CN101711000B - Coding scheme based on acquisition of three primary colors with widest sensible color gamut - Google Patents

Abstract

The invention relates to digital television, wide color gamut theory and technology. Specifically, it relates to the coding scheme corresponding to ITU-R BT.1361 based on obtaining the three primary colors of the widest perceivable color gamut. The technical solution adopted by the present invention is: based on the coding scheme for obtaining the three primary colors of the widest perceivable color gamut, using traversal The method of point calculation is to let the gamma correction input signals LR, LG, and LB randomly select values within the range of [-0.25, 1.33], and compare the color and tongue-shaped spectral curves constructed for each set of values to obtain all possible values. Perceive the color, and according to the characteristics of the color bar signal, the three primary colors corresponding to the widest perceivable color gamut of ITU-RBT. The invention is mainly used for compatible data transmission in the color television system.

Description

Coding scheme based on obtaining the three primary colors of the widest perceivable color gamut

technical field

The invention relates to digital television, wide color gamut theory and technology. Specifically, it involves a coding scheme corresponding to ITU-R BT.1361 based on obtaining the three primary colors of the widest perceivable color gamut.

technical background

With the rapid development of modern technology and industry, a variety of new display devices and display technologies have emerged in recent years. In addition to the traditional cathode ray tube (CRT), liquid crystal display (LCD), plasma display (PDP), digital optical processing A variety of new display devices such as DLP, liquid crystal display on silicon (LCoS), light-emitting diode backlight liquid crystal display (LED-LCD) have been put into practical use or have been successfully developed. In terms of display methods, in addition to the direct view type, front projection, rear projection and laser projection displays have also been put into practical use. These new high-end display devices and display methods are based on different principles, using different materials, devices and technologies. The color reproduction ability and performance are improving, and some "future" displays will emerge. On the other hand, the consumer market has higher and higher requirements for display effects. Just improving the definition can no longer meet people's requirements for true reproduction of scenes, and the color reproduction ability is also becoming an important indicator for measuring the display effect of displays.

The current general-purpose TV system is still based on early scientific and technological achievements, and the system parameters are selected according to the characteristics of CRT, which limits the color gamut that exists in nature, artificially synthesized or generated by computers, and can be visually perceived, so the TV system should transmit and reproduce. The width makes the current color gamut coverage less than 40% of the visually perceptible color gamut range. Can not meet satellite DTV (digital television), cable DTV and terrestrial DTV broadcasting, digital television is replacing analog television, and digital television technology has been used in film production and the requirement of digital theater etc. The advancement of contemporary camera and imaging technology, computer and digital signal processing technology have penetrated into the field of digital TV, which has made it possible to widen the color gamut of digital TV. In view of this, the principle of building a wide color gamut TV system, the transmission and reproduction methods of wide color gamut TV signals, etc. have become a hot topic in the international academic circles and a new growth point in related industries. A generation of digital television encoding, transmission and reception display will have a major impact.

At present, relevant international standardization organizations have successively formulated some wide color gamut standards. Among them, ITU-R BT.1361 and IEC61966 series standards are wide color gamut standards for digital video systems. The former takes the Pointer color gamut as the target color gamut, stipulates that the dynamic range of the red, green and blue three primary colors gamma correction input signals L _R , L _G , and L _B is [-0.25, 1.33], and adopts a positive and negative asymmetrical gamma correction curve Realize the compression of wide color gamut video signal. The latter standardized xvYCC color space has no limit on the amplitude range of the input signal, adopts positive and negative symmetrical gamma correction curves, and realizes the transmission of wide color gamut video signals by expanding the available quantization range. IEC 61966 also formulates standards for color management of cameras, CRT, LCD, PDP, etc.

ITU-R BT.1361 is a wide color gamut standard for video systems. It takes the Pointer color gamut as the target color gamut, and stipulates that the dynamic range of the red, green and blue three-color gamma-corrected input signals L _R , L _G , and L _B is [- 0.25, 1.33]. Obviously, when the signals L _R , L _G , and _LB are randomly selected within this range, some colors constructed will be outside the tongue-shaped spectral curve, that is, colors invisible to human eyes.

