature determination information value JMi can be acquired for each frame. Even if tone correction is performed based on the multiple content feature information values Fi output from 11, the real-time property of tone correction is not lost.

  As described above, in the image display device according to the second embodiment, the feature determination unit including the multiple luminance information detection unit 12 and the content feature detection unit 10 performs video content feature determination on the image signal Db for a plurality of frames. In order to obtain the performed content feature determination information value JMi, a more accurate feature determination value can be obtained.

  Then, the gradation correction unit 6 performs gradation correction on a newly obtained image signal for one frame on the basis of the plurality of content feature information values Fi, so that it is automatically performed without performing a separate gradation correction operation. Gradation correction can be performed.

  Furthermore, the multiple content feature detection unit 11 in the image display device of the second embodiment analyzes the content feature determination information value JMi output from the content feature detection unit 20 to obtain the multiple content feature information value Fi. The characteristics of the content obtained from the image signal Db can be determined more accurately.

  Although the real-time property of the gradation correction is slightly lost, it can be considered that the multiple luminance information detection unit 12 sequentially outputs the multiple luminance information values Yical every m frames.

<Embodiment 3>
FIG. 16 is a block diagram showing a configuration of an image display apparatus according to Embodiment 3 of the present invention. The image display device according to the third embodiment includes an image processing device 27 instead of the image processing device 7 in the image processing device of the first embodiment described above.

  The image processing device 27 in the image display device according to the third embodiment includes a luminance information detection unit 19, a content feature detection unit 30 (feature determination unit), a multiple content feature detection unit 21 (multiple feature detection unit), and a gradation correction unit. 6 is configured.

  The luminance information detection unit 19 receives a luminance signal included in the image signal Db output from the receiving unit 2, detects luminance information at each pixel from the luminance signal, creates luminance histogram information Dby, and generates a luminance histogram. A pixel number information value Ni, which is a luminance related information value obtained from the information Dby, is output.

Figure 17 is a block diagram showing the details of an example of the configuration of the luminance information detecting unit 19. As shown in the figure, the luminance information detection unit 19 in the image display apparatus according to the third embodiment includes a histogram generation unit 191, a maximum luminance pixel number detection unit 192n, an intermediate luminance pixel number detection unit 193n, and a minimum luminance pixel number detection. 194n and an average luminance pixel number detection unit 195n.

  An image signal Db output from the receiving unit 2 and including the luminance signal Y is input to the histogram generating unit 191.

  The histogram generation unit 191 generates a luminance signal histogram based on the image signal Db for one frame to obtain luminance histogram information Dby. The maximum luminance pixel number detection unit 192 detects the maximum luminance signal pixel number in the image signal Db for one frame of luminance histogram information Dby generated by the histogram generation unit 191 and outputs the maximum luminance pixel number information value Nimax. The intermediate luminance pixel number detection unit 193n detects the intermediate luminance pixel number in the image signal Db for one frame from the luminance histogram information Dby generated by the histogram generation unit 191, and outputs an intermediate luminance pixel number information value Nimid. . The minimum luminance pixel number detection unit 194 detects the minimum luminance signal pixel number in the image signal Db for one frame from the luminance histogram information Dby generated by the histogram generation unit 191, and outputs the minimum luminance pixel number information value Nimin. . The average luminance detection unit 195 detects the average luminance pixel number in the image signal Db for one frame from the luminance histogram information Dby generated by the histogram generation unit 191 and outputs an average luminance pixel number information value Yiave.

  FIG. 18 is a diagram illustrating an example of a histogram generated by the histogram generation unit 191. In the figure, the horizontal axis indicates the gradation value (class), and the vertical axis indicates the frequency, that is, the number of pixels with respect to the luminance of the image signal Db for one frame. In the following description, the luminance signal Y of the image signal Db is composed of, for example, 8-bit data, and its gradation value takes a value from “0” to “255”, and the number of gradations is “ 256 ".

