Video processing device, method of operating the video processing device, and recording medium

Abstract

We propose an image processing device that improves color accuracy by correcting color distortion after gamut mapping of the image. [Solution] This is achieved by an image processing device (method) comprising one or more processors that convert first image data in a first color space into second image data in a second color space via gamut mapping, obtain the luminance level of the second image data, obtain a saturation correction value corresponding to the obtained luminance level, and adjust the saturation of the second image data based on the obtained saturation correction value while maintaining the luminance level.

Description

Technical Field

[0001] The present disclosure relates to a video processing apparatus, and more particularly to a video processing apparatus capable of enhancing color accuracy.

Background Art

[0002] Generally, an imaging device or a display device can capture or reproduce only limited colors compared to natural colors perceivable by humans. Usually, the range of colors that can be reproduced by primary color coordinates is determined, and such a color reproduction range is referred to as a color gamut.

[0003] Generally, in a display device, an RGB color space is used, and a color gamut is formed using three primary colors of red, green, and blue that can be added to each other.

[0004] By the way, if the color gamuts between the output display device and the input imaging device are different, the colors of the input video and the output video will not be equal. Also, when output through display devices with different color gamuts for the same input, the output videos are expressed with different colors.

[0005] Thus, it is necessary to adjust the data so that the intended reproduction is achieved during color reproduction between devices with different color gamuts, and this is referred to as gamut mapping.

[0006] However, conventionally, gamut mapping has been performed regardless of the gradation of the video. As a result, in the case of an HDR (High Dynamic Range) video, for example, there is a problem that the color gamut size becomes narrow for each gradation level during gamut mapping, and the color is distorted.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The purpose of this disclosure is to improve color accuracy by correcting color distortion after gamut mapping of video.

[0008] The purpose of this disclosure may be to improve color reproduction accuracy by correcting the saturation of video data according to brightness levels after gamut mapping of the video.

[0009] The purpose of this disclosure may be to improve color accuracy while maintaining luminance levels after gamut mapping. [Means for solving the problem]

[0010] An image processing apparatus according to an embodiment of the present disclosure may include one or more processors that convert first image data in a first color space into second image data in a second color space via gamut mapping, obtain a luminance level of the second image data, obtain a saturation correction value corresponding to the obtained luminance level, and adjust the saturation of the second image data based on the obtained saturation correction value while maintaining the luminance level.

[0011] The operation method of the image processing apparatus according to the embodiment of this disclosure may include the steps of: converting first image data in a first color space into second image data in a second color space via gamut mapping; obtaining the luminance level of the second image data; obtaining a saturation correction value corresponding to the obtained luminance level; and adjusting the saturation of the second image data based on the obtained saturation correction value while maintaining the luminance level.

[0012] In a computer-readable inactive recording medium on which a program for executing an operation method of an image processing apparatus according to an embodiment of the present disclosure is recorded, the operation method may include the steps of: converting first image data in a first color space into second image data in a second color space via gamut mapping; obtaining a luminance level of the second image data; obtaining a saturation correction value corresponding to the obtained luminance level; and adjusting the saturation of the second image data based on the obtained saturation correction value while maintaining the luminance level. [Effects of the Invention]

[0013] According to the embodiments of this disclosure, color accuracy can be improved by correcting color distortion after gamut mapping.

[0014] According to the embodiments of this disclosure, the color reproduction rate can be significantly improved by performing saturation correction on video data according to brightness levels.

[0015] According to the embodiments of this disclosure, it is possible to improve color accuracy while maintaining the luminance level after gamut mapping. [Brief explanation of the drawing]

[0016] [Figure 1] This diagram shows a block diagram illustrating the configuration of a display device according to one embodiment of the present invention. [Figure 2] This is a diagram illustrating the configuration of an image processing device according to one embodiment of the present disclosure. [Figure 3] This is a flowchart illustrating the operation method of an image processing apparatus according to one embodiment of the present disclosure. [Figure 4] This figure shows an example of a color gamut conversion after gamut mapping according to one embodiment of the present disclosure. [Figure 5] This diagram illustrates that when gamut mapping is applied to video regardless of the gradation of the image using conventional technology, color accuracy deteriorates in the low-gradation region. [Figure 6A-6B]A diagram showing that the gamma size increases by adjusting the saturation correction value after gamma mapping according to an embodiment of the present disclosure. [Figures 7A-7B] A diagram for comparing the case where the saturation correction value is not applied to the video data after gamma mapping and the case where the saturation correction value is applied to the video data after gamma mapping according to an embodiment of the present disclosure. [Figure 8A-8B] A diagram for comparing the case where the saturation correction value is not applied to the video data after gamma mapping and the case where the saturation correction value is applied to the video data after gamma mapping according to an embodiment of the present disclosure. [Figure 9] A diagram for explaining a method of measuring the values of coordinates on the CIE1976u’v’ chromaticity diagram to confirm color accuracy in order to confirm the applicability of an embodiment of the present disclosure.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In the following description, the suffixes "module" and "section" of the components used are given or mixed only for the ease of preparing the specification, and do not have a meaning or role that distinguishes them from each other by themselves.

