WO2017163685A1 - Dispositif de traitement vidéo, appareil d'affichage, procédé de traitement vidéo, programme de commande, et support d'enregistrement - Google Patents

Dispositif de traitement vidéo, appareil d'affichage, procédé de traitement vidéo, programme de commande, et support d'enregistrement Download PDF

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WO2017163685A1
WO2017163685A1 PCT/JP2017/005763 JP2017005763W WO2017163685A1 WO 2017163685 A1 WO2017163685 A1 WO 2017163685A1 JP 2017005763 W JP2017005763 W JP 2017005763W WO 2017163685 A1 WO2017163685 A1 WO 2017163685A1
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gradation value
value
luminance level
gradation
maximum luminance
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Japanese (ja)
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下田　裕紀
神田　貴史
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Sharp Corp
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Sharp Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/01—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level

Definitions

  • the present invention relates to a video processing device or the like that converts a gradation value of an HDR signal.
  • HDR High Dynamic Range
  • SDR Standard Dynamic Range
  • the SDR signal is produced on the premise of reproduction in a reproduction environment (hereinafter referred to as “SDR environment”) having an EOTF (Electro-Optical Transfer Function) equivalent to ⁇ 2.2, while the HDR signal is , And SMPTE-ST2084 (hereinafter abbreviated as “ST2084”), etc., are manufactured on the premise of reproduction in a reproduction environment (hereinafter referred to as “SDR environment”) having an EOTF. For this reason, when the HDR signal is reproduced in the SDR environment, the luminance of the obtained video is different from the luminance intended by the manufacturer.
  • Patent Document 1 discloses a liquid crystal display device that performs dimming control of a backlight by changing a change width of an average luminance level before and after dynamic range expansion by an average luminance level and a ⁇ adjustment value of an input video signal. Has been.
  • a scan conversion unit that scan-converts an input video signal into a signal having a predetermined number of scanning lines, a gamma correction unit that gamma-corrects a signal from the scan conversion unit, and a signal level from the input video signal.
  • a plasma display that includes a level detection unit that detects and controls a gamma correction unit based on the detection signal, and controls the average luminance in accordance with the input signal level.
  • Japanese Patent Publication Japanese Patent Publication “Japanese Laid-Open Patent Publication No. 2002-108305 (published on April 10, 2002)” Japanese Patent Publication “Japanese Laid-Open Patent Publication No. 2002-354378 (Released on Dec. 6, 2002)”
  • the EOTF of the HDR signal is different from that of the SDR signal. Therefore, when converting the gradation value taken by each pixel by the HDR signal, if the entire domain of the HDR signal EOTF is mapped to the domain of the SDR signal EOTF, the gradation value is reduced (different levels). The tone value is mapped to the same tone value).
  • the number of gradations per unit luminance difference is particularly large in a low luminance region in order to express a slight difference in brightness in a dark part. For this reason, when the gradation value taken by each pixel is converted by the HDR signal by such mapping, the gradation value is likely to be degenerated in the low luminance region.
  • a range corresponding to a luminance level equal to or lower than the maximum luminance level of content in the EOTF definition region for HDR signals is mapped to the EOTF definition region for SDR signals.
  • a method is conceivable.
  • each pixel can take a gradation value corresponding to a luminance of 10000 cd / m 2 or less, but not all of these gradation values are used in actual content. For this reason, if pixel values taken by each pixel with the HDR signal are converted by such mapping, it is possible to suppress black crushing and gradation value degeneration.
  • the HDR signal includes metadata representing the maximum luminance of content called MAX_CLL (Maximum Content Light Level). The maximum brightness of the content can be specified by referring to this metadata.
  • the maximum luminance level of the content is the luminance level of a specific pixel in a specific frame of a specific scene. Therefore, in a frame other than this specific frame or in a scene other than this specific scene, a gradation value that is not actually used is mapped to the definition area of the SDR signal EOTF. That is, in the method of mapping the range corresponding to the luminance level equal to or lower than the maximum luminance level of the content in the EOTF definition area for the HDR signal to the EOTF definition area for the SDR signal, the level that can occur in the low luminance area There remains room for further suppression of degeneration of the tone value.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a gradation value conversion apparatus for converting gradation values of HDR signals, which can reduce gradation values that can occur in a low luminance region. Is to realize a gradation value conversion apparatus in which the above is further suppressed.