Contents of the invention

In order to overcome the deficiencies in the prior art, the object of the present invention is to avoid that when the signals _LR , L _G , and _LB take values randomly within this range, some colors constructed will be located outside the tongue-shaped spectral curve, That is, the color is invisible to the human eye, and realizes the transmission and reproduction of the widest perceivable color gamut of ITU-RBT.1361.

The technical solution adopted by the present invention is: use the method of traversal point calculation, that is, make the red, green and blue primary color gamma correction input signals L _R , L _G , and _LB be randomly selected within the range of [-0.25, 1.33], and the The color obtained by taking each set of values is compared with the tongue-shaped spectral curve to obtain all perceivable colors, and according to the characteristics of the color bar signal, the three primary colors corresponding to the widest perceivable color gamut of ITU-R BT.1361 are obtained through derivation. And derive the coding implementation scheme based on the three primary colors of the aforementioned widest perceivable color gamut.

The gamma correction input signals L _R , L _G , and L _B are randomly selected in the range of [-0.25, 1.33], and the color and tongue-shaped spectral curves obtained by each set of values are compared to obtain all possible Perceived color is to take the traversal step of L _R , L _G , and L _B as 0.01, and test a total of 159 ³ colors to detect whether each color is located in the area surrounded by the tongue-shaped spectral curve. If so, it indicates that the color is the color perceivable by the human eye, record the color and calculate its u'v' coordinate in the three-dimensional color space L*u'v', the white bar and the black bar correspond to the maximum and minimum values of the luminance signal E' _Y respectively, The blue and yellow signals correspond to the maximum and minimum values of the blue color signal E′ _CB, respectively, while the red and cyan colors correspond to the maximum and minimum values of the red color signal E′ _CR , respectively, compared by the range [-0.25 , 1.33] to obtain the maximum and minimum values of the luminance signal values and chrominance signal values of all perceivable colors defined by 1.33], the results are listed in Table 1:

Table 1. The maximum and minimum values of luminance and chrominance signals and the corresponding six colors and their chromaticity coordinates

According to the results shown in Table 1, the primary colors of blue and red and the complementary colors of yellow and cyan can be obtained.

The derivation of the three primary colors corresponding to the widest perceivable color gamut of ITU-R BT.1361 is that the chromaticity coordinates of the blue and red primary colors and the yellow and cyan complementary colors are obtained by using the method of traversal and point calculation, and the mapping method is adopted: first Under the u'v' coordinate system, respectively determine the "blue" corresponding to "E' _CB _max", the "yellow" corresponding to "E' _CB _min", and the "red" corresponding to "E' _CR _max", Corresponding to the "cyan" of "E′ _CR _min", the intersection point of rays "blue-cyan" and "red-yellow" is "green", and the intersection point of rays "green-D65" and "blue-red" is "Magenta", thus, the coordinates of the green primary color and its complementary magenta color in the u'v' coordinate system can be obtained, and the calculated data are (0.1038, 0.5830) and (0.3594, 0.2717) respectively. Continue to use the traversal method, In the range of [-0.25, 1.33], find the same values as the chromaticity coordinates of "green" (0.1038, 0.5830) and "magenta" (0.3594, 0.2717), so we know the L _R , L _G , L _B value.

