CN104796679A - Laser display color adjusting method and device thereof - Google Patents

Abstract

The invention discloses a laser display color adjusting method, which comprises steps: raw data signals in a RGB format of one frame of laser image are acquired; the format of the raw data signals is converted to generate data signals in an L*C*h format; a tone corresponding to a tone range with concentrated pixel points is recorded to be a main tone of the laser image and a main tone influence function is set; a saturation influence function is set, the main tone influence function is introduced at the same time if the main tone exists in the laser image, and saturation mapping is carried out on all pixel points in the data signals; a tone weight function is set to carry out tone mapping on all pixel points in the data signals; a light illumination mapping function is set to carry out light illumination mapping on all pixel points; and the format of the data signals is converted to the RGB format and display is carried out. By adopting different tone, saturation and light illumination mapping relationships, ill questions of over saturation, over illumination, easy visual fatigue and the like can be solved. The invention also discloses a laser display color adjusting device.

Description

Color adjusting method and device for laser display

Technical Field

The invention belongs to the field of semiconductor lasers, and particularly relates to a color adjusting method and device for laser display.

Background

The traditional color management means that the color is automatically and uniformly managed and adjusted in a production system by using a method of combining software and hardware so as to ensure the consistency of the color in the whole process. Conventional color management methods are the mapping from a large gamut to a small gamut, including gamut clipping algorithms and gamut compression algorithms. Color gamut clipping algorithm: colors inside the target color gamut are not processed and colors outside the target color gamut are replaced with edge colors. Color gamut compression algorithm: and the effect of the whole image is uniformly changed, and the same or different functions are adopted for mapping the pixel points in different color gamut spaces. Both algorithms will cause different colors in the original image to appear in the same or close colors after passing through the gamut mapping algorithm.

As shown in fig. 8, since the color gamut of the laser source is much larger than that of the original tv standard signal, which is equal to 185% of the color gamut of the conventional NTSC, more than 90% of the colors that can be recognized by human eyes can be reproduced theoretically. Since most conventional image signals are encoded in the NTSC color gamut (or other standards, such as PAL system with smaller color gamut), if the image is reproduced directly in the laser color gamut, the image will be oversaturated and showy visual perception for the user, and the visual fatigue is easily generated.

Disclosure of Invention

The invention overcomes the defect that oversaturated and gorgeous images are caused by carrying out color adjustment on images of an NSTC color gamut in a laser color gamut in the prior art, and provides a color adjustment method and a device for laser display.

The invention provides a color adjusting method for laser display, which comprises the following steps:

the method comprises the following steps: acquiring an original data signal of a frame of laser image in an RGB format;

step two: converting the format of the original data signal to generate a data signal with an L C h format;

step three: calculating the distribution of pixel points of the data signal in a hue range, recording the hue corresponding to the hue range in the pixel point set as the dominant hue of the laser image and setting a dominant hue influence function, otherwise, the laser image has no dominant hue;

step four: dividing the hue range into at least one hue interval, setting a saturation influence function of pixel points in the at least one hue interval about saturation mapping, and if the laser image has a dominant hue, simultaneously introducing the dominant hue influence function to perform saturation mapping on all the pixel points in the data signal;

step five: setting a mappable range of each tone to obtain a tone weight function, and carrying out tone mapping on all pixel points in the data signal;

step six: calculating the illuminance values of all the pixel points in the original data signal, setting an illuminance mapping function of the illuminance values in a plurality of illuminance intervals, and mapping the illuminance of all the pixel points in the data signal;

step seven: and converting the format of the data signal into an RGB format, and outputting the data signal to a laser for laser display.

In the color adjustment method for laser display provided by the invention, in the second step, the original data signal in the RGB format is converted into the data signal in the XYZ format, and then the data signal in the XYZ format is converted into the data signal in the L × C × h format.