[0018] The display device according to an embodiment of the present invention can be, for example, an intelligent display device in which a computer support function is added to a broadcast reception function, and an Internet function or the like is added while being faithful to the broadcast reception function, and a handwriting input device, a touch screen, or a spatial remote control, etc. can be provided with a more convenient interface for use. And it is connected to the Internet and a computer by supporting a wired or wireless Internet function, and functions such as e-mail, web browsing, banking, or games can also be executed. A general-purpose OS standardized for such various functions can be used.

[0019] Therefore, the display device described in the present invention can freely add or delete various applications on, for example, a general-purpose OS kernel, and thus can execute various user-friendly functions. More specifically, the display device can be, for example, a network TV, HBBTV, smart TV, LED TV, OLED TV, etc., and in some cases, it is also applicable to smartphones.

[0020] FIG. 1 is a block diagram showing the configuration of a display device according to an embodiment of the present invention.

[0021] Referring to FIG. 1, the display device 100 can include a broadcast receiving unit 130, an external device interface 135, a memory 140, a user input interface 150, a controller 170, a wireless communication interface 173, a display 180, a speaker 185, and a power circuit 190.

[0022] The broadcast receiving unit 130 can include a tuner 131, a demodulator 132, and a network interface 133.

[0023] The tuner 131 can select a specific broadcast channel according to a channel selection command. The tuner 131 can receive a broadcast signal of the selected specific broadcast channel.

[0024] The demodulator 132 can separate the received broadcast signal into a video signal, an audio signal, and a data signal related to a broadcast program, and can restore the separated video signal, audio signal, and data signal into an outputable form.

[0025] The external device interface 135 can receive an application or a list of applications in an adjacent external device and transmit it to the controller 170 or the memory 140.

[0026] The external device interface 135 can provide a connection path between the display device 100 and an external device. The external device interface 135 can receive one or more of the video and audio output from an external device connected to the display device 100 wirelessly or via a wired connection and transmit them to the controller 170. The external device interface 135 can include multiple external input terminals. These multiple external input terminals can include RGB terminals, one or more HDMI (High Definition Multimedia Interface) terminals, and component terminals.

[0027] Video signals from an external device input via the external device interface 135 can be output via the display 180. Audio signals from an external device input via the external device interface 135 can be output via the speaker 185.

[0028] External devices that can be connected to the external device interface 135 may include, but are not limited to, any one of the following: a set-top box, a Blu-ray® player, a DVD player, a game console, a soundbar, a smartphone, a PC, a USB memory stick, or a home theater system.

[0029] The network interface 133 can provide an interface for connecting the display device 100 to a wired / wireless network, including an internet network. The network interface 133 can send and receive data with other users or other electronic devices via the connected network or other networks linked to the connected network.

[0030] Furthermore, some of the content data stored in the display device 100 can be transmitted to other users or other electronic devices that are pre-registered with the display device 100, or to selected users or selected electronic devices.

[0031] The network interface 133 can connect to a designated web page via the connected network or another network linked to the connected network. In other words, it can connect to a designated web page via the network and send and receive data with the corresponding server.

[0032] Furthermore, the network interface 133 can receive content or data provided by a content provider or network operator. In other words, the network interface 133 can receive content such as movies, advertisements, games, VOD, and broadcast signals, as well as related information, provided by a content provider or network provider via the network.

[0033] Furthermore, the network interface 133 can receive firmware update information and update files provided by the network operator, and can transmit data to the Internet, a content provider, or the network operator.

[0034] The network interface 133 can select and receive desired applications from among those publicly available (open) via the network.

[0035] The memory 140 can store programs for each signal processing and control within the controller 170, and can also store processed video, audio, or data signals.

[0036] Furthermore, the memory 140 may also perform functions for the temporary storage of video, audio, or data signals input from the external device interface 135 or the network interface 133, and can store information about a predetermined image via the channel storage function.

[0037] Memory 140 can store applications or lists of applications that are input from the external device interface 135 or the network interface 133.

[0038] The display device 100 can play and provide to the user content files (video files, still image files, music files, document files, application files, etc.) stored in the memory 140.

[0039] The user input interface 150 can transmit signals input by the user to the controller 170, and transmit signals from the controller 170 to the user. For example, the user input interface 150 can receive and process control signals from the remote control device 200, such as power on / off, channel selection, and screen settings, depending on various communication methods such as Bluetooth (registered trademark; hereinafter the same), WB (Ultra Wideband), ZigBee, RF (Radio Frequency) communication, or infrared (IR) communication, and can process control signals from the controller 170 to transmit to the remote control device 200.

[0040] Furthermore, the user input interface 150 can transmit control signals input from local keys (not shown), such as the power key, channel key, volume key, and setting value, to the controller 170.