  The histogram generation unit 191 in Embodiment 3 divides, for example, 256 gradations into five areas for every 51 gradations, and the five areas are used as the histogram class. Then, a value near the center value in each class, in this example, an integer value closest to the center value and larger than that is used as the representative value of the class. For example, in a class composed of gradation values “0” to “50”, the central value is “24.5”, so the representative value of the class is “25”. The numbers on the horizontal axis in FIG. 18 indicate the representative values of each class. In this example, the gradation is divided into five stages, the area including the minimum gradation 25 is set as the minimum luminance area, the area including the intermediate gradation 122 is set as the intermediate luminance area, and the area including the maximum gradation 224 is set as the maximum. The brightness area is preset.

  As described above, in the image display apparatus according to the third embodiment, the pixel number information value Ni includes the maximum luminance pixel number information value Nimax that is the frequency of the luminance histogram information Dby in the maximum luminance area and the like. An accurate pixel number information value Ni corresponding to the number of pixels in each area can be obtained.

  In the example of FIG. 18, the gradation is generated by dividing the gradation into five stages. However, differently, the histogram may be divided into areas other than five. For example, it may be divided into three or seven regions, and each number of regions may be configured. As a result, higher-speed calculation is possible, or finer feature detection is possible.

  Based on the luminance histogram information Dby generated as described above, the maximum luminance pixel number detection unit 192 extracts the maximum number of pixels of the class or the pixel number information value corresponding to the number of pixels. The maximum luminance pixel number detecting unit 192 outputs the extracted pixel number information value as the maximum luminance pixel number information value Nimax.

  Based on the luminance histogram information Dby generated as described above, the intermediate luminance pixel number detection unit 193 extracts the intermediate number of pixels of the class or a pixel number information value corresponding to the number of pixels. Then, the intermediate luminance pixel number detection unit 193 outputs the extracted pixel number information value as the intermediate luminance pixel number information value Nimid.

  Based on the luminance histogram information Dby generated as described above, the minimum luminance pixel number detection unit 194 extracts the pixel number information value corresponding to the minimum number of pixels of the class or the number of pixels. Then, the minimum luminance pixel number detection unit 194 outputs the extracted pixel number information value as the minimum luminance pixel number information value Nimin.

  The average luminance detecting unit 195 calculates an average luminance gradation information value in the luminance signal Y for one frame from the luminance signal Y obtained from the image signal Db for one frame, and calculates the average luminance gradation information value Yiave for the luminance signal. Output as. Since this operation is the same as that of the average luminance gradation detecting unit 95 of the first embodiment, description thereof is omitted.

  Further, in the configuration example of the luminance histogram by the histogram generation unit 191 shown in FIG. 18, the histogram is divided evenly. However, the range of gradation values to be subjected to frequency counting is divided into non-uniform histograms. You may comprise so that it can set freely.

  The luminance information detection unit 19 having the configuration shown in FIG. 17 is an example, and the luminance information detection unit 17 can output a value corresponding to the luminance pixel number information value based on the luminance signal Y included in the image signal Db. Any configuration can be used.

  FIG. 19 is a block diagram showing a detailed configuration example of the content feature detection unit 30. As shown in the figure, the content feature detection unit 30 of the image display device according to the third embodiment includes a maximum luminance determination unit 301, an intermediate luminance determination unit 302, a minimum luminance determination unit 303, an average luminance determination unit 304, and a content And a feature determination unit 305.

  The maximum luminance pixel number information value Nimax output from the luminance information detection unit 19 is input to the maximum luminance determination unit 301, and the intermediate luminance pixel number information value Nimid is input to the intermediate luminance determination unit 302, and the minimum luminance pixel number information value Nimin. Is input to the minimum luminance determination unit 303, and the average gradation information value Yiave is input to the average luminance determination unit 304.

