JP6913004B2 - Signal level converter and program - Google Patents

Description

The present invention is an input of a video signal that is electro-optically converted based on the first electro-optical transfer function (EOTF), such as a standard dynamic range video signal for SDR-TV (Standard Dynamic Range television). It is possible to measure the signal of a video signal that is electro-optically converted based on the second electro-optical transfer function, such as a video signal with a high dynamic range for HDR-TV (High Dynamic Range television). The present invention relates to a signal level converter and a program.

In recent years, in response to the problem that viewers who watched TV programs developed light-sensitive attacks due to video flicker, the "Guidelines for Video Techniques such as Animation" by the Japan Broadcasting Corporation and the National Association of Commercial Broadcasters in Japan (1998) , And the "ITC Guidance Note for Licensees on Flashing Image and Regular Pattern in Television" (1994, 1998, 2001-2002) by the Independent Television Commission of the United Kingdom. Further, in accordance with these guidelines, signal measuring instruments such as "The Harding Flash and Pattern Analyzer" (hereinafter referred to as "Harding Machine") have been developed, or devices for improving the signal measuring instruments have been developed (for example, Patent Documents 1 and 1). 2).

Further, in the Appendix (Appendix) of ITU-R Recommendation BT.1702, the blinking brightness difference is equal to or more than a predetermined value, and the blinking area area exceeds 25% of the entire screen. If so, it is more likely to cause a photosensitivity attack.

A typical signal measuring instrument as an existing harding machine first divides a screen into a predetermined first block size, performs motion compensation between fields as needed, and image difference (or motion compensation) between fields. The error) is calculated, and the first threshold value processing (the first threshold value is, for example, the calculation of the difference value of the pixel values corresponding to the predetermined value) with respect to the average value of the image differences within the predetermined second block size. )I do. Then, this signal measuring instrument aggregates the number of blocks of the predetermined second block size that is equal to or larger than the first threshold value, and the number of blocks of the aggregation result is the second threshold value (the second threshold value is, for example, , The number of blocks corresponding to the area of 25% of the entire screen) is exceeded, it is determined that there is significant blinking. Further, this signal measuring instrument blinks 3 times because the significant blinking is counted a predetermined number of times (for example, 6 times (increasing and decreasing brightness separately) within a predetermined time interval (for example, 1 second). Equivalent)) It is configured to issue a warning when the above is detected.

Patent No. 4933782 Patent No. 4870990

Conventional signal measuring instruments are suitable for signal measurement of video signals for standard dynamic range, and this signal measuring instrument is used to convert high dynamic range video signals to high dynamic range without any signal conversion. Even if the signal measurement of the video signal is performed, a measurement error occurs especially in the measurement related to the brightness value.

The following two are the causes of this error.
(Factor 1) The measurement standard differs between the standard dynamic range video signal and the high dynamic range video signal.
(Factor 2) There is a difference in the electro-optical transfer function (EOTF) that expresses the relationship between the brightness value on the display and the signal level between the standard dynamic range video signal and the high dynamic range video signal.

As described above, conventionally, a signal measuring device for detecting harmful light blinking that induces a photosensitivity attack has been known for measuring a video signal having a standard dynamic range. This conventional signal measuring instrument determines the harmfulness according to the measurement criteria (blinking luminance difference, blinking frequency, and blinking area) defined for the video signal of the standard dynamic range.

On the other hand, a signal measuring instrument for detecting harmful light blinking that measures a video signal having a high dynamic range does not yet exist, and its measurement standard is undecided. Since the degree of stimulation to the human visual system differs between the standard dynamic range video signal and the high dynamic range video signal, it is assumed that different measurement criteria are specified. For example, it is generally known that the visual system responds more proportionally to contrast than absolute brightness difference, especially in the case of high brightness.

Therefore, the threshold value of the blinking luminance difference for the standard dynamic range ^{is defined as 40 [cd / m 2} ] as shown in FIG. 8, while the threshold value of the blinking luminance difference for the high dynamic range is shown in FIG. As such, the following metrics may be specified.
The threshold value for the brightness difference when the average brightness value is 180 [cd / m ² ] or less is 40 [cd / m ² ].
The threshold value for the luminance difference when the average luminance value exceeds 180 [cd / m ^{2 ] is y / 4.5 [cd / m 2} ] with respect to the average luminance value y.

Alternatively, it can also be expressed as follows as a threshold value of the blinking luminance difference for a high dynamic range.
The threshold value for the brightness difference when the brightness value of the blinking dark part is 160 [cd / m ² ] or less is 40 [cd / m ² ].
The threshold value for the brightness difference when the brightness value of the blinking dark part exceeds 160 [cd / m ² _{] is y min} / 4 [cd / m ² ] with respect to _{the brightness value y min of the blinking dark part.}

Such a difference in the measurement criteria for the standard dynamic range video signal and the high dynamic range video signal becomes the error factor described in the above factor 1.