In the color adjustment method for laser display provided by the invention, the converted data signal in XYZ format is as shown in the following formula table:

$\left[\begin{array}{c}{C}_r\\ C_g\\ C_b\end{array}\right]={\left[\begin{array}{ccc}{x}_r& x_g& x_b\\ y_r& y_g& y_b\\ z_r& z_g& z_b\end{array}\right]}^{-1}\left[\begin{array}{c}{x}_n/y_n\\ 1\\ z_n/y_n\end{array}\right];$

in the above formula, C_r，C_g，C_bCoefficient of matching component, x, of the three primary colors R, G, B, respectively_rX-axis coordinate, y, representing the primary color r_rY-axis coordinate, z, representing the primary color r_rZ-axis coordinate, x, representing the primary color r_gX-axis coordinate, y, representing the primary color g_gY-axis coordinate, z, representing the primary color g_gZ-axis coordinate, x, representing the primary color g_bX-axis coordinate, y, representing the primary color b_bY-axis coordinate, z, representing the primary color b_bZ-axis coordinate, X, representing the primary color b_n，Y_n，Z_nFor reference illuminationBody tristimulus values.

In the color adjustment method for laser display provided by the invention, the converted data signals in L, C, h format are expressed by the following formula:

<math> <mrow> <mfenced open='{' close=','> <mtable> <mtr> <mtd> <mi>L</mi> <mo>*</mo> <mo>=</mo> <mn>116</mn> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mn>16</mn> </mtd> </mtr> <mtr> <mtd> <mi>a</mi> <mo>*</mo> <mo>=</mo> <mn>500</mn> <mo>[</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>X</mi> <mo>/</mo> <msub> <mi>X</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>]</mo> </mtd> </mtr> <mtr> <mtd> <mi>b</mi> <mo>*</mo> <mo>=</mo> <mn>200</mn> <mo>[</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Z</mi> <mo>/</mo> <msub> <mi>Z</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>]</mo> </mtd> </mtr> </mtable> </mfenced> <mo>,</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msup> <mi>C</mi> <mo>*</mo> </msup> <mo>=</mo> <msqrt> <msup> <mrow> <mo>(</mo> <msup> <mi>a</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msup> <mrow> <mo>(</mo> <msup> <mi>b</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mn>2</mn> </msup> </msqrt> </mtd> </mtr> <mtr> <mtd> <mi>h</mi> <mo>=</mo> <mrow> <mo>(</mo> <mn>180</mn> <mo>/</mo> <mi>&pi;</mi> <mo>)</mo> </mrow> <mi>arctan</mi> <mrow> <mo>(</mo> <msup> <mi>b</mi> <mo>*</mo> </msup> <mo>/</mo> <msup> <mi>a</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mo>,</mo> </mtd> </mtr> </mtable> </mfenced> </mrow> </math>

wherein, <math> <mrow> <mi>f</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msup> <mi>t</mi> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> <mtd> <mi>t</mi> <mo>&GreaterEqual;</mo> <msup> <mrow> <mo>(</mo> <mn>6</mn> <mo>/</mo> <mn>29</mn> <mo>)</mo> </mrow> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> </mtr> <mtr> <mtd> <mfrac> <mn>1</mn> <mn>3</mn> </mfrac> <msup> <mrow> <mo>(</mo> <mfrac> <mn>29</mn> <mn>6</mn> </mfrac> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mi>t</mi> <mo>+</mo> <mn>16</mn> <mo>/</mo> <mn>116</mn> </mtd> <mtd> <mi>t</mi> <mo>&lt;</mo> <msup> <mrow> <mo>(</mo> <mn>6</mn> <mo>/</mo> <mn>29</mn> <mo>)</mo> </mrow> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> </mtr> </mtable> </mfenced> <mo>;</mo> </mrow> </math>

in the above formula, X_n，Y_n，Z_nThe three stimulation values of the reference illuminants in the laser images, L represents the illuminance of the pixel points, a and b represent opposite dimensions of the pixel points,c denotes the saturation of the pixel, h denotes the hue of the pixel, and t is a variable of the function f (t).

In the method for adjusting color of laser display provided by the invention, in the third step, if the number of pixels in a color gamut range exceeds 30% of the total number of pixels and is averagely higher than the number of pixels in the remaining color gamut range by more than 50%, or the number of pixels in the color gamut range exceeds 50% of the total number of pixels, the color tone corresponding to the color gamut range is recorded as the main color tone of the laser image.

In the color adjustment method for laser display provided by the invention, in the fourth step, after saturation mapping, the saturation of the pixel point is represented as the following formula:

C*₁－C*₀×P(C*₀×h×L*)×I(h)；

in the formula, C₁Representing the saturation value, C, of the pixel point after saturation mapping₀Representing the saturation value, P (C), of a pixel that has not been mapped to saturation₀Xh × L) represents an influence function of the hue of the pixel with respect to saturation mapping, and i (h) represents a dominant hue influence function of the dominant hue with respect to saturation mapping.

