JP4506548B2 - Video processing apparatus and video display apparatus - Google Patents

Description

  The present invention relates to a video display device such as a television receiver, or a video processing device such as a DVD player or a set top box including a digital tuner, and in particular, according to the characteristics of an input video signal. The present invention relates to a video display device that performs correction.

  With the spread of digital broadcasting, high-quality video sources such as high-definition broadcasting are increasing. In addition, the market for high-priced plasma televisions and LCD televisions is expanding, and interest in higher image quality is increasing.

  As a technique for improving the image quality in these video display apparatuses, there is a method of detecting the characteristics of an input video signal and correcting the image quality for each frame according to the characteristics. In this method, if the luminance and saturation correction of the video signal, the edge enhancement, etc. are frequently performed, the video displayed on the video display device may flicker. In the prior art, in order to suppress such flicker, the correction amount to be changed at a time in the image quality correction is reduced, and the correction operation is delayed in time.

  However, if the image changes significantly, such as when changing from a bright image to a dark image, the image quality correction cannot keep up with the change in the image if the amount of change in the image quality correction is reduced. Correction is continued gradually, and optimal image quality correction cannot be performed on the displayed image.

  In order to improve this problem, there are image quality correction methods described in Patent Document 1 and Patent Document 2. In Patent Document 1, by providing a scene detection means for detecting a large video change, the amount of change in correction is controlled, and flicker and correction deviation are suppressed. Further, in Patent Document 2, the scene detection means detects the degree of scene change and enables higher-level image quality correction.

  Below, the image quality correction method by the prior art represented by patent document 2 is demonstrated.

  FIG. 9 is a block diagram of image quality correction means in a conventional video display device. The conventional image quality correction means includes a correction processing unit 20, a target correction amount calculation unit 30, a correction amount calculation unit 40, a frame memory 50, and a scene change amount calculation unit 60. The video signal input to the input terminal 10 is input to the correction processing unit 20, the target correction amount calculation unit 30, the frame memory 50, and the scene change amount calculation unit 60. The target correction amount calculation unit 30 calculates a target image quality correction amount according to the input video signal. The calculated target image quality correction amount is input to the correction amount calculation unit 40. The scene change amount calculation unit 60 compares the input current frame video signal with the previous frame video signal output from the frame memory 50 to calculate a scene change amount. The calculated scene change amount is input to the correction amount calculation unit 40. The correction amount calculation unit 40 calculates a final image quality correction amount according to the input target correction amount and scene change amount. In the correction processing unit 20, image quality correction is performed according to the image quality correction amount calculated by the correction amount calculation unit 40, and the video signal subjected to the image quality correction is output to the output terminal 11.

  Next, the configuration for calculating the image quality correction value according to the scene change amount will be described.

  FIG. 10 shows the relationship between the scene change amount and the correction amount in the conventional image quality correction means. The correction amount calculation unit 40 performs processing for bringing the image quality correction value closer to the input target correction value by adding or subtracting the change amount determined by the scene change amount with respect to the current image quality correction amount. Here, as shown in FIG. 10, the amount of change is a small amount of change when the scene change amount is small, and a large amount of change when the scene change amount is large.

  As described above, in the case of a small video change, the amount of change in the image quality correction value is suppressed to suppress flickering of the video. The deviation is suppressed.

JP 2002-262303 A JP 2005-039786 A

  However, since the conventional image quality correction means requires a minimum of one frame as the time to acquire the video data for calculating the target correction value and calculating the scene change amount, the correction amount is input to the correction processing unit 20. At the time of input, the input video signal used for the calculation of the target correction value and the scene change amount has already been output, and there is a problem that the optimum image quality correction according to the scene change cannot be performed.

