JP6388431B2 - Signal conversion device, signal restoration device, and program thereof - Google Patents

Description

  The present invention relates to a signal conversion device, a signal restoration device, and a program thereof.

  As a color definition system of HDTV (High Definition Television), the RGB color system defined in Non-Patent Document 1 (hereinafter referred to as 709RGB) is used. The RGB color system represents a color by a red pixel value, a green pixel value, and a blue pixel value. Non-Patent Document 1 also defines a conversion method from 709RGB to a luminance / color difference color system (hereinafter referred to as 709YC) that expresses a color using luminance values and color difference values. Video captured using 709 RGB is also converted into a video signal based on 709 YC during transmission and storage.

  On the other hand, the RGB color system defined in Non-Patent Document 2 (hereinafter referred to as 2020RGB) is used as a color system for super-high definition television. 2020RGB assumes a display using a laser light source, and has a wide color gamut color system that can express a color with higher saturation than a color gamut that can be represented by 709RGB.

“Parameter values for the HDTV standards for production and international program exchange”, ITU-R BT-709 “Parameter values for ultra-high definition television systems for production and international program exchange”, ITU-R BT-2020

  However, even if a television camera or the like is compatible with a wide color gamut such as 2020RGB and can create a video with a wide color gamut, an apparatus for transmitting and storing video targeted for a narrow color gamut such as 709YC Then, there is a problem that it cannot handle wide color gamut images.

  The present invention has been made in view of such circumstances, and is a signal conversion device and a signal restoration device that can handle a wide color gamut image in a device that transmits and stores video for a narrow color gamut. Provide devices and their programs.

(1) The present invention has been made to solve the above-described problems. In one embodiment of the present invention, a first image representing a video by a red pixel value, a green pixel value, and a blue pixel value is provided. A video in a second format that is a format that targets a video gamut narrower than the color gamut that can be expressed by the first format, and that represents the video by a luminance value and a color difference value. When converting the video signal of the first format into the video signal of the second format, the video signal of the first format exceeds the defined area in the second format. The signal conversion device is characterized in that a signal value of a certain portion is assigned to a signal value that is not used in the domain of the second format.

(2) According to another aspect of the present invention, there is provided the signal conversion device according to (1), wherein at least a part of the continuous part is an assignment destination by the assignment. It is also characterized by being continuous.

(3) According to another aspect of the present invention, there is provided the signal conversion device according to (1) or (2), wherein the signal value to which the signal value of the portion exceeding the defined area in the second format is assigned. Is at least a predetermined distance away from the signal gamut in the second format corresponding to the color gamut that can be represented by the first format.

(4) According to another aspect of the present invention, there is provided a signal restoration device that performs inverse conversion of conversion performed by the signal conversion device according to any one of (1) to (3).

(5) According to another aspect of the present invention, there is provided the signal restoration device according to (4), wherein the signal is a signal in the middle of the inverse transformation and corresponds to the second format, and is red. A clipping unit that performs clipping outside the domain of the third format with respect to a signal of the third format, which is a format that represents video by the pixel value of green, the pixel value of green, and the pixel value of blue It is characterized by that.

(6) According to another aspect of the present invention, a video signal in a first format representing a video by a red pixel value, a green pixel value, and a blue pixel value is transmitted to the computer. A program for converting a video signal of a second format, which is a format that targets a color gamut narrower than a color gamut that can be expressed by the format, and that represents a video by a luminance value and a color difference value, When the computer converts the video signal of the first format into the video signal of the second format, the definition signal in the second format of the video signal of the first format is exceeded. The signal value of a certain portion is assigned to a signal value that is not used in the second format.

(7) According to another aspect of the present invention, a computer is caused to function as a signal restoration device that performs inverse conversion of conversion performed by the signal conversion device according to any one of (1) to (3). It is a program.

  According to the present invention, it is possible to handle an image with a wide color gamut with an apparatus that transmits and stores video for a narrow color gamut.

