JP6565330B2 - Video processing apparatus, video processing method, and video processing program - Google Patents

Description

  The present invention relates to a video processing apparatus, a video processing method, and a video processing program for converting a video signal in a certain color space into another video signal having a different color component range.

  As a video signal standard for HDTV (High Definition TeleVision), there is ITU-R (International Telecommunication Union Radiocommunication Sector) recommendation BT.709-5 (hereinafter referred to as BT.709-5 standard). In addition, there is IEC (International Electrotechnical Commission) recommendation 61966-2-4 (also called xvYCC, hereinafter referred to as IEC 61966-2-4 standard) as an extended color space standard for moving images.

  In addition, there is ITU-R recommendation BT.2020 (hereinafter referred to as BT.2020 standard) as a video signal standard for UHDTV (Ultra High Definition Television (UHDTV): also referred to as SHV (Super Hi-Vision)).

  It is required to convert video signals so that video content created based on the BT.709-5 standard or the IEC 61966-2-4 standard can be handled by a UHDTV receiver.

  For example, Patent Documents 1 and 2 describe video signal conversion apparatuses that convert a video signal created according to a certain standard into a video signal according to another standard.

  The color conversion device described in Patent Document 1 converts an IEC 61966-2-4 standard video signal into an sRGB (standard RGB) color space video signal that is an IEC 61966-2-1 standard. In sRGB, each of R, G, and B is expressed in a range of 0 to 1 ([0, 1]). The color gamut of the BT.709-5 standard is equivalent to the color gamut of sRGB.

The video signal conversion device described in Patent Document 2, whether the input video signal is a video signal of the IEC 61966-2-4 standard, video YC _b C _r standards (according to ITU-R BT.601) Determine if it is a signal. Based on the determination result, the input video signal is converted into a video signal in the sRGB color space.

  The color component range of sRGB is [0, 1], but the color component range of IEC 61966-2-4 is wider than [0, 1] and is [−1.1206, 2.1305]. Therefore, in the video signal conversion device described in Patent Document 2, when a video signal of the IEC 61966-2-4 standard is converted to an sRGB video signal, the conversion result deviates from the range [0, 1]. The conversion result falls within the range [0, 1] by a predetermined method.

JP 2009-207115 A JP 2008-187695 A

  However, Patent Document 2 does not disclose a method for converting a video signal based on a standard having a narrow color component range into a video signal based on a standard having a wide color component range.

  In particular, when converting video signals based on each of multiple standards, including the BT.709-5 standard, which has a wide color gamut in the BT.2020 standard but a relatively narrow color gamut, to a video signal based on the BT.2020 standard. In addition, unless some contrivance is applied, the color reproducibility of the converted video signal is lowered.

  Accordingly, the present invention provides a video processing apparatus, a video processing method, and a video processing program capable of converting a video signal based on each of a plurality of standards into a video signal based on a standard having a wide color gamut while preventing a decrease in color reproducibility. The purpose is to provide.

Image processing apparatus according to the present invention, a video signal of YC _b C _r format or RGB format based on each of a plurality of standards, the conversion processing for converting the video signal of the YC _b C _r format or RGB format based on other standards An image processing apparatus having conversion means for executing, comprising an input signal determination means for determining a standard to which an input video signal complies, and the conversion means generates RGB format video signals in the course of conversion processing An RGB video signal generating unit that adjusts a range of data indicated by the RGB format video signal based on the determination result of the input signal determining unit, and the video signals of a plurality of standards are at least ITU- R includes a video signal in accordance with BT.709-5 recommendation and a video signal in accordance with IEC recommendation 61966-2-4. Special To.

Image processing method according to the present invention, a video signal of YC _b C _r format or RGB format based on each of a plurality of standards, the conversion processing for converting the video signal of the YC _b C _r format or RGB format based on other standards An image processing method for executing an image processing method for determining a standard followed by an input video signal and generating an RGB format video signal in the process of conversion processing based on the determined standard The range of data indicated by the video signal is adjusted, and the video signals of multiple standards include at least a video signal according to ITU-R recommendation BT.709-5 and a video signal according to IEC recommendation 61966-2-4. And a process of converting the input video signal into a video signal in accordance with ITU-R recommendation BT.2020 .