The coding implementation scheme for deriving the three primary colors based on the aforementioned widest perceivable color gamut is to use the above-mentioned three primary colors of the widest perceivable color gamut and the xyz chromaticity coordinates of the light source to derive the color from the RGB space to the xyz space The space transformation matrix is shown in formula (1):

$\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}\\ \mathrm{<span\; class="notranslate">\; Y</span>}\\ \mathrm{<span\; class="notranslate">\; Z</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 0.4545</span>}& \mathrm{<span\; class="notranslate">\; 0.3147</span>}& \mathrm{<span\; class="notranslate">\; 0.1822</span>}\\ \mathrm{<span\; class="notranslate">\; 0.1665</span>}& \mathrm{<span\; class="notranslate">\; 0.7857</span>}& \mathrm{<span\; class="notranslate">\; 0.0478</span>}\\ \mathrm{<span\; class="notranslate">\; 0.0082</span>}& \mathrm{<span\; class="notranslate">\; 0.0097</span>}& \mathrm{<span\; class="notranslate">\; 1.0715</span>}\end{array}\right]\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; R</span>}\\ \mathrm{<span\; class="notranslate">\; G</span>}\\ \mathrm{<span\; class="notranslate">\; B</span>}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

According to equation (1), the luminance and two chrominance signals are:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}\mathrm{<span\; class="notranslate">\; B</span>}\\ \mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.8335</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}\mathrm{<span\; class="notranslate">\; B</span>}\\ \mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.9522</span>}\mathrm{<span\; class="notranslate">\; B</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

With the new three primary colors of the gained of the present invention, according to the color matching ratio, the color bar signal is as shown in table 3:

Table 3. New Sanji color bar signal color matching ratio

_LR , L _G , and L _B correspond to E′ _R , E′ _G , and E′ _B after gamma correction. Based on the new three primary colors and using formula (2) to encode the color bar signal, its luminance and two chrominance component signals are shown in Table 4:

Table 4. The luminance and chrominance signals obtained by encoding the new three-base color bar signal according to formula (2)

The peak-to-peak value of E' _R -E' _Y signal in table 4 is 1.667, and the present invention determines that the compression factor of signal E' _CR is 1.667;

Similarly, the compression factor of the signal E′ _CB is 1.9044;

Based on the above analysis and formula (2), the present invention obtains transmission signals E′ _Y , E′ _CB , E′ _CR by encoding as shown in the encoding equation (3):

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; CR</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.4713</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0287</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; CB</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0874</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.4126</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The luminance and chrominance component signals of the color bar signal based on the new three primary colors encoded by formula (3) are shown in Table 5:

Table 5. Luminance and chrominance component signals obtained by encoding the new three-base color bar signal formula (3)

The dynamic range of the luminance signal E′ _Y encoded in Table 5 of the present invention is [0,1], and the dynamic range of the chrominance signal E′ _CB , E′ _CR is [-0.5, 0.5], and this dynamic range signal can be used by ITU- In the traditional linear quantization method given by R BT.709, E′ _Y will be quantized to [16, 235], and E′ _CB and E′ _CR will be quantized to [16, 240]. In the current color TV system Compatible transmission.

The present invention has the following technical effects:

The present invention is based on ITU-R BT.1361, uses the traversal method to obtain the maximum color gamut visible to the human eye of the video system within the range specified by ITU-R BT.1361, and uses the color bar signal composed of three primary colors and their complementary colors to derive the corresponding New three primary colors with wide color gamut, and then give the implementation of luminance and chrominance signal encoding using the new three primary colors.

Description of drawings

Figure 1 The widest color gamut achievable by ITU-R BT.1361 and its comparison with the conventional color gamut of ITU-R BT.709.

Detailed ways

The present invention is based on the ITU-R BT.1361 standard, and derives the widest perceivable color gamut corresponding to the standard and a coding implementation scheme.

ITU-R BT.1361 is a wide color gamut standard for video systems. It takes the Pointer color gamut as the target color gamut, and stipulates that the dynamic range of the red, green and blue three-color gamma-corrected input signals L _R , L _G , and L _B is [- 0.25, 1.33]. Obviously, when the signals L _R , L _G , and _LB are randomly selected within this range, some colors constructed will be outside the tongue-shaped spectral curve, that is, colors invisible to human eyes.

In order to obtain the widest perceivable color gamut defined by the range [-0.25, 1.33], the present invention uses the method of traversal point calculation, that is, the values of L _R , L _G , and L _B are randomly selected within the range of [-0.25, 1.33] , compare the color obtained by taking each set of values with the tongue-shaped spectral curve to obtain all perceivable colors, and according to the characteristics of the color bar signal, the three corresponding to the widest perceivable color gamut of ITU-R BT.1361 are deduced Primary colors, and derive the coding implementation scheme based on the new three primary colors.