1 is a schematic block diagram showing a configuration of a video system 1 according to an embodiment of the present invention. It is a schematic block diagram which shows the structure of the signal converter 20 by the same embodiment. It is a schematic block diagram which shows the structure of the signal converter 21 by the same embodiment. It is a graph (the 1) which shows the definition area of 709YC by the same embodiment, and the area | region which the conversion result of the YC conversion part 203 occupies. It is a graph (the 2) which shows the definition area of 709YC by the same embodiment, and the area | region which the conversion result of the YC conversion part 203 occupies. It is a graph (the 3) which shows the definition area of 709YC by the same embodiment, and the area | region which the conversion result of the YC conversion part 203 occupies. It is a flowchart which shows the example of the production | generation method of LUT which the out-of-domain mapping part 205 by the embodiment memorize | stores. It is a figure which shows the example of the determination method of the movement destination outside the domain by the same embodiment. It is a figure which shows the example of the area | region Rr of predetermined distance from the area | region R by the embodiment. It is a schematic block diagram which shows the structure of the signal restoration apparatus 50 by the same embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of a video system 1 according to an embodiment of the present invention. The video system 1 includes a wide color gamut camera 10, a signal conversion device 20, a signal conversion device 21, a narrow color gamut transmission system 30, a narrow color gamut storage device 40, a signal restoration device 50, a narrow color gamut display device 60, a wide color gamut. An editing device 70 and a wide color gamut display device 80 are included.

  The wide color gamut camera 10 is a television camera that captures an image of a wide color gamut. The wide color gamut camera 10 outputs the image of the imaging result as a video signal B0 in a format (first format) using 2020RGB. Since the video signal B0 is a signal in a format using 2020RGB, it is a video signal with a wide color gamut. The video signal B0 is an analog signal.

  The signal converter 20 converts the video signal B0 into a video signal T0 in a format (second format) using 709YC. When the signal conversion apparatus 20 converts 2020RGB into 709YC, the signal value of a part of the 2020RGB that exceeds the definition area in 709YC is assigned to a signal value that is not used by 2020RGB in 709YC. As a result, since the video signal T0 is a format using 709YC, the video signal T0 is a video signal having a narrow color gamut that is narrower than the color gamut that can be expressed by 2020RGB, but does not lose information on the wide color gamut. doing. The video signal T0 is a digital signal.

  The narrow color gamut transmission system 30 transmits the video signal T0. For example, the narrow color gamut transmission system 30 transmits a video signal from a location to a broadcast station. The narrow color gamut storage device 40 stores an input video signal such as the video signal T0. The signal restoration device 50 reads out the video signal stored in the narrow color gamut storage device 40 as a video signal T1, and converts it into a video signal B1 in a format using 2020RGB. In addition, the signal restoration device 50 converts the video signal T1 into a video signal N in a format (third format) using 709 RGB.

  The narrow color gamut display device 60 is a display device corresponding to 709 RGB, and displays the video represented by the video signal N. The wide color gamut editing device 70 is a video editing device that supports 2020 RGB, edits the video represented by the video signal B1, and generates a video signal B2 that represents the edited video. The video signal B2 is a video signal in a format using 2020RGB.

  The wide color gamut display device 80 is a display device corresponding to 2020 RGB, and displays the video represented by the video signal B1. Similarly to the signal conversion device 20, the signal conversion device 21 converts the video signal B <b> 2 into a video signal of the second format, and causes the narrow color gamut storage device 40 to store the conversion result video signal. However, the video signal B2 is a digital signal.

