Image processing method, image processing device, and program

Abstract

This video processing method comprises: acquiring a first video signal (S101); detecting a first region including graphics different from a main video, from a region of a first video indicated by the acquired first video signal (S104); calculating first peak luminance of a second region obtained by excluding the first region from the region of the first video (S105); executing a tone mapping process on the first video so as to reduce luminance larger than the first peak luminance (S106); and outputting a second video signal indicating a second video having undergone the tone mapping process (S109).

Description

[Technical field]

[0001] The present disclosure relates to a video processing method, a video processing device, and a program. [Background technology]

[0002] Patent Document 1 discloses a video playback device that extracts a main video signal and sub-video information such as subtitles from a video signal, adds the sub-video to the main video, and outputs the result to an external display device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-194311 A [Patent Document 2] JP 2011-015068 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technique of Patent Document 1, it is difficult to adjust the brightness of a sub-video (graphics) such as subtitles in a video in which the sub-video is embedded.

[0005] The present disclosure provides an image processing method capable of adjusting the brightness of graphics. [Means for solving the problem]

[0006] The video processing method according to the present disclosure includes acquiring a first video signal, and processing a first video represented by the acquired first video signal. A first image in which graphics are superimposed on a main image Of the areas, The above Graphics It is superimposeda first region is detected, a first peak luminance of a second region obtained by excluding the first region from the region of the first image is calculated, a tone map process is performed on the first image to reduce luminance greater than the first peak luminance, and a second image signal indicating the second image after the tone map process is output. In the tone map process, the luminance below the first peak luminance is not reduced. .

[0007] Also, the image processing device according to the present disclosure includes an acquisition unit that acquires a first image signal, and a first image represented by the first image signal acquired by the acquisition unit. A first image in which graphics are superimposed on a main image Of the areas, The above Graphics It is superimposed a detection unit that detects a first region; a calculation unit that calculates a first peak luminance of a second region obtained by excluding the first region from the region of the first image; a tone map processing unit that performs a tone map process on the first image to reduce luminance that is greater than the first peak luminance; and an output unit that outputs a second image signal that represents the second image after the tone map process. In the tone map process, the luminance below the first peak luminance is not reduced. .

[0008] These general or specific aspects may be realized as a system, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized as any combination of an apparatus, a system, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0009] According to the video processing method and the like of the present disclosure, the brightness of graphics embedded in a video can be adjusted. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a configuration of an AV system according to the first embodiment. [Figure 2A] FIG. 2A is a diagram showing examples of EOTFs corresponding to HDR and SDR. [Figure 2B] FIG. 2B is a diagram showing an example of OETFs compatible with both HDR and SDR. [Diagram 3] FIG. 3 is a block diagram illustrating an example of a functional configuration of the video processing device according to the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining the processing by the first conversion unit, the tone map processing unit, and the second conversion unit. [Diagram 5] FIG. 5 is a diagram showing an example of a video in which graphics (subtitles) are embedded. [Figure 6] FIG. 6 is a diagram showing an example of region division for detecting a first region from an image. [Figure 7] FIG. 7 is a diagram showing an example of a histogram of a block including graphics. [Figure 8] FIG. 8 is a diagram showing an example in which the area including the graphics in FIG. 5 is detected as the first area. [Figure 9] FIG. 9 is a diagram showing an example of the first region and the second region detected by the detection unit. [Figure 10] FIG. 10 is a diagram showing an example of a histogram of the second region. [Figure 11] FIG. 11 is a diagram showing an example of a plurality of tone curves used in tone map processing. [Figure 12] FIG. 12 is a diagram for explaining an example of tone map processing when the video is a dark scene. [Figure 13] FIG. 13 is a diagram for explaining an example of tone map processing when the video is a bright scene. [Figure 14] FIG. 14 is a flowchart showing an example of the operation (video processing method) of the video processing device according to the first embodiment. [Figure 15] FIG. 15 is a block diagram illustrating an example of a functional configuration of a video processing device according to the second embodiment. As illustrated in FIG. [Figure 16] FIG. 16 is a flowchart showing an example of the operation (video processing method) of the video processing device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Findings on which this disclosure is based) The present inventor has found that the video reproducing device described in the "Background Art" section has the following problems.

[0012] The video playback device disclosed in Patent Document 1 generates a main video based on a main video signal, generates a sub-video based on sub-video information, and outputs the video obtained by superimposing the sub-video on the main video to a display device. Therefore, the brightness of the main video and the sub-video can be adjusted independently, and the brightness of the sub-video can be easily adjusted according to the brightness of the main video.

[0013] However, when this video playback device acquires a video signal of a video that has already been generated by superimposing a sub-video on a main video, this video signal does not include sub-video information, and is a video in which the sub-video is embedded, so it is difficult to adjust the brightness of the main video and the sub-video independently, and therefore it is difficult to adjust the brightness of the sub-video according to the brightness of the main video.