The transmission and reproduction of the widest perceivable color gamut of ITU-R BT.1361 can be realized by using the three primary colors and its coding scheme proposed by the present invention.

Below in conjunction with accompanying drawing and embodiment further illustrate the present invention.

In the data calculation, the present invention takes the traversal step length of _LR , L _G and _LB as 0.01, tests ¹⁵⁹³ colors in total, and detects whether each color is located in the area surrounded by the tongue-shaped spectral curve. If yes, it means that the color is perceivable by human eyes, record the color and calculate its u'v' coordinate in the three-dimensional color space L*u'v'. The test results show that among a total of 159 ³ tested colors, 81.59% are perceivable by human eyes.

The color TV system is based on the principle of three primary colors and the principle of additive color mixing. The triangular area defined by the three primary colors on the chromaticity diagram is the maximum color gamut that the color TV system can achieve. Color bar signals based on this design are commonly used in color TV system design and testing. Usually the color bar signal consists of three primary colors of red (R), green (G), and blue (B) and their complementary colors (cyan, magenta, yellow), as well as a white bar and a black bar. Among the eight colors, the white and black bars correspond to the maximum and minimum values of the luminance signal E′ _Y , the blue and yellow signals correspond to the maximum and minimum values of the blueness signal E′ _CB , and the red and cyan correspond to the maximum and minimum values of the redness signal E′ _CB respectively. Based on the above analysis, compare the luminance signal values and chrominance signal values of all perceivable colors defined by the range [-0.25, 1.33] to obtain the maximum and minimum values. The results are listed in Table 1.

Table 1. The maximum and minimum values of luminance and chrominance signals and the corresponding six colors and their chromaticity coordinates

Table 1 gives the maximum and minimum values of the signals E' _Y , E' _CB , E' _CR , their corresponding colors and their chromaticity coordinates in the u'v' coordinate system. According to the experimental results shown in Table 1, the primary colors of blue and red and the complementary colors of yellow and cyan can be obtained.

To obtain another green primary color, the present invention adopts a mapping method. First, in the u'v' coordinate system, respectively determine the "blue" corresponding to "E' _CB _max", the "yellow" corresponding to "E' _CB _min", and the "red" corresponding to "E' _CR _max" , corresponding to the "cyan" of "E′ _CR _min", the intersection point of rays "blue-cyan" and "red-yellow" is "green", and the intersection point of rays "green-D65" and "blue-red" is For "color". In this way, the coordinates of the green primary color and its complementary magenta color in the u'v' coordinate system can be obtained, and the calculated data are (0.1038, 0.5830) and (0.3594, 0.2717) respectively.

The triangular area defined by the three primary colors obtained above is the widest color gamut that can be realized by a video system based on the principle of three primary colors in accordance with the ITU-R BT.1361 standard, as shown in the dotted line triangle in Figure 1, and its color gamut covers The rate is 60.65%. Figure 1 also compares the conventional color gamut given by the ITU-R BT.709 standard, as shown by the dotted triangle in Figure 1, and its color gamut coverage is 33.24%.

Because the green and magenta coordinates found in the u'v' coordinate system by the above mapping method do not contain brightness information, it is not yet possible to obtain the L _R , L _G , and L _B values of these two colors according to their u'v' coordinates . For this reason, the present invention continues to use the traversal method, and within the scope of [-0.25, 1.33], respectively find the same value as "green" (0.1038, 0.5830), "magenta" (0.3594, 0.2717) chromaticity coordinates, then Get the _LR , L _G , and _LB values of these two colors. The results show that there is a set of values corresponding to the chromaticity coordinates of these two colors.

