JP2013046320A - Video processing apparatus and video processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video processing technique which performs color correction more suitably.SOLUTION: A video processing apparatus comprises an input part for receiving an inputted video signal and a video processing part for performing hue correction on the video signal inputted to the input part. The video processing part, in the video processing, performs processing to vary hue value input/output properties being the properties of the correction of a hue output value with respect to a hue input value, in accordance with the inputted video signal, and performs processing to prevent the inclination of the polygonal line of the variable hue value input/output properties from becoming a negative number.

Description

  The present invention relates to a video processing technique.

  High-resolution display devices that receive and display images from digital broadcasts or optical discs have become widespread, and LCD (Liquid Crystal Display), PDP (Plasma Display Panel), and the like have become common. However, in these display devices, the color reproduction range may be variously limited, and various correction processes are performed on the color information.

  For example, Patent Document 1 discloses a correction technique for performing a plurality of color corrections.

  In video content, the spread of video for 3D stereoscopic viewing has also begun.

JP 2010-258759 A

  In Patent Document 1, each correction is set in parameters of correction amount, correction center, correction range, and inclination in FIG. 2, but in this method, the correction amount can be set only in an isosceles trapezoidal shape. There are challenges. In this method, particularly when the hue (hue) is corrected, the absolute values of the slopes of the correction start portion and the correction end portion become the same value, and there is a possibility that the correction is not preferable visually. Further, depending on the correction setting, the hue order may be changed, and there is a possibility that the correction is not preferable visually.

  In addition, in the case of images taken for 3D stereoscopic viewing, in the case of images taken of natural images, etc., images are usually taken using a plurality of cameras. There is a problem that a color difference occurs between them.

  The present invention has been made in view of the above problems, and an object thereof is to perform color correction more suitably.

  In order to solve the above-described problem, for example, an input unit that inputs video and a video processing unit that performs a hue correction process on the input video are provided, and the video processing unit outputs a hue output value with respect to a hue input value. The hue value input / output characteristics that are correction characteristics may be varied according to the input video, and the slope of the broken line of the variable hue value input / output characteristics may be configured not to take a negative number.

  According to the present invention, it is possible to perform color correction more suitably.

It is explanatory drawing which showed the implementation method of the hue conversion apparatus which concerns on Example 1 of this invention. It is the schematic diagram which showed the data definition of the hue which concerns on Example 1 of this invention. It is explanatory drawing which showed the hue correction table which concerns on Example 1 of this invention. It is explanatory drawing which showed the implementation method of the hue conversion apparatus which concerns on Example 2 of this invention. It is explanatory drawing which showed the implementation method of the hue conversion apparatus which concerns on Example 2 of this invention. It is explanatory drawing which showed the hue correction table which concerns on Example 2 of this invention. It is explanatory drawing which showed the effect of the offset process part which concerns on Example 2 of this invention.

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

  FIG. 1 is a block diagram of a hue conversion apparatus according to Embodiment 1 of the present invention. The input terminal 11 receives digitized hue data. When the video data is analog, sampling is performed by an analog-digital converter (not shown) and digitized. In addition, when the video data is not in a format including hue (for example, RGB format), matrix conversion is performed and converted to a format including hue (for example, hue, saturation, lightness, but not limited to this combination) Enter the hue data.

  Here, an example of hue data definition in the first embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram in which colors are displayed in two dimensions, with color saturation (darkness) in the radial direction and hue (hue) in the phase direction. As the hue increases from red at an angle of 0, it is defined as changing from yellow, green, cyan, blue, magenta, and back to red. In the present embodiment, for example, the hue is expressed by 8-bit data, but red that has made one round is indicated by 192, and the same color as 0 red is indicated. When the input hue data indicates an 8-bit full range (0 to 255, 256 is the same red as 0), 192/256 times is assumed to be converted and input. Alternatively, a conversion processing unit may be provided after the input terminal 11. The reason for performing the conversion will be described later.