  The maximum luminance determination unit 301 classifies the size of the maximum luminance pixel number from the maximum luminance pixel number information value Nimax, and generates a maximum luminance number information value D301 (Nimax information value) defining the classification information. The intermediate luminance determination unit 302 classifies the size of the intermediate luminance from the intermediate luminance information value Nimid, and generates an intermediate luminance number information value D302 (Nimid information value) that defines the classification information. The minimum luminance determination unit 303 classifies the magnitude of the minimum luminance from the minimum luminance information value Nimin, and generates a minimum luminance number information value D303 (Nimin information value) that defines the classification information. The average luminance determining unit 304 classifies the average luminance magnitude from the average gradation information value Yiave, and generates a minimum luminance number information value D303 (Yiave information value) that defines the classification information.

  FIG. 20 is an explanatory diagram showing a luminance histogram for explaining the operation of the maximum luminance determination unit 301. As shown in FIG. 20, the maximum brightness determination unit 301 has a maximum brightness information value Nmax that is smaller than a predetermined maximum brightness pixel number determination threshold Nmaxa or a predetermined threshold Nmaxa value that is larger than the predetermined threshold Nmaxa value. It is determined whether the value is between the threshold value Nmaxb value or larger than the maximum brightness determination threshold value Nmaxb, and indicates one of three classification information values, Nimax low, during Nimax, or Nimax high. The maximum luminance number information value D301 to be output is output and input to the content feature determination unit 305. Specifically, in the case of the example in FIG. 20, since it is larger than a predetermined threshold Nmaxb value, the maximum luminance number information value D301 that indicates the Nimax height is output and input to the content feature determination unit 305.

  FIG. 21 is an explanatory diagram showing a luminance histogram for explaining the operation of the intermediate luminance determining unit 302. As shown in FIG. 21, the intermediate luminance determining unit 302 has a value of the intermediate luminance pixel number information value Nmid smaller than a predetermined intermediate luminance pixel number determination threshold Nmida or larger than a predetermined threshold Nmida value. It is determined whether the value is between a predetermined threshold value Nmidb value or larger than the intermediate luminance determination threshold value Nmidb, and one of three classification information values Nimid low, Nimid, and Nimid high is selected. The instructed intermediate luminance number information value D302 is output and input to the content feature determination unit 305. Specifically, in the case of the example in FIG. 21, the value is larger than a predetermined threshold Nimidb value, so an intermediate luminance number information value D302 that indicates Nimid high is output and input to the content feature determination unit 305.

  FIG. 22 is an explanatory diagram showing a luminance histogram for explaining the operation of the minimum luminance determination unit 303. As shown in FIG. 22, the minimum brightness determination unit 303 has a minimum brightness information value Nimin that is smaller than a predetermined minimum brightness pixel number determination threshold Nmina or a predetermined threshold Nmina value that is larger than the predetermined threshold Nmina. It is determined whether it is a value between the Nminb values that are threshold values or larger than the minimum luminance determination threshold value Nminb, and the minimum value that indicates one of the three classification information values Nimin low, Nimin, or Nimin high The luminance number information value D303 is output and input to the content feature determination unit 205. Specifically, in the case of the example in FIG. 22, since it is between a predetermined threshold value Nmina value and Nminb, the minimum luminance number information value D303 that indicates that Nimin is being output is output and input to the content feature determination unit 305. .

  In addition, the average luminance determination unit 304 has a value of the average gradation information value Yiave calculated from the equation (1) smaller than a predetermined average luminance determination threshold value Yavea or larger than a predetermined threshold value Yavea value. It is determined whether the value is between a predetermined threshold value Yaveb value or larger than the average luminance determination threshold value Yaveb, and one of three classification information values Yiave low, Yiave medium, and Yiave high is indicated. The average luminance number information value D304 is output and input to the content feature determination unit 305.

  The content feature determination unit 305 performs content feature determination from combinations of the four luminance number information values D301 to D304 based on the combinations shown in FIG. The content feature determination unit 305 outputs the content feature determination information value Ji and inputs it to the multiple content feature detection unit 21. Note that the content feature determination combination table can be arbitrarily created based on the viewer's preference and the video database, as in the first embodiment. For example, if the average luminance determination value Yiave is “low”, the minimum luminance information value Nimin is “low”, the intermediate luminance information value Nimid is “low”, and the maximum luminance information value Nimax is “low”, the characteristic determination value J1 is determined and output to the multiple content feature detector 21.