[0014] In order to solve the above problem, an image processing device according to the present disclosure acquires a first image signal, detects a first area of ​​a first image indicated by the acquired first image signal, which detects a first area including graphics different from a main image, calculates a first peak luminance of a second area obtained by excluding the first area from the area of ​​the first image, performs tone mapping processing on the first image to reduce luminance greater than the first peak luminance, and outputs a second image signal indicating the second image after the tone mapping processing.

[0015] According to this, the first peak luminance of the second region of the image excluding the first region including the graphics is calculated, and tone map processing is performed on the image to reduce the luminance of the image that is greater than the first peak luminance. In other words, the luminance of the image that is greater than the first peak luminance, which is the peak luminance of the main image, is reduced. Therefore, when the image includes an area having a luminance greater than the main image, that is, when the first region includes an area having a luminance greater than the main image, the luminance of the area having a luminance greater than the main image can be reduced. Therefore, it is possible to easily adjust the luminance of the first region including the graphics according to the luminance of the main image.

[0016] In addition, the first video may be a moving image having a plurality of frames, and the detection of the first region, the calculation of the first peak luminance, and the tone map processing may be performed for each of the plurality of frames.

[0017] According to this, the video processing device executes processing for each of a plurality of frames included in a video, and therefore can perform tone map processing according to the luminance of each frame.

[0018] In addition, in detecting the first region, a second peak luminance of each of one or more sub-regions constituting a predetermined third region in the first image may be calculated, and an area obtained by integrating one or more sub-regions among the one or more sub-regions whose second peak luminance is greater than a predetermined threshold may be detected as the first region.

[0019] Therefore, the first area including the graphics can be easily detected without performing complex processing.

[0020] Furthermore, in the tone map process, it is not necessary to reduce luminance equal to or lower than the first peak luminance.

[0021] Therefore, when the luminance of the graphics is greater than the luminance of the main video, the luminance of the graphics can be reduced without reducing the luminance of the main video.

[0022] In addition, in the tone map process, when an input luminance value is in the range of 0 or more and the first peak luminance or less, a value equal to the input value may be output as the output value.

[0023] Therefore, when the luminance of the graphics is greater than the luminance of the main video, the luminance of the graphics can be reduced while maintaining the luminance of the main video.

[0024] In addition, in the tone map process, in a range where the input luminance value is greater than the first peak luminance, an output value corresponding to the input luminance value may be output in such a correspondence relationship that as the input luminance value increases, the output luminance value increases at a smaller rate relative to the increase in the input value.

[0025] Therefore, when the luminance of the graphics is greater than the luminance of the main video, the luminance of the graphics can be reduced so as to reduce the sense of incongruity.

[0026] In addition, the video processing device of the present disclosure includes an acquisition unit that acquires a first video signal, a detection unit that detects a first area of ​​a first video indicated by the first video signal acquired by the acquisition unit, the first area including graphics different from a main video, a calculation unit that calculates a first peak luminance of a second area obtained by excluding the first area from the area of ​​the first video, a tone map processing unit that performs tone map processing on the first video to reduce luminance greater than the first peak luminance, and an output unit that outputs a second video signal indicating a second video after the tone map processing.

[0027] According to this, the first peak luminance of the second region of the image excluding the first region including the graphics is calculated, and tone map processing is performed on the image to reduce the luminance of the image that is greater than the first peak luminance. In other words, the luminance of the image that is greater than the first peak luminance, which is the peak luminance of the main image, is reduced. Therefore, when the image includes an area having a luminance greater than the main image, that is, when the first region includes an area having a luminance greater than the main image, the luminance of the area having a luminance greater than the main image can be reduced. Therefore, it is possible to easily adjust the luminance of the first region including the graphics according to the luminance of the main image.

[0028] In addition, these general or specific aspects may be realized by a system, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized by any combination of a system, an integrated circuit, a computer program, and a non-transitory recording medium.

[0029] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0030] The inventor provides the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and does not intend for them to limit the subject matter described in the claims.

[0031] (Embodiment 1) Hereinafter, the first embodiment will be described with reference to FIGS.

[0032] [1-1. Configuration] FIG. 1 is a diagram showing a configuration of an AV system according to the first embodiment.

[0033] As shown in Fig. 1, an AV system 1 includes a video processing device 100 and a display device 200. The video processing device 100 and the display device 200 are connected to each other so as to be able to communicate with each other via a cable 300 compatible with a digital interface (for example, HDMI (registered trademark): High-Definition Multimedia Interface). Note that the video processing device 100 and the display device 200 may be connected using a digital interface, and the connection may be wired or wireless.

[0034] The video processing device 100 is a source device, and is, for example, a recorder device capable of receiving high-definition broadcasting or 4K broadcasting and recording the broadcasting on a recording medium such as an HDD (Hard Disk Drive) or an optical disc, or a playback device (Ultra HD Blu-ray (registered trademark) player) that plays back video data recorded on an optical disc. The video processing device 100 may be an Ultra HD Blu-ray (registered trademark) player or a Set Top Box (STB) that receives distribution of HDR-compatible video data by VOD (Video On Demand) and provides the received video data to the display device 200. The video processing device 100 converts a first video signal included in the first video data acquired from the optical disc or VOD into a second video signal, and outputs the second video data including the second video signal to the display device 200 via a cable 300.

