JP5337736B2 - Transmission signal conversion apparatus, transmission signal conversion program, reception signal conversion apparatus, and reception signal conversion program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission signal converting device for converting a video signal into a YCC format signal, which performs constant luminance transmission that satisfies constant luminance principles while preventing deterioration in SN ratio caused by compression and decompression of non-linear conversion. <P>SOLUTION: The transmission signal converting device 3 includes: a linear converting means 30 for converting an input non-linear luminance signal into a linear luminance signal; a bandwidth limiting means 31 for extracting low frequency components from the linear luminance signal; a downsampling means 32 for downsampling the extracted signal at predetermined sampling intervals; a non-linear converting means 33 for converting the downsampled low frequency luminance signal into a low-band non-linear luminance signal by non-linear conversion; and a color difference signal generating means 34 for generating two color difference signals from the low-band non-linear luminance signal, and the low frequency first color signal and the low-band non-linear second color signal. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a transmission signal conversion device and a transmission signal conversion program, and a reception signal conversion device and a reception signal conversion program according to a video signal transmission technique.

  Conventionally, as a method of transmitting a television video signal, luminance is obtained from an R (red) signal, a G (green) signal, and a B (blue) signal, which are three primary color signals photographed by a camera or electronically generated. A method of generating and transmitting a signal and a color difference signal is used (see Non-Patent Document 1).

Here, with reference to FIG. 15, a conventional technique (conventional technique 1) for transmitting a video signal using a luminance signal and a color difference signal will be described. First, as shown in FIG. 15A, the video signal transmitting apparatus 1C uses a non-linear conversion means (gamma correction means) 70 to perform gamma correction on the RGB signal which is a linear signal (the gamma characteristic of the receiving apparatus 2C). By performing the inverse characteristics, a signal is decompressed for a region with a low signal level, and a signal compression (nonlinear compression / decompression processing) is performed for a region with a high signal level. As a result, the RGB signal that is a linear signal is converted into an R ^α G ^α B ^α signal that is a non-linear signal.
Then, the transmitting apparatus 1C performs matrix conversion shown in the following equation (1) on the R ^α G ^α B ^α signal that has been gamma corrected by the matrix conversion unit 71, thereby obtaining the luminance signal Y ′ and the color difference signal. Cb ′ and Cr ′ are generated.

Here, r, g, and b are coefficients for generating a luminance signal. For example, in the HDTV signal standard, r = 0.2126, g = 0.7152, and b = 0.0722.
Further, KCB, because kcr is with about twice the dynamic range of the (B α -Y ^') and (R α ^-Y') is the original signal ^{(B (B α), R} (R α)), This is a coefficient for keeping the color difference signals Cb ′ and Cr ′ within the dynamic range.

Then, the transmitting apparatus 1C performs band limitation for extracting a low frequency component by the band limiting unit (LPF; low pass filter) 72 with respect to the color difference signals Cb ′ and Cr ′. The pixels are converted to color difference signals Cb ′ _LD and Cr ′ _LD by down-sampling every other pixel in the horizontal direction or horizontal and vertical direction.
As a result, the transmitting apparatus 1C generates signals (Y ′, Cb ′ _LD , Cr ′ _LD ) in the 4: 2: 2 format, 4: 2: 0 format, and the like.
The luminance signal Y ′ and the color difference signals Cb ′ _LD and Cr ′ _LD generated in this way are transmitted to the receiving side.

On the other hand, as shown in FIG. 15 (b), the video signal receiving device 2C up-samples the color difference signals Cb ′ _LD and Cr ′ _LD by the up-sampling means 80 among the received video signals. Thus, the sample number and the pixel structure are returned to the same sample number and pixel structure as the luminance signal Y ′.
Then, the receiving apparatus 2C generates an R ^α G ^α B ^α signal by performing the inverse transformation (inverse matrix transformation) of the equation (1) by the inverse matrix conversion unit 81.
Then, the receiving device 2C generates an RGB signal by giving the R ^α G ^α B ^α signal the inverse characteristic of the gamma correction in the nonlinear converting unit 70 of the transmitting device 1C by the linear converting unit 82. If the display device is a display device having a gamma characteristic such as a CRT, the linear conversion means 82 corresponds to the display device, and the R ^α G ^α B ^α signal is obtained as light having passed through the gamma characteristic of the display device. Played.

However, in the conventional method 1, the matrix conversion unit 71 generates a luminance signal and a color difference signal from a non-linear RGB signal (R ^α G ^α B ^α signal) subjected to gamma correction, and further, a band limiting unit 72 Therefore, the band of the color difference signal is limited. Therefore, the receiving apparatus 2C has a problem that the luminance information cannot be correctly reproduced when the RGB signal is restored from the luminance signal and the color difference signal. This is because the information for restoring the luminance is transmitted only by the luminance signal for transmission and does not satisfy the constant luminance principle that it is important that the information is not affected by the color signal (see Non-Patent Document 1).
Furthermore, in the conventional method 1, since the band limitation on the color difference signal is the band limitation on the nonlinear signal, a part of information (harmonic component) included in the nonlinear signal is lost due to the band limitation, and the color information. There is also a problem that cannot be reproduced correctly.

  In order to solve this problem, the luminance signal is generated from the linear RGB signal, and the band limitation is performed on the linear signal instead of the band limitation on the nonlinear signal. As such a method, there is a method adopted by an analog transmission method (MUSE method) of HDTV (High Definition TeleVision).

Here, with reference to FIG. 16, a MUSE transmission method, which is another method (conventional method 2) for transmitting a video signal using a conventional luminance signal and color difference signal, will be described.
As shown in FIG. 16A, the MUSE transmission device 1D is different from the transmission device 1C described in FIG. 15A in that the nonlinear conversion means 70 is replaced with a matrix conversion means 71, a band limiting means 72, and a down-converter. It is provided in the subsequent stage of the sample means 73.

Also, as shown in FIG. 16 (b), the MUSE-type receiving device 2D arranges the linear conversion means 82 before the inverse matrix converting means 81 with respect to the receiving device 2C described in FIG. 15 (b). The received luminance signal and color difference signal are first converted into linear signals.
That is, in the transmission apparatus 1D, band limitation is performed on the difference signals RY and BY of the R and B signals that are linear signals and the luminance signal Y that is a linear signal, and then gamma correction is performed to perform transmission. The video signal is generated.
As described above, the MUSE transmission method enables constant luminance transmission that satisfies the constant luminance principle.

However, this conventional method 2 performs nonlinear conversion on the difference signal RY (such as Cr in FIG. 16) and the difference signal BY (such as Cb in FIG. 16). In the case where the difference signal is large (high saturation portion), conversion for compressing the amplitude is performed.
Therefore, the conventional method 2 has a problem that the signal-to-noise ratio (SN ratio) decreases in the high saturation portion.

In the conventional MUSE system, the non-linear characteristic of the color difference signal is made gentler than that of the luminance signal, and the amplitude is doubled to suppress a decrease in the SN ratio of the high saturation portion. However, doubling the amplitude in an analog video signal has the problem of increasing the number of bits in the digital video signal and increasing the data amount of the video signal.
In order to solve such problems, the inventor of the present invention invented a video signal transmission device, a transmission video signal generation program, a video signal reception device, a transmission video signal conversion program, and a video signal transmission system (Patent Literature). 1).

Japanese Patent Application No. 2010-28259

Supervised by Hideo Kusaka, “Color Image Engineering”, The Institute of Image Information and Television Engineers, Ohmsha, April 25, 1997, pp. 126-129 ITU-R BT.709: Parameter values for the HDTV standards for production and international program exchange

The invention described in Patent Document 1 (the previous invention) reduces the SN ratio of luminance information and color information due to compression / expansion of nonlinear conversion (gamma correction) while performing constant luminance transmission that satisfies the constant luminance principle. It has an excellent effect that it can be suppressed.
According to the previous invention, a luminance signal (nonlinear luminance signal) and two color signals (a low-frequency nonlinear first color signal and a low-frequency nonlinear second color signal) are transmitted as a video signal for transmission. On the other hand, there are digital compression encoding devices that compress and encode a video signal and the like that compress and encode a video signal using a luminance signal and a color difference signal. Therefore, a technique for converting (inversely converting) luminance information and color information transmitted by the above invention into luminance signals and color difference signals that can be processed by a digital compression encoding device or the like is also desired.

  The present invention has been made in view of the above demands, and suppresses a decrease in the SN ratio caused by compression / expansion of nonlinear conversion (gamma correction) while performing constant luminance transmission that satisfies the constant luminance principle. A transmission signal conversion device and a transmission signal conversion program for converting (inverse conversion) a luminance signal and a color signal transmitted in a video signal transmission device and a video signal reception device into a luminance signal and a color difference signal, and It is an object of the present invention to provide a reception signal conversion apparatus and a reception signal conversion program.

  The present invention has been made to solve the above-mentioned problems. First, the transmission signal conversion apparatus according to claim 1 is a luminance signal generated from first to third color signals which are color signals of three primary colors. A non-linear luminance signal obtained by non-linear conversion, a low-frequency non-linear first color signal and a low-frequency non-linear second color signal obtained by performing non-linear conversion after extracting a low-frequency component from the first color signal and the second color signal Is a transmission signal conversion device that converts the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal into two color difference signals, and converts the low-frequency nonlinear first color signal into two color difference signals. Means, band limiting means, downsampling means, non-linear conversion means, and color difference signal generation means.

In such a configuration, the transmission signal conversion device converts the non-linear luminance signal into a linear luminance signal by giving the inverse characteristic of the non-linear conversion performed when the non-linear luminance signal is generated by the linear conversion means.
Then, the transmission signal converter extracts a low frequency component from the linear luminance signal by the band limiting unit, and down-samples the signal extracted by the band limiting unit by a down-sampling unit at a predetermined sampling interval. As a result, a signal (low frequency linear luminance signal) in which the low frequency component of the luminance signal is down-sampled is generated.

The transmission signal conversion device converts the low-frequency linear luminance signal into a low-frequency nonlinear luminance signal by non-linear conversion by the non-linear conversion means.
Then, the transmission signal conversion device generates two color difference signals from the low-frequency nonlinear luminance signal, the low-frequency nonlinear first color signal, and the low-frequency nonlinear second color signal by the color difference signal generating means.
As a result, the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal are converted into two color difference signals.

  The transmission signal conversion program according to claim 2 is a non-linear luminance signal obtained by non-linear conversion of a luminance signal generated from first to third color signals, which are three primary color signals, and the first color signal and the second color signal. A low-frequency non-linear first color signal and a low-frequency non-linear second color signal, which are non-linearly converted after extracting a low-frequency component from the signal and down-sampled, are input as a video signal for transmission. In order to convert the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal into two color-difference signals, the computer is converted into linear conversion means, band limiting means, down-sampling means, nonlinear conversion means, and color-difference signal generation means. It was set as the structure made to function as.