  Further, the content feature determination unit 305 may perform determination using only three or less pieces of information among the four luminance information values D301 to D304. For example, it is possible to select information such as classifying content features based only on the average luminance number information value D304, or classifying the content features based on two values: the average luminance number information value D304 and the maximum luminance number information value D301. Thus, by reducing the amount of information for obtaining the content feature determination information value Ji, the feature detection speed can be increased and the required memory capacity can be reduced.

  The configuration example of the content feature detection unit 30 illustrated in FIG. 19 is an example, and the content feature detection unit 30 may be any configuration that can output the content feature information value Ji based on the pixel number information value Ni. It may be anything.

  As an example of a method for outputting the content feature information value Ji based on the pixel number information value Ni, there is a method of calculating the likelihood of the pixel number information value Ni and outputting the content feature information value Ji from statistical processing. Conceivable.

  The multiple content feature detection unit 21 according to the third embodiment has the same configuration as the multiple content feature detection unit 11 according to the first embodiment, and performs the same operation as that described in the first embodiment. A detailed description of the operation related to 11 will be omitted.

  The correction control unit 4 and the correction execution unit 5 in the gradation correction unit 6 have the same configuration as the correction control unit 4 and the correction execution unit 5 in the first embodiment described above. Since the gradation correction unit 6 and the display unit 8 perform the same operations as those of the gradation correction unit 6 and the display unit 8 described in the first embodiment, a detailed description of their operations is omitted.

  As described above, in the image display device according to the third embodiment, content features are determined from feature amounts for a plurality of frames based on content feature information for one frame determined from the pixel number information value. , The characteristics of the content can be determined more accurately. Further, since tone correction is performed on the image signal Db based on the determination result, tone correction is not frequently performed, and optimal contrast adjustment is possible.

  In order to perform content feature determination corresponding to the image display device according to the third embodiment using the technique described in Patent Document 2, the key frame for characterizing the content is identified, and the key frame based on the information is identified. The frame number associated with is required to be preserved during processing.

  However, in the image processing apparatus according to the third embodiment, the feature (content feature determination information value Ji) is extracted for each frame to determine the content feature, and finally the multiple content feature information obtained by the multiple content feature detection unit 21. Since the tone correction unit 6 performs tone correction on the image signal Db based on the value Fi, it is possible to perform optimum contrast adjustment for each frame while performing content feature determination while maintaining real-time characteristics.

<Embodiment 4>
FIG. 24 is a block diagram showing a configuration of an image display apparatus according to Embodiment 4 of the present invention. The image display device according to the fourth embodiment includes an image processing device 37 instead of the image processing device 17 in the image processing device according to the second embodiment described above (see FIG. 14).

  The image processing device 37 according to the fourth embodiment includes a luminance information detection unit 19, a multiple luminance information detection unit 22, a content feature detection unit 40, a multiple content feature detection unit 21, and a gradation correction unit 6. Similar to the first embodiment, the gradation correction unit 6 includes a correction control unit 4 and a correction execution unit 5 inside.

  The luminance information detection unit 19 receives the luminance signal Y included in the image signal Db output from the reception unit 2, detects luminance information at each pixel from the luminance signal Y, creates a histogram, and obtains the histogram from the histogram. The pixel number information value Ni to be output is output.

  The image signal Db output from the reception unit 2 is input to the luminance information detection unit 19 and the correction execution unit 5 of the image processing device 37. The luminance information detection unit 19 detects the pixel number information value Ni in each pixel from the luminance signal Y included in the input image signal Db, and outputs it to the multiple luminance information detection unit 22.

  The multiple luminance information detection unit 22 calculates the integration and average for a plurality of frames based on the pixel number information value Ni, and outputs the result to the content feature detection unit 40 as the multiple pixel number information value Nical. The content feature detection unit 40 determines the feature Ji of the video content based on the multiple pixel number information value Nical, and outputs the content feature determination information value JMi to the multiple content feature detection unit 21. The multi-brightness information detection unit 22 and the content feature detection unit 40 constitute a feature determination unit.