  FIG. 11 shows the detection timing of the video feature data, and the problem will be described using this timing. FIG. 11 shows the timing at which video feature data is determined when a video signal that changes from video A to video B is input at timing T111. In order to perform image quality correction in accordance with video features for each frame, it is necessary to acquire video feature data for one frame. Therefore, when the video changes from the video A to the video B, the feature data of the video B is determined at a timing T112 delayed by one frame from the timing T111. As described above, the acquisition of the video feature data ends at least one frame after the video signal is input. Accordingly, one frame of time elapses from the input of the video signal until the respective calculated values are output from the target correction amount calculation unit 40 and the scene change amount calculation unit 60. For this reason, a time of one frame elapses after the video signal is input until the image quality correction value suitable for the input video signal is output from the correction amount calculation unit 40. From the above, in the configuration of the conventional image quality correction means, the video signal of the next frame is already input at the timing of image quality correction to the correction processing unit 20, and image quality correction that completely follows the scene change can be performed. Absent. In particular, when the target correction amount calculation unit, the scene change amount calculation unit, the correction amount calculation unit, and the like are configured by a CPU and the correction processing unit is controlled using a serial bus such as an I2C bus, it takes time to control. There is a risk that a delay of one frame or more may occur. For example, when the scene changes from a bright scene to a dark scene, there is a state in which the image quality correction amount for the bright scene is applied to the dark scene for a moment, so that the image quality is deteriorated due to the correction shift.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of reducing image quality degradation due to a correction shift caused by a scene change when performing image quality correction of a video signal. .

  In order to achieve the above object, the present invention detects video information from video signals before and after a video processing unit that performs predetermined signal processing on the video signal using a memory unit such as a frame memory, for example. Two video information detectors were provided. In the present invention, a scene change is determined from the video information detected by the detection unit before the video processing unit, and the image quality correction amount is calculated from the video information detected by the detection unit after the video processing unit. As described above, when the scene change occurs, the image quality correction amount is corrected and the image quality correction is performed.

  Specifically, the present invention includes a video display processing unit that performs signal processing for converting a signal format of an input video signal into a format that can be displayed on a display device such as a PDP or an LCD using a frame memory; From the first video information detection unit that detects video information in the previous stage of the video display processing unit, the second video information detection unit that detects video information in the subsequent stage of the video display processing unit, and the first video information detection unit A video change amount calculation unit that detects a video change amount from the video information of the video information, a target correction amount calculation unit that calculates an image quality correction amount from the video information from the second video information detection unit, and a video change amount detection unit The amount of image change and the target image quality correction amount from the target correction amount calculation unit are input, and the correction amount calculation unit that calculates the image quality correction amount from the input data and the image quality correction amount from the correction amount calculation unit Depending on the image, Comprising a correction processing unit.

  According to the above configuration, by calculating the video change amount from the video information detected by the first video information detection unit in the previous stage of the video display processing unit using the frame memory, and using this for the image quality correction amount calculation, the frame memory By using the video delay caused by the image quality, it is possible to suppress image quality deterioration due to a correction shift at the time of a scene change. In addition, since the image quality correction amount is determined based on the video information detected by the second video information detection unit subsequent to the video display processing unit, the image quality correction amount can be calculated based on the actually displayed video information. More accurate image quality correction is possible.

  According to the present invention, it is possible to reduce image quality deterioration due to a correction shift caused by a scene change and display a high-quality image.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of a video display apparatus according to a first embodiment of the present invention. The video display apparatus according to the present embodiment includes a video display processing unit 102, a frame memory 103, an image quality correction processing unit 104, a first video information detection unit 105, a video change amount calculation unit 106, a second video information detection unit 107, and a target correction. An amount calculation unit 108 and a correction amount calculation unit 109 are provided.