Also, the electric optical transfer function (EOTF) is expected to be different between the standard dynamic range video signal and the high dynamic range video signal. For example, the electro-optical transfer function (EOTF) specified in BT.1886 is applied for a standard dynamic range video signal, whereas for a high dynamic range video signal, for example, it is specified in BT.2100. It is expected that an electro-optical transfer function (EOTF) called the Hybrid Log-Gamma (HLG) method or the Perceptual Quantization (PQ) method will be applied.

Such a difference in the electric optical transfer function (EOTF) between the standard dynamic range video signal and the high dynamic range video signal becomes the error factor described in the above factor 2.

Therefore, even if the signal measurement of the high dynamic range video signal is performed using the signal measuring device for the standard dynamic range without converting the high dynamic range video signal at all, the measurement is particularly performed in the measurement related to the luminance value. There will be an error.

On the other hand, re-developing a signal measuring instrument for a high dynamic range causes problems in the utilization of resources or the responsiveness to fluctuations in standards, and further increases the cost of the signal measuring instrument for a high dynamic range. It is not preferable because it causes.

Therefore, in view of the above problems, an object of the present invention is to input a video signal that is electro-optically converted based on the first electro-optical transfer function (EOTF), such as a video signal having a standard dynamic range for SDR-TV. A signal level converter and a signal level converter that enables signal measurement of video signals that are electro-optically converted based on the second electro-optical transfer function, such as video signals with a high dynamic range for HDR-TV, with respect to the assumed signal measuring device. To provide a program.

The signal level converter of the present invention uses a signal measuring device that measures a signal related to light obtained by electro-luminance conversion based on the first electro-optical transfer function (EOTF) for a video signal based on the first measurement standard. , A signal level converter that performs preprocessing in front of the signal measuring device in order to measure the signal of the video signal that is electro-optically converted based on the second electro-optical transfer function according to the second measurement standard. In the preprocessing, the signal level conversion function F that inputs the video signal to be measured and converts it into a luminance value based on the second electric light transfer function, the first measurement reference, and the second A conversion based on the luminance conversion function G for performing the luminance conversion obtained by integrating the ratio of the threshold values of the luminance difference as a measurement reference with respect to the luminance component and the inverse function H of the first electric light transfer function. It is characterized in that the signal level of the input video signal is converted by processing to generate a converted video signal to be provided to the signal measuring instrument.

Further, in the signal level conversion device of the present invention, the conversion process includes a function of subtracting or adding a constant value between the brightness conversion function G and the inverse function H to adjust the offset. do.

Further, in the signal level conversion device of the present invention, the conversion process is characterized in that a lookup table is used for a part of the processes constituting the conversion process and a function calculation is performed for the other parts of the process.

Further, in the signal level conversion device of the present invention, the conversion process is characterized in that a lookup table is used for all the processes constituting the conversion process, or a function calculation is performed.

Further, in the signal level conversion device of the present invention, the conversion process is characterized in that the signal measuring device generates a converted video signal for processing a part of the dynamic range of the video signal to be measured. ..

Further, the program of the present invention is configured as a program for operating the computer as the signal level converter of the present invention.

According to the present invention, the first electro-optical transfer function and the first metric are defined by using a signal measuring device that measures the signal of a video signal according to the first electro-optical transfer function and the first metric. Since the signal measurement of the video signal to be measured can be performed according to a different second electric optical transfer function and the second measurement standard, it is excellent in terms of utilization of resources. Further, according to the present invention, even if a change occurs in the second electro-optical transfer function and the second measurement standard, it can be immediately dealt with without changing the signal measuring instrument, so that it is responsive to changes in the standard. It will be excellent from the viewpoint.

Further, according to one aspect of the present invention, it is possible to obtain an effect of reducing the cost when configuring the signal measuring device for a standard dynamic range as a signal measuring device for a high dynamic range.

Further, according to one aspect of the present invention, when the video signal to be measured is converted into a converted video signal that can be processed by the signal measuring device, all the signal values within the dynamic range of the video signal to be measured are set. A part of the dynamic range of the video signal to be measured can be processed, and it is possible to adjust which part of the video signal is to be processed. Further, for example, by performing signal measurement by a plurality of signal measuring instruments via the signal level conversion device according to one aspect of the present invention, it is possible to perform signal measurement of the entire dynamic range of the video signal to be measured. It becomes.

Further, according to one aspect of the present invention, the amount of calculation can be reduced and the processing speed can be increased.