Image processing program according to the present invention, a video signal of YC _b C _r format or RGB format based on each of a plurality of standards, the conversion processing for converting the video signal of the YC _b C _r format or RGB format based on other standards A program for executing a process for determining a standard to which a video signal input to a computer complies, and when generating an RGB format video signal in the course of a conversion process, based on the determined standard, The processing to adjust the range of data indicated by the RGB format video signal is executed, and the video signal of multiple standards is at least a video signal according to ITU-R recommendation BT.709-5 and a video according to IEC recommendation 61966-2-4 And converting the input video signal into a video signal conforming to ITU-R recommendation BT.2020 through conversion processing .

  According to the present invention, it is possible to convert a video signal based on each of a plurality of standards into a video signal based on a standard having a wide color gamut while preventing a decrease in color reproducibility.

1 is a block diagram illustrating a first embodiment of a video processing apparatus. It is a block diagram which shows the structural example of a conversion part. It is a flowchart which shows operation | movement of a video processing apparatus. It is a flowchart which shows operation | movement of a conversion part. It is a block diagram which shows 2nd Embodiment of a video processing apparatus. It is a block diagram which shows the example of the information processing system using a program. It is a block diagram which shows the principal part of a video processing apparatus. It is a block diagram which shows the principal part of the video processing apparatus of another aspect.

Embodiment 1. FIG.
FIG. 1 is a block diagram showing a first embodiment of a video processing apparatus according to the present invention. The video processing apparatus shown in FIG. 1 discriminates according to which standard the input signal is a video signal and generates standard information as a discrimination result, according to the discrimination result of the input signal discrimination unit 10. A conversion unit 20 that converts an input signal (video signal) into a video signal based on a predetermined standard.

  As an example, standards to be discriminated by the input signal discrimination unit 10 are the BT.709-5 standard and the IEC 61966-2-4 standard. The standard of the video signal after conversion by the converter 20 is, for example, the BT.2020 standard.

  In this embodiment, the input signal is a BT.709-5 standard video signal and an IEC 61966-2-4 standard video signal, and the converted video signal is a BT.2020 standard video signal. However, if a video signal with a narrow color gamut compared to the color gamut based on the converted video signal is included in a plurality of types of input signals, the input signal and the video signal are images based on other standards. It may be a signal.

  Furthermore, standards other than the BT.709-5 standard and the IEC 61966-2-4 standard may be included as standards for video signals that can be input. That is, the video processing apparatus may be configured to be able to convert video signals based on each of three or more standards.

  FIG. 2 is a block diagram illustrating a configuration example of the conversion unit 20. In the configuration example illustrated in FIG. 2, the conversion unit 20 includes an inverse quantization unit 21, a first conversion unit 22, a first correction unit 23, a signal conversion unit 24, a second correction unit 25, a second conversion unit 26, and a quantization. Part 27 is included.

In the present embodiment, the input signal is a video signal of _YC b _{C r} schemes including a luminance signal and two color difference signals (hereinafter, also referred to as _YC b _{C r} signal.). Further, it may a luminance signal Y signal, a color difference signal of C _b signals and C _r signal.

Inverse quantization unit 21, Y signal, and inverse quantizing the _{C b} signals and _{C r} signal, Y 'signal, _{C b'} generates a signal and _{C r} 'signal. The first conversion unit 22 converts the Y ′ signal, the C _b ′ signal, and the C _r ′ signal into RGB signals (RGB signals, that is, R signals, G signals, and B signals). However, the RGB signals output from the first converter 22 are R ′ signal, G ′ signal, and B ′ signal.

  The first correction unit 23 performs processing for correcting RGB signals (R ′ signal, G ′ signal, and B ′ signal). As an example of the correction, there is a correction using an electro-optical transfer function (EOTF).

The signal converter 24 converts the video signal of the BT.709-5 standard or the video signal of the IEC 61966-2-4 standard into a video signal of the BT.2020 standard. The output signal of the signal converter 24 is an RGB video signal (R ₂₀₂₀ signal, G ₂₀₂₀ signal, and B ₂₀₂₀ signal).

The 2nd correction | amendment part 25 performs the process which correct _| amends _R2020 signal, _G2020 signal, and _B2020 signal. As an example of the correction, there is an optical-electro transfer function (OETF) correction. Note that the OETF correction is substantially a gamma correction. Further, the output signals of the second correction unit 25 are R ′ ₂₀₂₀ signal, G ′ ₂₀₂₀ signal, and B ′ ₂₀₂₀ signal.

The second conversion unit 26 converts the R ′ ₂₀₂₀ signal, the G ′ ₂₀₂₀ signal, and the B ′ ₂₀₂₀ signal into video signals of the YC _{b Cr} format. The quantization unit 27 quantizes the video signal output from the second conversion unit 26.