In such a configuration, the transmission signal conversion program converts the non-linear luminance signal into a linear luminance signal by giving the inverse characteristic of the non-linear conversion performed when the non-linear luminance signal is generated by the linear conversion means.
Then, the transmission signal conversion program extracts a low-frequency component from the linear luminance signal by the band limiting unit, and down-samples the signal extracted by the band limiting unit at a predetermined sampling interval by the down-sampling unit. As a result, a signal (low frequency linear luminance signal) in which the low frequency component of the luminance signal is down-sampled is generated.

The transmission signal conversion program converts the low-frequency linear luminance signal into a low-frequency non-linear luminance signal by non-linear conversion by the non-linear conversion means.
Then, the transmission signal conversion program generates two color difference signals from the low-frequency nonlinear luminance signal, the low-frequency nonlinear first color signal, and the low-frequency nonlinear second color signal by the color difference signal generating means.

  Furthermore, the received signal conversion apparatus according to claim 3 is a non-linear luminance signal obtained by non-linear conversion of a luminance signal generated from first to third color signals which are color signals of three primary colors, and the first color signal and the second color signal. A non-linear luminance signal that is a video signal generated from a low-frequency nonlinear first color signal and a low-frequency nonlinear second color signal that are nonlinearly converted after extracting a low-frequency component from the signal, down-sampled, and two color difference signals; Is received as a video signal for transmission, and among the video signals, the two color difference signals are converted into the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal, A linear conversion unit, a band limiting unit, a down-sampling unit, a non-linear conversion unit, and a color signal generation unit are provided.

In such a configuration, the received signal conversion device converts the non-linear luminance signal into a linear luminance signal by giving the inverse characteristic of the non-linear conversion performed when the non-linear luminance signal is generated by the linear conversion means.
Then, the reception signal converting apparatus extracts the low frequency component from the linear luminance signal by the band limiting unit, and down-samples the signal extracted by the band limiting unit at a predetermined sampling interval by the down-sampling unit. As a result, a signal (low frequency linear luminance signal) in which the low frequency component of the luminance signal is down-sampled is generated.

In addition, the received signal conversion device converts the low-frequency linear luminance signal into a low-frequency nonlinear luminance signal by non-linear conversion by the non-linear conversion means.
Then, the reception signal converter generates a low-frequency nonlinear first color signal and a low-frequency nonlinear second color signal from the low-frequency nonlinear luminance signal and the two color difference signals by the color signal generation means.

  The received signal conversion program according to claim 4 is a non-linear luminance signal obtained by nonlinearly converting a luminance signal generated from first to third color signals which are color signals of three primary colors, and the first color signal and the second color signal. A non-linear luminance signal that is a video signal generated from a low-frequency nonlinear first color signal and a low-frequency nonlinear second color signal that are nonlinearly converted after extracting a low-frequency component from the signal, down-sampled, and two color difference signals; To convert the two color difference signals of the video signals into the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal. Means, band limiting means, down-sampling means, non-linear conversion means, and color signal generation means.

In such a configuration, the received signal conversion program converts the non-linear luminance signal into the linear luminance signal by giving the inverse characteristic of the non-linear conversion performed when the non-linear luminance signal is generated by the linear conversion means.
Then, the received signal conversion program extracts a low frequency component from the linear luminance signal by the band limiting unit, and down-samples the signal extracted by the band limiting unit at a predetermined sampling interval by the down-sampling unit. As a result, a signal (low frequency linear luminance signal) in which the low frequency component of the luminance signal is down-sampled is generated.

The received signal conversion program converts the low-frequency linear luminance signal into a low-frequency nonlinear luminance signal by non-linear conversion by the non-linear conversion means.
The received signal conversion program generates a low-frequency nonlinear first color signal and a low-frequency nonlinear second color signal from the low-frequency nonlinear luminance signal and the two color difference signals by the color signal generation means.

The present invention has the following excellent effects.
According to the first and second aspects of the present invention, luminance information (nonlinear luminance) capable of suppressing a decrease in the SN ratio due to compression / expansion of nonlinear transformation while performing constant luminance transmission satisfying the constant luminance principle. Signal) and two color signals (low-band nonlinear first color signal, low-band nonlinear second color signal) can be converted into a video signal composed of a luminance signal and two color difference signals. Thus, the first and second aspects of the invention can generate a video signal that can be used in a conventional digital encoding device or the like while exhibiting the effect of suppressing constant luminance transmission and a decrease in the SN ratio.

  According to the third and fourth aspects of the present invention, while performing constant luminance transmission that satisfies the constant luminance principle, two luminance signals and two luminance signals that can suppress a decrease in SN ratio due to compression / expansion of nonlinear transformation A video signal composed of a color difference signal can be converted into a video signal composed of luminance information (non-linear luminance signal) and two color signals (a low-frequency nonlinear first color signal and a low-frequency nonlinear second color signal). Thus, the inventions according to claims 3 and 4 can obtain the luminance from the video signal obtained by coding and decoding the video signal with a conventional digital encoding device or the like while exhibiting the effect of suppressing the constant luminance transmission and the decrease in the SN ratio. Information and two color signals can be generated.

It is a system configuration | structure figure which shows the structure of the video signal transmission system which concerns on embodiment of the reference example 1 of this invention. It is a block block diagram which shows the structure of the video signal transmission apparatus which concerns on embodiment of the reference example 1 of this invention. It is a block block diagram which shows the structure of the video signal receiver which concerns on embodiment of the reference example 1 of this invention. It is a flowchart which shows operation | movement of the video signal transmission apparatus which concerns on embodiment of the reference example 1 of this invention. It is a flowchart which shows operation | movement of the video signal receiver which concerns on embodiment of the reference example 1 of this invention. It is a block block diagram which shows the structure of the transmission signal converter which converts into the signal of YCC format from the signal of YBR format which the video signal transmitter which concerns on embodiment of the reference example 1 of this invention transmits. 6 shows a configuration of a reception signal conversion apparatus that converts a YCC format signal transmitted by the transmission signal conversion apparatus of FIG. 6 into a YBR format signal that can be received by the video signal reception apparatus according to the first embodiment of the present invention. It is a block block diagram. It is a system block diagram which shows the structure of the video signal transmission system which concerns on embodiment of the reference example 2 of this invention. It is a block block diagram which shows the structure of the video signal transmission apparatus which concerns on embodiment of the reference example 2 of this invention. It is a block block diagram which shows the structure of the video signal receiver which concerns on embodiment of the reference example 2 of this invention. It is a flowchart which shows operation | movement of the video signal transmission apparatus which concerns on embodiment of the reference example 2 of this invention. It is a flowchart which shows operation | movement of the video signal receiver which concerns on embodiment of the reference example 2 of this invention. It is a block block diagram which shows the structure of the transmission signal converter which converts the video signal which the video signal transmitter which concerns on embodiment of the reference example 2 of this invention transmits into the signal of a YCC format. FIG. 13 is a block diagram illustrating a configuration of a reception signal conversion apparatus that converts a YCC format signal transmitted by the transmission signal conversion apparatus of FIG. 13 into a YBR format signal that can be received by the video signal reception apparatus according to the first embodiment of the present invention. FIG. It is a figure for demonstrating the method (conventional method 1) which transmits the conventional video signal, Comprising: (a) is a block diagram which shows the structure of a transmitter, (b) is a receiver. It is a figure for demonstrating the method (conventional method 2) which transmits the conventional video signal, Comprising: (a) is a block diagram which shows the structure of a transmitter, (b) is a receiver.

Embodiments of the present invention will be described below with reference to the drawings.
[Embodiment of Reference Example 1: Configuration of Video Signal Transmission System]
First, the configuration of a video signal transmission system according to an embodiment of Reference Example 1 of the present invention will be described with reference to FIG.

The video signal transmission system S is a YBR component type transmission system that handles a digital video signal (hereinafter simply referred to as a video signal) with a luminance signal and two color signals.
This video signal transmission system S transmits a video signal via a transmission line N as shown in FIG. Here, the video signal transmission system S includes the video signal transmission device 1 on the side that transmits the video signal, and the video signal reception device 2 on the side that receives the video signal via the transmission path N.

The video signal transmission device 1 generates and transmits a video signal for transmission from an R (red) signal, a G (green) signal, and a B (blue) signal that are color signals of three primary colors.
The video signal transmitting apparatus 1 uses a RGB signal input from the camera C to obtain a luminance signal (Y ^α ) subjected to nonlinear compression / decompression and low frequency components (B _LD ^α , R _LD ^α ) of two color signals. It is generated and transmitted to the video signal receiving apparatus 2 via a transmission line N such as a cable or a communication line. Here, the video signal transmitting apparatus 1 inputs RGB signals from the camera C, but may be configured to input video signals from an apparatus that electronically generates video signals, such as a CG apparatus.

The video signal receiving device 2 receives a luminance signal and low frequency components of two color signals, generates an RGB signal from the signals, and outputs the RGB signal.
This video signal receiver 2 receives the luminance signal (Y ^α ) and the low frequency components (B _LD ^α , R _LD ^α ) of the two color signals from the video signal transmitter 1 via the transmission path N. And output to the display device D as RGB signals. The display device D may be configured to be provided inside the video signal receiving device 2.

Further, the RGB signals output from the video signal receiving device 2 may be transmitted again by the video signal transmission system after being processed by various video signal processing devices.
Hereinafter, configurations of the video signal transmitting device 1 and the video signal receiving device 2 according to the embodiment of the first reference example of the present invention will be described.

[Configuration of video signal transmitter]
First, referring to FIG. 2 (refer to FIG. 1 as appropriate), the configuration of the video signal transmitting apparatus 1 according to the embodiment of the reference example 1 of the present invention will be described. Here, the video signal transmission device 1 includes a luminance signal generation unit 10, a band limiting unit 11, a down-sampling unit 12, and a non-linear conversion unit 13. The video signal transmission device 1 also includes input means for inputting RGB signals, and output means for outputting the luminance signal and the low frequency components of the color signals to the video signal reception device 2 via the transmission line N. However, illustration is omitted here. Also, illustration of the delay means (delay circuit) for correcting the processing delay of each means is omitted here.

  The RGB signal input to the video signal transmitting apparatus 1 is a linear signal having a linear relationship between the signal level and the light intensity. In the case where the RGB signal is a non-linear signal subjected to gamma correction, the input RGB signal is further provided with linear conversion means (not shown) for converting it into a linear signal by inverse gamma characteristics.

  The luminance signal generation means 10 generates a luminance signal by mixing RGB signals, which are linear signals input via an input means (not shown), at a predetermined mixing ratio. The luminance signal generation means 10 generates a luminance signal (linear luminance signal) Y, which is a linear luminance signal, by a mixing equation shown in the following equation (2).