  • a video processing device converts a gradation value taken by each pixel in a video signal according to a second video format having a wider luminance range than the first video format.
  • a virtual maximum that sets a virtual maximum luminance level lower than a maximum luminance level indicated by metadata included in the video signal by referring to a gradation value taken by each pixel in the video signal.
  • a luminance level setting unit; and a gradation value conversion unit that converts a gradation value corresponding to each luminance level equal to or lower than the virtual maximum luminance level among gradation values taken by each pixel in the video signal.
  • a video processing method is a video processing method for converting a gradation value taken by each pixel in a video signal according to a second video format having a wider luminance range than the first video format.
  • a virtual maximum luminance level setting step for setting a virtual maximum luminance level lower than a maximum luminance level indicated by metadata included in the video signal by referring to a gradation value taken by each pixel in the video signal;
  • a gradation value conversion apparatus that further suppresses gradation value degeneration that may occur in a low luminance region.
  • Embodiment 1 (Display device 1) A display device 1 including a gradation value conversion device (video processing device) 2 according to a first embodiment of the present invention will be described with reference to FIGS.
  • FIG. 1 is a block diagram illustrating a configuration of a display device 1 including a gradation value conversion device 2 according to the present embodiment.
  • FIG. 2 is a perspective view showing the appearance of the display device 1.
  • the display device 1 includes a gradation value conversion device 2, a panel control unit 6, and a display panel 7.
  • the gradation value conversion device 2 is a device that converts the gradation value of each pixel of the HDR signal (video signal according to the second video format), and includes a video data acquisition unit 3, a virtual maximum luminance level setting unit 4, and a floor.
  • a tone value conversion unit 5 is provided.
  • the video data acquisition unit 3 acquires an HDR signal.
  • the HDR signal acquired by the video data acquisition unit 3 is an HDMI signal based on the HDMI (registered trademark) (High-Definition Multimedia Interface) standard, a Tuner signal (a signal received by the tuner), and a CVBS. (Composite Video, Blanking, and Sync: composite video signal) signal or the like.
  • the HDR signal includes metadata such as MAX_CLL indicating the maximum luminance level of content in addition to the gradation value taken by each pixel.
  • the virtual maximum luminance level setting unit 4 refers to the gradation value or metadata included in the HDR signal acquired by the video data acquisition unit 3, and sets a virtual maximum luminance level having a value smaller than the maximum luminance level indicated by MAX_CLL for each frame. Or set for each scene.
  • the gradation value conversion unit 5 refers to the virtual maximum luminance level set by the virtual maximum luminance level setting unit 4, and converts the gradation value taken by each pixel in the HDR signal from the first gradation value to the second gradation. Convert to value.
  • the gradation value converting unit 5 corresponds to each luminance level equal to or lower than the virtual maximum luminance level set by the virtual maximum luminance level setting unit 4 among the gradation values that each pixel can take in the HDR signal. Is used for mapping each tone value in the EOTF domain for the SDR signal (video signal according to the first video format).
  • the panel control unit 6 controls the luminance of each pixel of the display panel 7 to a luminance value corresponding to the gradation value obtained by the gradation value conversion unit 5 in the SDR EOTF. As a result, the video represented by the HDR signal is displayed on the display panel 7 with the original luminance.
  • the display panel 7 may be realized by any device as long as it is capable of displaying images. Specific examples include a liquid crystal display, an organic EL (Electro Luminescence) display, a plasma display, and the like. Is mentioned.
  • FIG. 3 is a flowchart showing the flow of gradation conversion processing.
  • FIG. 4 is a graph showing the content of the gradation conversion process.
  • the gradation value conversion apparatus 2 performs the steps S0 to S4 described below for each frame, thereby changing the gradation value of each pixel constituting the HDR signal from the first gradation value. Conversion to the second gradation value.