  The multiple content feature detection unit 21 determines the features of video content for multiple frames based on the content feature determination information value JMi, and outputs the multiple content feature determination information value Fi to the correction control unit 4. The correction control unit 4 calculates a correction parameter Pi used when the correction execution unit 5 performs gradation correction on the image signal Db based on the multiple content feature information Fi, and outputs the correction parameter Pi to the correction execution unit 5.

  The luminance information detection unit 19 according to the fourth embodiment has the same configuration as the luminance information detection unit 19 according to the third embodiment (see FIG. 17), and performs the same operation as that described in the third embodiment. A detailed description of the operation relating to the luminance information detection unit 19 is omitted.

  The multiple luminance information detection unit 22 calculates the integration and average for a plurality of frames based on the pixel number information value Ni, and outputs the result to the content feature detection unit 20 as the multiple pixel number information value Nical. As a specific example, the maximum luminance pixel number information value Nimax output from the luminance information detection unit 19 is calculated for a predetermined number of frames m to obtain an average, and the maximum luminance pixel number information value Nicmax is obtained in the content feature detection unit 40. Output. Further, the intermediate luminance pixel number information value Nimid is calculated for a fixed number of frames m to obtain an average, and the average luminance pixel number information value Nicmid is output to the content feature detection unit 40. Further, the minimum luminance pixel number information value Nimin is calculated for a predetermined number of frames m to obtain an average, and is output to the content feature detection unit 40 as the minimum luminance pixel number information value Nicmin. The average gradation information value Yiave is calculated for a certain number of frames m to obtain an average, and is output to the content feature detection unit 40 as Yicave.

  In addition, after the luminance information value Yi of the fixed number of frames m is input, the luminance information value Yi for the latest m frames is set as the calculation target, so that the multiple luminance information detecting unit 22 sets the multiple pixel number information value Nical to one frame. Each can be output sequentially.

  It should be noted that the maximum luminance pixel number information value Nimax, the intermediate luminance pixel number information value Nimid, the minimum luminance pixel number information value Nimin, and the average gradation information value Yiave are not obtained by performing all calculations, Only the calculation may be performed only on the information value of the part to obtain the average value.

  FIG. 25 is a block diagram showing in detail a configuration example of the content feature detection unit 40. As shown in FIG. 25, the content feature detection unit 40 according to the fourth embodiment includes a maximum luminance determination unit 401, an intermediate luminance determination unit 402, a minimum luminance determination unit 403, an average luminance determination unit 404, and a content feature determination unit 405. And.

  The maximum luminance pixel number information value Nicmax output from the multiple luminance information detection unit 22 is input to the maximum luminance determination unit 401, and the intermediate luminance pixel number information value Nicmid is input to the intermediate luminance determination unit 402, and the minimum luminance pixel number information value Nicmin is input to the minimum luminance determination unit 403, and the average luminance information value Yicave is input to the average luminance determination unit 404.

  The maximum luminance determination 401 classifies the magnitude of the maximum luminance from the maximum luminance pixel number information value Nicmax, and generates a maximum luminance number information value D401 (Nicmax information value) that defines the classification information. The intermediate luminance determination unit 402 classifies the size of the intermediate luminance from the intermediate luminance pixel number information value Nicmid, and generates an intermediate luminance number information value D402 (Nicmid information value) that defines the classification information. The minimum luminance determination unit 403 classifies the size of the minimum luminance from the minimum luminance pixel number information value Nicmin, and generates a minimum luminance number information value D403 (Nicmin information value) that defines the classification information. The average luminance determination unit 404 classifies the average luminance magnitude from the average luminance information value Yicave, and generates an average luminance number information value D404 (Yicave information value) that defines the classification information.

  Maximum luminance determination unit 401, intermediate luminance determination unit 402, minimum luminance determination unit 403, and average luminance determination unit 404 are respectively the maximum luminance determination unit 301, intermediate luminance determination unit 302, minimum luminance determination unit 303, and Since the same operation as that of the average luminance determination unit 304 is performed, a detailed description of operations regarding these determination units 401 to 104 is omitted.