  The hue correction unit 31 first obtains hue data obtained by correcting the input hue data according to a table as shown in FIG. The correction table is a method of designating each broken line by output values and inclinations for a plurality of inputs. By using such a correction table, there is an advantage that it becomes easy to grasp the hue correction for the hue input. Further, unlike the correction in which the correction amount is an isosceles trapezoid as in the correction disclosed in Patent Document 1, it is possible to set correction amounts having different inclinations at the correction start point and the correction end point. Thereby, it becomes possible to correct color information more suitably.

  This correction table is variably set for the input video in the hue correction unit 31, but the corrected hue is reversed with respect to the input hue by not permitting a negative value for the inclination of each broken line ( It is possible to prevent the phenomenon that the output hue does not increase monotonously.

  In this embodiment, the hue correction output range has 32 offsets, and 32 is set as red and 224 is set as red. Under this condition, the hue correction range is limited to, for example, a range of −32 to +31.

  Here, as described above, since the hue expression range (hue expression gradation) of the number of bits of the input hue data has already been reduced to 192, the remaining 64 ranges of the number of bits of the input hue data are used. If hue correction is performed, the maximum hue expression range after correction is 255. As a result, the bit width of the data representation of the video signal can be kept at 8 bits and not expanded. That is, the hue expression range of the input hue data is reduced by conversion, and the limited range of hue correction is set to be equal to or less than the decrease of the hue expression range. As a result, the circuit scale can be kept small.

  In this embodiment, an example of 8-bit data expression has been described. However, the present invention is not limited to this, and hue expression may be performed using another predetermined number of bits such as 10 bits. . In this case as well, if the hue representation range of the input hue data is reduced by conversion and the hue correction limit range is less than or equal to the decrease of the hue representation range, color complementarity is efficiently achieved within the predetermined number of bits. Is possible.

  Subsequently, the hue correction input value and the offset are subtracted from the hue correction output, and the hue correction amount in each hue correction unit is calculated as shown in FIG. The hue correction unit 31 outputs the calculated hue correction amount to the correction addition unit 61.

  The correction addition unit 61 adds the correction amount output from the hue correction unit 31 and the hue value input from the input terminal 11, and outputs the corrected hue value from the output terminal 71.

  Thereby, visually preferable color correction can be easily set, and color complementation that can be implemented with a relatively easy configuration can be performed.

  Note that the hue correction unit 31 and the correction addition unit 61 may be configured as a video processing unit.

  In addition, when the above-described bit number reduction processing is performed after video input, a processing unit that performs the bit number reduction processing, a hue correction unit 31, and a correction addition unit 61 are configured as a single unit. Also good.

  Next, a video processing apparatus according to the second embodiment of the present invention will be described with reference to FIG.

  The video information input terminal 201 receives a synchronization signal, a data valid period signal, video information, and a digitized hue value similar to the first embodiment. Here, the video information input to the video information input terminal 201 is not only a 2D video but also a 3D stereoscopic video. For example, a 3D stereoscopic video includes a plurality of viewpoints. The input video information is sent to the color correction processing unit 211 and the histogram unit 221.

  In the histogram unit 221, when the information output from the video information output terminal 141 of the color correction processing unit 211 is a 3D stereoscopic video, for each of the left and right eye images, for each constant hue. A histogram of the number of pixels included in each hue (for example, every 16 gradations) is acquired.

  The CPU 251 acquires information of the histogram unit 221 based on a program recorded in the storage device 241. When the input video is a three-dimensional stereoscopic video, the hue correction processing of the hue correction unit of the color correction processing unit 211 is controlled so that the video for the left and right eyes has a similar histogram.

  Next, details of the color correction processing unit 211 will be described with reference to FIG.

  The hue value input from the video information input terminal 201 is input to the input terminal 11. However, in this embodiment, the hue value is input as an 8-bit full range (0 to 255, 256 is the same red as 0).