In the color adjustment method for laser display provided by the invention, in the fourth step, the tone of the pixel point after tone mapping is represented by the following formula:

h₁－h₀×e(h₀)；

in the formula, h₁Representing the tone value, h, of the tone-mapped pixel₀Representing tone values of non-tone-mapped pixels, e (h)₀) Representing a tone weight function.

In the color adjustment method for laser display provided by the present invention, the relationship of the illuminance mapping in the fourth step is represented by the following formula:

L*₁－L*₀×f(L*₀)；

in the formula, L₁Representing the illuminance, L, of the mapped pixel₀Representing the illumination of the unmapped pixel points, and f (L0) represents an illumination weighting function.

The invention also provides a color adjusting device for laser display, comprising: a format conversion device for converting an original data signal in an RGB format for laser display into a data signal in an L × C × h format; image analysis means for acquiring a dominant hue of an image displayed by the laser light; saturation mapping means, respectively connected to the format conversion means and the image analysis means, for performing saturation mapping on the data signal; tone mapping means, connected to said format conversion means and said image analysis means, respectively, for tone mapping said data signal; illumination intensity mapping means, respectively connected to the format conversion means and the image analysis means, for performing tone mapping on the data signal; and a format inverse conversion device which is respectively connected with the saturation mapping device, the tone mapping device and the illumination mapping device and is used for converting the data signals in the L C h format into RGB format data signals for laser display.

The beneficial effects of the invention include: the method has the advantages of fully playing the advantage of large laser color gamut, converting the RGB format data signal into the L C h format data signal, carrying out color adjustment in the L C h format, providing a mapping relation suitable for different hues, saturation and illuminance in the mode, and solving the problems of over-saturation, over-gorgeous, easy visual fatigue and the like. The invention also realizes the real-time dynamic color gamut range adjustment, and adjusts the discovery range of the color gamut in real time according to the image content so as to achieve the dynamic image display and achieve a better visual effect.

Drawings

FIG. 1 is a flow chart of a color adjustment method for laser display according to the present invention.

Fig. 2 is a graph of maximum saturation for different hues.

Fig. 3 is a schematic diagram of the division of the saturation C intervals before the saturation mapping of the present invention.

FIG. 4 is a tone map during tone mapping of the present invention.

FIG. 5 is a diagram illustrating the correspondence between the Y component value and the brightness level of the image according to the present invention.

FIG. 6 is a schematic structural diagram of a color adjusting apparatus for laser display according to the present invention.

Fig. 7 is a circuit diagram of the present embodiment for implementing the functions of the present invention by an FPGA architecture.

Fig. 8 is a prior art laser color gamut and NTSC color gamut comparison.

Detailed Description

The present invention will be described in further detail with reference to the following specific examples and the accompanying drawings. The procedures, conditions, experimental methods and the like for carrying out the present invention are general knowledge and common general knowledge in the art except for the contents specifically mentioned below, and the present invention is not particularly limited.

FIG. 1 is a flow chart showing a color adjustment method for laser display according to the present invention, which comprises the following steps:

the method comprises the following steps: and acquiring an RGB format raw data signal of a frame of laser image.

Step two: and converting the format of the original data signal to generate the data signal with the format of L C h.

Step three: and calculating the distribution of the pixel points of the data signal in a hue range, recording the hue corresponding to the hue range in the pixel point set as the dominant hue of the laser image and setting a dominant hue influence function, otherwise, the laser image has no dominant hue.

Step four: dividing the hue range into at least one hue interval, setting a saturation influence function of pixel points in the at least one hue interval about saturation mapping, and if the laser image has a dominant hue, introducing the dominant hue influence function at the same time to perform saturation mapping on all the pixel points in the data signal.

Step five: and setting the mappable range of each tone to obtain a tone weight function, and performing tone mapping on all pixel points in the data signal.

Step six: and calculating the illuminance values of all the pixel points in the original data signal, setting an illuminance mapping function of the illuminance values in different illuminance intervals, and mapping the illuminance of all the pixel points in the data signal.

Step seven: and converting the format of the data signal into an RGB format, and outputting the data signal to a laser for laser display.