Next, the operation of this embodiment will be described. The video signal input from the input terminal 101 is input to the video display processing unit 102 and the first video information detection unit 105. The video display processing unit 102 performs an IP conversion process that converts an interlace signal into a non-interlace signal, a scaling process such as enlargement or reduction, a scan conversion process that changes the frequency of an output signal, and the like. Convert the signal into a format that can be displayed on a video display device. In this video processing, processing through the frame memory 102 is performed, so that the video signal input to the video display processing unit 102 is output with a delay of one frame. The video signal output from the video display processing unit 102 is input to the image quality correction processing unit 104 and the second video information detection unit 107. The image quality correction processing unit 104 performs image quality correction on the input video signal in accordance with the image quality correction amount from the correction amount calculation unit 109, and outputs the video signal whose image quality has been corrected from the output terminal 101. The first video information detection unit 105 detects video information such as average luminance, maximum value, and minimum value of the input video signal, and the detected video information is sent to the video change amount calculation unit 106 one frame after the video signal is input. Is output. Image change amount calculation unit 106 has a storage memory of image information inputted, it calculates the difference between the video information currently input and video information previously input as image variation amount. The calculated video change amount is input to the correction amount calculation unit 109. The second video information detection unit 107 detects more detailed video information than the first video information detection unit 105 such as an average luminance, maximum value, minimum value, luminance and saturation histogram of the input video signal, The detected video information is input to the target correction amount calculation unit 108 one frame after the video input. The target correction amount calculation unit 108 calculates a target image quality correction amount according to the input video information, and inputs the target image quality correction amount to the correction amount calculation unit 109. The correction amount calculation unit 109 has a storage memory for the image quality correction amount, calculates a final image quality correction amount from the input image change amount, target image quality correction amount, and previous image quality correction amount, and the image quality correction processing unit 104. Enter the image quality correction amount in.

  Next, timing of video information detection and image quality correction will be described with reference to FIG. FIG. 2 is a time chart of video information detection timing with respect to an input video change in the first embodiment. When the input video signal changes from video A to video B at the timing of T201, the first video information detection unit 105 detects the video information of video B at the timing of T202. When the video delay in the video display processing unit 102 is one frame, the video A changes from the video A to the video B at the timing of T202 as in the first video information detection unit 105. The second video information detection unit 107 detects video information data in a format displayed on the video display device at the timing of T203 in order to detect video information from the output result of the video display processing unit 102. The video change amount calculation unit 106 receives video information from the first video information detection unit at the timing of T202, and outputs a difference from the previous video information to the correction amount calculation unit 109. In addition, the target correction amount input from the target correction amount calculation unit 108 to the correction amount calculation unit 109 at the timing of T202 is a target correction amount for the video A that is the image one frame before. Here, when the video change amount input to the video change amount calculation unit 109 is large, it can be determined that the target correction amount input at the same timing is unreliable.

  Next, the operation of the correction amount calculation unit 109 will be described with reference to FIG. FIG. 3 is a detailed configuration diagram of the correction amount calculation unit 109.

  As illustrated in FIG. 3, the correction amount calculation unit 109 includes a change amount determination unit 309, a correction amount determination unit 319, a correction amount determination unit 329, and a memory 339. The change amount determination unit 309 determines whether the input video change amount is greater than or equal to the change amount and an arbitrarily determined change amount, and the result is input to the correction amount determination unit 329. The correction amount determination unit 319 receives the target correction amount and the previous image quality correction amount from the memory 339, determines a correction direction from the magnitude relationship between the target correction amount and the previous image quality correction amount, and the result is the correction amount determination unit. 329. The correction amount determination unit 329 uses the image quality correction direction from the correction amount determination unit 319 and the previous image quality correction amount from the memory 339 to calculate the final image quality correction amount. When the target correction amount is T, the arbitrarily determined correction amount is α, the previous correction amount is D ′, and the calculated correction amount is D, for example, the following operation is performed.

(When T> D ′) D = D ′ + α
(When T <D ′) D = D′−α
(When T = D ') D = D'
In this example, the same correction amount α is used for addition and subtraction, but the correction amount may be determined separately according to the calculation direction. Further, when T <D as a result of addition of the correction amount α, and when T> D as a result of subtraction of the correction amount α, the target correction amount T is limited.