  In the offset processing units 81 and 82, the hue value input from the input terminal 11 is added to or subtracted from the value set by the setting information input from the parameter setting terminal 21 connected to the internal bus shown in FIG. To convert the hue value and output it. At this time, if the calculated value is a negative value, the expression width for one round of hue (256 in this embodiment) is added, and if the calculated value is 256 or more, the expression for one hue is expressed. A process of subtracting the width 256 is performed so that the value falls within the full range of the used bit width. This process is the same as the process for obtaining a positive remainder for one round of hue.

  The hue correction units 91 and 92 directly obtain correction amounts for the hue data input from the offset processing units 81 and 82 according to the correction characteristics shown in FIG. The correction characteristic specifies a polygonal line by output values and inclinations for a plurality of inputs set from the parameter setting terminal 21. It should be noted that by limiting the range in which the inclination can be taken to a predetermined range, it is possible to prevent the phenomenon that the hue after correction is reversed (the output hue does not increase monotonously). This is a control equivalent to the control for preventing the slope from taking a negative value in the input / output characteristics of the hue information in the first embodiment.

  Here, when a 3D stereoscopic video is input to the color correction processing unit 211, for example, the offset correction unit 81 and the hue correction unit 91 of the hue correction unit perform color correction processing for the right-eye video. The hue correction unit offset processing unit 82 and the hue correction unit 92 perform color correction processing for the left-eye video. Based on the information of the histogram unit 221 in FIG. 4, the CPU 251 reduces the color difference between the images of the plurality of viewpoints of the 3D stereoscopic video, the offset processing unit 81 of the hue correction unit, the hue correction unit 91, The parameter setting values of the offset processing unit 82 and the hue correction unit 92 are calculated, and the parameter setting values calculated via the parameter setting terminal 21 in FIG. 5 are transmitted to the above-described units to change the settings.

  Next, video format determination and hue correction processing switching will be described. The synchronization signal and the data valid period signal input from the video information input terminal 201 to the video processing apparatus in FIG. 4 are input from the input terminal 111 in the color correction processing unit 211 in FIG. The format determination unit 121 determines the video format based on the signal input from the input terminal 111. For example, counting is performed based on horizontal and vertical synchronization signals, and by confirming at what timing and for how long the data valid signal enters, (1) video size, (2) synchronization Coordinate range of video for signal, (3) 2D video or 3D stereoscopic video, or (4) 3D stereoscopic video, what kind (method) of 3D stereoscopic It is determined whether or not the video is for performing. In addition, a video format determination signal as a determination result is output to the coordinate processing unit 131. Here, the determination method using the synchronization signal and the data valid signal is described. Alternatively, the video format may be determined based on accompanying information transmitted accompanying the video data. In this case, the video processing apparatus of FIG. 4 receives the video format (for example, whether the video size is a 3D stereoscopic video, whether it is a 3D stereoscopic video from the video information input terminal 201 or an input terminal not shown). Accompanying information in which information for identifying a 3D stereoscopic method) is stored is input. The incidental information may be input from the input terminal 111 in FIG. 5 and used by the format determination unit 121 for format determination.

  In the coordinate processing unit 131, among the video format determination signals received from the format determination unit 121, the determination signal as to whether the video is a 2D video or a 3D stereoscopic video is a 3D stereoscopic video. In the case shown, a determination signal indicating that the video is for the right eye or the video for the left eye is sent to the switching unit 101 and the coordinate information output terminal 141 in accordance with the timing of the correction amount based on the synchronization signal or the data valid period signal. Output.

  In the switching unit 101, the hue correction unit 91 is set as the correction amount for the right eye, the correction amount from the hue correction unit 92 is set as the correction amount for the left eye, and is switched according to the determination signal from the coordinate processing unit 131 and output.

  In the correction addition unit 61, the correction amount from the switching unit 101 is added and output from the output terminal 71 as in the first embodiment, thereby correcting the hue.