FIG. 2 is a schematic block diagram showing the configuration of the signal conversion apparatus 20. The signal conversion apparatus 20 includes an input unit 200, an XYZ conversion unit 201, a 709 RGB conversion unit 202, a YC conversion unit 203, a quantization unit 204, an out-of-domain mapping unit 205, and an output unit 206. The input unit 200 acquires a video signal B0 represented by 2020RGB. The XYZ conversion unit 201 converts each pixel value of the video signal B0 acquired by the input unit 200 into an XYZ color system. As the conversion method, for example, a red video signal B0, green, blue, the inverse gamma processing on the vector with a value obtained by elements in each of the pixel values, by multiplying the following matrix T _709, X, Y, and Z A method of converting into a vector as an element is used. Note that the inverse gamma process is a reverse process of a so-called gamma process (also referred to as a non-linear transfer function). The XYZ conversion unit 201 performs reverse processing of gamma processing used in 2020 RGB as reverse gamma processing.

The 709 RGB conversion unit 202 converts each pixel value converted into the XYZ color system by the XYZ conversion unit 201 into 709 RGB. The 709 RGB conversion unit 202 performs the same conversion as that in the definition area even if the pixel value exceeds the definition area of 709 RGB. As the conversion method, for example, X, Y, a vector having the Z element, by performing the gamma processing elements each of vector obtained by multiplying the inverse matrix of the following matrix T _2020, red, green, blue, respectively A method of converting a pixel value into a vector having elements as elements is used. Note that the 709 RGB conversion unit 202 performs gamma processing used in 709 RGB.

  The YC conversion unit 203 converts each pixel value converted by the 709 RGB conversion unit 202 into a luminance value Y and color difference values Cb and Cr. The color difference value Cb is a color difference value related to the blue color difference, and the color difference value Cr is a color difference value related to the red color difference. As a conversion method, the YC conversion unit 203 performs the same conversion as in the definition area even if the pixel value exceeds the definition area of 709 RGB. As a conversion method, ITU-R BT. 709 is used. For example, the YC conversion unit 203 performs conversion using the following equation (1).

  The quantization unit 204 quantizes (digitizes) the luminance value Y and the color difference values Cb and Cr obtained by the conversion of the YC conversion unit 203. The out-of-domain mapping unit 205 stores in advance a pixel that is out of the 709 YC definition region among the luminance value Y and color difference values Cb and Cr of each pixel quantized by the quantization unit 204. Using (Look Up Table), conversion into the domain of 709YC. The out-of-domain mapping unit 205 keeps the pixels within the 709YC definition area. The out-of-domain mapping unit 205 determines that it is out of the 709 YC definition area when | Cb |> 0.5 or | Cr |> 0.5. The output unit 206 outputs the processing result by the out-of-domain mapping unit 205 as a video signal T.

  FIG. 3 is a schematic block diagram showing the configuration of the signal conversion device 21. The signal conversion device 21 includes an input unit 200a, an XYZ conversion unit 201a, a 709 RGB conversion unit 202a, a YC conversion unit 203a, an out-of-domain mapping unit 205, and an output unit 206. The input unit 200a acquires the video signal B2. The XYZ conversion unit 201a performs the same conversion as the XYZ conversion unit 201 in FIG. 2 on the video signal B2 acquired by the input unit 200a, but is different from the XYZ conversion unit 201 in that the target signal is a digital signal. . The 709RGB conversion unit 202a performs the same conversion as the 709RGB conversion unit 202 in FIG. 2 on the conversion result of the XYZ conversion unit 201a, but is different from the 709RGB conversion unit 202 in that the target signal is a digital signal.

  The YC conversion unit 203a performs the same conversion as the YC conversion unit 203 in FIG. 2 on the conversion result of the 709 conversion unit 202a, but is different from the YC conversion unit 203 in that the target signal is a digital signal. The out-of-domain mapping unit 205 is the same as the out-of-domain mapping unit 205 of FIG. The output unit 206 outputs the processing result of the out-of-domain mapping unit 205 as a video signal T2.

  4, 5, and 6 are graphs showing the definition area of 709 YC and the area occupied by the conversion result of the YC conversion unit 203. FIG. 4 has three axes: a luminance value Y, a blue color difference value Cb, and a red color difference value Cr. FIG. 5 is an orthogonal projection of the luminance value Y and the red color difference value Cr in FIG. 4 onto the plane. FIG. 6 is an orthogonal projection of the luminance value Y and the blue color difference value Cb in FIG. 4 onto the plane.