Further, according to one aspect of the present invention, it is possible to suppress an increase in the scale of the apparatus while considering the amount of calculation and the speeding up of processing.

It is a block diagram which illustrates the schematic structure of the signal level conversion apparatus of 1st Embodiment by this invention. It is a figure which illustrates the electric optical transfer function for high dynamic range (HDR) which concerns on the signal level conversion apparatus of 1st Embodiment by this invention. It is a figure which illustrates the conversion function applied by the luminance conversion part in the signal level conversion apparatus of 1st Embodiment by this invention. It is a block diagram which illustrates the schematic structure of the signal level conversion apparatus of 2nd Embodiment by this invention. It is a figure which illustrated the input / output characteristic at the time of offset when a part section of the dynamic range of the video signal of the measurement target which concerns on the signal level conversion apparatus of 2nd Embodiment by this invention is processed. It is a block diagram which illustrates the schematic structure of the signal level conversion apparatus of 3rd Embodiment by this invention. It is a block diagram which illustrates the schematic structure of the signal level conversion apparatus of 4th Embodiment by this invention. It is a figure which illustrates the measurement standard of the blinking luminance difference for a standard dynamic range (SDR). It is a figure which illustrates the measurement standard of the blinking luminance difference for high dynamic range (HDR).

[First Embodiment]
FIG. 1 is a block diagram illustrating a schematic configuration of the signal level conversion device 1 according to the first embodiment of the present invention. The signal level conversion device 1 according to the present invention is placed in front of a signal measuring device 5 that assumes the input of a video signal that is electro-optically converted based on the first electro-optical transfer function (EOTF), and is the first electricity. It functions as a preprocessing device that enables signal measurement of video signals that are electro-optically converted based on a second electro-optical transfer function (EOTF) that is different from the optical transfer function (EOTF).

The signal measuring device 5 is obtained by measuring a signal relating to display brightness in a video signal that is electro-optically converted based on the first electro-optical transfer function (EOTF) (electro-optical conversion based on the first electro-optical transfer function (EOTF)). It is a device for performing signal measurement related to light), and is a subtraction unit according to each purpose such as flicker detection of the video signal, noise detection of the video signal, and brightness evaluation for each scene in the video signal. It suffices as long as it performs No. 13, and operates according to the first measurement standard according to each purpose.

In the following description, the signal measuring instrument 5 typically inputs a standard dynamic range video signal (hereinafter, also referred to as “SDR video signal”) based on the electric light transfer function (EOTF) for SDR-TV. A device that detects flicker of the video signal based on the first measurement standard, and the signal level conversion device 1 of the present embodiment is a video signal having a high dynamic range based on an electric light transfer function (EOTF) for HDR-TV. Hereinafter, it will be described as a preprocessing device that inputs (also referred to as “HDR video signal”) and enables flicker detection of the video signal with a second measurement standard different from the first measurement standard by using the signal measuring device 5. ..

Therefore, the signal level conversion device 1 of the present embodiment includes a signal conversion unit 10 and a parameter control unit 20.

The signal conversion unit 10 converts the input HDR video signal into an SDR conversion signal that can be processed by the signal measuring device 5, and outputs the signal to the signal measuring device 5. This conversion process mainly includes input / output conversion processing performed in the order of the HDR electric light transmission function, the brightness conversion function, and the SDR electric light transmission function inverse function, which will be described later, from the input HDR video signal. The SDR conversion signal is derived. The signal measuring device 5 inputs the SDR-converted video signal to enable signal measurement related to display brightness.

The parameter control unit 20 is a functional unit that controls the setting of conversion parameters, which will be described later, when the signal conversion unit 10 performs conversion processing from the signal level of the HDR video signal to the signal level of the SDR-converted video signal.

Hereinafter, the configurations of the signal conversion unit 10 and the parameter control unit 20 will be described more specifically.

The signal conversion unit 10 includes an HDR electric light transfer function calculation unit 11, a luminance conversion unit 12, a subtraction unit 13, an SDR electric light transfer function inverse function calculation unit 14, and a limiter 15.

However, in this example, a preferable example in which the subtraction unit 13 is provided between the luminance conversion unit 12 and the electric light transfer function inverse function calculation unit 14 for SDR is shown, but if it is unnecessary for the purpose of signal measurement, the subtraction unit is shown. 13 may be omitted. Further, in this example, a preferable example in which the limiter 15 is provided after the electric light transfer function inverse function calculation unit 14 for SDR is shown, but the limiter 15 may be omitted if it is unnecessary for the purpose of signal measurement.

On the other hand, the parameter control unit 20 includes a conversion parameter setting unit 21 and a luminance component integration processing unit 22.