Here, r, g, and b are coefficients for generating a luminance signal. This coefficient may be based on a general standard for generating a luminance signal from an RGB signal. For example, in the case of an HDTV signal standard, r = 0.2126, g = 0.7152, and b = 0.0722. . Alternatively, although the luminance is not strictly expressed, these may be simplified so that r = 0.2, g = 0.7, b = 0.1, and the like.
The luminance signal generation unit 10 outputs the generated luminance signal Y to the non-linear conversion unit 13.

The band limiting unit 11 extracts a signal (B _L , R _L ) having a predetermined low frequency component from the B signal and the R signal input via the input unit (not shown). The band limiting unit 11 can be configured by a general low-pass filter.

  This low frequency component is determined in advance according to the degree of down sampling in the down sampling means 12 to be described later. For example, if the down sampling is halved, the low frequency component of the frequency component Half of the ingredients.

That is, for example, when the transmission format of the video signal is 4: 2: 2, the band limiting unit 11 can be configured by a horizontal one-dimensional filter, and among the horizontal frequency components, the low frequency side It is assumed that only a half band signal is passed. For example, when the transmission format of the video signal is 4: 2: 0 format, the band limiting unit 11 can be configured by a horizontal and vertical two-dimensional filter, and each of frequency components in the horizontal direction and the vertical direction. It is assumed that only the signal of the half band on the low frequency side is allowed to pass.
The band limiting unit 11 outputs the extracted signals (B _L , R _L ) to the downsampling unit 12.

The down-sampling unit 12 down-samples each signal (B _L , R _L ) extracted by the band limiting unit 11 at a predetermined sampling interval (down-sampling ratio).
This sampling interval is a predetermined interval according to the transmission format of the video signal. For example, when the video signal transmission format is 4: 2: 2, the down-sampling means 12 down-samples every other pixel in the horizontal direction. For example, when the video signal transmission format is 4: 2: 0, the down-sampling unit 12 down-samples the pixels every other pixel in both the horizontal direction and the vertical direction.

By changing the filter characteristics in the band limiting unit 11 and the downsampling ratio in the downsampling unit 12, a format other than the 4: 2: 2 format or 4: 2: 0 format, for example, the 3: 1: 1 format. It is possible to obtain a desired sample number ratio.
The downsampling unit 12 outputs the downsampled signals (B _LD , R _LD ) to the nonlinear conversion unit 13.

The non-linear conversion unit 13 converts each signal (B _LD , R _LD ) that is a linear signal down-sampled by the down-sampling unit 12 and the luminance signal Y that is a linear signal generated by the luminance signal generation unit 10 into a non-linear signal. To convert.
This non-linear transformation is a process (non-linear compression / decompression process) for expanding a signal in a region with a low signal level and compressing a signal in a region with a high signal level. In general, the nonlinear transformation can be expressed by the following equations (3) and (4).

Here, E is a linear signal before nonlinear transformation, E ′ is a nonlinear signal after nonlinear transformation, and α, a, b, c, and d are coefficients. It should be noted that a region where E is small may be given a linear characteristic with respect to E ′ = eE (e is a coefficient).
For example, in the HDTV signal standard, the conversion equation from the linear signal E to the nonlinear signal E ′ is defined as shown in the following equation (5).

The non-linear conversion means 13 may perform non-linear conversion using the equation (5).
Here, the above equation (3) is simplified so that a = 1, b = 0, and c = 0, so that E ^α (notation of power of α) is nonlinear after nonlinear transformation in the nonlinear transformation means 13. Signal notation.

That is, the nonlinear conversion means 13 converts the signal B _LD down-sampled by the down-sampling means 12 into a low-frequency nonlinear blue signal B _LD ^α, and converts the signal R _LD into a low-frequency nonlinear red signal R _LD ^α . Further, the non-linear conversion means 13 converts the luminance signal Y, which is a linear signal generated by the luminance signal generation means 10, into a non-linear luminance signal Y ^α by non-linear conversion.

The non-linear luminance signal Y ^α , the low-frequency non-linear blue signal B _LD ^α and the low-frequency non-linear red signal R _LD ^α converted by the non-linear conversion means 13 are video signals for transmission output to the outside.
In this way, the non-linear luminance signal Y ^α , the low-frequency non-linear blue signal B _LD ^α and the low-frequency non-linear red signal R _LD ^α converted by the non-linear conversion means 13 are output to the video signal receiving device 2 via the output means not shown. Sent to.

  The configuration of the video signal transmission device 1 according to the embodiment of the reference example 1 of the present invention has been described above, but the present invention is not limited to the form of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the video signal transmitting apparatus 1 is realized by software, a general computer equipped with a CPU and a memory (not shown) can be operated by a transmission video signal generation program that functions as the above-described units.

[Configuration of video signal receiver]
Next, referring to FIG. 3 (refer to FIG. 1 as appropriate), the configuration of the video signal receiving apparatus 2 according to the embodiment of Reference Example 1 of the present invention will be described. Here, the video signal receiving device 2 includes a linear conversion unit 20, a band limiting unit 21, a high frequency signal generating unit 22, an upsampling unit 23, a color signal generating unit 24, and a high frequency signal adding unit 25. It is equipped with. Note that the video signal receiving apparatus 2 receives an input means for inputting the luminance signal (Y ^α ) and the low frequency components (B _LD ^α , R _LD ^α ) of the color signal via the transmission line N, and RGB signals. Although an output means for outputting is also provided, the illustration is omitted here. Also, illustration of the delay means (delay circuit) for correcting the processing delay of each means is omitted here.

The linear conversion means 20 is transmitted from the video signal transmission apparatus 1 and inputted through the input means (not shown), and the luminance signal (nonlinear luminance signal Y ^α ) and the low frequency component of the color signal (low frequency nonlinear blue signal B). _LD ^α , low-frequency non-linear red signal R _LD ^α ) is given the inverse characteristic of non-linear transformation performed in the video signal transmitting apparatus 1, so that a linear luminance signal (Y) and a linear low-frequency component color signal (Low band linear blue signal B _LD , low band linear red signal R _LD ). The nonlinear luminance signal ^Yα is generated from the RGB signal which is a linear signal by the video signal transmitting apparatus 1 according to the equation (2) and then nonlinearly converted. By performing conversion based on the inverse characteristic of the nonlinear conversion, the (linear) luminance signal Y is correctly reproduced.
The linear converting means 20 outputs the converted linear luminance signal Y to the band limiting means 21 and the high frequency signal generating means 22. The linear conversion means 20 outputs the converted low-frequency linear blue signal B _LD and low-frequency linear red signal R _LD to the up-sampling means 23.

The band limiting unit 21 extracts a predetermined low frequency component (Y _L ) from the linear luminance signal Y converted by the linear conversion unit 20. The band limiting unit 21 extracts the same low frequency component as the band limiting unit 11 (see FIG. 2) of the video signal transmitting apparatus 1. The band limiting unit 21 outputs the extracted signal (low band linear luminance signal Y _L ) to the high band signal generating unit 22 and the color signal generating unit 24.

The high frequency signal generating means 22 extracts a high frequency component signal (high frequency luminance signal Y _H ) from the linear luminance signal Y converted by the linear conversion means 20. Here, the high frequency signal generating means 22 subtracts the low frequency linear luminance signal Y _L band-limited by the band limiting means 21 from the linear luminance signal Y, so that a high frequency signal component of the linear luminance signal Y is high. generating a frequency luminance signal _{Y H.}

The high frequency signal generating means 22 may be configured to extract a predetermined high frequency component from the linear luminance signal Y. In this case, the high-frequency signal generation means 22 can be configured by a general high-pass filter. The high frequency component is determined in advance as the remaining high frequency component of the low frequency component performed in the band limiting unit 21. When the high-frequency signal generating unit 22 is configured with a high-pass filter, the high-frequency signal generating unit 22 does not use the low-frequency linear luminance signal Y _L band-limited by the band limiting unit 21.
The high frequency signal generating means 22 outputs the generated high frequency luminance signal Y _H to the high frequency signal adding means 25.

The up-sampling means 23 converts the low-frequency linear blue signal B _LD and the low-frequency linear red signal R _LD that are the linear signals converted by the linear conversion means 20 into the same number of samples and pixel structure as the (linear) luminance signal Y. It is intended to upsample.

  For example, when the transmission format of the video signal transmitted from the video signal transmission device 1 is 4: 2: 2, the up-sampling unit 23 inserts a pixel for each pixel in the horizontal direction. When the transmission format of the video signal transmitted from the video signal transmission device 1 is 4: 2: 0 format, the up-sampling unit 23 inserts a pixel for each pixel in both the horizontal direction and the vertical direction. Here, the pixel is inserted by inserting a pixel having a pixel value obtained from an interpolation filter from adjacent pixels.

The up-sampling unit 23 outputs the up-sampled low-frequency linear blue signal B _L and low-frequency linear red signal R _L to the color signal generating unit 24 and the high-frequency signal adding unit 25.

The chrominance signal generation unit 24 generates a low-frequency signal from the low-frequency linear luminance signal Y _L band-limited by the band-limiting device 21, the low-frequency linear blue signal B _L and the low-frequency linear red signal R _L up-sampled by the up-sampling device 23. It generates a gamut green signal _GL . The color signal generation unit 24 generates a low-frequency linear green signal _{GL according} to the following equation (6).

Here, r, g, and b are the same as the coefficients used in the equation (2) in the luminance signal generating means 10 (see FIG. 2) of the video signal transmitting apparatus 1.
The color signal generation unit 24 outputs the generated low frequency linear green signal _GL to the high frequency signal addition unit 25.

High band signal adding means 25, and the low frequency linear blue signal B _L and a low linear red R _L which is upsampled in upsampling unit 23, into a low-frequency linear green signal G _L generated by the color signal generator 24, by adding the high-frequency luminance signal Y _H generated by each high frequency signal generator 22, and generates an RGB signal. That is, the high frequency signal adding means 25 generates an RGB signal by the following equation (7).

As described above, the high-frequency signal adding means 25 includes the low-frequency component signal (R _L , G _L , B _L ) of the RGB signal band-limited and the high-frequency component signal (Y _H ) of the luminance signal. From this, an RGB signal can be generated.

  The configuration of the video signal receiving apparatus 2 according to the embodiment of Reference Example 1 of the present invention has been described above, but the present invention is not limited to the form of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the video signal receiving apparatus 2 is realized by software, a general computer equipped with a CPU and a memory (not shown) can be operated by the transmission video signal conversion program that functions as the above-described units.

[Embodiment of Reference Example 1: Operation of Video Signal Transmission System]
Next, the operation of the video signal transmission system S according to the embodiment of the first reference example of the present invention will be described. In the following, the operation of the video signal transmitting apparatus 1 and the operation of the video signal receiving apparatus 2 will be described sequentially.