[0041] The video signal processed by the controller 170 is input to the display 180 and can be displayed as the corresponding video signal. The video signal processed by the controller 170 can also be input to an external output device via the external device interface 135.

[0042] The audio signal processed by the controller 170 can be output as audio through the speaker 185. Alternatively, the audio signal processed by the controller 170 can be input to an external output device via the external device interface 135.

[0043] In addition, the controller 170 can control the overall operation within the display device 100.

[0044] Furthermore, the controller 170 can control the display device 100 by user commands or internal programs entered via the user input interface 150, and can connect to a network to download applications or lists of applications desired by the user into the display device 100.

[0045] The controller 170 ensures that the channel information selected by the user, along with the processed video or audio signal, is output via the display 180 or speaker 185.

[0046] Furthermore, the controller 170 is configured to output video signals or audio signals from an external device, such as a camera or camcorder, input via the external device interface 135, through the display 180 or speaker 185, in accordance with external device video playback commands received via the user input interface 150.

[0047] On the other hand, the controller 170 can control the display 180 to display video, for example, broadcast video input via the tuner 131, external input video input via the external device interface 135, video input via the network interface unit, or video stored in the memory 140, so that it is displayed on the display 180. In this case, the video displayed on the display 180 may be a still image or a moving image, and may be 2D or 3D video.

[0048] Furthermore, the controller 170 can control the display device 100 to play back content stored within it, received broadcast content, and external input content received from an external source. This content can take various forms, such as broadcast video, external input video, audio files, still images, connected web pages, and document files.

[0049] The wireless communication interface 173 can communicate with external devices via wired or wireless connection. The wireless communication interface 173 can perform short-range communication with external devices. To this end, the wireless communication interface 173 uses Bluetooth. TM The wireless communication interface 173 can support short-range communication using at least one of the following technologies: RFID (Radio Frequency Identification), Infrared Data Association (IrDA), UWB (Ultra Wideband), ZigBee, NFC (Near Field Communication), Wi-Fi (Wireless-Fidelity), Wi-Fi Direct, or Wireless USB (Wireless Universal Serial Bus). Such a wireless communication interface 173 can support wireless communication between the display device 100 and a wireless communication system, between the display device 100 and other display devices 100, or between the display device 100 and a network where an external server is located, via a Wireless Area Network. The Near-Range Wireless Network may be a Wireless Personal Area Network.

[0050] Here, the other display device 100 may be a wearable device (such as a smartwatch, smart glass, or HMD (head-mounted display)) or a mobile terminal such as a smartphone that is capable of exchanging (or interacting with) the display device 100 according to the present invention. The wireless communication interface 173 can sense (or recognize) communicable wearable devices around the display device 100.

[0051] Furthermore, if the sensed wearable device is authenticated to communicate with the display device 100 according to the present invention, the controller 170 can transmit at least a portion of the data processed by the display device 100 to the wearable device via the wireless communication interface 173. Therefore, the user of the wearable device can access the data processed by the display device 100 through the wearable device.

[0052] The display 180 can generate drive signals by converting video signals, data signals, OSD signals processed by the controller 170, or video signals and data signals received by the external device interface 135, into R, G, and B signals, respectively.

[0053] On the other hand, since the display device 100 shown in Figure 1 is merely one embodiment of the present invention, some of the illustrated components may be integrated, added, or omitted according to the specifications of the display device 100 that will actually be implemented.

[0054] In other words, two or more components can be combined into one component as needed, or one component can be subdivided into two or more components. Note that the functions performed by each block are for illustrative purposes only, and their specific operations or devices do not limit the scope of the present invention.

[0055] In another embodiment of the present invention, the display device 100 may receive and play video via a network interface 133 or an external device interface 135 without having a tuner 131 and a demodulator 132, as shown in Figure 1.

[0056] For example, the display device 100 may be implemented by separating it into a video processing device such as a set-top box for receiving broadcast signals and content corresponding to various network services, and a content playback device for playing back the content input from the video processing device.

[0057] In this case, the operation method of the display device according to the embodiment of the present invention described below may be performed not only by the display device 100 as described with reference to Figure 1, but also by one of the following: an image processing device such as the separated set-top box or a content playback device equipped with a display 180 and a speaker 185.

[0058] Figure 2 is a diagram illustrating the configuration of an image processing apparatus according to one embodiment of the present disclosure.

[0059] In one embodiment, the video processing device 1 may be included in the controller 170 shown in Figure 1.

[0060] In another embodiment, the video processing device 1 is included in the display device 100, but it may be a component provided separately from the controller 170 in Figure 1.

[0061] The video processing device 1 may include a processor 250 and a memory 260. The processor 250 may consist of one or more units.

[0062] The processor 250 may include a gamut mapping unit 210, a brightness level extraction unit 220, a saturation value acquisition unit 230, and a color gamut correction unit 240.

[0063] The gamut mapping unit 210 can convert the first video data in the first color space, obtained through gamut mapping, into second video data in the second color space.