First, the HDR electric light transmission function calculation unit 11 is a functional unit that performs an operation of converting the signal level x of the input HDR video signal into the display luminance value y by using the HDR electric light transmission function. The electric light transfer function for is, for example, an electric light transfer function for a video signal having a high dynamic range defined as the above-mentioned HLG method or PQ method. Here, the input to the HDR electric optical transfer function calculation unit 11 is x, and the output from the HDR electric light transfer function calculation unit 11 is y.

For example, in the HLG system, the relationship of the signal level x of the video signal with respect to the average brightness E of a certain scene is defined as an opto-electronic transfer function (OETF) as shown in equation (1). ..

On the other hand, in the HLG method, the electric light transfer function, which is the conversion of the video signal from the signal level x to the display brightness, is a composite function of the inverse function of the optical electric transfer function and the optical transfer function (OOTF). Is defined as. Therefore, the HDR electric optical transfer function based on the HLG method is as shown in the equation (2) as the relationship between the signal level x of the input HDR video signal and the signal level y of the output display luminance.

In BT.2100, the electric light transfer function is specified for each color component of red, green, and blue, but the equation (2) is arranged by paying attention only to the luminance component. Further, _{L W} is the nominal value of the display of the peak luminance for achromatic (unit cd ^{/ m} 2) _{(e.g., L W = 1000 [cd /} m 2]) and, _{L B} is the display of the luminance to black (unit cd / m ²⁾ (for _example, a ^{L B = 0 [cd / m} 2]). Further, x and y are expressed at a level normalized to 0 or more and 1 or less.

Therefore, the HDR electric light transmission function calculation unit 11 performs an calculation using the function (signal level conversion function F) according to the equation (2) on the signal level x of the input HDR video signal, and the display luminance value y [. cd / m ² ] is output. For _{^{example, L W = 1000 [cd /}} m 2], shows L B = 0 HDR electric optical transfer function in the case of [cd / ^{m 2]} in Figure 2.

The luminance conversion unit 12 adjusts the sensitivity with respect to the display luminance value y using the luminance conversion function in order to enable the signal measuring device 5 to measure the display luminance in the HDR video signal (desired signal measurement), and after the sensitivity adjustment. This is a functional unit that converts the display brightness value e into.

In this example, since the signal measuring device 5 detects the flicker, the luminance conversion unit 12 receives the average luminance (maximum value and minimum value (for example, adjacent to each other) of the luminance of the flicker) from the photoelectric light transmission function calculation unit 11 for HDR. _{The brightness difference (value obtained by subtracting the minimum value from the maximum value of the flicker brightness) exceeds θ SDR} (y) in the display brightness value y input so that it can be treated as the additive average value of the maximum value and the minimum value). The blinking in the case is detected, and the blinking when the luminance difference becomes _{more than θ HDR} (y) in the display luminance value y input as the average luminance is detected.

_{That is, as the threshold value θ SDR} (y) of the luminance difference as the first measurement reference handled by the signal measuring device 5, and as the second measurement reference of the desired signal measurement targeted by the signal level conversion device 1 of the present embodiment. From the luminance difference threshold θ _HDR (y) of, the sensitivity to be set for the desired signal measurement (sensitivity to the luminance difference) is θ _SDR (y) of the sensitivity to be set so that the signal measuring device 5 can handle it. / Θ _HDR (y) times. This sensitivity ratio (ratio of the threshold value of the luminance difference) is g (y) as shown in the equation (3).

_{For example, the threshold value θ SDR} (y) handled by the signal measuring device 5 and _{the threshold value θ HDR} (y) of the desired signal measurement targeted by the signal level conversion device 1 are shown in FIGS. 8 and 9, respectively. If it is, the sensitivity ratio function g (y) can be expressed as shown in the equation (4).

In order to perform the desired signal measurement targeted by the signal level converter 1 of the present embodiment using the signal measuring device 5, it is necessary to compensate for the sensitivity ratio between them. When the desired signal measurement needs to be g times more sensitive than the signal measuring device 5, the contrast of luminance may be converted to g times and input. Therefore, in order to multiply the contrast at the display brightness y before the sensitivity adjustment by g (y), the brightness conversion function G (y) in which the slope of the tangent line at the display brightness y before the sensitivity adjustment is g (y) is used. Luminance conversion may be performed. That is, for example, as shown in the equation (5), the luminance conversion function G (y) can be derived by an indefinite integral with respect to the luminance component of the sensitivity ratio function g (y).