  • the video data acquisition unit 3 acquires an HDR signal (step S0).
  • the video data acquisition unit 3 supplies the virtual maximum luminance level setting unit 4 and the gradation value conversion unit 5 with the gradation values taken by each pixel constituting the processing target frame in the acquired HDR signal.
  • the virtual maximum luminance level setting unit 4 acquires the gradation value taken by each pixel constituting the processing target frame from the video data acquisition unit 3, and acquires the maximum value of the acquired gradation value (the maximum gradation value in the frame). ) (The maximum luminance value in the frame) corresponding to) is set as the virtual maximum luminance level (step S1).
  • FIG. 4A shows a correspondence relationship (OETF) between the luminance value and the gradation value in the HDR signal.
  • the maximum luminance value in the frame corresponding to the maximum gradation value in the frame is lower than the maximum luminance level of the content indicated by MAC_CLL. Therefore, the virtual maximum brightness level set in this step is lower than the maximum brightness level of the content indicated by MAC_CLL.
  • the virtual maximum luminance level setting unit 4 supplies the set virtual maximum luminance level to the gradation value conversion unit 5.
  • the gradation value conversion unit 5 acquires the gradation value taken by each pixel constituting the processing target frame from the video data acquisition unit 3, and acquires the acquired gradation value from the first gradation value to the second value. Conversion into gradation values (step S2). For this conversion, the gradation value conversion unit 5 acquires the virtual maximum luminance level from the virtual maximum luminance level setting unit 4, and among the gradation values that each pixel can take for the HDR signal, the acquired virtual maximum luminance level A mapping is used in which the gradation value x corresponding to each luminance level y below the level is associated with each gradation value X in the definition area of the EOTF for the SDR signal.
  • MAX_y represents a virtual maximum brightness level
  • MAX_Y represents a maximum value of the EOTF value range for the SDR signal (corresponding to the maximum brightness level of the display device).
  • 4B is a graph showing the relationship between the luminance value x before conversion and the gradation value y (HETF signal OETF), and FIG. 4C shows the luminance value X after conversion. It is a graph showing the relationship with the gradation value Y (OETF for SDR signal).
  • the gradation value conversion unit 5 supplies the converted gradation value taken by each pixel constituting the processing target frame to the panel control unit 6.
  • the panel control unit 6 acquires the converted gradation value taken by each pixel constituting the processing target frame from the gradation value conversion unit 5, and converts the acquired gradation value into a luminance value (step S3). ).
  • the panel control unit 6 uses an EOTF for SDR, for example, an EOTF equivalent to ⁇ 2.2. This conversion is also called tone mapping, and the correspondence between the gradation value and the luminance value in this conversion is also called a tone curve.
  • the panel control unit 6 controls the luminance of each pixel constituting the display panel 7 to the luminance value obtained by tone mapping. As a result, the processing target frame is displayed on the display panel 7 (step S4).
  • the range corresponding to the luminance value equal to or lower than the virtual maximum luminance level is defined as the EOTF definition region for the SDR signal in the definition region of the HDR signal EOTF.
  • Use mapping to associate Since the virtual maximum luminance level is lower than the maximum luminance level indicated by MAC_CLL, the range corresponding to the luminance value equal to or lower than the maximum luminance level indicated by MAX_CLL is defined in the EOTF definition region for HDR signal. Compared with the case of using the mapping associated with the area, it is possible to suppress the black crushing and the gradation value degeneration.
  • the gradation value conversion process is executed for each frame, and the maximum luminance value in each frame is set as the virtual maximum luminance level.
  • the present embodiment is not limited to this.
  • gradation value conversion processing is executed for each scene, and the maximum in-scene luminance value of each scene (the maximum in-frame of all the frames constituting the scene). It is also possible to adopt a configuration in which the maximum luminance value) is set to the virtual maximum luminance level. In this case, before starting the gradation value conversion of the first frame constituting the processing target scene, the gradation values taken by the pixels constituting all the frames constituting the processing target scene are acquired, and the maximum luminance value in the scene is obtained.