  Similar to the content feature determination unit 305 of the third embodiment, the content feature determination unit 405 performs content feature determination based on the combination shown in FIG. 23 from the combination of the four luminance number information values D401 to D404. The content feature determination information value JMi is output. However, the content feature determination information value Ji in FIG. 23 is replaced with the content feature determination information value JMi.

  The content feature detection unit 40 having the configuration shown in FIG. 25 is an example, and the content feature detection unit 40 has any configuration that can output the content feature determination information value JMi based on the pixel number information value Nical. Anything is acceptable.

  As an example of a method for outputting the content feature determination information value JMi based on the pixel number information value Nical, the likelihood of the pixel number information value Nical is calculated, and the content feature information value Ji is output from statistical processing. Can be considered.

  The multiple content feature detection unit 21 according to the fourth embodiment has the same configuration as the multiple content feature detection unit 11 of the first embodiment, and the operation is the same as the operation described in the first embodiment. Detailed operation description regarding the feature detection unit 21 is omitted.

  Similar to the gradation correction unit 6 of the image display device according to the first embodiment, the gradation correction unit 6 includes a correction control unit 4 and a correction execution unit 5 having the same configuration. The correction control unit 4 according to the fourth embodiment has the same configuration as that of the first embodiment, and the gradation correction unit 6 and the display unit 8 perform the same operations as those described in the first embodiment. Detailed operation description is omitted.

  As described above, in the image display device according to the fourth embodiment, by summing a plurality of frames from the pixel number information value and obtaining the average, the content feature determination information value JMi is used as a feature amount for a plurality of frames. Since the characteristics of the content are determined, the characteristics of the content can be determined more accurately. In addition, since the gradation correction unit 6 performs gradation correction on the image signal Db based on the plurality of content feature information values Fi that are finally detected using the content feature determination information value JMi as an analysis target, the gradation The correction is not frequently performed, and the optimum contrast adjustment is possible.

  In order to perform content feature determination corresponding to the image display device according to the fourth embodiment using the technique described in Patent Document 2, the key frame for characterizing the content is identified, and the key frame is based on the information. The frame number associated with is required to be preserved during processing.

  However, in the image processing apparatus according to the fourth embodiment, once the content feature determination information value JMi is obtained, the feature can be extracted for each frame and the content feature can be determined. Therefore, the content feature determination information value JMi By performing tone correction on the image signal Db based on the detected multiple content feature information values Fi, content feature determination can be performed while maintaining real-time characteristics, and optimal contrast adjustment can be performed for each frame. .

  Although the real-time property of gradation correction is slightly lost, it can be considered that the multiple luminance information detection unit 22 sequentially outputs the multiple pixel number information value Nical every m frames.