  Next, it is determined from the change amount determination signal whether the calculated image quality correction amount is reliable. Since the image quality correction amount is calculated based on the video information of the previous frame, when the video change amount is large, the image quality correction amount is an image quality correction amount that causes image quality degradation to the video signal that is actually subjected to image quality correction. there is a possibility. An example of the image quality correction amount reliability determination method will be described below.

  For example, when the video change amount is calculated using the average luminance signal, when the video changes from a bright scene to a dark scene, a large negative video change amount is detected. Here, when the target correction amount is large in a bright scene and small in a dark scene, the correction amount calculation unit 109 has a large target according to a large negative image change amount and video information of the previous frame. The correction amount is input. At this time, the correction amount calculation unit performs an operation to increase the image quality correction amount according to the target correction amount, but since a large change is input in the negative direction (darkening) as the image change amount, in a dark scene, It can be seen that this conflicts with the operation of setting a small value as the target of the image quality correction amount. At this time, the calculation result of the image quality correction amount is determined as unreliable. In addition, in the above contents, when a bright scene becomes brighter, the amount of video change becomes a large value in the positive direction. Therefore, the calculation direction of the image quality correction amount matches the target of image quality correction. The calculation result of the quantity shall be reliable.

  As described above, the reliability of the image quality correction amount is determined from the change amount determination result. If the image quality correction amount is reliable, the calculation result is output to the image quality correction processing unit 104 as it is and stored in the memory 339. If the image quality correction amount is not reliable, the image quality correction amount is input to the image quality correction processing unit 104 and the memory 339 instead of an arbitrarily determined image quality correction amount. As an example of the arbitrarily determined image quality correction amount in this case, it is conceivable that the image quality correction amount is set to 0 and the image quality correction amount is not applied.

  Through the above operation, the reliability of the image quality correction amount is determined from the change amount of the video information in the previous stage of the video display processing unit 102 via the frame memory, and the image quality correction amount is determined, thereby determining the correction shift at the time of the scene change. It is possible to suppress the image quality deterioration due to. Further, in the case of a stable video signal with little scene change, the image quality correction amount is calculated based on the video information that is actually displayed by performing image quality correction based on the video information in the subsequent stage of the video display processing unit 102. Accurate image quality correction is possible.

  As described above, in this embodiment, the video information is detected from the output signal of the video display processing unit 102 to obtain the image quality correction amount, and the video information is detected from the input signal to the video display processing unit 102 to change the scene. Judgment is made. Then, when information about a scene change is obtained from the video information before the display process, the image quality correction amount obtained from the video information after the display process is changed. Therefore, according to the present embodiment having such a configuration, the followability with respect to the scene change of the video related to the image quality correction is improved, and appropriate image quality correction can be given even if the scene change occurs. Therefore, it is possible to perform good image quality correction on the images before and after the scene change (particularly immediately after), and display high-quality images.

FIG. 4 is a block diagram of an image quality correction apparatus according to the second embodiment of the present invention. In FIG. 4, the same number is used for the same operation as in the first embodiment. In the second embodiment, video information from the first video information detection unit 105 is input to the correction amount calculation unit 109 in the first embodiment, and the accuracy of reliability determination performed by the correction amount calculation unit is improved. It is. Since the difference from the first embodiment is only the correction amount calculation unit 409, the operation of the correction amount calculation unit 409 will be described with reference to FIG.

  FIG. 5 is a detailed configuration diagram of the correction amount calculation unit 409. In FIG. 5, the same number is used for the same operation as in the first embodiment.