  In FIG. 4 to FIG. 6, a region D is a definition region of 709YC. In 709YC, the definition range of the luminance value Y is 0.0 to 1.0, and the definition ranges of the color difference values Cb and Cr are both -0.5 to 0.5. The region D is a cube whose length of each side is 1.0.

  4 to 6, a region R is a region that can be obtained by the conversion results of the YC conversion unit 203 and the YC conversion unit 203a. That is, the signal gamut in 709YC corresponding to the color gamut that can be expressed by 2020RGB. 4 to 6 show the case where γ = 1.0 in 2020RGB and 709RGB. When γ is not 1.0, the position of the vertex of the region R is the same as when γ is 1.0, but each side is not a straight line.

  The coordinates (Y, Cb, Cr) of the eight vertices R1 to R8 of the region R are R1 (0, 0, 0), R2 (0.68, -0.42, -0.80), R3 (0 .74, 0.15, -0.89), R4 (0.06, 0.57, -0.08), R5 (0.94, -0.57, 0.08), R6 (0.26) , −0.15, 0.89), R7 (0.32, 0.42, 0.80), R8 (1.00, 0.00, 0.00).

  Therefore, the length of the side R1R2 is 1.13, the length of the side R2R3 is 0.58, the length of the side R3R4 is 1.13, and the length of the side R1R4 is 0. .58. That is, the rectangle R1R2R3R4 is a parallelogram having a base length of 1.13 and a hypotenuse length of 0.58, and its area is smaller than 1.13 × 0.58 = 0.66. The length of the side R5R6 is 1.14, the length of the side R6R7 is 0.58, the length of the side R7R8 is 1.13, and the length of the side R8R5 is 0. 58. That is, the area of the quadrangle R5R6R7R8 is smaller than the parallelogram having a base length of 1.14 and a hypotenuse length of 0.58. That is, the area of the rectangle R5R6R7R8 is smaller than 1.14 × 0.58 = 0.66.

  In addition, since the lengths of the side R1R6, the side R2R5, the side R3R8, and the side R4R7 are all 0.94, the distance between the square R1R2R3R4 and the square R5R6R7R8 is shorter than 0.94. From these, the volume of the region R is smaller than 0.66 × 094 = 0.62. As described above, since the volume of the region D is 1.0, the volume of the region R is smaller than the volume of the region D. Therefore, it is possible to create an LUT that maps each point in the region R to any point in the region D.

  The conversion results of the YC conversion unit 203 and the YC conversion unit 203a are the results of conversion from 2020RGB to the XYZ color system, conversion to 709RGB, and further conversion to 709YC. That is, since this conversion result was originally expressed in 2020 RGB, there is a portion outside the definition area of 709YC. As described above, since 2020RGB is once converted to the XYX color system, the conversion result when the color represented by the original pixel value is included in the 709RGB color gamut is represented by 709YC. This is the value when

  The LUT stored in advance by the out-of-domain mapping unit 205 maps a portion outside the definition area D of the conversion result area R into the definition area D. In this LUT, it is desirable that the distance between points in the region R and the distance in the mapping result of these points do not change as much as possible. Thereby, it is possible to suppress a change in color when encoding and decoding such as MPEG (Moving Picture Experts Group) is performed on the conversion results by the signal converters 20 and 21.

  In order to reduce the points where the distance between the points in the region R and the distances in the mapping result of these points change, the portion outside the domain D of the region R is not divided as much as possible. Then, it maps in the domain D as it is.