  • the HDR signal includes metadata indicating the in-scene maximum luminance value of each scene
  • a configuration in which the virtual maximum luminance level is set with reference to the metadata may be employed. With such a configuration, gradation value conversion processing can be performed not only on HDR signals recorded on a recorder or the like but also on HDR signals received by a tuner or the like.
  • a configuration in which the temporal average value of the maximum luminance value in each frame is the virtual maximum luminance level may be adopted.
  • a known time average filter may be used.
  • the display device 1 including the gradation value conversion device 2 shown in FIG. 1 is used as in the first embodiment.
  • FIG. 5 is a flowchart showing the flow of the gradation value conversion process executed by the gradation value conversion apparatus according to the present embodiment. Note that the processing executed in steps S10 and S13 to S15 shown in FIG. 5 is the same as the processing executed in steps S0 and S2 to S4 shown in FIG. 3, respectively. For this reason, the processing executed in steps S11 to S12 will be described below.
  • step S11 the virtual maximum luminance level setting unit 4 generates a histogram of luminance values corresponding to the gradation values taken by each pixel constituting the processing target frame, and obtains the maximum histogram value from the generated histogram.
  • step S12 the virtual maximum luminance level setting unit 4 sets the virtual maximum luminance level to the maximum histo value obtained in step S11.
  • the maximum histogram value is a maximum value of luminance values excluding a specifically large luminance value among luminance values corresponding to gradation values taken by pixels constituting the processing target frame, and is an average value M of the histogram.
  • the standard deviation ⁇ is a typical example of the maximum histo value.
  • FIG. 6 shows an example of the histogram generated in step S11.
  • some pixels take a specifically large luminance value close to the maximum luminance level indicated by MAX_CLL.
  • the gradation value conversion step In S13 the region between the specifically large luminance value and the maximum value of the luminance value excluding the specifically large luminance value is unnecessarily associated with the SDR EOTF value range.
  • the luminance value excluding the large luminance value is specifically determined.
  • the SDR EOTF value range can be associated without waste.
  • a configuration has been described in which a histogram of luminance values is created for each frame, and the maximum value within the frame of each frame is a virtual maximum luminance level, but the present embodiment is not limited to this.
  • a histogram of luminance values is executed for each scene and the maximum value of the in-scene hist of each scene is set as a virtual maximum luminance level. It is.
  • a histogram of luminance values corresponding to the gradation values taken by the pixels constituting all the frames constituting the processing target scene is created.
  • the maximum value of the hist in the scene is set to the virtual maximum luminance level.
  • the HDR signal includes metadata indicating the in-scene maximum value of each scene, it is possible to adopt a configuration in which the virtual maximum luminance level is set with reference to this metadata. With such a configuration, gradation value conversion processing can be performed not only on HDR signals recorded on a recorder or the like but also on HDR signals received by a tuner or the like.
  • a configuration in which the time average value of the in-frame maximum value of each frame is the virtual maximum luminance level may be adopted.
  • a known time average filter may be used in calculating the time average value of the intra-frame maximum value of each frame.
  • FIG. 7 is a flowchart showing the flow of the gradation value conversion process executed by the gradation value conversion apparatus according to this embodiment.
  • the processes executed in step S100 and steps S106 to S108 shown in FIG. 7 are the same as the processes executed in steps S0 and S2 to S4 shown in FIG. 3, respectively. For this reason, the processing executed in steps S101 to S105 will be described below.
  • step S101 the virtual maximum luminance level setting unit 4 generates a histogram of luminance values corresponding to the gradation values taken by each pixel constituting the processing target frame, and obtains a maximum histogram value from the generated histogram.
  • the definition of the maximum hysteresis value is the same as that given in the second embodiment.
  • the virtual maximum brightness level setting unit 4 sets a limit value that is lower than the maximum brightness level indicated by MAC_CLL by a predetermined value.
  • the predetermined value is an arbitrary value and may be set at the time of shipment from the factory, or may be set by the user after shipment from the factory.
  • step S103 the virtual maximum luminance level setting unit 4 determines whether or not the maximum histogram value calculated in step S101 is lower than the limit value calculated in step S102.