[0064] The luminance level extraction unit 220 can extract the luminance level (Y level) of the second video data in the second color space. The luminance level extraction unit 220 can calculate the luminance level based on the second video data in the second color space.

[0065] The saturation value acquisition unit 230 can acquire a saturation correction value corresponding to the brightness level. The saturation value acquisition unit 230 can acquire a saturation correction value corresponding to the brightness level range to which the acquired brightness level belongs.

[0066] The color gamut correction unit 240 can acquire corrected video data for the second color gamut according to a saturation correction value corresponding to the brightness level, while maintaining the brightness level of the second video data in the second color space.

[0067] Memory 260 may store multiple saturation correction values ​​corresponding to each of multiple luminance level ranges. The video processing device 1 can extract a saturation correction value from memory 260 that corresponds to the luminance level range to which the acquired luminance level belongs.

[0068] In yet another embodiment, the memory 260 may store a curve look-up table for saturation correction. The curve look-up table may be a table showing a curve that maps saturation correction values ​​according to the luminance level of the second video data in the second color space. The curve look-up table may be a table used to correct only the saturation while maintaining the luminance level.

[0069] Memory 260 may be memory 140 in Figure 1, and may be a separate component.

[0070] Figure 3 is a flowchart illustrating the operation method of an image processing apparatus according to one embodiment of the present disclosure.

[0071] Referring to Figure 3, the video processing device 1 can acquire the first video data in the first color space (S301).

[0072] The video data may be data received from the tuner 131, network interface 133, or external device interface 135. The video data may be high dynamic range (HDR) video.

[0073] The first video data can contain multiple video data corresponding to a single scene. Each of the multiple video data may correspond to each of the multiple pixels that make up the display 180. Each video data may be RGB data.

[0074] The first video data may be the first video data in the first color space without gamut mapping.

[0075] The first color space can be an RGB-based color space.

[0076] The video processing device 1 can perform HDR processing on the first video data in the first color space if the first video data is HDR video data.

[0077] HDR processing can include EOTF (Electro-Optical Transfer Function) processing, tone mapping, and OETF (Opto-Electrical Transfer Function) processing.

[0078] EOTF processing can be a process that converts the electrical signals of an HDR image into brightness signals.

[0079] Tone mapping can be a process that adjusts the brightness and contrast ratio of HDR images according to the maximum brightness range of the display 180 based on the converted luminance signal.

[0080] OETF processing can be a process that converts the brightness signal of HDR video after tone mapping back into an electrical signal.

[0081] The video processing device 1 can convert the first video data in the first color space, obtained by gamut mapping, into second video data in the second color space (S303).

[0082] Gamut mapping can be the process of converting an RGB-based color space to a standard color space. The first and second color spaces can each be RGB-based color spaces, but this is merely an example.

[0083] The second color space can follow either BT.709 or BT.2020.

[0084] Gamut mapping can be a mapping technique that adjusts colors to a range that can be represented while minimizing color distortion when performing color conversions on devices or color spaces with different color gamuts.

[0085] A gamut can be referred to as a color gamut. Gamut mapping can be referred to as the concept of color gamut.

[0086] The image processing device 1 can convert first image data in the first color space to second image data in the second color space via a 3x3 gamut matrix. The 3x3 gamut matrix may differ depending on the relationship between the two color spaces being converted.

[0087] The video processing device 1 can convert the first video data RGB in the first color space to the second video data R'G'B' in the second color space according to the following [Equation 1].

number

[0088] Figure 4 shows an example of a color gamut conversion after gamut mapping according to one embodiment of the present disclosure.

[0089] Referring to Figure 4, we see the color gamut of the input terminal as represented in the color space and the color gamut after gamut mapping.

[0090] Gamut mapping can prevent color distortion and potentially improve color reproduction accuracy.

[0091] Let's explain Figure 3 again.

[0092] On the other hand, the video processing device 1 can apply a gain value for post-processing of the second video data in the second color space. The gain value may be a value used to adjust the ratio of RGB data. For example, if the color values ​​of the second video data in the second color space exceed a set range, the video processing device 1 can adjust the color values ​​to within the set range via the gain value.

[0093] The video processing device 1 can acquire the luminance level (Y level) of the second video data in the second color space (S305).

[0094] The video processing device 1 can calculate the luminance level from the second video data in the second color space. The luminance level can be divided into 1024 levels from 0 to 1023 based on 10 bits.

[0095] The image processing device 1 can obtain a saturation correction value corresponding to the brightness level (S307).

[0096] The saturation correction value can also be called the saturation gain value. The saturation correction value can represent the adjustment ratio of the saturation of the second video data in the second color space.

[0097] For example, a saturation correction value of 0.1 can indicate a 10% increase in saturation, and a saturation correction value of -0.1 can indicate a -10% decrease in saturation.

[0098] The image processing device 1 can acquire multiple saturation correction values ​​corresponding to each of the multiple luminance level ranges. The image processing device 1 can acquire a saturation correction value corresponding to the luminance level range to which the acquired luminance level belongs.