[0035] The display device 200 is a sink device, for example, a TV capable of displaying HDR video (hereinafter, referred to as "HDR TV"). The display device 200 acquires second video data via a cable 300, and displays a video (HDR video) of a second video signal included in the acquired second video data.

[0036] Here, the EOTF will be explained with reference to FIGS. 2A and 2B.

[0037] Fig. 2A is a diagram showing examples of EOTFs corresponding to HDR and SDR, respectively. Fig. 2A (a) is a diagram showing an example of EOTF (PQ (Perceptual Quantizer) curve) corresponding to HDR, and Fig. 2A (b) is a diagram showing an example of EOTF (gamma curve) corresponding to SDR.

[0038] As shown in Fig. 2A, the EOTF indicates the correspondence between code values ​​and luminance values, and is used to convert the code values ​​into luminance values. In other words, the EOTF is relationship information that indicates the correspondence between multiple code values ​​and luminance values.

[0039] Fig. 2B is a diagram showing examples of OETFs compatible with HDR and SDR, where (a) in Fig. 2B is a diagram showing an example of an OETF compatible with HDR (the inverse characteristic of a PQ curve), and (b) in Fig. 2B is a diagram showing an example of an OETF compatible with SDR (the inverse characteristic of a gamma curve).

[0040] OETF indicates the correspondence between luminance values ​​and code values, and is used to convert luminance values ​​into code values ​​in the opposite manner to EOTF. In other words, OETF is relationship information indicating the correspondence between luminance values ​​and a plurality of code values. For example, when the luminance values ​​of an HDR-compatible image are expressed as 10-bit gradation code values, the luminance values ​​in the HDR luminance range up to 10,000 nit are quantized and mapped to integer values ​​of 64 to 940 (limited range). Note that the luminance values ​​of an HDR-compatible image may be mapped to integer values ​​of 0 to 1023 (full range). In other words, by quantizing based on OETF, the luminance values ​​in the luminance range up to 10,000 nit (luminance values ​​of an HDR-compatible image) are converted into HDR signals that are 10-bit code values. An EOTF compatible with HDR (hereinafter referred to as "EOTF of HDR") or an OETF compatible with HDR (hereinafter referred to as "OETF of HDR") can express a higher luminance value than an EOTF compatible with SDR (hereinafter referred to as "EOTF of SDR") or an OETF compatible with SDR (hereinafter referred to as "OETF of SDR"). For example, in FIG. 2A and FIG. 2B, the maximum luminance value (peak luminance) is 10,000 nit. In other words, HDR includes the entire luminance range of SDR, and the maximum luminance value of HDR is greater than the maximum luminance value of SDR. HDR is a dynamic range in which the maximum value is expanded from 100 nit, which is the maximum value of SDR, to the maximum luminance value of HDR (for example, 10,000 nit).

[0041] Here, the first video signal in this example is an HDR signal corresponding to HDR. The image after grading is converted into a non-linear first video signal by using the HDR OETF, and image coding and the like are performed based on the first video signal to generate a video stream. For example, during playback, the display device 200 converts the decoded result of the stream into a linear signal by converting it using the HDR EOTF, and displays the HDR video.

[0042] Next, the functional configuration of the video processing device 100 will be described.

[0043] FIG. 3 is a block diagram illustrating an example of a functional configuration of the video processing device according to the first embodiment.

[0044] As shown in FIG. 3, the image processing device 100 includes an acquisition unit 110, a YCbCr-RGB conversion unit 120, a first conversion unit 130, a detection unit 140, a calculation unit 150, a tone map processing unit 160, a second conversion unit 170, an RGB-YCbCr conversion unit 180, and an output unit 190.

[0045] The acquisition unit 110 acquires first image data including a non-linear first image signal generated by the first OETF. The first image signal is an HDR image signal.

[0046] As described above, the acquisition unit 110 may acquire the first video data by playing the first video data recorded on an optical disc, or may acquire the first video data by receiving distribution of the first video data corresponding to HDR from an external device such as a server via a network, or may acquire the first video data from a broadcast wave received by an antenna (not shown). The acquisition unit 110 may be realized, for example, by an optical disc drive that reads and plays data recorded on an optical disc, or may be realized by a communication interface for connecting to a content provider via a network such as the Internet. The acquisition unit 110 may also be realized by a tuner that decodes the first video data from a broadcast wave.

[0047] In the following description, it is assumed that the first video represented by the first video signal is a video in which graphics are superimposed on the main video, that is, the main video has graphics embedded therein. The first video represented by the first video signal does not necessarily have to have graphics embedded in the main video. In the case of a video in which graphics are embedded, the video processing device 100 can adjust the luminance of the graphics according to the luminance of the main video.