  • step S104 when the maximum histo value is lower than the limit value, in step S104, the virtual maximum luminance level setting unit 4 sets the virtual maximum luminance level to the limit value.
  • step S106 the range below the limit value in the definition area of the HDR signal OETF is mapped to the whole definition area of the ODR for SDR signal.
  • the virtual maximum luminance level setting unit 4 sets the virtual maximum luminance level to the maximum histogram value in step S105.
  • step S106 the range below the maximum histogram value in the HDR signal EOTF value range is mapped to the entire SDR signal EOTF value range.
  • the virtual maximum luminance that can occur when the maximum value of the histogram becomes extremely small by providing a limit value for the virtual maximum luminance level. It is possible to prevent a decrease in image quality due to a large level fluctuation.
  • the flow of the gradation value conversion process executed by the gradation value conversion apparatus 2 according to the present embodiment is similar to the gradation conversion process executed by the gradation value conversion apparatus 2 according to the third embodiment, as shown in FIG. Is expressed by the flowchart shown in FIG.
  • the limit value setting process S102 in the third embodiment is replaced with a limit value setting process S109 described below.
  • the virtual maximum luminance level setting unit 4 has a predetermined ratio between the difference obtained by subtracting the limit value from the maximum luminance level indicated by MAX_CLL and the difference obtained by subtracting the maximum histogram value in the luminance histogram from the limit value.
  • the predetermined ratio is an arbitrary ratio, and may be set at the time of shipment from the factory, or may be set by the user after shipment from the factory.
  • step S104 when the maximum histo value is lower than the limit value, in step S104, the virtual maximum luminance level setting unit 4 sets the virtual maximum luminance level to the limit value.
  • step S106 the range below the limit value in the definition area of the HDR signal OETF is mapped to the whole definition area of the SDR signal OETF.
  • the virtual maximum luminance level setting unit 4 sets the virtual maximum luminance level to the maximum histogram value in step S105.
  • step S106 the range below the maximum value of the histories of the EOTF for the HDR signal is mapped to the entire range of the EOTF for the SDR signal.
  • the virtual maximum luminance that can occur when the maximum value of the histogram becomes extremely small by providing a limit value for the virtual maximum luminance level. It is possible to prevent a decrease in image quality due to a large level fluctuation.
  • the virtual maximum luminance level setting unit 4 has a luminance value (maximum intra-frame luminance value) corresponding to the maximum gradation value (maximum intra-frame gradation value) taken by each pixel constituting the processing target frame. It was explained that is set to the virtual maximum luminance level. With this configuration, gradation values can be converted according to peak luminance, which is the greatest advantage of HDR.
  • the gradation value in the low gradation value region with respect to the luminance value is relatively lowered (blackout).
  • blackout the area in the image displayed with the gradation value in the low gradation value area becomes completely dark, resulting in insufficient expression.
  • the gradation value conversion apparatus 11 has the gradation value in the low gradation value region among the gradation values converted by the gradation value conversion unit 5.
  • the gradation value taken by each pixel constituting each frame or each scene is adjusted so as to have a lifting portion.
  • the low gradation value region indicates a gradation value region near the origin (a point where the gradation value and the corresponding luminance value are zero) in the converted gradation value.
  • the low gradation value area indicates an area having a gradation value of about one fifth when the gradation value is quantized with 8 bits (256 gradations (0 to 255)). (A region where the gradation value is 0 to 51).
  • the gradation value area having the gradation value larger than the maximum gradation value in the low gradation value area as the lowest gradation value is defined as the intermediate gradation value area, and the largest gradation in the intermediate gradation value area.
  • a region of gradation values having a gradation value larger than the tone value as the lowest gradation value is defined as a high gradation value region.
  • “having a lifting portion in the gradation value of the low gradation value region” means a low-order image generated by converting the gradation value by the gradation value conversion method described in the first embodiment. This means that the gradation value in the low gradation area is increased in order to improve the relative decrease (blackout) in the gradation value area.