[0099] The video processing device 1 can classify the video data contained in the second video data of the second color space according to a pre-set number of brightness level ranges. The number of pre-set ranges may be four, but is not limited to this and can vary depending on the hardware specifications of the video processing device 1 and the display 180.

[0100] In one embodiment, if the number of pre-set values ​​is four, the luminance level range can be classified based on 10 bits into a first luminance level range (0 to 255), a second luminance level range (256 to 512), a third luminance level range (513 to 768), and a fourth luminance level range (769 to 1023).

[0101] The range from 0 to 255 is the low-gradation region, the range from 256 to 768 is the medium-gradation region, and the range from 769 to 1023 may be the high-gradation region.

[0102] In another embodiment, if the number of pre-configured values ​​is four, the luminance level range can be classified into a first luminance level range (0-81), a second luminance level range (82-163), a third luminance level range (164-255), and a fourth luminance level range (255-1023) based on 10 bits.

[0103] In other words, the luminance level range can be set so that the low-gradation region is further subdivided. This is because, due to bit depth limitations, nonlinear color conversion, and limitations of the image processing device 1, a lot of color distortion occurs in the low-gradation region.

[0104] In the example above, four brightness level ranges were used as an example, but the number of brightness level ranges may vary depending on the settings or the hardware specifications of the video processing device 1.

[0105] The memory 260 of the video processing device 1 may store multiple saturation correction values ​​corresponding to each of multiple luminance level ranges. The video processing device 1 can extract a saturation correction value from the memory 260 that corresponds to the luminance level range to which the acquired luminance level belongs.

[0106] In yet another embodiment, the memory 260 may store a curve look-up table for saturation correction. The curve look-up table may be a table containing information about curves that map saturation correction values ​​according to the luminance levels of the second video data in the second color space. The curve look-up table may be a table used to correct only the saturation while maintaining the luminance levels.

[0107] The image processing device 1 can extract a saturation correction value corresponding to the brightness level of the second color gamut data from a curved lookup table.

[0108] The video processing device 1 can acquire corrected video data in the second color space according to a saturation correction value corresponding to the brightness level, while maintaining the brightness level of the second video data in the second color space (S309).

[0109] The video processing device 1 can correct the second video data in the second color space using a saturation correction value corresponding to the luminance level while maintaining the luminance level.

[0110] The video processing device 1 can adjust the ratio of sub-video data values ​​included in the second video data of the second color space in order to adjust the saturation while maintaining the brightness level.

[0111] For example, if the second color gamut is the CIE 1976 color gamut, saturation can be represented as the length between the u' and v' coordinate values, which represent the color difference. The vector obtained by concatenating the u' and v' coordinates is called the color difference vector.

[0112] The image processing device 1 can adjust the saturation by adjusting the length of the color difference vector while keeping the L value representing brightness fixed. The image processing device 1 can also adjust the saturation by changing the length of the color difference vector to a length corresponding to the saturation correction value while keeping the L value representing brightness fixed.

[0113] The image processing device 1 can increase saturation by increasing the length of the color difference vector while keeping the L value fixed, and can decrease saturation by decreasing the length of the color difference vector.

[0114] The video processing device 1 can output corrected video data of the corrected second color gamut to the display 180. (S309)

[0115] Display 180 can output a color-gamut corrected image based on second-gamut correction video data.

[0116] Figure 5 illustrates that when gamut mapping is applied to video regardless of the gradation of the image according to the conventional technology, color accuracy decreases in the low-gradation region.

[0117] Referring to Figure 5, the target and converted coordinates of RGB data for the low-gradation region are shown on the CIE (International Commission on Illumination) color diagram. The low-gradation region can represent an area with gradation levels from 0 to 255 based on 10 bits, but this is only an example.

[0118] Comparing the target coordinates 510 with the transformed coordinates 520 obtained by gamut mapping, we can confirm that color distortion occurs.

[0119] In particular, the area of ​​the gamut size formed by the transformed coordinates may become smaller than the area of ​​the gamut size formed by the target coordinates, which can lead to a decrease in color reproduction accuracy.

[0120] Figures 6A and 6B show that the gamut size increases by adjusting the saturation correction value after gamut mapping according to the embodiment of this disclosure.

[0121] Figure 6A shows the case where the saturation correction value is increased for the low-tone region after gamut mapping, and Figure 6B shows the case where the saturation correction value is increased for the high-tone region after gamut mapping.

[0122] The low-gradation region may be the region of pixels where the brightness level is in the range of 0 to 255 based on 10 bits, while the high-gradation region may be the region of pixels where the brightness level is in the range of 769 to 1023 based on 10 bits.

[0123] Referring to Figure 6A, it can be seen that when the saturation correction value is increased while maintaining the luminance level after gamut mapping, the gamut size for the low-gradation region is increased from the existing first size 610 to the second size 620. This improves color accuracy.