  As illustrated in FIG. 5, the correction amount calculation unit 409 includes a change amount determination unit 309, a correction amount determination unit 319, a correction amount determination unit 529, and a memory 339. The correction amount calculation unit 409 inputs the video information from the first video information detection unit 105 to the correction amount determination unit 529 to the correction amount calculation unit 109. Similar to the correction amount 329, the correction amount determination unit 529 calculates the final image quality correction amount using the image quality correction direction from the correction amount determination unit 319 and the previous image quality correction amount from the memory 339. Also, the reliability of the image quality correction value is determined from the change amount determination result from the change amount determination unit 309. If it is determined that the image quality correction value is not reliable, the image quality correction value is determined based on the input video information. FIG. 6 shows an output example of the image quality correction value when it is determined that it is not reliable. In the example of FIG. 6, the image quality correction amount when it is determined that it is not reliable is 0 when the video information data is P or less, and increases in proportion to the video information data when the video information data is greater than or equal to P.

  Through the above operation, the reliability of the image quality correction amount is determined from the amount of change in the video information in the previous stage of the video display processing unit 102 via the frame memory, and the image quality correction amount is determined from the video information, whereby the scene is determined. It is possible to more accurately suppress deterioration in image quality due to a correction shift at the time of change.

  FIG. 7 is a block diagram of an image quality correction apparatus according to the third embodiment of the present invention. In FIG. 7, the same number is used for the same operation as in the first and second embodiments. The third embodiment is the same as the second embodiment except that a second video change amount detection unit 710 that detects a video change amount from the video information of the second video information detection unit is added. The second video change amount data from the second video change amount detection unit 710 is input to the correction amount calculation unit 709. Here, in the calculation for making the previous image quality correction amount close to the target correction amount performed by the correction amount calculation unit 709, the change amount is controlled by using the input second image change amount, whereby the image quality correction amount image is obtained. Improve change tracking. Next, the operation of the correction amount calculation unit 709 will be described with reference to FIG.

  FIG. 8 is a detailed configuration diagram of the correction amount calculation unit 709. In FIG. 8, the same number is used for the same operation as in the first and second embodiments.

  As illustrated in FIG. 8, the correction amount calculation unit 709 includes a change amount determination unit 309, a correction amount determination unit 319, a correction amount determination unit 829, and a memory 339. The correction amount calculation unit 709 is configured to input the second video change amount from the second video change amount detection unit 710 to the correction amount determination unit 829 with respect to the correction amount calculation unit 409. Similar to the correction amount 529, the correction amount determination unit 829 calculates a final image quality correction amount using the image quality correction direction from the correction amount determination unit 319 and the previous image quality correction amount from the memory 339. Here, when the target correction amount is T, the arbitrarily determined correction amount is α, the previous correction amount is D ′, and the calculated correction amount is D, for example, the following operation is performed.

(When T> D ′) D = D ′ + α
(When T <D ′) D = D′−α
(When T = D ') D = D'
In the first embodiment, α is an arbitrarily determined correction amount, but the third embodiment is characterized in that the value of α is changed in accordance with the second image change amount. For example, if the second video change amount is small, the value of α is decreased, and if the second video change amount is large, the value of α is increased. When there is a large scene change, the image quality correction amount is adjusted to the video at high speed. When the scene change is small, flicker due to the change in the image quality correction amount can be suppressed by following the image quality correction amount at a low speed.

  The video processing apparatus according to the present invention can be used in, for example, a television receiver using a CRT, PDP, LCD, FED, or other display device. In the above description, a video processing apparatus such as a television receiver has been described as an example of the video processing apparatus. However, the present invention can also be applied to a set top box equipped with a DVD player or a digital tuner, or a hard disk record. Needless to say, the present invention is applicable not only to LCDs, PDPs, and FEDs but also to rear projection display devices.