In the present embodiment, the input signal is a video signal of the YC _b C _r method, although the format of the video signal after conversion also YC _b C _r method, in the apparatus the video signal of the RGB system is input, The inverse quantization unit 21 and the first conversion unit 22 are not necessary. In addition, the second conversion unit 26 and the quantization unit 27 are unnecessary in an apparatus that outputs the converted video signal in the RGB format.

  FIG. 3 is a flowchart showing the operation of the video processing apparatus. In the video processing apparatus, as shown in FIG. 3, the input signal determination unit 10 determines the standard on which the input signal is based (step S101).

  The input signal determination unit 10 determines, for example, the standard that the input signal conforms to based on the data range of the luminance signal (the data range indicated by the signal) or the data range of the color difference signal. As an example, when the luminance signal data range is 16 to 235, or when the color difference signal data range is 16 to 240, a video signal of the BT.709-5 standard is input. It is determined that If there is any luminance signal data that does not fit within the range of 16 to 235, or some of the color difference signal data does not fit within the range of 16 to 240, the IEC 61966-2-4 standard Is determined to be input.

  The input signal discriminating unit 10 may discriminate the standard that the input signal follows on the basis of other than the data range. For example, the standard on which the input signal is based may be determined based on metadata accompanying the video signal.

  When the input signal determination unit 10 determines that the standard based on the input signal is the BT.709-5 standard (step S102), the conversion unit 20 transmits information indicating the BT.709-5 standard to the conversion unit 20. Output (step S103). When it is determined that the standard based on the input signal is the IEC 61966-2-4 standard, information indicating the IEC 61966-2-4 standard is output to the conversion unit 20 as standard information (step S104).

  The converter 20 converts the input signal into a video signal of the BT.2020 standard according to the standard information (step S105).

  Next, the operation of the conversion unit 20 will be described. FIG. 4 is a flowchart showing the operation of the conversion unit 20.

In the conversion unit 20, inverse quantization unit 21, using equation (1), Y signal, and inverse quantizing the _{C b} signals and _{C r} signal, Y 'signal, _{C b'} signals and _{C r} 'signal Generate (step S131).

Y '= (Y / 2 ^N- 8-16) / 219
C _b ′ = (C _b / 2 ^N−8 −128) / 224 (1)
C _r ′ = (C _r / 2 ^N− 8−128) / 224

  In the equation (1), N is the number of bits. In the case of N = 8, the expression (1) is expressed as the expression (1) ′.

Y ′ = (Y−16) / 219
C _b ′ = (C _b −128) / 224 (1) ′
C _r ′ = (C _r −128) / 224

Next, the first converter 22 converts the Y ′ signal, the C _b ′ signal, and the C _r ′ signal into RGB signals (R ′ signal, G ′ signal, and B ′ signal) using the equation (2). (Step S132).

  Next, the first correction unit 23 performs a process of correcting the RGB signals (R ′ signal, G ′ signal, and B ′ signal) (step S133). In the process of step S133, the first correction unit 23 performs correction using EOTF. The correction using EOTF is, for example, correction using the following equations (3) to (5).

  When the calculation result of the correction using the equations (3) to (5) deviates from the predetermined range, the first correction unit 23 stores the calculation result within the predetermined range.

  For example, when the standard information indicates the BT.709-5 standard, the first correction unit 23 changes the calculation result to 0 when the R signal, G signal, or B signal that is the calculation result is smaller than 0. And output. When the R signal, G signal, or B signal, which is the calculation result, is greater than 1, the calculation result is changed to 1 and output.

  The first correction unit 23 calculates the calculation result when the R information, the G signal, or the B signal, which is the calculation result, is smaller than −1.1206 when the standard information indicates the IEC 61966-2-4 standard. Is changed to -1.1206 and output. When the R signal, G signal, or B signal, which is the calculation result, is greater than 2.1305, the calculation result is changed to 2.1305 and output.

Further, the signal conversion unit 24 converts the R signal, the G signal, and the B signal output from the first correction unit 23 into a video signal (R ₂₀₂₀ signal, G ₂₀₂₀ standard) using the following equation (6). Signal and B ₂₀₂₀ signal) (step S134).

Next, the second correction unit 25 performs processing for correcting the R ₂₀₂₀ signal, the G ₂₀₂₀ signal, and the B ₂₀₂₀ signal by OETF, and the R ′ ₂₀₂₀ signal, the G ′ ₂₀₂₀ signal, and the B ′ ₂₀₂₀ that are the corrected signals. A signal is output (step S135). The correction in the OETF is, for example, correction using the following equations (7) to (9).