[0048] The first video represented by the first video signal may be a moving image having a plurality of frames. The first conversion unit 130, the detection unit 140, the calculation unit 150, the tone map processing unit 160, the second conversion unit 170, and the RGB-YCbCr conversion unit 180 described below perform processing for each of the plurality of frames. The output unit 190 may perform processing for each of the plurality of frames, or may perform processing in units of a plurality of frames.

[0049] The YCbCr-RGB conversion unit 120 converts the video signal composed of YCbCr signals into an RGB signal. The YCbCr-RGB conversion unit 120 converts the first video signal from a YCbCr signal into an RGB signal, and outputs a first RGB signal including a first R signal, a first G signal, and a first B signal by the conversion.

[0050] FIG. 4 is a diagram for explaining the processes performed by the first conversion section 130, the tone map processing section 160, and the second conversion section 170. As shown in FIG.

[0051] As shown in (a) of Fig. 4, the first conversion unit 130 converts the first RGB signal into a linear signal using the EOTF. This EOTF has the inverse characteristics of the first OETF. In the present embodiment, the first conversion unit 130 converts the first R signal, the first G signal, and the first B signal included in the first RGB signal into a linear signal using the EOTF.

[0052] The detection unit 140 detects a first region that includes graphics different from the main image from the region of the first image indicated by the first RGB signal. The detection unit 140 may detect the first region from a predetermined third region that is likely to include graphics in the first image.

[0053] Here, a specific example of a method for detecting the first region will be described with reference to FIGS.

[0054] FIG. 5 is a diagram showing an example of video in which graphics (subtitles) are embedded. FIG. 6 is a diagram showing an example of region division for detecting a first region from a video. FIG. 7 is a diagram showing an example of a histogram of a block including graphics. FIG. 8 is a diagram showing an example in which a region including graphics in FIG. 5 is detected as a first region. For ease of explanation, FIG. 8 is a diagram including only subtitles 402 as graphics from the video 400 shown in FIG. 5.

[0055] As shown in FIG. 5, the video 400 is an example of a first video in which the subtitles 402 are embedded in the main video 401. The subtitles 402 are often arranged in the lower area of ​​the video 400. For this reason, as shown in FIG. 6, the third area 420 is set in the area below the area 410. The area 410 corresponds to the entire area of ​​the video 400. The area 410 may be divided into, for example, 64 blocks 411, 8×8 in length and width, and the area of ​​a total of 12 blocks 421 including 6 blocks per row in the lower two rows is set as the third area 420. In FIG. 6, the third area 420 is an area surrounded by a dashed line. The 12 blocks 421 are an example of one or more sub-areas. In other words, the third area 420 is not limited to including 12 blocks 421, but may include one or more blocks (sub-areas).

[0056] The detection unit 140 calculates the second peak luminance of each of the 12 blocks 421 constituting a predetermined third region 420 in the video 400. Specifically, as shown in FIG. 7, the detection unit 140 calculates the luminance value of each of the plurality of pixels from the pixel values ​​of the plurality of pixels included in each block 421, and generates a histogram in which the frequency on the vertical axis is the number of pixels and the class on the horizontal axis is the luminance value based on the plurality of pixels in each block 421 and their luminance values. The detection unit 140 uses the generated histogram to remove the luminance values ​​of the pixels up to the first number in descending order of luminance value as noise. The detection unit 140 calculates the maximum luminance value of the plurality of pixels after noise removal as the second peak luminance. The first number may be determined based on a first ratio, which is the ratio of the first number to the number of all pixels in the block. In other words, the first number may be calculated by multiplying the number of all pixels in the block by the first ratio.

[0057] The detection unit 140 does not necessarily need to generate a histogram to calculate the second peak luminance, but may rank the pixels in each block 421 in descending order of luminance value and remove the luminance values ​​of the first highest number of pixels in the order of luminance value as noise. The detection unit 140 may also calculate the maximum luminance value of the pixels in each block 421 as the second peak luminance without removing noise.

[0058] Then, the detection unit 140 determines whether the calculated second peak luminance is greater than a predetermined threshold (for example, 180 nit). If the second peak luminance is greater than the predetermined luminance value, the detection unit 140 determines that the block 421 in which the second peak luminance was calculated contains graphics. On the other hand, if the second peak luminance is equal to or less than the predetermined luminance value, the detection unit 140 determines that the block 421 in which the second peak luminance was calculated does not contain graphics.

[0059] 8, detection unit 140 detects an area obtained by integrating one or more blocks 423 among the 12 blocks 421, the second peak luminance of which is determined to be greater than a predetermined threshold, that is, one or more blocks 423 determined to include graphics, as first area 422. That is, first area 422 is composed of one or more blocks 423. Also, among the 12 blocks 421 constituting third area 420, one or more blocks 424 determined not to include graphics are treated as an area including the main video (that is, the second area) together with the area of ​​area 410 other than third area 420.

[0060] In this manner, the detection unit 140 detects, from within the areas of the image 400, a first area 422 that includes graphics different from the main image, and a second area 412 excluding the first area 422, as shown in FIG.