The laser image obtained through the steps has a better visual effect, and the steps are further described as follows:

in the first step, the original data signal of the laser image of one frame is obtained from the continuous laser display images for mapping. The laser image is displayed in red, green and blue colors (i.e., three primary colors of light), and the format of the raw data signal is the corresponding RGB format. R, G, B show red, green, and blue light data, respectively.

In the second step, the original data signal in the RGB format is converted into the data signal in the L C h format, the original data signal is firstly converted into the XYZ format from the RGB format, and then the XYZ format is converted into the L C h format, so that the data signal in the L C h format to be mapped subsequently is obtained. Generally, a data signal in RGB format is represented by the following formula 1:

X＝C_rx_rR+C_gx_gG+C_bx_bB

Y＝C_ry_rR+C_gy_gG+C_bY_bB

Z＝C_rz_rR+C_gz_gG+C_bz_bB；------------------(1)

in formula 1, x_rX-axis chromaticity coordinate, y, representing the primary color r_rY-axis chromaticity coordinate, z, representing the primary color r_rZ-axis chromaticity coordinate, x, representing a primary color r_gX-axis chromaticity coordinate, y, representing the primary color g_gY-axis chromaticity coordinate, z, representing the primary color g_gZ-axis chromaticity coordinate, x, representing the primary color g_bX-axis chromaticity coordinate, y, representing the primary color b_bY-axis chromaticity coordinate, z, representing the primary color b_bRepresenting the z-axis chromaticity coordinate of the primary color b. Under different color temperature standards, chromaticity coordinates of three primary colors of RGB are different, and at present, the standard color temperature has a plurality of specifications such as D65 and D50.

The RGB format is a data signal in which an original data signal is converted into XYZ format by the following equation 2, where equation 2 is expressed as follows:

$\left[\begin{array}{c}{C}_r\\ C_g\\ C_b\end{array}\right]={\left[\begin{array}{ccc}{x}_r& x_g& x_b\\ y_r& y_g& y_b\\ z_r& z_g& z_b\end{array}\right]}^{-1}\left[\begin{array}{c}{x}_n/y_n\\ 1\\ z_n/y_n\end{array}\right];---\left(2\right)$

in the formula 2, C_r，C_g，C_bCoefficient of matching component, x, of the three primary colors R, G, B, respectively_rX-axis coordinate, y, representing the primary color r_rY-axis coordinate, z, representing the primary color r_rZ-axis coordinate, x, representing the primary color r_gX-axis coordinate, y, representing the primary color g_gY-axis coordinate, z, representing the primary color g_gZ-axis coordinate, x, representing the primary color g_bX-axis coordinate, y, representing the primary color b_bY-axis coordinate, z, representing the primary color b_bZ-axis coordinate, X, representing the primary color b_n，Y_n，Z_nIs the reference illuminant tristimulus value in the image.

After converting the signal into XYZ format, the signal is converted into L × C × h format, and the generated data signal is represented by the following formula 3:

<math> <mrow> <mfenced open='{' close=','> <mtable> <mtr> <mtd> <mi>L</mi> <mo>*</mo> <mo>=</mo> <mn>116</mn> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mn>16</mn> </mtd> </mtr> <mtr> <mtd> <mi>a</mi> <mo>*</mo> <mo>=</mo> <mn>500</mn> <mo>[</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>X</mi> <mo>/</mo> <msub> <mi>X</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>]</mo> </mtd> </mtr> <mtr> <mtd> <mi>b</mi> <mo>*</mo> <mo>=</mo> <mn>200</mn> <mo>[</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Z</mi> <mo>/</mo> <msub> <mi>Z</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>]</mo> </mtd> </mtr> </mtable> </mfenced> <mo>,</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msup> <mi>C</mi> <mo>*</mo> </msup> <mo>=</mo> <msqrt> <msup> <mrow> <mo>(</mo> <msup> <mi>a</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msup> <mrow> <mo>(</mo> <msup> <mi>b</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mn>2</mn> </msup> </msqrt> </mtd> </mtr> <mtr> <mtd> <mi>h</mi> <mo>=</mo> <mrow> <mo>(</mo> <mn>180</mn> <mo>/</mo> <mi>&pi;</mi> <mo>)</mo> </mrow> <mi>arctan</mi> <mrow> <mo>(</mo> <msup> <mi>b</mi> <mo>*</mo> </msup> <mo>/</mo> <msup> <mi>a</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mo>,</mo> </mtd> </mtr> </mtable> </mfenced> </mrow> </math>