[Operation of video signal transmitter]
First, the operation of the video signal transmitting apparatus 1 will be described with reference to FIG. 4 (refer to FIGS. 1 and 2 as appropriate).

First, the video signal transmitting apparatus 1 inputs a video signal from the outside by an input unit (not shown) (step S1). This video signal is a three-primary color signal (RGB signal) which is a linear signal.
Then, the video signal transmission apparatus 1 generates the luminance signal Y by mixing the RGB signals input in step S1 at a predetermined mixing ratio by the luminance signal generation means 10 (step S2). Specifically, the luminance signal generation unit 10 generates the luminance signal Y by the above equation (2).

Then, the video signal transmitting apparatus 1 extracts a predetermined low frequency component (B _L , R _L ) from the B signal and the R signal input in step S1 by the band limiting unit 11 (step S3).
Further, the video signal transmitting apparatus 1 uses the down-sampling means 12 to convert each signal (B _L , R _L ) extracted in step S3 according to the transmission format (4: 2: 2 format, 4: 2: 0 format, etc.). A signal (B _LD , R _LD ) downsampled at a predetermined sampling interval (downsample ratio) is generated (step S4).

Then, the video signal transmitting apparatus 1 uses the nonlinear conversion means 13 to nonlinearly convert the low frequency component signal (B _LD , R _LD ) generated in step S4 and the luminance signal Y generated in step S2 by nonlinear conversion. It converts into a signal (step S5). That is, the non-linear conversion means 13 converts the luminance signal Y into a non-linear luminance signal Y ^α , converts the low frequency linear blue signal B _LD into a low frequency non-linear blue signal B _LD ^α, and converts the low frequency linear red signal R _LD into a low frequency non-linearity. Convert to red signal R _LD ^α .

Thereafter, the video signal transmitting apparatus 1 transmits the non-linear luminance signal Y ^α , the low-frequency non-linear blue signal B _LD ^α, and the low-frequency non-linear red signal R _LD ^α converted in step S5 by the output unit (not shown). As a video signal for use, the video signal is output to the video signal receiver 2 via the transmission line N (step S6).
Through the above operation, the video signal transmitting apparatus 1 converts the luminance signal (non-linear luminance signal Y ^α ) and the color signal (low-frequency nonlinear blue signal B _LD ^α , low-frequency nonlinear red signal R _LD ^α ) into the video signal receiving device. 2 can be transmitted.

[Operation of video signal receiver]
Next, the operation of the video signal receiving device 2 will be described with reference to FIG.

First, the video signal receiving device 2 transmits a luminance signal (nonlinear luminance signal Y ^α ) and a color signal, which are video signals for transmission, from the video signal transmitting device 1 via the transmission path N by an input unit (not shown). (Low-frequency nonlinear blue signal B _LD ^α , Low-frequency nonlinear red signal R _LD ^α ) is input (step S10).
Then, the video signal receiving apparatus 2 gives the inverse characteristic of the nonlinear conversion to the nonlinear luminance signal Y ^α , the low-frequency nonlinear blue signal B _LD ^α and the low-frequency nonlinear red signal R _LD ^α input in step S10 by the linear conversion means 20. Thus, each signal is converted into a linear luminance signal Y, a low-frequency linear blue signal B _LD , and a low-frequency linear red signal R _LD (step S11).

Then, the video signal receiving apparatus 2 extracts the low frequency component (Y _L ) from the linear luminance signal Y converted in step S11 by the band limiting unit 21 (step S12).

The video signal receiving device 2, the high frequency signal generating unit 22, a linear luminance signal Y converted in step S11, by subtracting the low frequency linear luminance signal Y _L extracted in step S12, the luminance signal high generating a high-frequency luminance signal _{Y H,} which is the frequency component (step S13).

Further, the video signal receiving apparatus 2 uses the up-sampling means 23 to convert the low-frequency linear blue signal B _LD and the low-frequency linear red signal R _LD converted in step S11 into the same number of samples and pixel structure as the (linear) luminance signal Y. Up-sampling is performed as follows (step S14).

The video signal receiving device 2, by the color signal generator 24, low-frequency linear luminance signal band-limited in Step S12 Y _L and the low frequency linear blue signal B _L and low linear red R which upsample in step S14 _A low-pass linear green signal _GL is generated from _L (step S15). Specifically, the color signal generation unit 24 generates the low-pass linear green signal _{GL according} to the equation (6).

The video signal receiving device 2, the high frequency signal adding means 25, and the low frequency linear blue signal B _L and a low linear red R _L which is upsampled at step S14, the low-frequency linear green signal G generated in step S15 in the _L, by adding the high-frequency luminance signal _{Y H} generated at the step S13, and generates an RGB signal (step S16).

Thereafter, the video signal receiving apparatus 2 outputs the RGB signal (video signal) generated in step S16 by output means (not shown) (step S17).
Through the above-described operation, the video signal receiving device 2 has the luminance signal (non-linear luminance signal Y ^α ) and color signal (low-frequency non-linear blue signal B _LD ^α , low-frequency non-linear red signal R _LD ^α ) output from the video signal transmitting device 1. ), A video signal of three primary color signals (RGB signals) can be generated.

[Comparison of color reproduction errors]
Next, a video signal transmission method by the video signal transmission system S (video signal transmission device 1 and video signal reception device 2) according to the embodiment of Reference Example 1 of the present invention and a video signal transmission method by a conventional method are described. A performance comparison will be described.
Here, all combinations of 8-bit nonlinear R, G, and B signals using an index ΔE _ab ^* that indicates a color error in the L ^* a ^* b ^* uniform color space, which is a general color reproduction evaluation method. The reproduced color error ΔE _ab ^* was collected. The conventional method is the conventional method 2 shown in FIG.

As shown in this table, the average value and the maximum value of the color error ΔE _ab ^* are small in the method of the present invention, and the method of the present invention greatly improves the color reproduction error compared to the conventional method. I understand that
As described above, the present invention can suppress a decrease in the SN ratio while enabling constant luminance transmission.

  The configuration and operation of the video signal transmission system according to the embodiment of the reference example 1 have been described above. The embodiment of the reference example 1 is a YBR component type transmission system that handles a luminance signal and two color signals. However, in a digital compression encoding apparatus that compresses and encodes a video signal, the luminance signal and the color difference signal There is one that compresses and encodes a video signal using.

  Therefore, here, the transmission signal conversion that converts the video signal transmitted by the video signal transmission device 1 of the video signal transmission system according to the embodiment of the reference example 1 into a YCC format video signal including a luminance signal and two color difference signals. An apparatus and a reception signal conversion apparatus that converts a YCC format video signal converted by the transmission signal conversion apparatus into a YBR format video signal that is received by the video signal reception apparatus 2 will be described.

[Configuration of transmission signal converter]
First, the configuration of the transmission signal conversion apparatus 3 according to the embodiment of the present invention will be described with reference to FIG. Here, the transmission signal conversion device 3 includes a linear conversion unit 30, a band limiting unit 31, a downsampling unit 32, a non-linear conversion unit 33, and a color difference signal generation unit 34. The transmission signal conversion device 3 includes input means for inputting the luminance signal and color signal generated in the video signal transmission device 1 and output means for outputting the luminance signal and the color difference signal to the outside. Omitted. Also, illustration of the delay means (delay circuit) for correcting the processing delay of each means is omitted here.

The linear conversion unit 30 gives a luminance signal (non-linear luminance signal Y ^α ) input via an input unit (not shown) to the inverse characteristic of the non-linear conversion performed in the video signal transmission device 1, thereby obtaining a linear luminance signal ( The signal is converted into a linear luminance signal Y).
The linear conversion unit 30 outputs the converted linear luminance signal Y to the band limiting unit 31.

The band limiting unit 31 extracts a predetermined low frequency component (Y _L ) from the linear luminance signal Y converted by the linear conversion unit 30. The band limiting unit 31 extracts the same low frequency component as the band limiting unit 11 (see FIG. 2) of the video signal transmitting apparatus 1. The band limiting unit 31 outputs the extracted signal (low band linear luminance signal Y _L ) to the downsampling unit 32.

Down-sampling means 32 is for down-sampled low frequency linear luminance signal Y _L predetermined sampling interval extracted by the band limiting means 31 (downsampling ratio). The downsampling unit 32 performs downsampling at the same sampling interval (downsampling ratio) as the downsampling unit 12 (see FIG. 2) of the video signal transmitting apparatus 1.
The downsampling unit 32 outputs the downsampled low frequency linear luminance signal Y _LD to the non-linear conversion unit 33.

The nonlinear conversion means 33 converts the low-frequency linear luminance signal Y _LD that is the linear signal down-sampled by the down-sampling means 32 into a nonlinear signal (low-frequency nonlinear luminance signal Y _LD ^α ). The nonlinear conversion means 33 performs the same conversion as the nonlinear conversion performed in the nonlinear conversion means 13 (see FIG. 2) of the video signal transmission apparatus 1.
The nonlinear conversion means 33 outputs the converted low-frequency nonlinear luminance signal Y _LD ^α to the color difference signal generation means 34.

The chrominance signal generation means 34 is a low-frequency nonlinear luminance signal Y _LD ^α converted by the nonlinear conversion means 33, a low-frequency nonlinear blue signal B _LD ^α and a low-frequency nonlinear red signal R _LD input via an input means (not shown). Two color difference signals are generated from ^α by mixing these signals at a predetermined mixing ratio. The two color difference signals are often expressed by a difference signal between a blue signal and a luminance signal and a difference signal between a red signal and a luminance signal. In this case, the color difference signal generation means 34 is represented by the following equation (8). The difference signal between the low-frequency nonlinear blue signal B _LD ^α and the low-frequency nonlinear luminance signal Y _LD ^α is the color difference signal Cb _LD ^α , and the difference between the low-frequency nonlinear red signal R _LD ^α and the low-frequency nonlinear luminance signal Y _LD ^α. The signal is a color difference signal Cr _LD ^α .

Note that the color difference signal generation unit 34 may divide by a predetermined coefficient so that the dynamic range of the color difference signal is the same as the dynamic range of the luminance signal.
That is, the color difference signal generation means 34 divides the difference signal between the low-frequency nonlinear blue signal B _LD ^α and the low-frequency nonlinear luminance signal Y _LD ^α by the coefficient kcb as shown in the following equation (9). and cb _LD ^alpha, and the color difference signals _{Cr LD} ^alpha by dividing the difference signal and the low frequency non-linear red signal _{R LD} ^alpha and low nonlinear luminance signal _{Y LD} ^alpha by a factor kcr. The coefficients kcb and kcr are coefficients for making the dynamic range of the color difference signal the same as the dynamic range of the luminance signal. However, the values may be simplified to be “2”.