[0061] The calculation unit 150 calculates the first peak luminance of the second region 412 of the video 400. Specifically, as shown in FIG. 10, the calculation unit 150 calculates the luminance value of each of the plurality of pixels from the pixel values ​​of each of the plurality of pixels included in the second region 412 of the video 400, and generates a histogram in which the frequency on the vertical axis is the number of pixels and the class on the horizontal axis is the luminance value based on the plurality of pixels in the second region 412 of the video 400 and their luminance values. The calculation unit 150 uses the generated histogram to remove the luminance values ​​of the pixels up to the second number in descending order of luminance value as noise. The calculation unit 150 calculates the maximum luminance value of the plurality of pixels after noise removal as the first peak luminance. Note that the second number may be determined based on a second ratio, which is the ratio of the second number to the number of all pixels in the second region 412. In other words, the second number may be calculated by multiplying the number of all pixels in the second region 412 by the second ratio.

[0062] As shown in (b) of Fig. 4, the tone map processing unit 160 performs tone map processing on the linear signal obtained by the first conversion unit 130 according to the first peak luminance calculated by the calculation unit 150. Specifically, as the tone map processing, the tone map processing unit 160 performs processing on the first video represented by the first video signal converted into a linear signal, not reducing luminance whose input value is equal to or less than the first peak luminance, but reducing luminance whose input value is greater than the first peak luminance. The tone map processing unit 160 performs tone map processing on each of all of the multiple pixels constituting the first video represented by the first video signal.

[0063] For example, the tone map processing unit 160 outputs the same value as the input value of luminance as an output value when the input value of luminance is in a range of 0 or more and equal to or less than the first peak luminance. Also, the tone map processing unit 160 outputs a value smaller than the input value as an output value when the input value of luminance is greater than the first peak luminance. For example, the tone map processing unit 160 may output an output value corresponding to the input value of luminance in a correspondence relationship between input values ​​and output values ​​in which the output value increases at a smaller increase rate relative to the increase in the input value as the input value of luminance increases in a range of luminance input values ​​greater than the first peak luminance. In other words, the tone map processing unit 160 performs dynamic tone map processing in which the correspondence relationship used in tone map processing also changes when the first peak luminance calculated by the calculation unit 150 changes. For example, the tone map processing unit 160 performs tone map processing using a tone curve with a larger maximum output value as the first peak luminance increases, among the multiple tone curves shown in FIG. 11.

[0064] The correspondence between the input value and the output value may be represented by a tone curve, a relational expression, or a table. In this embodiment, the tone map processing unit 160 performs the above-described tone map processing on linear signals obtained by converting each of the 1R signal, the 1G signal, and the 1B signal using the EOTF.

[0065] Here, the tone map processing according to the first peak luminance will be described with reference to Fig. 12 and Fig. 13. Fig. 12 is a diagram for explaining an example of the tone map processing when the first video is a dark scene. Fig. 13 is a diagram for explaining an example of the tone map processing when the first video is a bright scene.

[0066] For example, as shown in FIG. 12, when the first video is a dark scene (i.e., when the first peak luminance is smaller than the subtitle luminance), the subtitle luminance is greater than the peak luminance (first peak luminance) of the main video other than the subtitle, so that the tone map processing unit 160 performs tone map processing to reduce the luminance greater than the first peak luminance, thereby making it possible to reduce the luminance of the subtitle without reducing the luminance of the main video. Also, as shown in FIG. 13, when the first video is a bright scene (i.e., when the first peak luminance is greater than the subtitle luminance), the subtitle luminance is less than the peak luminance (first peak luminance) of the main video, so that even if tone map processing unit 160 performs tone map processing to reduce the luminance greater than the first peak luminance, the luminance of the main video and the subtitle is not reduced. In this way, the tone map processing unit 160 performs tone map processing using a conversion curve according to the first peak luminance, so that it is possible to perform tone map processing according to the relationship between the peak luminance of the main video and the luminance of the subtitle.

[0067] As shown in FIG. 4C, the second conversion unit 170 generates a second video signal by converting the processed linear signal obtained by performing tone mapping in the tone map processing unit 160 using the second OETF. That is, the second video signal indicates the second video after tone mapping. In the present embodiment, the second conversion unit 170 converts each of the RGB of the processed linear signal composed of RGB signals using the second OETF. As a result of the conversion using the second OETF in the second conversion unit 170, a second R signal, a second G signal, and a second B signal are generated, and a second video signal including the generated second R signal, second G signal, and second B signal is output.

[0068] The first video signal input to the first conversion unit 130 may be a PQ HDR signal or a Hybrid Log-Gamma (HLG) HDR signal. When the first video signal is a PQ HDR signal, the first conversion unit 130 converts the non-linear first video signal into a linear signal using the EOTF of PQ as the EOTF. When the first video signal is an HLG HDR signal, the first conversion unit 130 converts the non-linear first video signal into a linear signal using the inverse characteristic of the OETF of HLG as the EOTF.