It is a block diagram which shows the structure of the image display apparatus by Embodiment 1 of this invention. It is a block diagram which shows the structure of the brightness | luminance information detection part shown in FIG. It is explanatory drawing which shows the detection conditions of the luminance information value based on the luminance histogram produced | generated by the histogram production | generation part shown in FIG. It is a block diagram which shows the structure of the content feature detection part shown in FIG. FIG. 5 is an explanatory diagram illustrating threshold conditions for maximum luminance information by a maximum luminance determination unit illustrated in FIG. 4. FIG. 5 is an explanatory diagram showing threshold conditions for intermediate luminance information by the intermediate luminance determining unit shown in FIG. 4. FIG. 5 is an explanatory diagram illustrating threshold conditions for minimum luminance information by a minimum luminance determination unit illustrated in FIG. 4. It is explanatory drawing which shows the content feature determination content by the content feature detection part shown in FIG. 1 in a table format. Explanatory view showing an example of the multiple content characteristic information values are thus determined to the multiple content feature detection unit shown in FIG. 1; FIG. Explanatory view showing an example of the multiple content characteristic information values are thus determined to the multiple content feature detection unit shown in FIG. 1; FIG. Explanatory view showing an example of the multiple content characteristic information values are thus determined to the multiple content feature detection unit shown in FIG. 1 is a diagram (part 3). Explanatory view showing an example of the multiple content characteristic information values are thus determined to the multiple content feature detection unit shown in FIG. 1 is a diagram (part 4). It is explanatory drawing for demonstrating operation | movement of the correction control part shown in FIG. It is a block diagram which shows the structure of the image display apparatus by Embodiment 2 of this invention. It is a block diagram which shows the structure of the content feature detection part shown in FIG. It is a block diagram which shows the structure of the image display apparatus by Embodiment 3 of this invention. It is a block diagram which shows the structure of the brightness | luminance information detection part shown in FIG. It is explanatory drawing which shows the histogram produced | generated by the histogram production | generation part shown in FIG. It is a block diagram which shows the structure of the content feature detection part shown in FIG. It is explanatory drawing which shows the threshold value conditions of the maximum luminance pixel number information by the maximum luminance determination part shown in FIG. It is explanatory drawing which shows the threshold value conditions of the intermediate brightness pixel number information by the intermediate brightness determination part shown in FIG. It is explanatory drawing which shows the threshold value conditions of the minimum luminance pixel number information by the minimum luminance determination part shown in FIG. It is explanatory drawing which shows the content feature determination content by the content feature determination part shown in FIG. 19 in a table format. It is a block diagram which shows the structure of the image display apparatus by Embodiment 4 of this invention. It is a block diagram which shows the structure of the content feature detection part shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input terminal, 2 receiving part, 4 correction control part, 5 correction execution part, 6 gradation correction part, 7, 17, 27, 37 Image processing apparatus, 8 display part, 9, 19 Luminance information detection part, 10, 20 , 30, 40 Content feature detection unit, 11, 21 Multiple content feature detection unit, 12 , 22 Multiple luminance information detection unit, 91, 191 Histogram generation unit, 92, 192 Maximum gradation detection unit, 93, 193 Intermediate gradation detection , 94, 194 Minimum gradation detection unit, 95, 195 Average luminance gradation detection unit, 101, 201, 301, 401 Maximum luminance determination unit, 102, 202, 302, 402 Intermediate luminance determination unit, 103, 203, 303 , 403 Minimum luminance determination unit, 104, 204, 304, 404 Average luminance determination unit, 105, 205, 305, 405 Content feature determination unit, 192 Maximum luminance pixel number detection , 193 intermediate luminance pixel number detection unit, 194 minimum luminance pixel number detection unit, 195 the average brightness detection unit.

Claims (8)