The color difference signals Cb _LD ^α and Cr _LD ^α generated by the color difference signal generation unit 34 are output to the outside through an output unit (not shown). Incidentally, the luminance signal output means (not shown) directly outputs a nonlinear luminance signal Y ^alpha input via the input means (not shown).
Thus, the transmission signal conversion device 3 can convert the video signal generated in the video signal transmission device 1 into a YCC format video signal of a luminance signal and two color difference signals.

  The configuration of the transmission signal conversion device 3 according to the embodiment of the present invention has been described above, but the present invention is not limited to the format of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the transmission signal conversion device 3 is realized by software, a general computer having a CPU and a memory (not shown) can be operated by the transmission signal conversion program that functions as the above-described units.

Here, the transmission signal conversion device 3 is configured as a device separate from the video signal transmission device 1 as a device that converts the video signal output from the video signal transmission device 1 (see FIG. 2). The transmission signal conversion device 3 may be configured by being incorporated in the video signal transmission device 1.
In this case, the transmission signal conversion device 3 may be disposed after the nonlinear conversion means 13 of the video signal transmission device 1. The linear conversion means 30 receives the non-linear luminance signal Y ^α from the non-linear conversion means 13, and the color difference signal generation means 34 receives the low-frequency non-linear blue signal B _LD ^α and the low-frequency non-linear red signal R _LD ^α from the non-linear conversion means 13. Enter.
As a result, the video signal transmission device 1 can be configured as a device that transmits a video signal in the YCC format.

[Configuration of received signal converter]
Next, the configuration of the received signal conversion apparatus 4 according to the embodiment of the present invention will be described with reference to FIG. Here, the received signal conversion apparatus 4 includes a linear conversion unit 30, a band limiting unit 31, a down-sampling unit 32, a non-linear conversion unit 33, and a color signal generation unit 40.
Since the configuration other than the color signal generation unit 40 is the same as that of the transmission signal conversion device 3 described with reference to FIG. 6, the same reference numerals are given and description thereof is omitted.

The color signal generation means 40 is a color signal obtained from the low-frequency nonlinear luminance signal Y _LD ^α converted by the nonlinear conversion means 33 and the color difference signals Cb _LD ^α and Cr _LD ^α input via the input means (not shown). A low-frequency nonlinear blue signal B _LD ^α and a low-frequency nonlinear red signal R _LD ^α are generated. The generation of the color signal corresponds to the inverse conversion of the color difference signal generation.

When the color difference signal generation unit 34 (see FIG. 6) calculates the color difference signals Cb _LD ^α and Cr _LD ^{α according} to the above equation (8), the color signal generation unit 40 is reduced by the following equation (10). A non-linear blue signal B _LD ^α and a low-frequency non-linear red signal R _LD ^α are generated.

Further, when the color signal generation unit 40 calculates the color difference signals Cb _LD ^α and Cr _LD ^{α according} to the equation (9) in the color difference signal generation unit 34 (see FIG. 6), the following equation (11) A low-frequency nonlinear blue signal B _LD ^α and a low-frequency nonlinear red signal R _LD ^α are generated.

It should be noted that the color difference signal generation means 34 (see FIG. 6) generates a color difference signal at what mixing ratio, for example, whether the color difference signals Cb _LD ^α and Cr _LD ^α are generated by the equation (8), Whether the color difference signals Cb _LD ^α and Cr _LD ^α are generated by the equation (9) is assumed to be known in the reception signal conversion device 4.
The low-frequency nonlinear blue signal B _LD ^α and the low-frequency nonlinear red signal R _LD ^α generated by the color signal generating means 40 are output to the outside through output means (not shown). Incidentally, the luminance signal output means (not shown) directly outputs a nonlinear luminance signal Y ^alpha input via the input means (not shown).

  In this manner, the reception signal conversion device 4 converts the YCC format video signal of the luminance signal and the two color difference signals generated by the transmission signal conversion device 3 into the YBR format video signal of the luminance signal and the two color signals. Can be converted to This video signal can be used as an input signal to the video signal receiving device 2 (see FIG. 3).

  The configuration of the received signal conversion apparatus 4 according to the embodiment of the present invention has been described above, but the present invention is not limited to the format of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the reception signal conversion device 4 is realized by software, a general computer having a CPU and a memory (not shown) can be operated by the reception signal conversion program that functions as the above-described units.

In addition, here, the reception signal conversion device 4 is configured to output the converted video signal to the video signal reception device 2 (see FIG. 3), and is configured as a separate device from the video signal reception device 2, The reception signal conversion device 4 may be configured to be incorporated in the video signal reception device 2.
In this case, the reception signal conversion device 4 may be arranged in the preceding stage of the linear conversion means 20 of the video signal reception device 2. Then, the input means (not shown) outputs the input nonlinear luminance signal Y ^α to the linear conversion means 20, and the color signal generation means 40 outputs the low-frequency nonlinear blue signal B _LD ^α and the low-frequency nonlinear red signal R _LD ^α . Output to the linear conversion means 20.
Accordingly, the video signal receiving device 2 can be configured as a device that receives a YCC format video signal.

[Embodiment of Reference Example 2: Configuration of Video Signal Transmission System]
Next, the configuration of the video signal transmission system according to the embodiment of the reference example 2 of the present invention will be described with reference to FIG.

Video signal transmission system S _B as a digital video signal (video signal), the color signals of RGB to the low frequency components has been band-limited, adding high frequency components of the luminance signal into one of the color signals Transmission system.
The video signal transmission system S _B, as shown in FIG. 8, for transmitting a video signal through the transmission path N. Here, the video signal transmission system S _B is provided with a video signal transmission apparatus 1B on the side of transmitting the video signal includes a video signal receiving apparatus 2B on the side that receives the video signal via the transmission path N.

The video signal transmitting apparatus 1B generates and transmits a video signal for transmission from an R (red) signal, a G (green) signal, and a B (blue) signal, which are three primary color signals.
This video signal transmission device 1B adds a high frequency component of a luminance signal to any one of the low frequency components (here, a G signal component) of each color signal of the RGB signal input from the camera C, The data is transmitted to the video signal receiving device 2 via a transmission line N such as a communication line. Here, the video signal transmission apparatus 1B receives RGB signals from the camera C, but, like the video signal transmission system S (see FIG. 1), an apparatus that electronically generates a video signal such as a CG apparatus. It may be configured to input from.

The video signal receiving device 2B receives a signal in which a high frequency component of a luminance signal is added to one of the low frequency components of each color signal of an RGB signal, and generates and outputs an RGB signal from the signal. .
This video signal receiving device 2B receives a signal in which the high frequency component of the luminance signal is added to one of the low frequency components of the color signal from the video signal transmitting device 1B via the transmission line N, and RGB It outputs to the display apparatus D as a signal. The display device D may be configured to be provided inside the video signal receiving device 2B.

Further, in the video signal transmission system S _B, it is assumed that the addition of high-frequency component of the luminance signal to the low frequency components of the G signal, the high-frequency component of the luminance signal is added to which color signals It is good as well.
Hereinafter, configurations of the video signal transmission device 1B and the video signal reception device 2B according to the embodiment of the reference example 2 of the present invention will be described.

[Configuration of video signal transmitter]
First, referring to FIG. 9 (refer to FIG. 2 and FIG. 8 as appropriate), the configuration of the video signal transmitting apparatus 1B according to the embodiment of the reference example 2 of the present invention will be described. Here, the video signal transmitting apparatus 1B includes a luminance signal generating unit 10, a band limiting unit 11B, a downsampling unit 12, a non-linear conversion unit 13B, a high frequency signal generating unit 14, and a high frequency signal adding unit 15. It is equipped with.
The configurations other than the band limiting unit 11B, the non-linear conversion unit 13B, the high frequency signal generating unit 14, and the high frequency signal adding unit 15 are the same as those of the video signal transmitting apparatus 1 described in FIG. The description is abbreviate | omitted and attached | subjected.

The video signal transmitting apparatus 1B outputs RGB signals to the video signal receiving apparatus 2B via the transmission line N, and the high frequency component of the luminance signal and the low frequency component of the color signal are output. Output means is also provided, but the illustration is omitted here. Also, illustration of the delay means (delay circuit) for correcting the processing delay of each means is omitted here.
In addition, the RGB signal input to the video signal transmission device 1B is a linear signal as in the video signal transmission device 1.

The band limiting unit 11B extracts predetermined low frequency component signals (G _L , B _L , R _L ) from the G signal, B signal, and R signal input via the input unit (not shown). To do. Note that the processing content of the band limiting in the band limiting unit 11B is the same as that of the band limiting unit 11 described with reference to FIG.
The band limiting unit 11B outputs the extracted signal (low-frequency linear green signal G _L ) to the high-frequency signal adding unit 15, and extracts the extracted signals (low-frequency linear blue signal B _L , low-frequency linear red signal R _L ). Output to the down-sampling means 12.

The high frequency signal generation unit 14 extracts a high frequency component signal (high frequency luminance signal Y _H ) from the linear luminance signal Y generated by the luminance signal generation unit 10. Here, the high-frequency signal generating unit 14 includes a band limiting unit 141 and a subtracting unit 142.

The band limiting unit 141 extracts a signal (Y _L ) of a predetermined low frequency component from the luminance signal Y generated by the luminance signal generating unit 10. Note that the processing content of the band limiting in the band limiting unit 141 is the same as that of the band limiting unit 11 described with reference to FIG. The band limiting unit 141 outputs the extracted signal (low band linear luminance signal Y _L ) to the subtracting unit 142.

The subtracting unit 142 subtracts the low frequency linear luminance signal Y _L band-limited by the band limiting unit 141 from the luminance signal Y generated by the luminance signal generating unit 10, thereby obtaining a high frequency that is a high frequency component of the luminance signal. and it generates a luminance signal Y _H. The subtracting unit 142 outputs the generated high frequency luminance signal Y _H to the high frequency signal adding unit 15.

Note that the high frequency signal generation means 14 may be configured to extract a predetermined high frequency component from the linear luminance signal Y. In this case, the high-frequency signal generation means 14 can be configured by a general high-pass filter. This high frequency component is determined in advance as the remaining high frequency component of the low frequency component performed in the band limiting unit 11B. In the case of constituting a high-frequency signal generating means 14 by the high-pass filter, band limiting device 11B does not need to generate a low-frequency linear luminance signal Y _L.
The high frequency signal generation unit 14 outputs the generated high frequency luminance signal Y _H to the high frequency signal addition unit 15.