[0069] The second video signal output from the second conversion unit 170 may be a PQ HDR signal or an HLG HDR signal. The second conversion unit 170 may output, for example, an HDR signal with characteristics compatible with the display device 200. When outputting a PQ HDR signal as the second video signal, the second conversion unit 170 generates a non-linear second video signal using the inverse characteristics of the PQ EOTF as the second OETF. When outputting an HLG HDR signal as the second video signal, the second conversion unit 170 generates a non-linear second video signal using the HLG OETF as the second OETF.

[0070] Thus, the first OETF and the second OETF may be the same or different.

[0071] Although the first video signal is described as being an HDR signal, the first video signal is not limited to this and may be an SDR signal generated by an OETF ((b) in FIG. 2B) compatible with SDR. In this case, an EOTF ((b) in FIG. 2A) compatible with SDR is used as the EOTF. Also, an OETF compatible with SDR is used as the second OETF.

[0072] Each of the YCbCr-RGB conversion unit 120, the first conversion unit 130, the detection unit 140, the calculation unit 150, the tone map processing unit 160 and the second conversion unit 170 may be realized, for example, by a processor that executes a program and a memory in which the program is recorded, or may be realized by a dedicated circuit.

[0073] The RGB-YCbCr conversion unit 180 converts the video signal composed of RGB signals into a YCbCr signal. The RGB-YCbCr conversion unit 180 converts the second video signal output from the second conversion unit 170 from an RGB signal into a YCbCr signal. As a result, the RGB-YCbCr conversion unit 180 outputs the second video signal obtained by the conversion and composed of a YCbCr signal. The RGB-YCbCr conversion unit 180 may be realized by, for example, a processor that executes a program and a memory in which the program is recorded, or may be realized by a dedicated circuit.

[0074] The output unit 190 outputs the second video signal obtained by conversion in the RGB-YCbCr conversion unit 180. The output unit 190 outputs the second video signal to the display device 200, for example. In this embodiment, the output unit 190 outputs second video data including the second video signal. The output unit 190 may be realized by, for example, a digital interface.

[0075] [1-2. Operation] The operation of the video processing device 100 configured as above will be described below.

[0076] FIG. 14 is a flowchart showing an example of the operation (video processing method) of the video processing device according to the first embodiment.

[0077] The image processing device 100 acquires a first image signal (S101). Step S101 is a process executed by the acquiring unit 110.

[0078] Next, the image processing device 100 converts the first image signal acquired by the acquisition unit 110 from a YCbCr signal to an RGB signal (S102). Step S102 is a process executed by the YCbCr-RGB conversion unit 120.

[0079] Next, the image processing device 100 converts the first image signal, which has been converted into an RGB signal, into a linear signal using the inverse characteristic of the first OETF (S103). Step S103 is a process executed by the first conversion unit .

[0080] Next, the video processing device 100 detects a first region 422 (graphics region) including graphics different from the main video, from within the region of the video 400 represented by the first video signal converted into a linear signal (S104). Step S104 is a process executed by the detection unit 140.

[0081] Next, the image processing device 100 calculates a first peak luminance of the second region 412 obtained by excluding the first region 422 from the region of the image 400 (S105).

[0082] Next, the image processing device 100 performs a tone map process on the image 400 represented by the first image signal converted into a linear signal, to reduce luminance greater than the first peak luminance (S106). Step S106 is a process executed by the tone map processing unit 160.

[0083] It should be noted that steps S104 and S105, and step S106 do not have to be performed in this order. Step S106 may be performed before step S104, or steps S104 and S105 and step S106 may be performed in parallel.

[0084] Next, the image processing device 100 generates a second image signal by converting the processed linear signal obtained by the tone map process using the second OETF (S107). Step S107 is a process executed by the second conversion unit 170.

[0085] Next, the image processing device 100 converts the second image signal from an RGB signal to a YCbCr signal (S108). Step S108 is a process executed by the RGB-YCbCr conversion unit 180.

[0086] Next, the image processing device 100 outputs the second image signal converted from the RGB signal to the YCbCr signal (S109). Step S109 is a process executed by the output unit 190.

[0087] [1-3. Effects, etc.] The video processing device 100 according to the present embodiment includes an acquisition unit 110, a detection unit 140, a calculation unit 150, a tone map processing unit 160, and an output unit 190. The acquisition unit 110 acquires a first video signal. The detection unit 140 detects a first region 422 including graphics different from the main video from the video represented by the first video signal acquired by the acquisition unit 110. The calculation unit 150 calculates a first peak luminance of a second region 412 obtained by excluding the first region 422 from the region 410 of the video 400. The tone map processing unit 160 performs a tone map process on the video to reduce luminance greater than the first peak luminance. The output unit 190 outputs a second video signal representing the video after the tone map process.

[0088] According to this, the first peak luminance of the second region 412 excluding the first region 422 including graphics in the region 410 of the video 400 is calculated, and a tone map process is performed on the video to reduce luminance greater than the first peak luminance. In other words, luminance greater than the first peak luminance, which is the peak luminance of the main video, in the video is reduced. Therefore, when the video includes a region having a luminance greater than the main video, that is, when the first region 422 includes a region having a luminance greater than the main video, the luminance of the region having a luminance greater than the main video can be reduced. Therefore, it is possible to easily adjust the luminance of the first region 422 including graphics according to the luminance of the main video.