_{Therefore, the threshold value θ SDR} (y) handled by the signal measuring device 5 and _{the threshold value θ HDR} (y) of the desired signal measurement targeted by the signal level conversion device 1 are shown in FIGS. 8 and 9, respectively. In the case of a thing, from the equation (4) and the equation (5), the luminance conversion function G (y) is expressed as the equation (6). In equation (6), C is an arbitrary constant (eg, C = 0).

Here, the signal level conversion device 1 of the present embodiment does not change the signal measuring device 5 even if the electric optical transfer function for detecting the flicker of the HDR video signal and the measurement standard thereof are changed. A parameter control unit 20 is provided so that an immediate response can be made.

The parameter control unit 20 includes a conversion parameter setting unit 21 and a luminance component integration processing unit 22.

The conversion parameter setting unit 21 changes the setting of the brightness-to-sensitivity ratio function g (y) from the outside, temporarily holds the function g (y), and automatically holds the brightness-to-sensitivity ratio when the operation of the signal level conversion device 1 starts. The function g (y) of is output to the luminance component integration processing unit 22.

The luminance component integration processing unit 22 performs indefinite integration processing of the luminance-to-sensitivity ratio function g (y) input from the conversion parameter setting unit 21, derives the luminance conversion function G (y), and causes the luminance conversion unit 12 to perform indefinite integration processing. Output.

Then, as shown in the equation (7), the luminance conversion unit 12 substitutes the display luminance value (input value) y before the sensitivity adjustment into the luminance conversion function G (y), and the display luminance value (output) after the sensitivity adjustment. Value) Convert to e.

FIG. 3 shows an example of conversion from the display brightness y before the sensitivity adjustment to the display brightness e after the sensitivity adjustment in the brightness conversion unit 12.

The subtraction unit 13 is a function unit that subtracts or adds a constant value to adjust the offset. For example, as shown in the equation (8), the subtraction unit 13 is offset from the sensitivity-adjusted display brightness value e output from the brightness conversion unit 12. The value (here, e ₀ ) is subtracted, and the offset-adjusted display brightness value d, which is the subtraction result, is output to the SDR electric light transfer function inverse function calculation unit 14.

The conversion parameter setting unit 21 _{also changes the setting of the offset value e 0 and temporarily holds it, and outputs the offset value e 0} automatically held at the start of operation of the signal level conversion device 1 to the subtraction unit 13. do. As a result, the signal level conversion device 1 of the present embodiment does not change the signal measuring device 5 even if the electric optical transfer function for detecting the flicker of the HDR video signal and the measurement standard thereof are changed. It is possible to respond immediately.

The inverse function calculation unit 14 of the electric light transfer function for SDR inputs the display brightness value d after offset adjustment obtained from the subtraction unit 13, and performs electric light conversion based on the electric light transfer function (EOTF) for SDR-TV. Converted to the signal level f of the video signal by using, for example, the inverse function of the electro-optical transfer function (EOTF) specified in ITU-R Recommendation BT.1886 so that the signal measuring device 5 assuming the input of the video signal can handle it. It is a functional part to do.

In the ITU-R recommendation BT.1886, the electric optical transfer function, which is the relationship between the signal level f of the video signal input to the signal measuring instrument 5 and the display luminance value d [cd / m ² ], is given by the equation (9). Is stipulated as.

Incidentally, _{M W} is a screen luminance for white (in cd ^{/ m} 2) ^{_{(e.g., M W = 200 [cd /}} m 2]) a, _{M B} is the screen luminance to black (in cd ^{/ m} 2) (e.g., M _B = 0 [cd / m ² ]). The display gamma value γ'= 2.40 is an example. Further, f is expressed at a level normalized to 0 or more and 1 or less.

Therefore, the inverse function of the electro-optical transfer function (EOTF) specified in ITU-R Recommendation BT.1886 solves Eq. (9) for the signal level f and restricts it so as not to deviate from the domain of the exponential function. As a result, it is derived as in the equation (10).

In the limiter 15, the output value (signal level of the video signal input to the signal measuring device 5) f from the electric light transfer function inverse function calculation unit 14 for SDR can deviate from the specified range (for example, 0 or more and 1 or less). It is provided when there is a sex. When the limiter 15 is provided, the limiter 15 is, for example, the minimum value of the specified range when the output value f from the electric light transfer function inverse function calculation unit 14 for SDR is less than the specified range (for example, 0 or more and 1 or less). (For example, value 0), the maximum value of the specified range (for example, value 1) when the output value f exceeds the specified range, and the output value f when the output value f is within the specified range. It operates so as to output the same value of the output value f as it is.

That is, the limiter 15 executes, for example, an operation according to the equation (11) with respect to the output value (signal level of the video signal input to the signal measuring device 5) f from the electric light transfer function inverse function calculation unit 14 for SDR. Then, it is output to the signal measuring device 5 as an SDR conversion signal z.