High frequency signal adding means 15 is for adding the high-band luminance signal Y _H generated by the high frequency signal generator 14, the low-frequency linear green signal G _L that is band-limited by band limiting device 11B. In the linear signal (luminance-added green signal) generated by the high-frequency signal adding means 15, the high-frequency component is the high-frequency component of the luminance signal Y, and the low-frequency component is the low-frequency component of the G signal. It becomes a frequency component.
The high-frequency signal adding unit 15 outputs the generated luminance addition green signal (G _L + Y _H ) to the non-linear conversion unit 13B.

The non-linear conversion means 13B is a signal (B _LD , R _LD ) that is a linear signal down-sampled by the down-sampling means 12 and a luminance addition green signal (G _L + Y) that is a linear signal generated by the high-frequency signal addition means 15. _H ) is converted into a nonlinear signal.
That is, the nonlinear conversion means 13B converts the signal B _LD down-sampled by the down-sampling means 12 into a low-frequency nonlinear blue signal B _LD ^α, and converts the signal R _LD into a low-frequency nonlinear red signal R _LD ^α . Further, the non-linear conversion unit 13B converts the luminance addition green signal (G _L + Y _H ) generated by the high frequency signal addition unit 15 into a non-linear luminance addition green signal (G _L + Y _H ) ^α by performing non-linear conversion. The processing content of the nonlinear conversion in the nonlinear conversion means 13B is the same as that of the nonlinear conversion means 13 described with reference to FIG.
The non-linear luminance addition green signal ( _GL + Y _H ) ^α , the low-frequency non-linear blue signal B _LD ^α, and the low-frequency non-linear red signal R _LD ^α converted by the non-linear conversion means 13B become a transmission video signal output to the outside. .
Thus, non-linear luminance addition green signal converted by the nonlinear conversion unit _{13B (G L + Y H)} α, the low-frequency nonlinear blue signal _{B LD} ^alpha and low nonlinear red _{R LD} ^alpha, via an output means which is not shown And transmitted to the video signal receiving device 2B.

  The configuration of the video signal transmission device 1B according to the embodiment of the reference example 2 of the present invention has been described above, but the present invention is not limited to the form of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the video signal transmitting apparatus 1B is realized by software, a general computer equipped with a CPU and a memory (not shown) can be operated by a transmission video signal generation program that functions as the above-described units.

[Configuration of video signal receiver]
Next, the configuration of the video signal receiving device 2B according to the embodiment of the reference example 2 of the present invention will be described with reference to FIG. Here, the video signal receiving device 2B includes linear conversion means 20B, high-frequency signal generation means 22B, up-sampling means 23, and high-frequency signal addition means 25B.
The components other than the linear conversion unit 20B, the high-frequency signal generating unit 22B, and the high-frequency signal adding unit 25B are the same as those of the video signal receiving device 2 described with reference to FIG. The description is omitted.

The video signal receiving apparatus 2B, via the transmission path N, the non-linear luminance addition green signal ^{_{(G L + Y H) α}} , low frequency non-linear blue signal _{B LD} ^alpha and the low nonlinear red input means for inputting _{R LD} ^alpha In addition, although an output means for outputting RGB signals is also provided, the illustration is omitted here. Also, illustration of the delay means (delay circuit) for correcting the processing delay of each means is omitted here.

Linear transformation means 20B is transmitted from the video signal transmission apparatus 1B, the non-linear luminance addition green signal input via the input means (not _{shown) (G L + Y H)} α, low frequency non-linear blue signal B _LD ^alpha and low nonlinear the red signal R _LD ^alpha, by providing an inverse characteristic of the nonlinear conversion performed in the video signal transmission apparatus 1B, linear signal (linear luminance addition green signal (G L _{+ Y H),} the low-pass linear blue signal B _LD and a low linear Red signal R _LD ).
The linear conversion means 20B outputs the converted linear luminance addition green signal (G _L + Y _H ) to the output means (not shown) as a G signal and also outputs it to the high frequency signal generation means 22B. The linear conversion means 20B outputs the converted low-frequency linear blue signal B _LD and low-frequency linear red signal R _LD to the up-sampling means 23.

The high-frequency signal generation unit 22B extracts a high-frequency component signal (high-frequency luminance signal Y _H ) from the linear luminance addition green signal (G _L + Y _H ) converted by the linear conversion unit 20B. Here, the high frequency signal generating means 22B includes a band limiting means 221 and a subtracting means 222.
The band limiting unit 221 extracts a predetermined low frequency component (G _L ) from the linear luminance addition green signal (G _L + Y _H ) converted by the linear conversion unit 20B. Note that the band limiting unit 221 extracts the same low frequency component as the band limiting unit 11B (see FIG. 9) of the video signal transmitting apparatus 1B. The band limiting unit 221 outputs the extracted signal (low band linear green signal G _L ) to the subtracting unit 222.
The subtracting means 222 subtracts the low-frequency linear green signal _GL band-limited by the band-limiting means 221 from the linear luminance-added green signal (G _L + Y _H ) converted by the linear converting means 20B, thereby increasing the luminance signal high. to thereby generate a high-frequency luminance signal Y _H, which is the frequency component. The subtraction unit 222 outputs the generated high-frequency luminance signal Y _H in the high band signal addition means 25B.

Incidentally, the high-frequency signal generating means 22B from the linear luminance addition green signal (G L _{+ Y H),} it may be constructed as to extract a high frequency component determined in advance. In this case, the high-frequency signal generating means 22B can be configured by a general high-pass filter. This high frequency component is determined in advance as the remaining high frequency component of the low frequency component performed in the band limiting unit 221.
The high frequency signal generating unit 22B outputs the generated high frequency luminance signal Y _H to the high frequency signal adding unit 25.
As a result, the high frequency signal adding means 25 adds the high frequency luminance signal Y _H to the low frequency linear blue signal B _L and the low frequency linear red signal R _L , thereby generating an RB signal.

  The configuration of the video signal receiving device 2B according to the embodiment of the reference example 2 of the present invention has been described above, but the present invention is not limited to the form of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the video signal receiving device 2B is realized by software, a general computer equipped with a CPU and a memory (not shown) can be operated by the transmission video signal conversion program that functions as the above-described units.

[Embodiment of Reference Example 2: Operation of Video Signal Transmission System]
Next, the operation of the video signal transmission system S _B according to the embodiment of Example 2 of the present invention. In the following, the operation of the video signal transmitting apparatus 1B and the operation of the video signal receiving apparatus 2B will be described sequentially.

[Operation of video signal transmitter]
First, the operation of the video signal transmitting apparatus 1B will be described with reference to FIG. 11 (refer to FIGS. 8 and 9 as appropriate).

First, the video signal transmitting apparatus 1B inputs a video signal from the outside by an input unit (not shown) (step S20). This video signal is a three-primary color signal (RGB signal) which is a linear signal.
Then, the video signal transmitting apparatus 1B generates the luminance signal Y by mixing the RGB signals input in step S20 at a predetermined mixing ratio by the luminance signal generating means 10 (step S2). Specifically, the luminance signal generation unit 10 generates the luminance signal Y by the above equation (2).

Then, the video signal transmitting apparatus 1B extracts a predetermined low frequency component (G _L , B _L , R _L ) from the G signal, B signal, and R signal input in step S20 by the band limiting unit 11B. (Step S22).
The video signal transmission apparatus 1B, the high frequency signal generating unit 14, a luminance signal Y generated in step S21, to produce a high frequency luminance signal Y _H, which is a high-frequency component of the luminance signal Y (step S23) .

Further, the video signal transmitting apparatus 1B uses the down-sampling means 12 in advance from the signal (B _L , R _L ) extracted in step S22 in the transmission format (4: 2: 2 format, 4: 2: 0 format, etc.) A signal (B _LD , R _LD ) down-sampled at a predetermined sampling interval (down-sampling ratio) is generated (step S24).
The video signal transmission apparatus 1B, the high frequency signal adding means 15, to the low frequency linear green signal G _L extracted in step S22, by adding the high-frequency luminance signal Y _H generated at the step S23, linear signal A luminance added green signal (G _L + Y _H ) is generated (step S25).

Then, the video signal transmitting apparatus 1B uses the nonlinear conversion unit 13B to generate the luminance-added green signal (G _L + Y _H ) generated in step S25 and the low-frequency component signal (B _LD , R _LD ) down-sampled in step S24. ) Is converted into a non-linear signal by non-linear conversion (step S26). That is, the nonlinear conversion means 13B converts the luminance added green signal (G _L + Y _H ) into a nonlinear luminance added green signal (G _L + Y _H ) ^α, and converts the low frequency linear blue signal B _LD to the low frequency nonlinear blue signal B _LD ^α . The low-frequency linear red signal R _LD is converted into a low-frequency nonlinear red signal R _LD ^α .

Thereafter, the video signal transmitting apparatus 1B uses the output means (not shown) to output the non-linear luminance addition green signal (G _L + Y _H ) ^α converted in step S26, the low-frequency non-linear blue signal B _LD ^α, and the low-frequency non-linear red signal. R _LD ^α is output as a transmission video signal to the video signal receiving device 2B via the transmission line N (step S27).
Through the above operation, the video signal transmitting apparatus 1B can add the high frequency component of the luminance signal to one of the color signals of the low frequency component and transmit it to the video signal receiving apparatus 2.

[Operation of video signal receiver]
Next, the operation of the video signal receiving apparatus 2 will be described with reference to FIG. 12 (refer to FIGS. 8 and 10 as appropriate).

First, the video signal receiving device 2B is connected to the non-linear luminance addition green signal (G _L + Y _H ) ^α that is a video signal for transmission from the video signal transmitting device 1B via the transmission path N by input means (not shown). Then, the low-frequency nonlinear blue signal B _LD ^α and the low-frequency nonlinear red signal R _LD ^α are input (step S30).

The video signal receiving apparatus 2B, the linear transformation unit 20B, the non-linear luminance addition green signal _(G L _{+ Y} H) input in step S30 ^alpha, low-pass linear blue signal _{B LD} ^alpha and low nonlinear red _{R LD} ^alpha by providing an inverse characteristic of the nonlinear conversion, the signals, respectively linear luminance addition green signal _(G L _{+ Y} H), converted to the low frequency linear blue signal _{B LD} and a low linear red _{R LD} (step S31). This linear luminance addition green signal (G _L + Y _H ) is an output G signal.

Then, the video signal receiving device 2B uses the high frequency signal generation unit 22B to convert the high frequency luminance signal Y _H that is a high frequency component of the luminance signal from the linear luminance addition green signal (G _L + Y _H ) converted in step S31. Is generated (step S32).

In addition, the video signal receiving device 2B uses the up-sampling unit 23 to increase the low-frequency linear blue signal B _LD and the low-frequency linear red signal R _LD converted in step S31 so that the same number of samples and pixel structure as the luminance signal are obtained. Sample (step S33).

The video signal receiving apparatus 2B, the high frequency signal adding means 25B, the low-pass linear blue signal B _L and a low linear red R _L which is upsampled at step S33, the high frequency luminance signal Y _H generated at the step S32 Is added to generate an RB signal (step S34).