wherein, <math> <mrow> <mi>f</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msup> <mi>t</mi> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> <mtd> <mi>t</mi> <mo>&GreaterEqual;</mo> <msup> <mrow> <mo>(</mo> <mn>6</mn> <mo>/</mo> <mn>29</mn> <mo>)</mo> </mrow> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> </mtr> <mtr> <mtd> <mfrac> <mn>1</mn> <mn>3</mn> </mfrac> <msup> <mrow> <mo>(</mo> <mfrac> <mn>29</mn> <mn>6</mn> </mfrac> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mi>t</mi> <mo>+</mo> <mn>16</mn> <mo>/</mo> <mn>116</mn> </mtd> <mtd> <mi>t</mi> <mo>&lt;</mo> <msup> <mrow> <mo>(</mo> <mn>6</mn> <mo>/</mo> <mn>29</mn> <mo>)</mo> </mrow> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> </mtr> </mtable> </mfenced> <mo>;</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow> </math>

in the above formula 3, X_n，Y_n，Z_nThe three stimulus values of the reference illuminants in the laser images are represented, L represents the illuminance of the pixel points, a and b represent opposite dimensions of the pixel points, C represents the saturation of the pixel points, h represents the hue of the pixel points, and t is a variable of a function f (t).

The obtained data signal in L × C × h format includes data on saturation C, illuminance L, and hue h, so that color adjustment of the laser image can be realized by changing the data.

First, the main tone of the laser image corresponding to the data signal is analyzed in step three. The hue range of the pixel points is from 0 to 360, and the distribution of the pixel points of the data signal in the whole color gamut range is calculated firstly. If the number of pixels in a color gamut range exceeds 30% of the total number of pixels and is averagely higher than the number of pixels in the rest color gamut range by more than 50%, or the number of pixels in the color gamut range exceeds 50% of the total number of pixels, recording the color tone corresponding to the color gamut range as the main color tone of the laser image

The reason why the main tone of the laser image is judged in the present invention is that the visual perception of the user is different when the main tone and other colors produce the same saturation change. For example, when the dominant hue of the image is a, then the visual difference of the a color by the user is lower, that is, when the a color and other colors have the same saturation change, the difference visual perception is different, and the user considers that the a color has less change. And similarly, the A color needs to change in a smaller range when the same visual difference change needs to be satisfied. When the dominant hue of the image is a, the visual difference of the B color by the user is higher, that is, when the same saturation changes occur between the B color and other colors, the difference visual perception is different, and the user considers that the B color changes more. And on the same reason, the required change range of the B color is wider when the same visual difference change needs to be met.

When it is determined through the above steps that there is a significant dominant hue in the laser image, the number of pixels corresponding to the dominant hue is significantly greater than the number of pixels corresponding to other hues, and a drastic regional change occurs in the hue analysis map. However, when the image is rich in color and does not have a dominant hue, the number of pixels corresponding to each hue is averaged, and there is no drastic regional variation in the hue analysis map. The saturation mapping effect is realized by setting a dominant hue influence function.

Since the pixels of different colors have different maximum saturation degrees under laser display, the abscissa in fig. 2 represents the range of the color hue h from 0 to 360, and the ordinate represents the range of the color saturation C. The saturation of the six colors identified in the figure, from left to right, is red, yellow, green, cyan, blue and magenta, with the saturation C of blue (fifth left) being the maximum and the transition color between green and blue being the lowest. Then, in the mapping, the influencing parameter of the saturation C cannot be changed according to the fixed threshold, but changes according to the different hues h corresponding to the different saturations C.

Therefore, in the process of performing saturation mapping on the data signal in the fourth step, the mapping curves of different colors are modified to generate the saturation influence function. As shown in fig. 3, the saturation range is divided into four intervals, namely C0, C1, C2 and C3. The saturation in the C0 interval is the lowest, and the saturation in the C3 interval is the highest. According to the difference of the saturation C and the corresponding hue h, different mapping standards are applied. The pixels in the lowest saturation C0 range generally appear blurred in hue appearance because their saturation C is very low, and very close to the reference white pixels. If the saturation C of the pixel point in the C0 interval is enlarged, some non-existent colors are brought to the image, and the contrast of the image is seriously affected. Therefore, the saturation C of the pixel points in the interval is kept unchanged or properly reduced as much as possible. For the pixel points in the interval C3, because the saturation C is very large, if the saturation C of the pixel points in the interval is simply enlarged, the image may have a bad visual effect of "cloud mud". Therefore, a reduced mapping rule is adopted for the saturation C of the pixel points in the interval to meet the normal visual requirement of human eyes. For the pixels in the interval between C1 and C2, the saturation C of the pixels can be properly amplified. By the method, the mapping parameters of the pixel points in different saturation ranges are obtained, and the saturation influence function is obtained.