1 is a block diagram of an image quality correction apparatus according to a first embodiment of the present invention. Time chart of video information detection timing with respect to input video change in the first embodiment of the present invention The detailed block diagram of the correction amount calculation part in 1st Embodiment of this invention. The block diagram of the image quality correction apparatus in 2nd Embodiment of this invention. The detailed block diagram of the correction amount calculation part in 2nd Embodiment of this invention Example of relationship between image quality correction amount and video information in second embodiment of the present invention The block diagram of the image quality correction apparatus in 3rd Embodiment of this invention. Detailed block diagram of correction amount calculation unit in the third embodiment of the present invention Block diagram of a conventional image quality correction device Relationship between scene change amount and correction amount in conventional image quality correction device Time chart of video information detection timing for input video change in conventional image quality correction device

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Input terminal, 11 ... Output terminal, 20 ... Correction processing part, 30 ... Target correction amount calculating part, 40 ... Correction amount calculating part, 50 ... Frame memory, 60 ... Scene change amount calculating part, 100 ... Input terminal, 101 DESCRIPTION OF SYMBOLS ... Output terminal, 102 ... Video display processing unit, 103 ... Frame memory, 104 ... Image quality correction processing unit, 105 ... First video information detection unit, 106 ... Video change amount calculation unit, 107 ... Second video information detection unit, 108 ... target correction amount calculation unit, 109 ... correction amount calculation unit, 309 ... change amount determination unit, 319 ... correction amount determination unit, 329 ... correction amount determination unit, 339 ... memory, 409 ... correction amount calculation unit, 529 ... correction amount Determination unit, 710 ... second video change amount calculation unit, 709 ... correction amount calculation unit, 829 ... correction amount determination unit

Claims (5)

In video processing equipment,
A first video information detector that detects video information of the input video signal;
A video display processing unit that converts the video signal into a format that can be displayed on a display device, using a frame memory that stores the video signal;
A second video information detection unit for detecting video information of a video signal output from the video display processing unit;
The current image information from the first image information detection unit, the last time of the video information stored, and the image change amount calculation unit for calculating a change amount of the image information,
A target correction amount calculating unit for calculating a target correction amount according to the image information from said second image information detector,
And image variation amount from the image change amount calculation unit, and the target correction amount from the target correction amount calculating unit, the stored previous time image quality correction amount and outputs the image quality correction amount of time obtained based on the correction A quantity calculator;
An image quality correction processing unit that performs image quality correction on the video signal output from the video display processing unit according to the image quality correction amount from the correction amount calculation unit ;
The correction amount calculation unit
A change amount determination unit that outputs a signal related to a change in the video based on the video change amount from the video change amount calculation unit;
Comparing the target correction amount from the target correction amount calculation unit with the stored previous image quality correction amount to calculate the image quality correction amount, and using the signal regarding the video change from the change amount determination unit The reliability of the calculated image quality correction amount is determined. When the reliability is determined to be reliable, the calculated image quality correction amount is determined. When the reliability is determined to be unreliable, the image quality correction amount different from the calculated image quality correction amount is determined. A correction amount determination unit that outputs the current image quality correction amount,
Image processing apparatus characterized by having a. The video processing apparatus according to claim 1, wherein the another image quality correction amount is a predetermined correction amount. The video processing apparatus according to claim 1,
The correction amount calculation unit receives the current video information detected by the first video information detection unit,
The video processing apparatus, wherein the correction amount determination unit calculates the other image quality correction amount from the current video information when it is determined that the calculated image quality correction amount is not reliable. The video processing apparatus according to claim 3.
And a second video change amount calculation unit for calculating a change amount of the video information from the video display processing unit from the video information detected by the second video information detection unit and the previous video information stored.
The correction amount determination unit sets a correction value that changes according to the amount of change in the video information from the video display processing unit calculated by the second video change amount calculation unit with respect to the previous image quality correction amount. An image processing apparatus, wherein the image quality correction amount is calculated by adding or subtracting according to a correction direction obtained by comparing the target correction amount with the stored previous image quality correction amount.   5. The video processing apparatus according to claim 1, wherein the video processing apparatus includes a display device that displays a video signal whose image quality has been corrected by the image quality correction processing unit. .

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