Thereafter, the video signal receiving device 2B outputs the G signal generated in step S31 and the RB signal generated in step S34 as video signals by output means (not shown) (step S35).
Through the above-described operation, the video signal receiving device 2B causes the non-linear luminance addition green signal (G _L + Y _H ) ^α output from the video signal transmitting device 1B, the low-frequency nonlinear blue signal B _LD ^α, and the low-frequency nonlinear red signal R. A video signal of the three primary color signals (RGB signals) can be generated from the _LD ^α .

The configuration and operation of the video signal transmission system according to the embodiment of the reference example 2 have been described above. Embodiment of this reference example 2 is a system for transmitting the non-linear luminance addition green signal ^{_{(G L + Y H) α}} , and the low frequency non-linear blue signal B _LD ^alpha, the low-frequency nonlinear red signal R _LD ^alpha as the color signals However, as described above, there are digital compression encoding devices that compress and encode a video signal and the like that compress and encode a video signal using a luminance signal and a color difference signal.

  Therefore, here, the transmission signal conversion for converting the video signal transmitted by the video signal transmission device 1B of the video signal transmission system according to the embodiment of the reference example 2 into a YCC format video signal including a luminance signal and two color difference signals. A device and a reception signal conversion device that converts a video signal in YCC format converted by the transmission signal conversion device into a video signal for reception by the video signal reception device 2B will be described.

[Configuration of transmission signal converter]
First, the configuration of the transmission signal conversion device 3B according to the embodiment of the present invention will be described with reference to FIG. Here, the transmission signal conversion device 3B includes a linear conversion unit 50, a band limiting unit 51, a high-frequency signal generation unit 52, a down-sampling unit 53, a non-linear conversion unit 54, a luminance color difference signal generation unit 55, A linear conversion unit 56, an upsampling unit 57, a high-frequency signal addition unit 58, and a non-linear conversion unit 59 are provided. The transmission signal conversion apparatus 3B, the chrominance signal (the nonlinear luminance addition green signal _(G L _{+ Y} H generated in the video signal transmitter 1B) ^alpha, low-frequency nonlinear blue signal _{B LD} ^alpha and low nonlinear red _{R LD} ^alpha ) And output means for outputting the luminance signal and the color difference signal to the outside, but are not shown here. Also, illustration of the delay means (delay circuit) for correcting the processing delay of each means is omitted here.

The linear conversion means 50 gives a color signal (non-linear luminance addition green signal (G _L + Y _H ) ^α ) input via input means (not shown) to the inverse characteristic of the non-linear conversion performed in the video signal transmission device 1B. by and converts it into a linear signal (luminance addition green signal _{(G L + Y H))} .
The linear conversion unit 50 outputs the converted luminance addition green signal (G _L + Y _H ) to the band limiting unit 51 and the high band signal generation unit 52.

The band limiting unit 51 extracts a predetermined low frequency component (G _L ) from the luminance addition green signal (G _L + Y _H ) converted by the linear conversion unit 50. Note that the band limiting unit 51 extracts the same low frequency component as the band limiting unit 11B (see FIG. 9) of the video signal transmitting apparatus 1B. The band limiting unit 51 outputs the extracted signal (low band linear green signal G _L ) to the high band signal generating unit 52 and the downsampling unit 53.

The high frequency signal generating means 52 extracts a high frequency component signal (high frequency luminance signal Y _H ) from the luminance added green signal ( _GL + Y _H ) converted by the linear conversion means 50. Here, the high frequency signal generating unit 52 subtracts the low frequency linear green signal _GL band-limited by the band limiting unit 51 from the luminance added green signal (G _L + Y _H ), thereby obtaining the luminance added green signal (G A high frequency luminance signal Y _H which is a high frequency component of _L + Y _H ) is generated.

Incidentally, the high-frequency signal generating means 52, the luminance addition green signal (G L _{+ Y H),} may be constructed as to extract a high frequency component determined in advance. In this case, the high-frequency signal generating means 52 can be configured by a general high-pass filter. This high frequency component is determined in advance as the remaining high frequency component of the low frequency component performed in the band limiting means 51. When the high-frequency signal generating unit 52 is configured with a high-pass filter, the high-frequency signal generating unit 52 does not use the low-frequency linear green signal _GL that is band-limited by the band-limiting unit 51.
The high frequency signal generating means 52 outputs the generated high frequency luminance signal Y _H to the high frequency signal adding means 58.

The down-sampling unit 53 down-samples the low-frequency linear green signal _GL extracted by the band limiting unit 51 at a predetermined sampling interval (down-sampling ratio). The downsampling unit 53 downsamples at the same sampling interval (downsampling ratio) as the downsampling unit 12 (see FIG. 9) of the video signal transmitting apparatus 1B.
The down-sampling unit 53 outputs the down-sampled signal G _LD to the non-linear conversion unit 54.

The nonlinear conversion means 54 converts the linear signal (G _LD ) down-sampled by the down-sampling means 53 into a nonlinear signal (low-frequency nonlinear green signal G _LD ^α ). The nonlinear conversion means 54 performs the same conversion as the nonlinear conversion performed in the nonlinear conversion means 13B (see FIG. 9) of the video signal transmitting apparatus 1B.
The non-linear conversion unit 54 outputs the converted low-frequency non-linear green signal G _LD ^α to the luminance / color difference signal generation unit 55.

The luminance color difference signal generation means 55 is a low-frequency nonlinear green signal G _LD ^α converted by the nonlinear conversion means 54, a low-frequency nonlinear blue signal B _LD ^α input via input means (not shown), and a low-frequency nonlinear red signal. A luminance signal and two color difference signals are generated from R _LD ^α . The luminance / color difference signal generating means 55 uses the low frequency nonlinear luminance signal Y _LD ^α and the color difference signal Cb _LD ^α from the color signals R _LD ^α , G _LD ^α , and B _LD ^{α according} to the mixing equation shown in the following equation (12). And a color difference signal Cr _LD ^α are generated.

Here, r _y , g _y , and b _y are coefficients for generating a luminance signal. For example, in the case of the HDTV signal standard, r _y = 0.2126, g _y = 0.7152, b _y = 0. 0722. R _Cb , g _Cb , b _Cb , r _Cr , g _Cr , and b _Cr are coefficients for generating a color difference signal. For example, in the case of the HDTV signal standard, r _Cb = −0.2126 / 1. 8556, g _Cb = −0.7152 / 1.8556, b _Cb = 0.5, r _Cr = 0.5, g _Cr = −0.7152 / 1.5748, b _Cr = −0.0722 / 1. 5748.
The luminance / chrominance signal generation means 55 outputs the generated low-frequency nonlinear luminance signal Y _LD ^α to the linear conversion means 56. Two color difference signals (color difference signals Cb _LD ^α and Cr _LD ^α ) are signals to be output to the outside.

The linear conversion unit 56 gives a low-frequency nonlinear luminance signal Y _LD ^α generated by the luminance / color-difference signal generation unit 55 to a linear signal (low-frequency linear luminance by giving inverse characteristics of nonlinear conversion performed in the video signal transmission device 1B. Signal Y _LD ).
The linear conversion means 56 outputs the converted low-frequency linear luminance signal Y _LD to the up-sampling means 57.

Upsampling means 57, becomes a low-frequency linear luminance signal Y _LD, the same number of samples and the pixel structure and the high frequency luminance signal Y _H generated in the high-frequency signal generating means 52 which is a linear signal which has been converted by the linear conversion unit 56 It is something to upsample.

For example, when the transmission format of the video signal transmitted from the video signal transmission device 1B is 4: 2: 2, the up-sampling unit 57 inserts a pixel for each pixel in the horizontal direction. When the transmission format of the video signal transmitted from the video signal transmission device 1B is 4: 2: 0 format, the upsampling unit 57 inserts a pixel for each pixel in both the horizontal direction and the vertical direction. Here, the pixel is inserted by inserting a pixel having a pixel value obtained from an interpolation filter from adjacent pixels.
The upsampling unit 57 outputs the upsampled low frequency linear luminance signal Y _L to the high frequency signal adding unit 58.

The high frequency signal adding means 58 adds the high frequency luminance signal Y _H generated by the high frequency signal generating means 52 to the low frequency linear luminance signal Y _L up-sampled by the up-sampling means 57, thereby (linear) luminance. The signal Y is generated.
The high frequency signal adding means 58 outputs the generated luminance signal Y to the non-linear conversion means 59.

The non-linear conversion means 59 converts the luminance signal Y generated by the high frequency signal adding means 58 into a non-linear signal (non-linear luminance signal Y ^α ). Note that the non-linear conversion means 59 performs the same conversion as the non-linear conversion performed in the non-linear conversion means 13B (see FIG. 9) of the video signal transmitting apparatus 1B.
The non-linear luminance signal Y ^α converted by the non-linear conversion unit 59 and the color difference signals Cb _LD ^α and Cr _LD ^α generated by the luminance color difference signal generation unit 55 are output to the outside through an output unit (not shown). .
In this way, the transmission signal conversion device 3B can convert the video signal generated in the video signal transmission device 1B into a YCC format video signal of a luminance signal and two color difference signals.

  The configuration of the transmission signal conversion device 3B according to the embodiment of the present invention has been described above, but the present invention is not limited to the format of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the transmission signal conversion device 3B is realized by software, a general computer having a CPU and a memory (not shown) can be operated by the transmission signal conversion program that functions as the above-described units.

Further, here, the transmission signal conversion device 3B is configured as a device separate from the video signal transmission device 1B, as a device that converts the video signal output from the video signal transmission device 1B (see FIG. 9). The transmission signal conversion device 3B may be configured to be incorporated in the video signal transmission device 1B.
In this case, the transmission signal conversion device 3B may be arranged after the nonlinear conversion means 13B of the video signal transmission device 1B. The linear conversion means 50 receives the non-linear luminance addition green signal ( _GL + Y _H ) ^α from the non-linear conversion means 13B, and the luminance color difference signal generation means 55 receives the low-frequency non-linear blue signal B _LD ^α and the non-linear conversion means 13B. A low-frequency nonlinear red signal R _LD ^α is input.
Thus, the video signal transmission device 1B can be configured as a device that transmits a YCC format video signal.

[Configuration of received signal converter]
Next, with reference to FIG. 14, the structure of the received signal converter 4B according to the embodiment of the present invention will be described. Here, the received signal conversion device 4B includes a linear conversion unit 50, a band limiting unit 51, a high-frequency signal generation unit 52, a down-sampling unit 53, a non-linear conversion unit 54, a linear conversion unit 56, and an up-sampling. Means 57, high-frequency signal adding means 58, non-linear conversion means 59, and color signal generating means 60 are provided.