Therefore, the data signal is subjected to saturation mapping by combining the saturation influence function and the dominant color influence function, and the saturation C subjected to saturation mapping is represented by the following formula:

C*₁＝C*₀×P(C*₀×h×L*)×I(h)；------------------------(4)

in formula 4, C₁Representing the saturation value, C, of the pixel point after saturation mapping₀Representing the saturation value, P (C), of a pixel that has not been mapped to saturation₀Xh × L) represents an influence function of the hue of the pixel with respect to saturation mapping, and i (h) represents a dominant hue influence function of the dominant hue with respect to saturation mapping.

And fifthly, setting the mappable range of each tone to obtain a tone weight function, and performing tone mapping on all pixel points in the data signal. For example, in fig. 4, a pixel point a is set as a pixel point to be mapped, and an included angle between a connection line between the point a and the center of the great circle and the horizontal axis is the hue h of the pixel point. And a small circular area taking A as the center of a circle is the area which can be mapped by the pixel point A. The diameter of the mapping area is determined according to different chromatic aberration, the larger the chromatic aberration is, the larger the diameter is, otherwise, the smaller the chromatic aberration is

However, in the actual mapping process, not all the pixels in the small circle can be mapped, because the straight line formed by different pixels and the center of the large circle has different included angles with the horizontal axis, that is, different pixels have different hues. While in the tone mapping process the tone of the color should not be changed, but can be moderately emphasized. E.g., pixel a (assuming that this pixel is red), it can be mapped to pixel a' and pixel a ", respectively, by the previous mapping criteria. But with respect to pixel a, pixel a' appears more yellow and pixel a "is more red. Therefore, according to the tone mapping criteria, pixel a should be mapped to pixel a ", not pixel a'. Thereby, a tone weight function is obtained, and the tone mapping process is completed by the weight function.

After the tone mapping process, the tone of the pixel point is as follows:

h₁＝h₀×e(h₀)；------------------------------(5)

in the formula 5, h₁Representing the tone value, h, of the tone-mapped pixel₀Representing tone values of non-tone-mapped pixels, e (h)₀) Representing a tone weight function.

And in the sixth step, the illumination mapping is carried out on the colors, so that the illumination contrast of the image is kept or improved, and the excellent visual perception is brought to the user. Table 1 shows the comparison of the Y component in the same color space for different gamuts.

TABLE 1 comparison table of Y components in the same color space for different color gamuts

According to the comparative analysis of the pixel points in table 1, two groups of data are pixel points having the same L, C, h components in NTSC (National Television system committee) and Laser (Laser) color gamut, component values in RGB color space, and component values in YUV space illuminance Y, respectively.

Through the analysis of table 1, it can be seen that after ordinary gamut mapping, the illuminance Y component of the pixel point changes, and the change is indeterminate, so the illuminance contrast of the image after gamut management is affected. The illuminance of an RGB color space image is represented by the following formula 5:

Y＝0.299*R+0.587*G+0.114*B：------------(6)

in equation 6, Y represents the illuminance Y component, R represents the red component value, G represents the green component value, and B represents the blue component value.

In step s5, not only the original bright-dark contrast relationship is maintained, but also the image contrast is increased as much as possible, so that the original bright pixel is brighter and the dark pixel is darker, and therefore, further optimized mapping is performed according to the difference of Y. Fig. 5 shows a corresponding relationship between a Y component value and an image brightness degree, where the Y component is used to define the visual brightness of an actual pixel point, and the larger the Y component is, the brighter the pixel point is, and otherwise, the darker the pixel point is.