  • FIG. 10 is a block diagram illustrating a configuration of the display device 10 including the gradation value conversion device (video processing device) 11 according to the present embodiment. As shown in FIG. 10, the gradation value conversion apparatus 11 further includes a gradation value adjustment unit 12 in addition to the configuration of the gradation value conversion apparatus 2 according to the first embodiment.
  • the gradation value adjustment unit 12 adjusts the gradation value converted by the gradation value conversion unit 5 to have a lifting unit in the gradation value in the low gradation value region.
  • FIG. 11 is a flowchart showing the flow of gradation value conversion processing.
  • the gradation value conversion process is executed for each frame, and the maximum luminance value in each frame is set as the virtual maximum luminance level.
  • the gradation value conversion process is executed for each scene, The same applies to the configuration in which the in-scene maximum luminance value of each scene is set as the virtual maximum luminance level.
  • the video data acquisition unit 3 acquires an HDR signal (step S20).
  • the video data acquisition unit 3 sets a gradation value taken by each pixel constituting the processing target frame in the acquired HDR signal as a virtual maximum luminance level setting unit. 4 and the gradation value converter 5.
  • the virtual maximum luminance level setting unit 4 acquires the gradation value taken by each pixel constituting the processing target frame from the video data acquisition unit 3, and acquires the maximum value of the acquired gradation value (the maximum gradation value in the frame). ) (The maximum luminance value in the frame) corresponding to) is set as the virtual maximum luminance level (step S21).
  • the gradation value conversion unit 5 acquires the gradation value taken by each pixel constituting the processing target frame from the video data acquisition unit 3, and among the acquired gradation values, the virtual maximum luminance level setting unit 4 The gradation value corresponding to each luminance level below the set virtual maximum luminance level is converted from the first gradation value to the second gradation value (step S22).
  • the gradation value adjustment unit 12 adjusts the gradation value converted by the gradation value conversion unit 5 to have a lifting unit in the gradation value in the low gradation value region (step S23).
  • a specific example of how the gradation value adjusting unit 12 adjusts the gradation value will be described later.
  • the gradation value adjusted by the gradation value adjustment unit 12 is preferably larger than the gradation value indicated by the predetermined format in the low gradation value region.
  • An example of the predetermined format is ST2084.
  • the panel control unit 6 acquires the adjusted gradation value taken by each pixel constituting the processing target frame from the gradation value adjustment unit 12, and converts the acquired gradation value into a luminance value (step S24). ) (Tone mapping).
  • the panel control unit 6 controls the luminance of each pixel constituting the display panel 7 to the luminance value obtained by tone mapping. Thereby, the processing target frame is displayed on the display panel 7 (step S25).
  • FIG. 12 is a graph showing the relationship between the converted gradation value and the corresponding luminance value.
  • a region A in FIG. 12 represents the above-described low gradation value region, a dotted line represents a curve before adjustment, and a solid line represents a curve after adjustment.
  • the gradation value adjustment unit 12 adjusts the converted gradation value so that the gradation value in the region A has a lifting part (adjusts from the dotted curve to the solid curve).
  • the gradation value adjusting unit 12 adjusts the gradation value in the low gradation value region by adding a value of about 10% of the gradation value.
  • the gradation value adjustment unit 12 graphs the gradation value corresponding to the gradation value with respect to the gradation value in the low gradation value region. In this case, adjustment is made so that the curve in the graph is equivalent to the curve of ⁇ 2.2.
  • the gradation value adjustment unit 12 may change the low gradation value region with reference to the average value of the luminance level corresponding to the gradation value converted by the gradation value conversion unit 5. Thereby, since the low gradation value region can be set according to the distribution of the luminance level, the gradation value can be adjusted according to the distribution of the luminance level.
  • the average value of the luminance levels referred to by the gradation value adjustment unit 12 may be calculated by the gradation value adjustment unit 12 itself or may be acquired from the outside.
  • the gradation value adjustment unit 12 has a gradation value in the low gradation value region and a gradation value in the high gradation value region in the graph of the gradation value converted by the gradation value conversion unit and the corresponding luminance level. Further, the gradation value in the middle gradation value region may be further adjusted so that “and” continuously change. As a result, in the image displayed with the adjusted gradation value, unnaturalness due to the difference between the gradation value in the low gradation value area and the gradation value in the high gradation value area can be eliminated.