  FIG. 7 is a flowchart illustrating an example of an LUT generation method stored in the out-of-domain mapping unit 205. First, the region R having the largest volume is selected from the portions outside the domain D (hereinafter, each part is referred to as the domain outside) (S1). Of the portions outside the domain D of the region R, consecutive portions are defined as one domain outside. Next, a plurality of destination candidates outside the selected domain are created (S2). The plurality of destination candidates are, for example, points at predetermined intervals in the directions of Y, Cb, and Cr in the definition area D. The destination candidates may include not only points but also directions outside the domain such as the directions of the Y, Cb, and Cr axes. For example, the negative direction of the Y axis is the direction in which the outside of the domain is moved to the plane object on the CbCr plane, and the positive direction of the Y axis is the direction not moved to the plane object. The direction may include rotation around each axis.

  Next, one of the destination candidates generated in step S2 that is not selected outside the domain is selected (S3). Next, when the outside of the definition area is moved so that the center of gravity comes to the destination candidate selected in step S3, the volume included in the unused area of the definition area D out of the definition area is calculated ( S4). Here, the unused area is an area that is not included in the area R in the definition area D and is not mapped outside any of the definition areas. Next, it is determined whether or not all destination candidates have been selected in step Sa3 (S5). If not all destination candidates have been selected (S5-No), the process returns to step S3. When all the movement destinations have been selected (S5-Yes), an LUT is created using the movement destination candidate when the volume calculated in step S4 is maximum as the mapping destination (S6). Thereby, when mapping of all the parts outside the selected domain is not completed (S7-No), that is, when a part outside the domain is outside the unused area in the destination candidate, A part that has not been mapped yet, that is, a part outside the unused area is set as one outside the definition area (S9), and the process returns to step S1.

  On the other hand, when mapping of all the parts outside the domain is completed in the destination candidate selected in step S6 (S7-Yes), it is determined whether mapping outside all the domain is completed (S8). ). If there is a domain outside the mapping that has not been completed (S8-No), the process returns to step S1, and if mapping outside all domains is completed (S8-Yes), the process ends.

  In the destination candidate selected in step S6, the distance between points before mapping and the distance between points after mapping do not change within the portion included in the unused area. Therefore, in step S6, the distance between points before mapping and the distance between points after mapping are created by selecting a destination candidate when the volume included in the unused area is maximum and creating an LUT. The number of points that change is reduced as much as possible. That is, the distance between points before mapping and the distance between points after mapping are prevented from changing as much as possible.

  In FIG. 7, the destination outside the domain is searched for brute force, and the destination with the largest volume overlapping with the unused area is selected, but the destination may be determined by the method shown in FIG. 8. . In the method illustrated in FIG. 8, the outside of the domain is moved to a line-symmetrical position about the side of the surface where the domain outside is in contact with the domain D. For example, the domain outside Ra is moved to a line-symmetric position Rb. Then, at the movement destination, the part Rc that is outside the domain D is moved to a line-symmetric position Rd with the side of the surface where the part Rc is in contact with the domain D as an axis. In FIG. 8, when the position is moved to the position Rd, there is no portion outside the definition area D, but if it does not disappear, it is moved in the same manner.

  Further, in the method shown in FIGS. 7 and 8, the unused area is set so that the area Rr having a predetermined distance from the area R and the area having a predetermined distance from the area outside the defined area are not mapped. May be. FIG. 9 is a diagram illustrating an example of a region Rr having a predetermined distance from the region R. By doing in this way, the area | region R and the area | region which mapped each domain outside are separated from each other more than a predetermined distance. For this reason, encoding and decoding such as MPEG are performed, and when the pixel value changes by a small amount, the pixel value of the pixel whose pixel value is in the region R moves to a region where the outside of the definition region is mapped. Thus, it is possible to suppress the color of the pixel from changing greatly.

  FIG. 10 is a schematic block diagram showing the configuration of the signal restoration device 50. The signal restoration apparatus 50 includes an input unit 500, an inverse mapping unit 501, a 709 RGB conversion unit 502, an XYZ conversion unit 503, a 2020 RGB conversion unit 504, an output unit 505, a clipping unit 506, and an output unit 507. The input unit 500 acquires the video signal B0. The inverse mapping unit 501 performs a reverse conversion to the out-of-domain mapping unit 205 on the video signal B0 acquired by the input unit 500. As a result, the pixel values that have fallen within the definition area D fall within the area R.