In summary, the human eyes derived from the present invention are visible, conform to the ITU-R BT.1361 standard, and have the largest signal dynamic range. The color bar signal parameters representing the primary color, complementary color and neutral color of the TV system are shown in Table 2.

Table 2. Color bar signal parameters visible to the human eye, conforming to the ITU-R BT.1361 standard, and having the widest color gamut

According to the present invention listed in Table 2, the new three primary colors corresponding to ITU-R BT.1361 and having the widest perceptual color gamut are derived, and the present invention further provides a coding implementation method. This approach is based on this new set of three primary colors, implemented by the following new encoding equations for luminance and chrominance signals.

The present invention is light source with D65, with the xyz chromaticity coordinates of above-mentioned new three primary colors and D65, the RGB space that derives is shown in formula (1) to the color space conversion matrix of XYZ space:

$\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}\\ \mathrm{<span\; class="notranslate">\; Y</span>}\\ \mathrm{<span\; class="notranslate">\; Z</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 0.4545</span>}& \mathrm{<span\; class="notranslate">\; 0.3147</span>}& \mathrm{<span\; class="notranslate">\; 0.1822</span>}\\ \mathrm{<span\; class="notranslate">\; 0.1665</span>}& \mathrm{<span\; class="notranslate">\; 0.7857</span>}& \mathrm{<span\; class="notranslate">\; 0.0478</span>}\\ \mathrm{<span\; class="notranslate">\; 0.0082</span>}& \mathrm{<span\; class="notranslate">\; 0.0097</span>}& \mathrm{<span\; class="notranslate">\; 1.0715</span>}\end{array}\right]\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; R</span>}\\ \mathrm{<span\; class="notranslate">\; G</span>}\\ \mathrm{<span\; class="notranslate">\; B</span>}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

According to equation (1), the luminance and two chrominance signals are:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}\mathrm{<span\; class="notranslate">\; B</span>}\\ \mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.8335</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}\mathrm{<span\; class="notranslate">\; B</span>}\\ \mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.9522</span>}\mathrm{<span\; class="notranslate">\; B</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

With the new three primary colors of the gained of the present invention, according to the color matching ratio, the color bar signal is as shown in table 3:

Table 3. New Sanji color bar signal color matching ratio

L _R , L _G , L _B are gamma-corrected to become E′ _R , E′ _G , E′ _B . Based on the new three primary colors and using formula (2) to encode the color bar signal, its luminance and two chrominance component signals are shown in Table 4:

Table 4. The luminance and chrominance signals obtained by encoding the new three-base color bar signal according to formula (2)

The peak-to-peak value of the E' _R -E' _Y signal in Table 4 is 1.667, and the present invention determines that the compression factor of the signal E' _CR is 1.667. Similarly, the compression factor of the signal E′ _CB is 1.9044.

Based on the above analysis and formula (2), the present invention obtains the transmission signal E′ _Y , E′ _CR , E′ _CB by encoding as shown in the encoding equation (3):

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; CR</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.4713</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0287</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; CB</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0874</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.4126</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.5</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The luminance and chrominance component signals of the color bar signal based on the new three primary colors encoded by formula (3) are shown in Table 5:

Table 5. Luminance and chrominance component signals obtained by encoding the new three-base color bar signal formula (3)

The dynamic range of the luminance signal E' _Y encoded according to Table 5 in the present invention is [0, 1], and the dynamic range of the chrominance signals E' _CR and E' _CB is [-0.5, 0.5]. This dynamic range signal can be quantized by the traditional linear quantization method given by ITU-R BT.709, E′ _Y will be quantized to [16, 235], E′ _CR and E′ _CB will be quantized to [16, 240 ], compatible transmission in the current color television system.

Beneficial effect

The current common conventional color gamut is far from the visible color gamut of the human eye. ITU-R BT.1361 is a wide color gamut standard for digital video systems. It takes the Pointer color gamut as the target color gamut and specifies the dynamics of the gamma correction input signal. The range is [-0.25, 1.33], and the positive and negative asymmetric gamma correction curve is used to realize the compression of the wide color gamut video signal. The present invention is based on ITU-R BT.1361, uses the traversal method to obtain the maximum color gamut visible to the human eye of the video system within the range specified by ITU-R BT.1361, and uses the color bar signal composed of three primary colors and their complementary colors to derive the corresponding New three primary colors with wide color gamut, and then give the implementation of luminance and chrominance signal encoding using the new three primary colors.