Assuming that all the pixels are represented in the RGB color space, the interval of the three RGB components is from 0 to 255, and then the interval of the Y component is from 0 to 255. Therefore, when the Y component of a certain pixel is smaller than 64, the pixel is determined to be visually a dark pixel, when the Y component of the certain pixel is larger than 192, the pixel is determined to be visually a bright pixel, and when the Y component is in the interval from 64 to 192, the pixel is determined to be a normal pixel. Therefore, by adopting optimized mapping, dark pixel points are darker, and bright pixel points are brighter.

Under the condition of keeping the three components of L, C, h to be the same, under the color gamut range of NTSC and LASER, the values of the three components of RGB are different, and the size of the component of Y can be obtained according to the formula (5), so that the illuminance contrast of the pixel point A and the pixel point B after saturation and tone mapping is different (namely, the illuminance of the pixel point A before mapping is higher than that of the pixel point B, and the illuminance of the pixel point A after mapping is lower than that of the pixel point B) possibly caused to influence the integral illuminance contrast of the image.

In the sixth step, different changes are made according to the illuminance interval to which the illuminance of the pixel belongs. For example: when the Y component of the pixel point is less than 64, the illuminance mapping may be performed according to the following formula:

$Y_1=A_0-\sqrt{{A_0}^2-{Y_0}^2};---\left(7\right)$

in formula 7, Y₁Is the illuminance, Y, of the mapped pixel₀The illuminance of the pixel point before mapping. The mapped illuminance Y₁Less than Y₀，A₀Is a boundary line of illuminance, less than A₀Are identified as low light pixel points.

When the Y component of the pixel is greater than 192, the illuminance mapping may be performed according to the following formula:

$Y_1=A_1+\sqrt{{(255-A_1)}^2-{(Y_0-255)}^2};---\left(8\right)$

in formula 8, Y₁Is the illuminance, Y, of the mapped pixel₀The illuminance of the pixel point before mapping. The mapped illuminance Y₁Greater than Y₀，A₁Is a boundary line of illuminance greater than A₁Are identified as high-illuminance pixel points. Y and L are components representing the illuminance in different color spaces.

The illuminance of other normal illuminance pixel points is not changed, and the illuminance of the pixel points is A₀And A₁Wherein A is₁Greater than A₀。

And step seven, converting the data signals in the format of L, C and h into data signals in the format of XYZ, converting the data signals into data signals in the format of RGB, and referring to a formula of the inverse conversion process in step one, so that the data signals in the format of L, C and h after color adjustment are converted into data signals in the format of RGB for laser display and output to a laser for display.

Fig. 6 is a schematic structural diagram of a laser display color adjustment apparatus according to the present invention, which mainly includes: a format conversion device 1 for converting an original data signal in an RGB format for laser display into a data signal in an L × C × h format; an image analysis device 2 for acquiring a dominant tone of an image displayed by laser light; a saturation mapping device 3, connected to the format conversion device 1 and the image analysis device 2, respectively, for performing saturation mapping on the data signal; tone mapping means 4 connected to said format conversion means 1 and said image analysis means 2, respectively, for tone mapping said data signals; illumination intensity mapping means 5, respectively connected to said format conversion means 1 and said image analysis means 2, for tone mapping said data signal; and a format inverse conversion device 6 connected to the saturation mapping device 3, the tone mapping device 4, and the illuminance mapping device 5, respectively, for converting the L × C × h format data signal into an RGB format data signal for laser display. The FPGA structure of the color adjusting device for laser display of the invention is shown in figure 7.

The protection of the present invention is not limited to the above embodiments. Variations and advantages that may occur to those skilled in the art may be incorporated into the invention without departing from the spirit and scope of the inventive concept, and the scope of the appended claims is intended to be protected.

Claims (9)

1. A color adjustment method for laser display is characterized by comprising the following steps:

the method comprises the following steps: acquiring an original data signal of a frame of laser image in an RGB format;

step two: converting the format of the original data signal to generate a data signal with an L C h format;

step three: calculating the distribution of pixel points of the data signal in a hue range, recording the hue corresponding to the hue range in the pixel point set as the dominant hue of the laser image and setting a dominant hue influence function, otherwise, the laser image has no dominant hue;

step four: dividing the hue range into at least one hue interval, setting a saturation influence function of pixel points in the at least one hue interval about saturation mapping, and if the laser image has a dominant hue, simultaneously introducing the dominant hue influence function to perform saturation mapping on all the pixel points in the data signal;

step five: setting a mappable range of each tone to obtain a tone weight function, and carrying out tone mapping on all pixel points in the data signal;

step six: calculating the illuminance values of all the pixel points in the original data signal, setting an illuminance mapping function of the illuminance values in a plurality of illuminance intervals, and mapping the illuminance of all the pixel points in the data signal;

step seven: and converting the format of the data signal into an RGB format, and outputting the data signal to a laser for laser display.