  Note that the hue correction range can be changed as shown in FIG. 7 without changing many settings of the hue correction units 91 and 92, only by changing the offset setting values in the offset processing units 81 and 82. It becomes. Therefore, when correcting the 3D stereoscopic video, the adjustment of the hues of the left and right images is performed independently of the change of the setting values of the hue correction units 91 and 92, and the setting values of the offset processing units 81 and 82 are changed. If the configuration is adjusted in (4), setting value change processing control is simplified, and the load on the CPU 251 can be reduced.

  In the present embodiment, the hue correction unit has two systems, and the respective outputs are switched to correct the left and right images of the image for 3D stereoscopic viewing. As another configuration example of the present embodiment, a hue correction unit may be used as one system to correct only the image of one eye and perform a hue correction that approaches the hue of the image of the other eye. In this case, the correction amount from the hue correction unit 91 is selected based on the determination signal from the coordinate processing unit 131, and the correction amount from the hue correction unit 91 is selected in the case of processing at the coordinate position of the correction target eye image. In the case of the processing at the coordinate position, control for switching to input the correction amount 0 to the correction adding unit 61 may be performed.

  Further, as another configuration example of the present embodiment, a configuration in which the switching unit 101 is not provided and the hue correction unit has only one system may be employed. In this case, two types of correction tables may be stored in one hue correction unit, and the correction table may be switched based on a determination signal from the coordinate processing unit 131.

  In the present embodiment, the processing is described as only the hue processing. However, as described in Patent Document 1, the color range may be set in three dimensions to correct the color. Note that the color representation expressed in three dimensions is not limited to that represented by saturation and lightness as long as the hue is included.

  According to the video processing apparatus according to the second embodiment of the present invention described above, it is possible to perform visually preferable color correction with reduced color difference between videos in a video for performing 3D stereoscopic viewing. .

  Note that a video processing unit in which the color correction processing unit 211 and the histogram unit 221 are integrated may be configured.

DESCRIPTION OF SYMBOLS 11 Input terminal 21 Parameter control terminal 31 Hue correction part 61 Correction addition part 71,231 Output terminal 81,82 Offset processing part 91,92 Hue correction part 101 Switching part 111 Synchronization signal / data valid signal input terminal 121 Format determination part 131 Coordinate Processing unit 141 Video information output terminal 201 Video information input terminal 211 Color correction processing unit 221 Histogram unit 241 Storage device 251 CPU

Claims (6)

An input unit for inputting video;
A video processing unit that performs a hue correction process on the input video,
The video processing unit varies a hue value input / output characteristic, which is a correction characteristic of a hue output value with respect to a hue input value, according to the input video, and a slope of a broken line of the variable hue value input / output characteristic does not take a negative number. A video processing apparatus characterized by the above. The video processing apparatus according to claim 1,
The video processing unit performs data conversion processing to reduce a range of expression within the number of bits at the time of input of hue data of the input video, and reduces the range of correction amount due to the variable hue value input / output characteristics. An image processing apparatus characterized in that the range is less than the expression range of hue data of an input image. An input unit for inputting images from multiple viewpoints;
The hue value input / output characteristic is varied so that the hue histogram of the video of one viewpoint approaches the hue histogram of the video of the other viewpoint for at least one of the inputted viewpoint videos. An image processing apparatus comprising: an image processing unit that performs hue correction processing. An input step for inputting video;
A video processing step for performing a hue correction process on the input video,
In the video processing step, a hue value input / output characteristic, which is a correction characteristic of the hue output value with respect to the hue input value, is varied according to the input video, and the slope of the broken line of the variable hue value input / output characteristic does not take a negative number. A video processing method characterized by the above. The video processing method according to claim 4,
In the video processing step, data conversion processing is performed to reduce an expression range within the number of bits at the time of input of hue data of the input video, and a range of correction amount due to the variable hue value input / output characteristics is reduced. An image processing method, wherein the range is less than a representation range of hue data of an input image. An input step for inputting images from multiple viewpoints;
The hue value input / output characteristic is varied so that the hue histogram of the video of one viewpoint approaches the hue histogram of the video of the other viewpoint for at least one of the inputted viewpoint videos. A video processing method comprising: a video processing step for performing hue correction processing.

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