[0124] Referring to Figure 6B, it can be seen that when the saturation correction value is increased while maintaining the luminance level after gamut mapping, the gamut size for the high-gradation region is increased from the existing third size 630 to the fourth size 640. This can improve color accuracy.

[0125] Figures 7A to 8B show a comparison between the case where no saturation correction value is applied to the gamut-mapped video data and the case where a saturation correction value is applied to the gamut-mapped video data according to the embodiment of this disclosure.

[0126] Figures 7A and 7B are diagrams for comparing color accuracy on the CIE1976u'v' chromaticity diagram in the low-gradation region.

[0127] In Figures 7A to 8B, the color accuracy of the coordinates at different luminance levels can be measured via the Kalman program.

[0128] Figures 7A to 8B may represent experimental results obtained for inputting HDR video patterns.

[0129] Figure 7A shows the case where no saturation correction value is applied to the video data in the low-tone region after gamut mapping, while Figure 7B may show the case where a saturation correction value is applied to the video data in the low-tone region after gamut mapping.

[0130] Referring to Figure 7A, we can see that color distortion occurs when comparing the target coordinates 710 with the transformed coordinates 720 obtained through gamut mapping.

[0131] In particular, the area of ​​the gamut size formed by the transformed coordinates becomes smaller than the area of ​​the gamut size formed by the target coordinates, which can lead to a problem of reduced color reproduction accuracy.

[0132] Referring to Figure 7B, we can see that no color distortion occurs when comparing the target coordinates 730 and the transformed coordinates 740 obtained through gamut mapping.

[0133] Since the gamut area formed by the transformed coordinates is similar to the gamut area formed by the target coordinates, a high color reproduction rate can be maintained.

[0134] Figure 8A shows the case where no saturation correction value is applied to the high-tone video data after gamut mapping, while Figure 8B may show the case where a saturation correction value is applied to the high-tone video data after gamut mapping.

[0135] Referring to Figure 8A, we can see that no color distortion occurs when comparing the target coordinates 810 with the transformed coordinates 820 obtained through gamut mapping.

[0136] Referring to Figure 8B, we can see that no color distortion occurs when comparing the target coordinates 810 with the transformed coordinates 820 obtained through gamut mapping.

[0137] In other words, the difference can be more clearly apparent in the low-gradation range than in the high-gradation range.

[0138] If a tendency is observed in the low-gradation region where the actual color becomes lighter compared to the target color (a characteristic of narrower gamut size is not yet confirmed), it can be inferred that the embodiments of this disclosure are not applicable.

[0139] Conversely, if a tendency is observed for the target color and the actual color to match in the low-gradation region (where the characteristic of narrowing the gamut size is not confirmed), it can be inferred that the embodiments of this disclosure have been applied.

[0140] Figure 9 illustrates a method for verifying color accuracy by measuring the coordinate values ​​on the CIE1976u'v' chromaticity diagram in order to determine whether the embodiments of this disclosure are applicable.

[0141] Users can measure the Calman saturation sweep to see the output coordinate values ​​after gamut mapping for each luminance level of the color pattern.

[0142] If the values ​​of the target coordinates and the transformed coordinates tend not to match as you move towards the lower grayscale region (as the brightness level decreases), it can be inferred that the embodiments of this disclosure are not applicable.

[0143] If the values ​​of the target coordinates and the transformed coordinates tend to match more closely as you move towards the lower grayscale region (as the brightness level decreases), it can be inferred that an embodiment of this disclosure has been applied.

[0144] The video processing device 1 may include one or more processors 250 that convert first video data in a first color space into second video data in a second color space via gamut mapping, obtain the luminance level of the second video data, obtain a saturation correction value corresponding to the obtained luminance level, and adjust the saturation of the second video data based on the obtained saturation correction value while maintaining the luminance level.

[0145] The one or more processors 250 can obtain a correction value as the saturation correction value that corresponds to the luminance level range to which the luminance level belongs, from among a plurality of luminance level ranges.

[0146] The image processing device 1 may further include a memory 260 that stores the plurality of luminance level ranges and a plurality of saturation correction values ​​corresponding to each of the plurality of luminance level ranges, and one or more processors 250 can extract from the memory the saturation correction value that matches the luminance level range to which the luminance level belongs.

[0147] The one or more processors 250 can adjust the saturation of the second video data to obtain corrected video data, and can output the corrected video data to the display 180.

[0148] The one or more processors 250 can increase or decrease the saturation of the second video data based on a saturation correction value obtained while maintaining the brightness level.

[0149] The aforementioned luminance level range may be further subdivided into lower-gradation regions than higher-gradation regions.

[0150] The image processing device 1 may further include a memory 260 that stores a table containing information about a curve mapping the saturation correction value according to the brightness level, and one or more processors 250 may extract the saturation correction value mapped to the brightness level from the memory.

[0151] The one or more processors 250 can perform EOTF (Electro-Optical Transfer Function) processing, tone mapping, and OETF (Opto-Electrical Transfer Function) processing on the first video data before gamut mapping.