Then, the second conversion unit 26 uses the following equation (10), R _'2020 signal, G' ₂₀₂₀ signal and B 'the ₂₀₂₀ signal, _YC b _{C r} system video signal (Y' of ₂₀₂₀ signal, C _{b '2020} signal and _{C r'} into a ₂₀₂₀ signal.

Y ' ₂₀₂₀ = 0.2627 x R' ₂₀₂₀ + 0.6780 x G ' ₂₀₂₀ + 0.0593 x B' _{2020
C b '2020 = (B'} 2020 -Y '2020) /1.8814 (10)
C _r ' ₂₀₂₀ = (R' ₂₀₂₀ -Y ' ₂₀₂₀ ) /1.4746

  And the quantization part 27 quantizes the video signal which the 2nd conversion part 26 output using the following (11) Formula.

Y ₂₀₂₀ = (219 x Y ' ₂₀₂₀ +16) x 2 ^N-8
_{C b2020 = (224 × C b} '2020 +128) × 2 N-8 (11)
C _r2020 = (224 x C _r ' ₂₀₂₀ +128) x 2 ^N-8

  In the equation (11), N is the number of bits. In the case of N = 8, the expression (11) is expressed as the expression (11) ″.

Y ₂₀₂₀ = 219 x Y ' ₂₀₂₀ +16
C _b2020 = 224 × C _b ' ₂₀₂₀ +128 (11)'
C _r2020 = 224 × C _r ' ₂₀₂₀ +128

  Further, the quantization unit 27 uses the integer part (integer) of the calculation result according to the expression (11) or the expression (11) ′ as a final quantized video signal.

  As described above, the video processing apparatus according to the present embodiment specifically processes the video signal of the BT.709-5 standard or the IEC 61966-2-4 standard into the video signal of the BT.2020 standard. In the middle of the conversion process, the conversion process is executed without departing from the color signal range of each standard. Therefore, it is possible to suppress a decrease in color reproducibility when executing a video signal conversion process.

  For example, the single correction method (for example, the first correction unit 23 is different from the BT.709-5 standard without distinguishing between the video signal of the BT.709-5 standard and the video signal of the IEC 61966-2-4 standard. When the conversion process is executed by a method that executes the process without distinguishing it from the IEC 61966-2-4 standard, the color reproducibility of the video signal based on one of the standards decreases. The decrease in color reproducibility is particularly remarkable near the boundary of the color component range.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing a second embodiment of the video processing apparatus according to the present invention. The video processing apparatus illustrated in FIG. 5 includes a switching unit 30 in addition to the input signal determination unit 10 and the conversion unit 20 illustrated in FIG.

  The switching unit 30 can input standard information indicating the BT.709-5 standard or the IEC 61966-2-4 standard. When the standard information is input, the switching unit 30 outputs the input signal to the conversion unit 20. Note that standard information from the outside is also input to the conversion unit 20. The standard information is set by an operator of the video processing apparatus, for example.

  The switching unit 30 outputs an input signal to the input signal determination unit 10 when the standard information is not input. Then, the input signal determination unit 10 and the conversion unit 20 perform the same processing as in the first embodiment. Also, when the standard information is input from the outside, the conversion unit 20 performs the same process as in the first embodiment, but executes the conversion process according to the standard information from the outside.

  As an example, a switch is provided in the video processing apparatus, and it is possible to set any of automatic (without inputting standard information) /BT.709-5 standard / IEC 61966-2-4 standard by the switch. It may be.

  Moreover, although each said embodiment can also be comprised with a hardware, it is also possible to implement | achieve by a computer program.

  The information processing system illustrated in FIG. 6 includes a processor 1001 and a program memory 1002. In the information processing system shown in FIG. 6, the program memory 1002 stores a program for realizing the function of each block shown in FIG. The processor 1001 implements the function of the video processing apparatus shown in FIG. 1 or 5 by executing processing according to the program stored in the program memory 1002.

  FIG. 7 is a block diagram showing the main part of the video processing apparatus according to the present invention. As shown in FIG. 7, the video processing apparatus includes an input signal discriminating unit 1 (for example, equivalent to the input signal discriminating unit 10 shown in FIG. 1) for discriminating a standard followed by an input video signal, and each of a plurality of standards. And a conversion unit 2 (for example, equivalent to the conversion unit 20 shown in FIG. 1) that executes a conversion process for converting a video signal based on the video signal into a video signal based on another standard. The RGB video signal generation unit 2A including the RGB video signal generation unit 2A (for example, realized by the first conversion unit 22 and the first correction unit 23 shown in FIG. 2) that generates an RGB format video signal. Is characterized in that the range of data indicated by the video signal in the RGB format is adjusted based on the discrimination result of the input signal discrimination unit 1.