A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
A feature determination unit that performs a feature determination of video content on the image signal for one frame based on the luminance-related information value output from the luminance information detection unit, and obtains a feature determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the feature determination values output from the feature determination unit for a plurality of frames; and
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the plurality of feature determination values ;
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
The first judgment criterion for counting the types indicated by the feature determination values obtained sequentially, recognizing the type whose counting result has reached the predetermined number of appearances earliest, and obtaining the plurality of feature determination values indicating the type Have
Image display device. A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
Based on the luminance-related information value output from the luminance information detection unit, a characteristic determination unit that performs a characteristic determination of video content on the image signal for one frame and obtains a characteristic determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the feature determination values output from the feature determination unit for a plurality of frames; and
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the plurality of feature determination values;
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
Counting the types indicated by the feature determination values obtained sequentially, recognizing the type whose count result is the earliest and continuously reaching a predetermined number of consecutive appearances, and obtaining the plurality of feature determination values indicating the types Has two criteria,
Image display device. A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
A feature determination unit that performs a feature determination of video content on the image signal for one frame based on the luminance-related information value output from the luminance information detection unit, and obtains a feature determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the feature determination values output from the feature determination unit for a plurality of frames; and
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the plurality of feature determination values;
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
Counting the types indicated by the characteristic determination values obtained sequentially, recognizing the type having the largest count value within a predetermined period, and having a third determination criterion for obtaining the multiple characteristic determination values indicating the types;
Image display device. A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
A feature determination unit that performs a feature determination of video content on the image signal for one frame based on the luminance-related information value output from the luminance information detection unit, and obtains a feature determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the feature determination values output from the feature determination unit for a plurality of frames; and
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the plurality of feature determination values;
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
A first criterion for counting the types indicated by the feature determination values obtained sequentially, recognizing a type whose counting result has reached a predetermined number of appearances earliest, and obtaining the plurality of characteristic determination values indicating the type; Recognizing the type that has the earliest counting result and continuously reaching the predetermined number of consecutive appearances, the second determination criterion for obtaining the multiple feature determination value indicating the type, and the count value within the predetermined period are the highest Recognizing a number of types and determining by a combination of a plurality of types including at least one criterion among the third determination criteria for obtaining the plurality of feature determination values indicating the type.
Image display device. A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
A feature determination unit that performs a feature determination of video content on the image signal for a plurality of frames and obtains a feature determination value based on the luminance-related information value output from the luminance information detection unit;
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the feature determination related value related to the feature determination value;
The feature determination unit can obtain the feature determination value for each frame after first obtaining the feature determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the plurality of feature determination values output from the feature determination unit;
The feature determination related value includes the plurality of feature determination values,
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
The first judgment criterion for counting the types indicated by the feature determination values obtained sequentially, recognizing the type whose counting result has reached the predetermined number of appearances earliest, and obtaining the plurality of feature determination values indicating the type Have
Image display device. A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
A feature determination unit that performs a feature determination of video content on the image signal for a plurality of frames and obtains a feature determination value based on the luminance-related information value output from the luminance information detection unit;
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the feature determination related value related to the feature determination value;
The feature determination unit can obtain the feature determination value for each frame after first obtaining the feature determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the plurality of feature determination values output from the feature determination unit;
The feature determination related value includes the plurality of feature determination values,
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
Counting the types indicated by the feature determination values obtained sequentially, recognizing the type whose count result is the earliest and continuously reaching a predetermined number of consecutive appearances, and obtaining the plurality of feature determination values indicating the types Has two criteria,
Image display device. A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
A feature determination unit that performs a feature determination of video content on the image signal for a plurality of frames and obtains a feature determination value based on the luminance-related information value output from the luminance information detection unit;
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the feature determination related value related to the feature determination value;
The feature determination unit can obtain the feature determination value for each frame after first obtaining the feature determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the plurality of feature determination values output from the feature determination unit;
The feature determination related value includes the plurality of feature determination values,
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
Counting the types indicated by the characteristic determination values obtained sequentially, recognizing the type having the largest count value within a predetermined period, and having a third determination criterion for obtaining the multiple characteristic determination values indicating the types;
Image display device. A luminance information detection unit that receives an image signal, creates a histogram relating to a luminance signal obtained from the image signal for one frame, and detects a luminance-related information value from the histogram;
A feature determination unit that performs a feature determination of video content on the image signal for a plurality of frames and obtains a feature determination value based on the luminance-related information value output from the luminance information detection unit;
A gradation correction unit that performs gradation correction on the image signal for one frame newly obtained based on the feature determination related value related to the feature determination value;
The feature determination unit can obtain the feature determination value for each frame after first obtaining the feature determination value;
A plurality of feature detection units for obtaining a plurality of feature determination values by analyzing the plurality of feature determination values output from the feature determination unit;
The feature determination related value includes the plurality of feature determination values,
The feature determination value indicates a plurality of types of features,
The multi-feature detection unit includes:
A first criterion for counting the types indicated by the feature determination values obtained sequentially, recognizing a type whose counting result has reached a predetermined number of appearances earliest, and obtaining the plurality of characteristic determination values indicating the type; Recognizing the type that has the earliest counting result and continuously reaching the predetermined number of consecutive appearances, the second determination criterion for obtaining the multiple feature determination value indicating the type, and the count value within the predetermined period are the highest Recognizing a number of types and determining by a combination of a plurality of types including at least one criterion among the third determination criteria for obtaining the plurality of feature determination values indicating the type.
Image display device.

Images