  For example, the inverse mapping unit 501 stores in advance an LUT that performs conversion opposite to that of the out-of-domain mapping unit 205, and performs conversion using the LUT. For example, the inverse mapping unit 501 determines whether or not the pixel value as a result of the same processing as that from the 709 RGB conversion unit 502 to the 2020 RGB conversion unit 504 exceeds the 2020 RGB definition area without performing conversion by this LUT. It is determined whether the pixel is mapped from outside the definition area. Then, conversion using this LUT is performed only for pixels mapped from outside the definition area. Note that the inverse mapping unit 501 does not perform this determination, and the LUT may be configured so that the pixel values in the domain D in the domain R do not change before and after conversion.

  The 709 RGB conversion unit 502 converts the conversion result of the inverse mapping unit 501 in reverse to the YC conversion unit 203. As a result, the color of each pixel represented by the luminance value Y and the color difference values Cb and Cr is represented by a red pixel value, a green pixel value, and a blue pixel value based on 709RGB. The XYZ conversion unit 503 converts the conversion result of the 709 RGB conversion unit 502 in the reverse manner to the 709 RGB conversion unit 202. As a result, the color of each pixel represented by the red pixel value, the green pixel value, and the blue pixel value based on 709RGB is represented in the XYZ color system.

  The 2020RGB conversion unit 504 converts the conversion result of the XYZ conversion unit 503 in the reverse manner to the XYZ conversion unit 201 to obtain a video signal B1. As a result, the color of each pixel represented in the XYZ color system is represented by 2020 RGB. The output unit 505 outputs the video signal B1. The clipping unit 506 clips a pixel value outside the domain D with respect to the conversion result of the 709 conversion unit 502 to obtain a video signal N. Specifically, the clipping unit 506 performs clipping so that the pixel value of the conversion result of the 709 conversion unit 502 falls within the definition area of 709 RGB. The output unit 507 outputs the video signal N.

The signal converters 20 and 21 perform four-step conversion, such as conversion from 2020 RGB to the XYZ color system, conversion to 709 RGB, conversion to 709 YC, and mapping outside the definition area. , Of these, a two-stage conversion may be performed using a combination of two, or a two-stage conversion may be performed using a combination of three of these. A one-step conversion may be performed using a conversion obtained by synthesizing all of these. The same applies to the signal restoration device 50. Since the gamma processing and the inverse gamma processing are non-linear operations, when these processes are included in the combined conversion, the combined conversion is performed using, for example, an LUT.
Further, in the above-described embodiment, 2020 RGB is described as the wide color gamut video signal, and 709 YC is described as the narrow color gamut video signal, but the present invention is not limited thereto.

As described above, when the signal conversion devices 20 and 21 convert the 2020 RGB video signal into the 709 YC video signal, the signal value of the portion of the 2020 RGB video signal that exceeds the defined range in 709 YC is represented in 709 YC. Assign to unused signal values.
Accordingly, a wide color gamut (2020 RGB) video can be handled by an apparatus that transmits and stores video for 709 YC (narrow color gamut).

Furthermore, the conversion result when the color represented in the 2020 RGB video signal is included in the 709 RGB color gamut is the luminance value and the color difference value when the color is represented by 709 YC.
Thereby, since the conversion result by the signal conversion devices 20 and 21 has the same color change width represented by 1 bit of the pixel value as the change width in 2020RGB, it is possible to suppress deterioration of information due to the conversion. it can. In addition, for pixels in which the color represented in the original video signal is included in the 709 RGB color gamut, when the conversion results by the signal conversion devices 20 and 21 are input to the display device in the narrow color gamut, Displayed in the color to represent.

Furthermore, the signal value to which the signal value of the portion exceeding the defined range in 709YC is at least a predetermined distance away from the signal value representing the color included in the 709RGB color gamut.
As a result, it is possible to prevent the color from changing greatly when encoding and decoding such as MPEG is performed on the conversion results of the signal conversion devices 20 and 21.