[0152] The first video data may be High Dynamic Range (HDR) video data.

[0153] The first color space may be the RGB color space of the display, and the second color space may be the standard color space.

[0154] In one embodiment of the present disclosure, the method described above can be implemented as processor-readable code on a medium on which a program is recorded. Examples of processor-readable media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage devices.

[0155] The display device described above is not limited to the configuration and methods of the embodiments described above, and the embodiments may be configured by selectively combining all or part of each embodiment so that they can be varied in many ways.

[0156] [One aspect of the present invention] [Claim 1] An image processing device, It comprises one or more processors, The one or more processors described above are: Through gamut mapping, the first image data in the first color space is converted to the second image data in the second color space; The brightness level of the second video data is obtained; A saturation correction value corresponding to the acquired brightness level is obtained; A video processing device configured (set; executed) to adjust the saturation of the second video data based on a saturation correction value obtained while maintaining the brightness level. [Claim 2] The image processing apparatus according to claim 1, wherein the one or more processors are configured to obtain a correction value corresponding to the luminance level range to which the luminance level belongs from among a plurality of luminance level ranges as a saturation correction value. [Claim 3] With even more memory, The memory stores the plurality of brightness level ranges and the plurality of saturation correction values ​​corresponding to each of the plurality of brightness level ranges. The image processing apparatus according to claim 2, wherein the one or more processors are configured to extract from the memory a saturation correction value that matches the luminance level range to which the luminance level belongs. [Claim 4] The aforementioned one or more processors further, The saturation of the second video data is adjusted to obtain corrected video data; The video processing apparatus according to claim 1, configured to output the corrected video data on a display. [Claim 5] The video processing apparatus according to claim 1, wherein one or more processors are configured to increase or decrease the saturation of the second video data based on a saturation correction value obtained while maintaining the brightness level. [Claim 6] The image processing apparatus according to claim 2, wherein the luminance level range is further subdivided into a lower gradation region than a higher gradation region. [Claim 7] With even more memory, The memory stores a table containing information about a curve that maps the saturation correction value according to the brightness level, The image processing apparatus according to claim 1, wherein one or more processors are configured to extract saturation correction values ​​mapped to the brightness levels from the memory; [Claim 8] The one or more processors, before gamut mapping, perform the following actions on the first video data: The image processing apparatus according to claim 1, which performs EOTF (Electro-Optical Transfer Function) processing, tone mapping, and OETF (Opto-Electrical Transfer Function) processing. [Claim 9] The video processing apparatus according to claim 1, wherein the first video data is High Dynamic Range (HDR) video data. [Claim 10] The first color space is the RGB color space of the display, The image processing apparatus according to claim 1, wherein the second color space is a standard color space. [Claim 11] A method for operating an image processing device, The step of converting first video data in the first color space to second video data in the second color space via gamut mapping; A step to obtain the brightness level of the second video data; The stage in which a saturation correction value corresponding to the acquired brightness level is obtained; A method for operating an image processing device, comprising the step of adjusting the saturation of the second image data based on a saturation correction value obtained while maintaining the brightness level. [Claim 12] The method of operating the image processing apparatus according to claim 11, wherein the step of obtaining the saturation correction value includes the step of obtaining a correction value corresponding to the luminance level range to which the luminance level belongs from among a plurality of luminance level ranges as the saturation correction value. [Claim 13] The process further includes the step of storing a plurality of luminance level ranges and a plurality of saturation correction values ​​corresponding to each of the plurality of luminance level ranges; The method of operating the image processing apparatus according to claim 12, further comprising the step of obtaining the saturation correction value, the step of extracting the saturation correction value that matches the luminance level range to which the luminance level belongs; [Claim 14] A step of obtaining corrected video data by adjusting the saturation of the second video data; A method for operating an image processing apparatus according to claim 11, further comprising the step of outputting the corrected image data to a display. [Claim 15] The method of operating the video processing apparatus according to claim 11, wherein the step of adjusting the saturation includes increasing or decreasing the saturation of the second video data based on a saturation correction value obtained while maintaining the brightness level. [Claim 16] The method for operating an image processing apparatus according to claim 12, wherein the luminance level range is further subdivided into a lower gradation region than a higher gradation region. [Claim 17] The further step includes storing a table containing information about a curve obtained by mapping the saturation correction value according to the brightness level; The method of operating the image processing apparatus according to claim 11, further comprising the step of obtaining the saturation correction value, the step of extracting the saturation correction value that is mapped to the luminance level via the table; [Claim 18] A method for operating an image processing apparatus according to claim 11, further comprising the step of performing EOTF (Electro-Optical Transfer Function) processing, tone mapping, and OETF (Opto-Electrical Transfer Function) processing on the first image data before the gamut mapping; [Claim 19] The method of operating the video processing apparatus according to claim 11, wherein the first video data is High Dynamic Range (HDR) video data. [Claim 20] A computer-readable inactive recording medium on which a program for executing the operation method of an image processing device is recorded, The aforementioned operation method is, The step of converting first video data in the first color space to second video data in the second color space via gamut mapping; A step to obtain the brightness level of the second video data; The stage in which a saturation correction value corresponding to the acquired brightness level is obtained; A method for operating an image processing device, comprising the step of adjusting the saturation of the second image data based on a saturation correction value obtained while maintaining the brightness level.