[0089] In the video processing device 100 according to the present embodiment, the video 400 is a moving image having a plurality of frames. The detection of the first region 422 by the detection unit 140, the calculation of the first peak luminance by the calculation unit 150, and the tone map processing by the tone map processing unit 160 are performed for each of the plurality of frames.

[0090] According to this, the video processing device 100 executes processing for each of a plurality of frames included in a video, and therefore can perform tone map processing according to the luminance of each frame.

[0091] In the video processing device 100 according to the present embodiment, the detection unit 140 detects the first region 422 by calculating the second peak luminance of each of the 12 blocks 421 constituting the predetermined third region 420 in the video 400. In the detection of the first region 422, the detection unit 140 further detects, as the first region 422, a region obtained by integrating the 12 blocks 421 having second peak luminance greater than a predetermined threshold value among the 12 blocks 421. Therefore, the first region 422 including graphics can be easily detected without performing complicated processing.

[0092] Furthermore, in the video processing device 100 according to the present embodiment, the tone map processing by the tone map processing unit 160 does not reduce luminance equal to or lower than the first peak luminance. Therefore, when the luminance of the graphics is greater than the luminance of the main video, the luminance of the graphics can be reduced without reducing the luminance of the main video.

[0093] Furthermore, in the tone map processing by tone map processing unit 160 in the video processing device 100 according to the present embodiment, the input value and the output value have the same linear relationship when the input luminance value is in the range from 0 to the first peak luminance. Therefore, when the luminance of the graphics is greater than the luminance of the main video, the luminance of the graphics can be reduced while maintaining the luminance of the main video.

[0094] In the tone map processing by the tone map processing unit 160 in the video processing device 100 according to the present embodiment, the luminance is reduced so that the reduction amount increases as the luminance increases at luminances higher than the first peak luminance. Therefore, when the luminance of the graphics is higher than the luminance of the main video, the luminance of the graphics can be reduced so as not to cause an unnatural feeling.

[0095] (Embodiment 2) Next, a fourth embodiment will be described with reference to FIGS.

[0096] [2-1. Configuration] FIG. 15 is a block diagram illustrating an example of a functional configuration of a video processing device according to the second embodiment. As illustrated in FIG.

[0097] The video processing device 101 according to the second embodiment differs from the video processing device 100 according to the first embodiment in that it does not have the YCbCr-RGB conversion unit 120 and the RGB-YCbCr conversion unit 180, and the first conversion unit 131, the detection unit 141, the tone map processing unit 161, and the second conversion unit 171 do not perform processing corresponding to each of the RGB signals. The other configurations of the video processing device 101 are similar to those of the video processing device 100, and therefore will not be described.

[0098] The first conversion unit 131 converts the first Y signal into a linear signal, the tone map processing unit 161 performs tone map processing on the linear signal, and the second conversion unit 171 converts the first Y signal into a non-linear signal. The detection unit 141 performs detection processing on the linear signal. As a result, the second conversion unit 171 outputs the second Y signal. Note that the first Cb signal and the first Cr signal indicating color difference signals of the first video signal acquired by the acquisition unit 110 are output to the output unit 190 without being processed by the first conversion unit 131, the tone map processing unit 161, and the second conversion unit 171.

[0099] The output unit 190 outputs a second video signal made up of the second Y signal, the first Cb signal, and the first Cr signal.

[0100] [2-2. Operation] FIG. 16 is a flowchart showing an example of the operation (video processing method) of the video processing device according to the second embodiment.

[0101] The video processing method of the second embodiment differs from the video processing method of the first embodiment shown in Fig. 14 in that steps S102 and S108 are omitted. The other steps of the video processing method are the same as those of the first embodiment, so they are denoted by the same reference numerals and description thereof is omitted.

[0102] That is, the processes of steps S101, S103 to S107, and S109 are performed, and the processes of steps S103, S106, and S107 are performed on the first Y signal of the first video signal constituted by a YCbCr signal.

[0103] [2-3. Effects, etc.] In the video processing device 101 according to the present embodiment, the conversion process is performed on the first video signal constituted by a YCbCr signal, so that the processing load can be reduced.

[0104] (Other embodiments) As described above, the first and second embodiments have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. In addition, it is also possible to combine the components described in the first and second embodiments to create new embodiments.

[0105] Therefore, other embodiments will be exemplified below.

[0106] In the above embodiment, the tone map processor 160 outputs an output value corresponding to an input value of luminance in a correspondence relationship between input values ​​and output values ​​in which, in a range where the input value of luminance is greater than the first peak luminance, the output value increases at a smaller rate relative to the increase in the input value as the input value of luminance increases, but this is not limited to the above. The correspondence relationship does not have to be such that, in a range where the input value of luminance is greater than the first peak luminance, the output value does not have to increase as the input value of luminance increases, and the output value may have a certain range.