When the limiter 15 is not provided, the output value (signal level of the video signal input to the signal measuring device 5) f from the electric light transfer function inverse function calculation unit 14 for SDR is used as the SDR conversion signal z for signal measurement. It is input to the vessel 5.

As a result, the signal measuring device 5 can input the SDR-converted video signal and measure the signal related to the display brightness.

Therefore, according to the signal level converter 1 of the present embodiment, the first electric light is used by using the signal measuring device 5 that measures the signal of the video signal according to the first electric light transfer function and the first measurement reference. Since the signal of the video signal to be measured can be measured according to the second electro-optical transfer function and the second measurement standard, which are different from the transfer function and the first measurement standard, it is excellent from the viewpoint of utilization of resources. It becomes a thing.

Further, according to the signal level conversion device 1 of the present embodiment, even if a change occurs in the second electric light transfer function and the second measurement standard, it can be immediately dealt with without changing the signal measuring device 5. It is excellent in terms of responsiveness to changes in standards.

Further, according to the signal level conversion device 1 of the present embodiment, it is possible to obtain an effect of reducing the cost when the signal measuring device 5 for the standard dynamic range is used to configure the signal measuring device for a high dynamic range.

The signal conversion unit 10 in the signal level conversion device 1 of the present embodiment includes the HDR electric light transmission function calculation unit 11, the brightness conversion unit 12, the subtraction unit 13, the SDR electric light transmission function inverse function calculation unit 14, and the signal conversion unit 10. For all or part of the limiter 15, a plurality of conversion sets may be combined as a composite function and implemented as one conversion function for each. As a result, the amount of calculation can be reduced and the processing speed can be increased.

Typically, signal conversion is performed by one function that combines all of the HDR electric light transmission function calculation unit 11, the luminance conversion unit 12, the subtraction unit 13, the SDR electric light transmission function inverse function calculation unit 14, and the limiter 15. Part 10 can be configured. For example, the signal conversion unit 10 can be configured by a single look-up table.

The lookup table sets the memory area (word) of the bit length (or the bit length required to represent the information after requantization) that can represent the signal level of the SDR-converted video signal to the signal level of the HDR video signal. It can be implemented using the memory allocated in the address space of the number of possible values (or the number of steps after requantization as needed). For example, 12-bit HDR video signal, when the SDR converted signal is 10 bits, the memory area of the 10-bit ^{word, 2 12} (i.e., 4096) is mounted, according to the signal level of the input HDR video signal If the "signal level of the SDR-converted video signal with respect to the signal level of each HDR video signal" derived by a series of operations in the internal block of the signal conversion unit 10 is recorded as a lookup table for the memory area of the address. good.

Therefore, each function is individually or synthesized for all the processes of the HDR electric light transfer function calculation unit 11, the luminance conversion unit 12, the subtraction unit 13, the SDR electric light transfer function inverse function calculation unit 14, and the limiter 15. It can be in the form of using a lookup table. As a result, the amount of calculation can be suppressed and the processing speed can be increased.

Further, each function is individually or synthesized for all the processes of the HDR electric light transfer function calculation unit 11, the brightness conversion unit 12, the subtraction unit 13, the SDR electric light transfer function inverse function calculation unit 14, and the limiter 15. It can be held and function-operated. As a result, the amount of calculation can be suppressed and the increase in the scale of the device can be suppressed.

In addition, a lookup table is used for some processing of the HDR electric light transfer function calculation unit 11, the luminance conversion unit 12, the subtraction unit 13, the SDR electric light transfer function inverse function calculation unit 14, and the limiter 15. It can be in the form of function calculation for the processing of the part. As a result, it is possible to suppress an increase in the scale of the apparatus while considering the amount of calculation and the speeding up of processing.

[Second Embodiment]
FIG. 4 is a block diagram illustrating a schematic configuration of the signal level conversion device 1 according to the second embodiment of the present invention. In FIG. 4, the same reference numbers are assigned to the same components as those in the first embodiment shown in FIG.

The signal conversion unit 10 of the first embodiment described above alone cannot cover the entire dynamic range of the signal level of the input HDR video signal (the output value f from the electric light transfer function inverse function calculation unit 14 for SDR is 0 or more. If the range exceeds 1 or less, the amplitude limitation by the limiter 15 operates and normal signal measurement cannot be performed).