  • the gradation value conversion apparatus 11 sets the virtual maximum luminance level to the maximum value of the luminance level, converts the gradation value with reference to the set virtual maximum luminance level, Of the converted gradation values, the gradation values in the low gradation value region are adjusted to have a lifting portion.
  • the virtual maximum luminance level to the maximum value of the luminance level, it is possible to maintain the fidelity of the peak feeling included in the video signal, and among the converted gradation values, the low gradation value
  • the gradation value of the region By adjusting the gradation value of the region so as to have a raised portion, it is possible to prevent black crushing due to a decrease in the gradation value of the low gradation value region, and to improve the gradation expressing ability of the low gradation value region.
  • the control block (particularly the video data acquisition unit 3, the virtual maximum luminance level setting unit 4 and the gradation value conversion unit 5) of the gradation value conversion device 2 is a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like. ) Or by software using a CPU (Central Processing Unit).
  • the gradation value conversion device 2 includes a CPU that executes instructions of a program that is software that realizes each function, and a ROM (Read Only) in which the program and various data are recorded so as to be readable by a computer (or CPU). Memory) or a storage device (these are referred to as “recording media”), a RAM (Random Access Memory) for expanding the program, and the like. And the objective of this invention is achieved when a computer (or CPU) reads the said program from the said recording medium and runs it.
  • a “non-temporary tangible medium” such as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used.
  • the program may be supplied to the computer via an arbitrary transmission medium (such as a communication network or a broadcast wave) that can transmit the program.
  • a transmission medium such as a communication network or a broadcast wave
  • the present invention can also be realized in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.
  • a video processing device (2, 11) converts a gradation value taken by each pixel in a video signal according to a second video format having a wider luminance range than the first video format.
  • a virtual maximum luminance level setting unit that sets a virtual maximum luminance level lower than the maximum luminance level indicated by the metadata included in the video signal by referring to the gradation value taken by each pixel in the video signal.
  • the gradation value conversion unit (5) is a level that each pixel can take in the second video format that the video signal follows.
  • a mapping is used in which tone values corresponding to each luminance level equal to or lower than the virtual maximum luminance level among tone values correspond to the tone values that each pixel can take in the first video format. The gradation value taken by each pixel is converted.
  • the video display quality can be further improved.
  • the first video format is an EOTF equivalent to ⁇ 2.2
  • the second format is an EOTF of SMPTE.
  • the format is ST2084.
  • the display quality of the video in the SDR playback environment can be improved.
  • the virtual maximum luminance level setting unit is a floor taken by each pixel constituting each frame or each scene in the video signal.
  • the virtual maximum luminance level is set by referring to the tone value.
  • the gradation value can be efficiently converted in accordance with the gradation value included in the video signal.
  • the virtual maximum luminance level setting unit (4) sets the virtual maximum luminance level in each frame or each scene in the video signal. Is set to the maximum value of the luminance level corresponding to the gradation value taken by each pixel.
  • the gradation value can be efficiently converted in accordance with the gradation value included in the video signal.
  • the video processing apparatus (11) according to aspect 6 of the present invention has a lifting unit in the gradation value of the low gradation value region among the gradation values converted by the gradation value conversion part in the aspect 5. Further, a gradation value adjusting unit (12) for adjusting to the above is further provided.
  • the gradation value adjustment unit refers to an average value of luminance levels corresponding to the gradation values converted by the gradation value conversion unit. Then, the low gradation value region is changed.
  • the gradation value region can be set according to the luminance level distribution, the gradation value can be adjusted according to the luminance level distribution.
  • the gradation value adjustment unit is a graph of the gradation value converted by the gradation value conversion unit and the corresponding luminance level. , The gradation value in the middle gradation value region is further adjusted so that the gradation value in the low gradation value region and the gradation value in the high gradation value region change continuously.
  • the gradation value adjusted by the gradation value adjustment unit is the gradation indicated by a predetermined format in the low gradation value region. Greater than the value.
  • the video conversion devices according to aspects 6 to 8 can be suitably used.