Claims

1. An image processing device, It comprises one or more processors, The one or more processors described above are: Gamut mapping converts the first video data in the first color space to the second video data in the second color space; The brightness level of the second video data is obtained; Obtain a saturation correction value corresponding to the acquired brightness level; An image processing device configured to adjust the saturation of the second image data based on a saturation correction value obtained while maintaining the brightness level.

2. The image processing apparatus according to claim 1, wherein one or more processors are configured to obtain a correction value corresponding to the luminance level range to which the luminance level belongs from among a plurality of luminance level ranges as a saturation correction value.

3. With even more memory, The memory stores the plurality of brightness level ranges and the plurality of saturation correction values ​​corresponding to each of the plurality of brightness level ranges. The image processing apparatus according to claim 2, wherein one or more processors are configured to extract from the memory a saturation correction value that matches the luminance level range to which the luminance level belongs.

4. The one or more processors further: Corrected video data is obtained by adjusting the saturation of the second video data; The video processing apparatus according to claim 1, configured to output the corrected video data on a display.

5. The video processing apparatus according to claim 1, wherein one or more processors are configured to increase or decrease the saturation of the second video data based on a saturation correction value obtained while maintaining the brightness level.

6. The image processing apparatus according to claim 2, wherein the luminance level range is further subdivided into a lower gradation region than a higher gradation region.

7. With even more memory, The memory stores a table containing information about a curve that maps the saturation correction value according to the brightness level, The image processing apparatus according to claim 1, wherein one or more processors are configured to extract saturation correction values ​​mapped to the brightness levels from the memory.

8. The one or more processors, before gamut mapping, perform the following on the first video data: The image processing apparatus according to claim 1, which performs EOTF (Electro-Optical Transfer Function) processing, tone mapping, and OETF (Opto-Electrical Transfer Function) processing.

9. The video processing apparatus according to claim 1, wherein the first video data is High Dynamic Range (HDR) video data.

10. The first color space is the RGB color space of the display. The image processing apparatus according to claim 1, wherein the second color space is a standard color space.

11. A method for operating an image processing device, The step of converting first video data in the first color space to second video data in the second color space via gamut mapping; Steps to obtain the brightness level of the second video data; The stage in which a saturation correction value corresponding to the acquired brightness level is obtained; A method for operating an image processing device, comprising the step of adjusting the saturation of the second image data based on a saturation correction value obtained while maintaining the brightness level.

12. The method of operating the image processing apparatus according to claim 11, wherein the step of obtaining the saturation correction value includes the step of obtaining a correction value corresponding to the luminance level range to which the luminance level belongs from among a plurality of luminance level ranges as the saturation correction value.

13. The process further includes storing the plurality of luminance level ranges and the plurality of saturation correction values ​​corresponding to each of the plurality of luminance level ranges; The method of operating the image processing apparatus according to claim 12, further comprising the step of obtaining the saturation correction value, the step of extracting the saturation correction value that matches the luminance level range to which the luminance level belongs;

14. A step of obtaining corrected video data by adjusting the saturation of the second video data; A method for operating an image processing apparatus according to claim 11, further comprising the step of outputting the corrected image data to a display.

15. The method of operating the video processing apparatus according to claim 11, wherein the step of adjusting the saturation includes increasing or decreasing the saturation of the second video data based on a saturation correction value obtained while maintaining the brightness level.

16. The method of operating the image processing apparatus according to claim 12, wherein the brightness level range is further subdivided into a lower gradation region than a higher gradation region.

17. The step of storing a table containing information about a curve mapping the saturation correction value according to the brightness level; further comprising: The method of operating the image processing apparatus according to claim 11, further comprising the step of obtaining the saturation correction value, the step of extracting the saturation correction value that is mapped to the luminance level via the table;

18. A method for operating an image processing apparatus according to claim 11, further comprising the steps of performing EOTF (Electro-Optical Transfer Function) processing, tone mapping, and OETF (Opto-Electrical Transfer Function) processing on the first image data before gamut mapping;

19. The method for operating the video processing apparatus according to claim 11, wherein the first video data is High Dynamic Range (HDR) video data.

20. A computer-readable inactive recording medium on which a program for executing the operation method of an image processing device is recorded, The aforementioned operation method is, The step of converting first video data in the first color space to second video data in the second color space via gamut mapping; Steps to obtain the brightness level of the second video data; The stage in which a saturation correction value corresponding to the acquired brightness level is obtained; A method for operating an image processing device, comprising the step of adjusting the saturation of the second image data based on a saturation correction value obtained while maintaining the brightness level.

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