In this case, with respect to the signal conversion unit 10 shown in FIG. 1, a plurality of signal conversion units 10-1, 10-2, ..., 10-N are provided in parallel as shown in FIG. 4 (N is an integer of 2 or more). A plurality of signal conversion units 10-1, 10-2, ..., 10-N in which different values e ₁ , e ₂ , ..., E _{N are set as offset values e 0} shown in FIG. 1 are operated in parallel, and each signal is operated. The SDR-converted signals of the conversion units 10-1, 10-2, ..., 10-N outputs z ₁ , z ₂ , ..., Z _N are signal-measured by the respective signal measuring instruments 5, and the measurement results e. _{It can be configured to integrate 1} , e ₂ , ..., E _N (for example, to execute a logical sum operation of measurement results or a maximum value operation).

According to the signal level conversion device 1 of the second embodiment shown in FIG. 4, the entire dynamic range of the signal level of the input HDR video signal can be covered.

For example, in FIG. 5, different values e ₁ , e ₂ , and e _{3 are set as the offset values e 0} shown in FIG. 1 for the three signal conversion units 10-1 to 1-3, and the signals are operated in parallel. The input / output characteristics of the input value (signal level of the input HDR video signal) x and the output value z (that is, the SDR conversion signals z ₁ , z ₂ , z _{3) are shown.}

In FIG. 5, HDR image peak luminance _L W = 1000 in the signal [cd ^{/ m} 2], the black luminance ^{_{L B = 0 [cd / m}} 2], the peak intensity in the SDR video signal _M W = 200 [cd / ^m 2], black luminance ^{_{M B = 0 [cd / m}} 2], the offset value ^{_{e 1 = 0 [cd / m}} 2], e 2 = 150 [cd / m 2], and _e 3 = 300 [ cd / m ² ].

In the example of FIG. 5, the portion of the limiter 15 of each curve to which the limiter is not applied, that is, the portion to which the case of 0 ≦ f ≦ 1 in the equation (11) is applied, is mutually at the signal level x of the input HDR video signal. It has an overlap. By providing the overlap in this way, it is possible to reduce the signal measurement error of the signal near the amplitude limiting operating point in the limiter 15. It is also possible to eliminate the need for the limiter 15.

[Third Embodiment]
FIG. 6 is a block diagram illustrating a schematic configuration of the signal level conversion device 1 according to the third embodiment of the present invention. In FIG. 6, the same reference numbers are assigned to the same components as those in the first embodiment shown in FIG.

Instead of being configured as in the second embodiment shown in FIG. 4 described above, it can be configured as shown in FIG. 6 to cover the entire dynamic range of the signal level of the input HDR video signal.

In the third embodiment shown in FIG. 6, common processing (electrical optical transmission function calculation unit for HDR) among the plurality of signal conversion units 10-1, 10-2, ..., 10-N of the second embodiment shown in FIG. 4 11 and the brightness conversion unit 12) are put together, the subtraction unit 13-1, 13-2, ..., 13-N, the electrooptical transfer function inverse function calculation unit for SDR 14-1, 14-2, ..., 14-N, And limiters 15-1, 15-2, ..., 15-N are individually provided. In the case of this third embodiment, the same effect as that of the second embodiment can be obtained.

[Fourth Embodiment]
FIG. 7 is a block diagram illustrating a schematic configuration of the signal level conversion device 1 according to the fourth embodiment of the present invention. In FIG. 7, the same reference numbers are assigned to the same components as those in the first embodiment shown in FIG.

Instead of configuring as in the second and third embodiments shown in FIGS. 4 and 5 above, it is configured as shown in FIG. 7 to cover the entire dynamic range of the signal level of the input HDR video signal. You can also do it.

In the signal level converting apparatus 1 of the fourth embodiment shown in FIG. 7, while the single signal converter 10 and the signal measuring instrument 5, respectively, offset value e ₁ the offset value e _n more used in the subtraction unit _13, e ₂ , ..., it is provided a switching portion 23 for switching from e _N to the parameter control unit 20.

Switching unit 23, a plurality of offset values _{e 1,} e 2 output from the conversion parameter specifying unit 21, ..., and outputs the offset value _{e n} obtained by switching _{e N} to the subtracting section 13.

Subtracting unit 13 outputs a signal value d _n in SDR electric light transfer function inverse function calculation unit 14 by performing the same subtraction processing in the first embodiment shown in FIG. 1 on the basis of the offset value e _n.

The SDR electro-optical transfer function inverse function calculation unit 14 _{inputs the signal value d n} obtained from the subtraction unit 13, performs the same calculation as in the first embodiment shown in FIG. 1, _{and outputs the signal value f n} to the limiter 15. do.

_{The limiter 15 inputs the signal value f n} obtained from the electric light transfer function inverse function calculation unit 14 for SDR, performs the same calculation as in the first embodiment shown in FIG. 1, and converts the output value z _n into the nth SDR. It is output to the signal converter 5 as a signal.