  The configuration other than the color signal generation unit 60 is the same as the transmission signal conversion device 3B described with reference to FIG. Therefore, configurations other than the color signal generation unit 40 are denoted by the same reference numerals as those of the transmission signal conversion device 3 described with reference to FIG.

The color signal generation means 60 is a low-frequency nonlinear signal based on the low-frequency nonlinear luminance signal Y _LD ^α converted by the nonlinear conversion means 54 and the color difference signals Cb _LD ^α and Cr _LD ^α input via the input means (not shown). A red signal R _LD ^α , a low-frequency nonlinear green signal G _LD ^α, and a low-frequency nonlinear blue signal B _LD ^α are generated.

This color signal generation means 60 is a luminance color difference signal generation means 55 (see FIG. 13) of the transmission signal conversion device 3B, and the low frequency nonlinear luminance signal Y _LD ^α , color difference signals Cb _LD ^α , Cr according to the equation (12). _When calculating _LD ^α , a low-frequency nonlinear red signal R _LD ^α , a low-frequency nonlinear green signal G _LD ^α, and a low-frequency nonlinear blue signal B _LD ^α are generated according to the following equation (13).

Here, (13), said (12) is the inverse conversion equation of _{equation, y R, c bR, c} rR, y G, c bG, c rG, y B, c bB, c rB represents luminance For example, in the HDTV signal standard, y _R = 1, c _bR = 0, c _rR = 1.5748, y _G = 1. , C _bG = −0.0722 × 1.8556 / 0.7152, c _rG = −0.2126 × 1.5748 / 0.7152, y _B = 1, c _bB = 1.8556, c _rB = 0 is there.
The color signal generation unit 60 outputs the generated low-frequency nonlinear green signal G _LD ^α to the linear conversion unit 56. Further, the low-frequency nonlinear red signal R _LD ^α and the low-frequency nonlinear blue signal B _LD ^α, which are other color signals, are signals to be output to the outside.

The non-linear luminance addition green signal (G _L + Y _H ) ^α converted by the non-linear conversion means 59 and the color signals generated by the color signal generation means 60 (low-frequency non-linear red signal R _LD ^α and low-frequency non-linear blue signal B _LD ^α ) , And output to the outside through an output unit (not shown).
As described above, the reception signal conversion device 4B converts the YCC format video signal of the luminance signal and the two color difference signals generated in the transmission signal conversion device 3B into an input signal to the video signal reception device 2B (see FIG. 10). Can be converted to

  The configuration of the received signal conversion device 4B according to the embodiment of the present invention has been described above, but the present invention is not limited to the format of the present embodiment. Each means described above can be realized by a hardware configuration using a circuit, or can be realized by software. When the reception signal conversion device 4B is realized by software, a general computer having a CPU and a memory (not shown) can be operated by the reception signal conversion program that functions as the above-described units.

  In addition, here, the reception signal conversion device 4B is configured to output the converted video signal to the video signal reception device 2B (see FIG. 10), and is configured as a separate device from the video signal reception device 2B. The reception signal conversion device 4B may be configured to be incorporated in the video signal reception device 2B.

In this case, the reception signal conversion device 4B may be arranged in front of the linear conversion means 20B of the video signal reception device 2B. Then, the non-linear conversion means 59 outputs the non-linear luminance addition green signal (G _L + Y _H ) ^α ) to the linear conversion means 20B, and the color signal generation means 60 outputs the low-frequency non-linear red signal R _LD ^α and the low-frequency non-linear blue signal. B _LD ^α is output to the linear conversion means 20B.
Accordingly, the video signal receiving device 2 can be configured as a device that receives a YCC format video signal.

As described above, the video signal transmission system S (S _B ) generates the luminance signal Y from the linear RGB signal in the video signal transmission device 1 (1B) and performs nonlinear conversion on the luminance signal Y. A non-linear luminance signal ^Yα is generated. This non-linear luminance signal Y ^alpha, in the video signal receiving device 2 (2B), by applying a inverse characteristic of the nonlinear conversion, it is possible to correctly reproduce the luminance signal Y.

Also, the video signal transmission system S (S _B ) converts the linear color signal into a non-linear signal by non-linear conversion after band limiting and down-sampling in the video signal transmitting apparatus 1 (1B). Since this nonlinear signal is returned to a linear signal by the inverse characteristic of the nonlinear transformation on the receiving side, it becomes possible to reproduce the color with low distortion.

Further, since the video signal transmission system S (S _B ) does not use the color difference signal in the video signal transmission apparatus 1 (1B), there is no processing for performing nonlinear conversion on the color difference signal as in the conventional case, and the high saturation portion of the video signal. The SN ratio can be prevented from decreasing.

As described above, the transmission signal conversion device 3 (3B) and the reception signal conversion device 4 (4B) convert the video signal transmitted in the video signal transmission system S (S _B ) into a luminance signal and a color difference signal. In addition to the effect of suppressing the decrease in the S / N ratio of luminance information and color information due to compression / expansion of nonlinear conversion, while performing constant luminance transmission that satisfies the constant luminance principle, A conventional digital compression encoding device or the like can be used.

S, _{S B} video signal transmission system 1,1B video signal transmission apparatus 10 luminance signal generating means 11,11B band limiting means 12 down-sampling means 13,13B nonlinear conversion unit 14 and high frequency signal generating unit 141 band limiting means 142 subtracting means 15 High-frequency signal adding means 2, 2B Video signal receiving device 20, 20B Linear conversion means 21 Band-limiting means 22, 22B High-frequency signal generating means 221 Band-limiting means 222 Subtracting means 23 Up-sampling means 24 Color signal generating means 25, 25B High Band signal adding means 3 Transmission signal converting means 30 Linear converting means 31 Band limiting means 32 Down-sampling means 33 Non-linear converting means 34 Color difference signal generating means 4 Reception signal converting means 40 Color signal generating means 50 Linear converting means 51 Band limiting means 52 High Area signal generation means 53 Downsampled hand Stage 54 Non-linear conversion means 55 Luminance color difference signal generation means 56 Linear conversion means 57 Up-sampling means 58 High-frequency signal adding means 59 Non-linear conversion means

Claims (4)

A non-linear luminance signal obtained by non-linear conversion of luminance signals generated from the first to third color signals, which are three primary color signals, and a low frequency component extracted from the first color signal and the second color signal, and then non-linear The converted low-frequency nonlinear first color signal and low-frequency nonlinear second color signal are input as video signals for transmission, and the low-frequency nonlinear first color signal and the low-frequency nonlinear second color of the video signals are input. A transmission signal converter for converting a signal into two color difference signals,
Linear conversion means for converting the non-linear luminance signal into a linear luminance signal by giving an inverse characteristic of the non-linear conversion performed when generating the non-linear luminance signal;
Band limiting means for extracting a low frequency component from the linear luminance signal converted by the linear conversion means,
Downsampling means for downsampling the signal extracted by the band limiting means at a predetermined sampling interval;
Non-linear conversion means for converting the low-frequency linear luminance signal down-sampled by this down-sampling means into a low-frequency non-linear luminance signal by non-linear conversion,
Color difference signal generating means for generating the two color difference signals from the low frequency nonlinear luminance signal, the low frequency nonlinear first color signal, and the low frequency nonlinear second color signal;
A transmission signal conversion apparatus comprising: A non-linear luminance signal obtained by non-linear conversion of luminance signals generated from the first to third color signals, which are three primary color signals, and a low frequency component extracted from the first color signal and the second color signal, and then non-linear The converted low-frequency nonlinear first color signal and low-frequency nonlinear second color signal are input as video signals for transmission, and the low-frequency nonlinear first color signal and the low-frequency nonlinear second color of the video signals are input. In order to convert the signal into two color difference signals,
Linear conversion means for converting the non-linear luminance signal into a linear luminance signal by giving an inverse characteristic of the non-linear conversion performed when generating the non-linear luminance signal;
Band limiting means for extracting a low frequency component from the linear luminance signal converted by the linear conversion means,
Down-sampling means for down-sampling the signal extracted by the band-limiting means at a predetermined sampling interval;
Non-linear conversion means for converting the low-frequency linear luminance signal down-sampled by this down-sampling means into a low-frequency non-linear luminance signal by non-linear conversion,
Color difference signal generating means for generating the two color difference signals from the low frequency nonlinear luminance signal, the low frequency nonlinear first color signal, and the low frequency nonlinear second color signal;
The transmission signal conversion program characterized by functioning as. A non-linear luminance signal obtained by non-linear conversion of luminance signals generated from the first to third color signals, which are three primary color signals, and a low frequency component extracted from the first color signal and the second color signal, and then non-linear The nonlinear luminance signal, which is a video signal generated from the converted low-frequency nonlinear first color signal and low-frequency nonlinear second color signal, and two color difference signals are input as transmission video signals, and the video signal Among these, the received signal conversion device converts the two color difference signals into the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal,
Linear conversion means for converting the non-linear luminance signal into a linear luminance signal by giving an inverse characteristic of the non-linear conversion performed when generating the non-linear luminance signal;
Band limiting means for extracting a low frequency component from the linear luminance signal converted by the linear conversion means,
Downsampling means for downsampling the signal extracted by the band limiting means at a predetermined sampling interval;
Non-linear conversion means for converting the low-frequency linear luminance signal down-sampled by this down-sampling means into a low-frequency non-linear luminance signal by non-linear conversion,
Color signal generating means for generating the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal from the low-frequency nonlinear luminance signal converted by the nonlinear conversion means and the two color difference signals;
A received signal conversion apparatus comprising: A non-linear luminance signal obtained by non-linear conversion of luminance signals generated from the first to third color signals, which are three primary color signals, and a low frequency component extracted from the first color signal and the second color signal, and then non-linear The nonlinear luminance signal, which is a video signal generated from the converted low-frequency nonlinear first color signal and low-frequency nonlinear second color signal, and two color difference signals are input as transmission video signals, and the video signal In order to convert the two color difference signals into the low-pass nonlinear first color signal and the low-pass nonlinear second color signal,
Linear conversion means for converting the non-linear luminance signal into a linear luminance signal by giving an inverse characteristic of the non-linear conversion performed when generating the non-linear luminance signal;
Band limiting means for extracting a low frequency component from the linear luminance signal converted by the linear conversion means,
Down-sampling means for down-sampling the signal extracted by the band-limiting means at a predetermined sampling interval;
Non-linear conversion means for converting the low-frequency linear luminance signal down-sampled by this down-sampling means into a low-frequency non-linear luminance signal by non-linear conversion,
Color signal generating means for generating the low-frequency nonlinear first color signal and the low-frequency nonlinear second color signal from the low-frequency nonlinear luminance signal converted by the nonlinear conversion means and the two color difference signals,
A received signal conversion program characterized in that it functions as

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