Adopting the new three primary colors and the luminance and chrominance signal coding equations proposed by the present invention can approximately double the color gamut coverage rate of the digital television system transmission color gamut, from 33.24% of the current conventional color gamut to 60.65%, realizing ITU -R BT.1361 allows the maximum perceivable color gamut of signal dynamic range and enables compatible transmission of coded luminance and chrominance signals in existing color television systems.

The three primary colors of the digital color television system are defined as the three primary colors proposed by the present invention, and their chromaticity coordinates are shown in Table 2. Perform nonlinear correction on the input wide color gamut color TV signal according to the gamma correction method specified in ITU-R BT.1361, and then perform analog component signal encoding on the corrected primary color signal according to formula (3) to obtain brightness and chrominance signals , and then through traditional digital encoding, it can be compatible with the current color TV system for transmission, so that the color gamut of the color TV signal obtained by the receiving end can reach a maximum of 60.65%.

Claims (4)

1. A coding method based on obtaining the three primary colors of the widest perceivable color gamut, which is characterized in that, using the method of traversal point calculation, that is, the red, green, and blue three primary colors gamma-corrected input signals L _R , L _G , and L _B are respectively Randomly select values within the range of [-0.25, 1.33], compare the color obtained by each set of values with the tongue-shaped spectral curve to obtain all perceptible colors, and according to the characteristics of the color bar signal, the corresponding ITU-R The three primary colors of the widest perceivable color gamut of BT.1361, and derive an encoding implementation scheme based on the aforementioned three primary colors of the widest perceivable color gamut. 2. The encoding method based on obtaining the three primary colors of the widest perceivable color gamut according to claim 1, wherein the gamma-corrected input signals L _R , L _G , and L _B of the three primary colors of red, green, and blue are respectively Randomly select values within the range of [-0.25, 1.33], compare the color constructed by each set of values with the tongue-shaped spectral curve to obtain all perceptible colors, and take the traversal step size of L _R , L _G , and L _B as 0.01, a total of 159 ³ colors are tested to detect whether each color is located in the area surrounded by the tongue-shaped spectral curve. If it is, it means that the color is a color that can be perceived by the human eye. Record the color and calculate it in the three-dimensional color space L * The u'v' coordinates in u'v', the white and black bars correspond to the maximum and minimum values of the luminance signal E' _Y respectively, and the blue and yellow signals correspond to the maximum values of the blueness signal E' _CB respectively and the minimum value, while red and cyan correspond to the maximum and minimum values of the redness signal _E′CR , respectively, comparing the luminance signal values and chrominance signal values of all perceivable colors defined by the range [-0.25, 1.33] , the maximum and minimum values can be obtained, and the results are listed in Table 1: Table 1. The maximum and minimum values of luminance and chrominance signals and the corresponding six colors and their chromaticity coordinates According to the results shown in Table 1, the primary colors of blue and red and the complementary colors of yellow and cyan can be obtained. 3. The encoding method based on obtaining the three primary colors of the widest perceivable color gamut according to claim 1, wherein the three primary colors obtained corresponding to the widest perceivable color gamut of ITU-R BT.1361 through derivation are , using the method of traversing the point calculation method to obtain the blue, red primary color and yellow, cyan complementary color chromaticity coordinates, using the mapping method: first determine the "blue" corresponding to "E' _CB _max respectively in the u'v' coordinate system, "Yellow" corresponding to "E′ _CB _min", "Red" corresponding to "E′ _CR _max", "cyan" corresponding to "E _CR _min", rays "blue-cyan" and "red-yellow" The intersection point of the ray is "green", and the intersection point of the rays "green-D65" and "blue-red" is the "magenta", thus, the green primary color and its complementary magenta color can be obtained in the u′v′ coordinate system coordinates, the calculated data are (0.1038, 0.5830) and (0.3594, 0.2717) respectively, continue to use the traversal method, in the range of [-0.25, 1.33], respectively find the "green" (0.1038, 0.5830), "magenta "(0.3594, 0.2717) have the same value in chromaticity coordinates, so we know the L _R , L _G , and L _B values of these two colors. 4. The encoding method based on obtaining the three primary colors of the widest perceivable color gamut according to claim 1, wherein said deriving the encoding implementation scheme based on the three primary colors of the aforementioned widest perceivable color gamut is to use the above-mentioned The xyz chromaticity coordinates of the three primary colors of the widest perceivable color gamut and the light source, the derived color space conversion matrix from RGB space to XYZ space is shown in formula (1): $\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}\\ \mathrm{<span\; class="notranslate">\; Y</span>}\\ \mathrm{<span\; class="notranslate">\; Z</span>}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; 0.4545</span>}& \mathrm{<span\; class="notranslate">\; 0.3147</span>}& \mathrm{<span\; class="notranslate">\; 0.1822</span>}\\ \mathrm{<span\; class="notranslate">\; 0.1665</span>}& \mathrm{<span\; class="notranslate">\; 0.7857</span>}& \mathrm{<span\; class="notranslate">\; 0.0478</span>}\\ \mathrm{<span\; class="notranslate">\; 0.0082</span>}& \mathrm{<span\; class="notranslate">\; 0.0097</span>}& \mathrm{<span\; class="notranslate">\; 1.0715</span>}\end{array}\right]\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; R</span>}\\ \mathrm{<span\; class="notranslate">\; G</span>}\\ \mathrm{<span\; class="notranslate">\; B</span>}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ According to equation (1), the luminance and two chrominance signals are: $\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}\mathrm{<span\; class="notranslate">\; B</span>}\\ \mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.8335</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.0478</span>}\mathrm{<span\; class="notranslate">\; B</span>}\\ \mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.1665</span>}\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.9522</span>}\mathrm{<span\; class="notranslate">\; B</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ With the new three primary colors of the gained of the present invention, according to the color matching ratio, the color bar signal is as shown in table 3: Table 3. New Sanji color bar signal color matching ratio