The switching unit 23 can switch the offset value in units of video sequences, and the signal converter 5 can perform signal measurement according to the switching and integrate the measurement results as post-processing.

The signal level conversion device 1 in each of the above embodiments can be configured by a computer, and a program for functioning each processing unit of the signal level conversion device 1 can be preferably used. Specifically, a program required to configure a control unit for controlling each processing unit of the signal level conversion device 1 with a central processing unit (CPU) in a computer and to operate each processing unit. The storage unit for appropriately storing the above can be configured by at least one memory. That is, by causing such a computer to execute the program by the CPU, the functions of each processing unit of the signal level conversion device 1 can be realized. Further, a program for realizing the function of each processing unit of the signal level conversion device 1 can be stored in a predetermined area of the above-mentioned storage unit (memory). Such a storage unit can be configured by a RAM or ROM inside the device, or can be configured by an external storage device (for example, a hard disk). Further, such a program can be configured as a part of software (stored in ROM or an external storage device) on an OS used in a computer. Further, a program for causing such a computer to function as each processing unit of the signal level converter 1 can be recorded on a computer-readable recording medium. Further, each processing unit of the signal level conversion device 1 may be configured as a part of hardware or software, and each may be combined and realized.

Although the present invention has been described above with reference to examples of specific embodiments, the present invention is not limited to the examples of the above-described embodiments, and various modifications can be made without departing from the technical idea. For example, in the example of the above-described embodiment, the signal measuring device 5 is mainly a device that inputs an SDR video signal based on an electric light transfer function (EOTF) for SDR-TV and detects flicker of the video signal. The signal level conversion device 1 of the embodiment is a preprocessing that inputs an HDR video signal based on an electric light transfer function (EOTF) for HDR-TV and enables flicker detection of the video signal by using a signal measuring device 5. Although described as a device, the present invention is not limited to this. The signal measuring device 5 may perform subtraction unit 13 according to the purpose, such as flicker detection of the video signal, noise detection of the video signal, and brightness evaluation for each scene in the video signal. Therefore, the signal level conversion device 1 according to the present invention can be configured as a device that converts the signal level to be adapted to the signal measuring device 5. Therefore, the transmitting device and the receiving device according to the present invention are not limited to the examples of the above-described embodiments, but are limited only by the description of the claims.

According to the present invention, the first electro-optical transfer function and the first metric are defined by using a signal measuring device that measures the signal of a video signal according to the first electro-optical transfer function and the first metric. Since the signal measurement of the video signal to be measured can be performed according to a different second electric optical transfer function and the second measurement standard, it is useful for the application of performing signal level preprocessing conversion for an existing signal measuring instrument.

1 Signal level converter 5,5-1,5-2,5-N signal measuring instrument 10,10-1,10-2,10-N signal converter 11 HDR electro-optical transmission function calculation unit 12 Brightness converter 13,13-1,13-2,13-N Subtraction part 14,14-1,14-2,14-N SDR electro-optical transfer function Inverse function calculation part 15,15-1,15-2,15- N limiter 20 Parameter control unit 21 Conversion parameter setting unit 22 Brightness component integration processing unit 23 Switching unit

Claims (6)

Using a signal measuring instrument that measures signals related to light obtained by electro-optical conversion based on the first electro-optical transfer function (EOTF) for video signals with the first metric, it is used as the second electro-optical transfer function. It is a signal level conversion device that performs preprocessing in front of the signal measuring device in order to measure the signal of the video signal to be electro-optically converted based on the second measurement standard.
The preprocessing includes a signal level conversion function F that inputs a video signal to be measured and converts it into a luminance value based on the second electric light transmission function, and the first measurement reference and the second measurement reference. By the conversion process based on the luminance conversion function G for performing the luminance conversion obtained by integrating the ratio of the thresholds of the luminance difference as A signal level conversion device characterized by converting the signal level of the input video signal and generating a converted video signal to be provided to the signal measuring instrument. The signal level conversion according to claim 1, wherein the conversion process includes a function for subtracting or adding a constant value between the luminance conversion function G and the inverse function H to adjust the offset. Device. The signal level conversion according to claim 1 or 2, wherein the conversion process uses a look-up table for a part of the processes constituting the conversion process and performs a function operation for the other parts of the process. Device. The signal level conversion device according to claim 1 or 2, wherein the conversion process uses a look-up table or is a function operation for all the processes constituting the conversion process. The conversion process is any one of claims 1 to 4, wherein the conversion process generates a converted video signal for the signal measuring device with a partial section of the dynamic range of the video signal to be measured as the processing target. The signal level converter according to. A program for causing a computer to function as the signal level converter according to any one of claims 1 to 5.

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