[0107] In the above embodiment, the detection unit 140 detects the first region from a predetermined third region among the regions of the image, but this is not limited thereto. The detection unit 140 may detect a region including pixels that satisfy a predetermined condition for all pixels of the image as the first region including graphics. The predetermined condition may be, for example, having a pixel value within a range of pixel values ​​that can be regarded as a predetermined color (for example, white). Furthermore, the predetermined condition may further be that a predetermined number or more of pixels within the above pixel value range are arranged adjacent to each other.

[0108] In the above embodiment, subtitles are exemplified as graphics, but the graphics are not limited to subtitles and may be a logo of a broadcasting station or a program, or a frame-shaped area or bar (rectangular area) displayed around the main video. The frame-shaped area or bar may include characters or a logo. The position of the graphics may be constant or may change over multiple frames of the video. Subtitles may be detected as graphics using the method described in Patent Document 2.

[0109] In the above embodiment, the video processing devices 100 and 101 are illustrated as source devices connected to the display device 200, but the present invention is not limited to this and may be included in the display device. In other words, the video processing device included in the display device may convert the first video signal into a second video signal and display the second video signal on a display (display unit) of the display device or on an external display.

[0110] In each of the above embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory. Here, the software that realizes the adjustment method of each of the above embodiments is a program such as the following.

[0111] In other words, this program causes a computer to execute an image processing method that acquires a first video signal, detects a first area of ​​a first image represented by the acquired first video signal, which area includes graphics different from a main image, calculates a first peak luminance of a second area obtained by excluding the first area from the area of ​​the first image, performs tone mapping processing on the first image to reduce luminance greater than the first peak luminance, and outputs a second video signal representing the second image after the tone mapping processing.

[0112] As described above, the embodiments have been described as examples of the technology in the present disclosure, and the accompanying drawings and detailed description have been provided for this purpose.

[0113] Therefore, among the components described in the attached drawings and the detailed description, not only are there components essential for solving the problem, but there may also be components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that such non-essential components are described in the attached drawings or the detailed description should not be interpreted as immediately indicating that such non-essential components are essential.

[0114] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0115] The present disclosure is applicable to video processing devices that can adjust the brightness of graphics embedded in a video. Specifically, the present disclosure is applicable to Ultra HD Blu-ray (registered trademark) players, STBs, TVs, monitors, and the like. [Explanation of symbols]

[0116] 1 AV system 100, 101 Image processing device 110 Acquisition Department 120 YCbCr-RGB conversion section 130, 131 First conversion unit 140, 141 Detector 150 Calculation section 160, 161 Tone map processing unit 170, 171 Second conversion unit 180 RGB-YCbCr conversion section 190 Output section 200 Display device 300 Cable 400 videos 401 Main Video 402 Subtitles 410 areas 411, 421, 423, 424 blocks 412 Second area 420 Third area 422 1st area

Claims

1. Obtaining a first video signal; Detecting a first area in which the graphics are superimposed on a main image, the first area being a first image represented by the acquired first video signal, the first area being a first image in which the graphics are superimposed on a main image; Calculating a first peak luminance of a second region obtained by excluding the first region from the region of the first image; performing a tone map process on the first image to reduce a luminance greater than the first peak luminance; outputting a second video signal indicating the second video after the tone map processing; In the tone map process, the luminance equal to or less than the first peak luminance is not reduced. Image processing method.

2. the first image is a moving image having a plurality of frames; The detection of the first region, the calculation of the first peak luminance, and the tone map process are performed for each of the plurality of frames. The video processing method according to claim 1 .

3. In detecting the first region, calculating a second peak luminance of each of one or more sub-regions constituting a predetermined third region in the first image; A region obtained by integrating one or more sub-regions in which the second peak luminance is greater than a predetermined threshold value among the one or more sub-regions is detected as the first region.

3. The image processing method according to claim 1.

4. In the tone map process, when the input luminance value is in the range of 0 or more and the first peak luminance or less, a value equal to the input luminance value is output as an output value. The video processing method according to claim 3 .

5. In the tone map process, in a range where the input value of luminance is greater than the first peak luminance, an output value corresponding to the input value of luminance is output in a correspondence relationship in which, as the input value of luminance increases, the output value of luminance increases at a smaller rate relative to the increase in the input value. The video processing method according to any one of claims 1 to 4.

6. an acquisition unit that acquires a first video signal; a detection unit that detects a first region in which graphics are superimposed on a main image, the first region being a first image indicated by the first video signal acquired by the acquisition unit, the first region being a first region in which the graphics are superimposed on a main image; a calculation unit that calculates a first peak luminance of a second region obtained by excluding the first region from a region of the first image; a tone map processing unit that performs a tone map process on the first image to reduce a luminance that is greater than the first peak luminance; an output unit that outputs a second video signal indicating the second video after the tone map processing; In the tone map process, the luminance equal to or less than the first peak luminance is not reduced. Image processing device.

7. A program for causing a computer to execute the video processing method according to any one of claims 1 to 5.

Images