_LR , L _G , and L _B correspond to E′ _R , E′ _G , and E′ _B after gamma correction. Based on the new three primary colors and using formula (2) to encode the color bar signal, its luminance and two chrominance component signals are shown in Table 4: Table 4. The luminance and chrominance signals obtained by encoding the new three-base color bar signal according to formula (2)

The peak-to-peak value of E' _R -E' _Y signal in table 4 is 1.667, and the present invention determines that the compression factor of signal E' _CR is 1.667; Similarly, the compression factor of the signal E′ _CB is 1.9044; Based on the above analysis and formula (2), the present invention obtains the transmission signals E′ _Y , E′ _CB , E′ _CR by encoding as shown in the encoding equation (3) $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 0.1665</span>}\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.7857</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; 0.0478</span>}\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; CR</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 0.5</span>}\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; 0.4713</span>}\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; 0.0287</span>}\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\\ {\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; CB</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; 0.0874</span>}\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 0.4126</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; 0.5</span>}\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$ The luminance and chrominance component signals of the color bar signal based on the new three primary colors encoded by formula (3) are shown in Table 5: Table 5. Luminance and chrominance component signals obtained by encoding the new three-base color bar signal formula (3)

The dynamic range of the luminance signal E′ _Y coded according to Table 5 is [0, 1], and the dynamic range of the chrominance signals E′ _CB and E′ _CR is [-0.5, 0.5]. This dynamic range signal can be used in ITU-R BT The traditional linear quantization method given in .709 quantizes, E′ _Y will be quantized to [16, 235], E _CB and E _CR will be quantized to [16, 240], and are compatible for transmission in the current color TV system.

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