Further, the signal restoration device 50 performs inverse conversion of the conversion performed by the signal conversion devices 20 and 21.
As a result, the conversion results obtained by the signal conversion devices 20 and 21 can be returned to 2020 RGB video signals even after being transmitted and stored.

Further, the signal restoration apparatus 50 includes a clipping unit 506 that performs clipping outside the 709 RGB definition area on the 709 RGB video signal, which is a signal in the middle of the inverse transformation.
As a result, the conversion results by the signal conversion devices 20 and 21 can be converted into a 709 RGB video signal after being transmitted and stored.

  Further, the program for realizing the functions of the signal conversion devices 20 and 21 and the signal restoration device 50 in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system. These devices may be realized by executing. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

In addition, each functional block of the signal conversion devices 20 and 21 and the signal restoration device 50 in FIG. 1 described above may be individually chipped, or a part or all of them may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and implementation using a dedicated circuit or a general-purpose processor is also possible. Either hybrid or monolithic may be used. Some of the functions may be realized by hardware and some by software.
In addition, when a technology such as an integrated circuit that replaces an LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology can be used.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Video system 10 ... Wide color gamut camera 20, 21 ... Signal converter 30 ... Narrow color gamut transmission system 40 ... Narrow color gamut storage device 50 ... Signal restoration device 60 ... Narrow color gamut display device 70 ... Wide color gamut editing device 80 ... Wide color gamut display device 200, 200a ... Input unit 201, 201a ... XYZ conversion unit 202, 202a ... 709 RGB conversion unit 203, 203a ... YC conversion unit 204 ... Quantization unit 205 ... Out-of-domain mapping unit 206 ... Output unit 500 ... input unit 501 ... inverse mapping unit 502 ... 709 RGB conversion unit 503 ... XYZ conversion unit 504 ... 2020 RGB conversion unit 505 ... output unit 506 ... clipping unit 507 ... output unit

Claims (6)

A video signal of the first format that represents video by a red pixel value, a green pixel value, and a blue pixel value is targeted for a color gamut that is narrower than the color gamut that can be expressed by the first format. A video signal of a second format that is a format that represents video by a luminance value and a color difference value;
When the video signal of the first format is converted into the video signal of the second format, the signal value of the portion of the video signal of the first format that exceeds the definition area in the second format Are assigned to signal values that are not used in the domain of the second format ,
The signal conversion apparatus according to claim 1, wherein at least a part of the continuous part is continuous even in an assignment destination by the assignment . The signal value to which the signal value of the portion exceeding the defined area in the second format is assigned at least a predetermined value from the signal area in the second format corresponding to the color gamut that can be expressed by the first format. The signal conversion apparatus according to claim 1, wherein the signal conversion apparatus is separated by a distance. A signal restoration device that performs inverse transformation of transformation performed by the signal transformation device according to claim 1 . A signal in the middle of the reverse conversion, which is a format corresponding to the second format, and is a format that represents a video by a red pixel value, a green pixel value, and a blue pixel value. against format of the signal, the signal restoration device according to claim 3, characterized in that it comprises a clipping unit for performing domain outside the clipping of the third format. On the computer,
A video signal of the first format that represents video by a red pixel value, a green pixel value, and a blue pixel value is targeted for a color gamut that is narrower than the color gamut that can be expressed by the first format. A program for converting into a video signal of a second format which is a format and represents a video by luminance value and color difference value,
The computer, when converting a video signal of the first format into the video signal of the second format, one of the first format of the video signal exceeds the domain of the second format Assigning signal values of parts to signal values not used in the second format ;
The program according to claim 1, wherein at least a part of the continuous parts is also continuous in an assignment destination by the assignment . Computer
The program for functioning as a signal decompression | restoration apparatus which performs reverse conversion of the conversion which the signal converter of Claim 1 or Claim 2 performs.

Images