  FIG. 8 is a block diagram showing a main part of a video processing apparatus according to another aspect of the present invention. The video processing apparatus shown in FIG. 8 includes a switching unit 3 (for example, FIG. 5) that outputs an input video signal to the input signal discrimination unit 1 or the conversion unit 2 in addition to the input signal discrimination unit 1 and the conversion unit 2. The switching unit 3 outputs an input video signal to the input signal determination unit 1 when the standard is not set from the outside, and is input when the standard is set. The obtained video signal is output to the converter 2.

DESCRIPTION OF SYMBOLS 1 Input signal discrimination | determination part 2 Conversion part 2A RGB image signal generation part 3 Switching part 10 Input signal discrimination | determination part 20 Conversion part 21 Inverse quantization part 22 1st conversion part 23 1st correction | amendment part 24 Signal conversion part 25 2nd correction | amendment part 26 Second conversion unit 27 Quantization unit 30 Switching unit 1001 Processor 1002 Program memory

Claims (9)

Image processing having a conversion means for performing conversion processing for converting the YC _b C _r format or RGB format video signals based on each of a plurality of standards, the video signal YC _b C _r format or RGB format based on other standards A device,
Provided with an input signal discriminating means for discriminating the standard followed by the input video signal,
The conversion means includes RGB video signal generation means for generating an RGB format video signal in the course of the conversion process,
The RGB video signal generation means adjusts the data range indicated by the video signal in RGB format based on the discrimination result of the input signal discrimination means ;
The video signals of the plurality of standards include at least a video signal according to ITU-R recommendation BT.709-5 and a video signal according to IEC recommendation 61966-2-4,
The video processing apparatus characterized in that the converting means converts an input video signal into a video signal according to ITU-R recommendation BT.2020 . The video processing apparatus according to claim 1, wherein the RGB video signal generation unit fits a data range indicated by a video signal in RGB format into a data range in a standard of a discrimination result of the input signal discrimination unit. A switching means for outputting the input video signal to the input signal discrimination means or the conversion means;
The switching unit outputs an input video signal to the input signal determination unit when a standard is not set from the outside, and outputs an input video signal to the conversion unit when a standard is set. Item 3. The image processing device according to item 1 or 2 . A plurality of each video signal of YC _b C _r format or RGB format based on standards, the video processing method for performing a conversion process for converting a video signal of YC _b C _r format or RGB format based on other standards There,
Determine the standard that the input video signal follows,
When generating the RGB format video signal in the process of the conversion process, based on the determined standard, adjust the data range indicated by the RGB format video signal ,
The video signals of the plurality of standards include at least a video signal according to ITU-R recommendation BT.709-5 and a video signal according to IEC recommendation 61966-2-4,
The conversion process includes a process of converting an input video signal into a video signal according to ITU-R recommendation BT.2020 . The video processing method according to claim 4 , wherein the data range indicated by the video signal in the RGB format falls within the data range in the determined standard. 6. The video according to claim 4 or 5 , wherein when a standard is set from the outside, the input video signal is converted into a video signal based on another standard without determining a standard that the input video signal complies with. Processing method. The YC _b C _r format or RGB format video signals based on each of a plurality of standards, a program for executing the conversion processing for converting the video signal of the YC _b C _r format or RGB format based on other standards ,
On the computer,
Processing to determine the standard that the input video signal complies with;
When generating the video signal of the RGB format in the course of the conversion process, based on the determined standards, to execute the processing for adjusting the range of the data indicated by a picture signal in RGB format,
The video signals of the plurality of standards include at least a video signal according to ITU-R recommendation BT.709-5 and a video signal according to IEC recommendation 61966-2-4,
A video processing program for executing a process of converting an input video signal into a video signal according to ITU-R recommendation BT.2020 in the conversion process. On the computer,
The video processing program according to claim 7, wherein a process of fitting a data range indicated by a video signal in RGB format into a data range in the determined standard is executed. On the computer,
If the outside from standard is set, without determining the standard input video signal conforms, claim 7 or claim to execute a process of converting the input video signal to a video signal based on other standards 8. The video processing program according to 8 .

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