  • the virtual maximum luminance level setting unit (4) takes each pixel constituting each frame or each scene in the video signal.
  • a virtual maximum luminance level is set by creating a histogram of luminance levels corresponding to gradation values and referring to the histogram.
  • the gradation value can be more efficiently converted in accordance with the gradation value included in the video signal.
  • the virtual maximum luminance level setting unit (4) configures the virtual maximum luminance level and each frame or each scene in the video signal.
  • the effective maximum value of the luminance level corresponding to the gradation value taken by each pixel is set to the effective maximum value defined by a constant multiple of the standard deviation of the histogram.
  • the gradation value can be more efficiently converted in accordance with the gradation value included in the video signal.
  • the virtual maximum luminance level setting unit (4) sets a limit value lower than the maximum luminance level by a predetermined value, and the effective maximum luminance If the value is lower than the limit value, the virtual maximum brightness level is set to the limit value, and if the effective maximum value is greater than or equal to the limit value, the virtual maximum brightness level is set to the effective maximum value. To do.
  • the virtual maximum luminance level setting unit (4) is configured to subtract the limit value from the maximum luminance level, When the effective maximum value is lower than the limit value, the virtual maximum luminance level is set to the limit value when the effective maximum value is lower than the limit value. If the effective maximum value is greater than or equal to the limit value, the virtual maximum luminance level is set to the effective maximum value.
  • the limit value can be set to a desired value.
  • the video processing device (2) according to aspect 14 of the present invention is the image processing apparatus (2) according to aspect 14, wherein the virtual maximum luminance level is a luminance corresponding to a gradation value taken by each pixel constituting each frame or each scene in the HDR signal.
  • the effective maximum value of the level is set to the time average value of the effective maximum value defined by a constant multiple of the standard deviation of the histogram.
  • the video quality can be improved.
  • the display device (1, 10) according to the aspect 15 of the present invention includes any one of the video processing apparatuses according to the above aspects 1 to 14.
  • the display device can obtain the effects that the video processing device has in each aspect.
  • a video processing method is a video processing method for converting a gradation value taken by each pixel in a video signal according to a second video format having a luminance range wider than that of the first video format,
  • a virtual maximum luminance level setting step for setting a virtual maximum luminance level lower than a maximum luminance level indicated by metadata included in the video signal by referring to a gradation value taken by each pixel in the video signal;
  • the display device may be realized by a computer.
  • the display device is realized by the computer by operating the computer as each unit (software element) included in the display device.
  • a control program for the display device and a computer-readable recording medium on which the control program is recorded also fall within the scope of the present invention.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Picture Signal Circuits (AREA)
  • Controls And Circuits For Display Device (AREA)

Abstract

Même dans un appareil d'affichage supportant un signal SDR, la présente invention convertit efficacement des caractéristiques de gradation indiquées par un signal HDR en des caractéristiques de gradation adaptées à l'appareil d'affichage et, par conséquent, améliore la qualité d'affichage. Un dispositif de traitement vidéo (2) comprend : une unité de réglage de niveau de luminance maximal virtuel (4) qui règle un niveau de luminance maximal virtuel qui est inférieur au niveau de luminance maximal indiqué par des métadonnées incluses dans un signal vidéo ; et une unité de conversion de valeurs de gradation (5) qui convertit des valeurs de gradation correspondant à des niveaux de luminance respectifs égaux ou inférieurs au niveau de luminance maximal virtuel, parmi les valeurs de gradation adoptées par des pixels respectifs dans le signal vidéo.
PCT/JP2017/005763 2016-03-24 2017-02-16 Dispositif de traitement vidéo, appareil d'affichage, procédé de traitement vidéo, programme de commande, et support d'enregistrement Ceased WO2017163685A1 (fr)

Applications Claiming Priority (4)

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JP2016-060857 2016-03-24
JP2016060857 2016-03-24
JP2016181002A JP2017184220A (ja) 2016-03-24 2016-09-15 映像処理装置、表示装置、映像処理方法、制御プログラム、および記録媒体
JP2016-181002 2016-09-15

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