2. The color adjustment method for laser display according to claim 1, wherein in the second step, the original data signals in RGB format are first converted into data signals in XYZ format, and then the data signals in XYZ format are converted into data signals in L x C h format.

3. The color adjustment method for laser display according to claim 2, wherein the converted XYZ-format data signal is expressed by the following formula:

$\left[\begin{array}{c}{C}_r\\ C_g\\ C_b\end{array}\right]={\left[\begin{array}{ccc}{x}_r& x_g& x_b\\ y_r& y_g& y_b\\ z_r& z_g& z_b\end{array}\right]}^{-1}\left[\begin{array}{c}{x}_n/y_n\\ 1\\ z_n/y_n\end{array}\right];$

in the above formula, C_r，C_g，C_bCoefficient of matching component, x, of the three primary colors R, G, B, respectively_rX-axis coordinate, y, representing the primary color r_rY-axis coordinate, z, representing the primary color r_rZ-axis coordinate, x, representing the primary color r_gX-axis coordinate, y, representing the primary color g_gY-axis coordinate, z, representing the primary color g_gZ-axis coordinate, x, representing the primary color g_bX-axis coordinate, y, representing the primary color b_bY-axis coordinate, z, representing the primary color b_bZ-axis coordinate, X, representing the primary color b_n，Y_n，Z_nReference illuminant tristimulus values.

4. The method for adjusting color for laser display according to claim 2, wherein the converted data signal in L x C x h format is expressed by the following formula:

<math> <mrow> <mfenced open='{' close=','> <mtable> <mtr> <mtd> <mi>L</mi> <mo>*</mo> <mo>=</mo> <mn>116</mn> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mn>16</mn> </mtd> </mtr> <mtr> <mtd> <mi>a</mi> <mo>*</mo> <mo>=</mo> <mn>500</mn> <mo>[</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>X</mi> <mo>/</mo> <msub> <mi>X</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>]</mo> </mtd> </mtr> <mtr> <mtd> <mi>b</mi> <mo>*</mo> <mo>=</mo> <mn>200</mn> <mo>[</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Y</mi> <mo>/</mo> <msub> <mi>Y</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>-</mo> <mi>f</mi> <mrow> <mo>(</mo> <mi>Z</mi> <mo>/</mo> <msub> <mi>Z</mi> <mi>n</mi> </msub> <mo>)</mo> </mrow> <mo>]</mo> </mtd> </mtr> </mtable> </mfenced> <mo>,</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msup> <mi>C</mi> <mo>*</mo> </msup> <mo>=</mo> <msqrt> <msup> <mrow> <mo>(</mo> <msup> <mi>a</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msup> <mrow> <mo>(</mo> <msup> <mi>b</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mn>2</mn> </msup> </msqrt> </mtd> </mtr> <mtr> <mtd> <mi>h</mi> <mo>=</mo> <mrow> <mo>(</mo> <mn>180</mn> <mo>/</mo> <mi>&pi;</mi> <mo>)</mo> </mrow> <mi>arctan</mi> <mrow> <mo>(</mo> <msup> <mi>b</mi> <mo>*</mo> </msup> <mo>/</mo> <msup> <mi>a</mi> <mo>*</mo> </msup> <mo>)</mo> </mrow> <mo>,</mo> </mtd> </mtr> </mtable> </mfenced> </mrow> </math>

wherein, <math> <mrow> <mi>f</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfenced open='{' close=''> <mtable> <mtr> <mtd> <msup> <mi>t</mi> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> <mtd> <mi>t</mi> <mo>&GreaterEqual;</mo> <msup> <mrow> <mo>(</mo> <mn>6</mn> <mo>/</mo> <mn>29</mn> <mo>)</mo> </mrow> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> </mtr> <mtr> <mtd> <mfrac> <mn>1</mn> <mn>3</mn> </mfrac> <msup> <mrow> <mo>(</mo> <mfrac> <mn>29</mn> <mn>6</mn> </mfrac> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mi>t</mi> <mo>+</mo> <mn>16</mn> <mo>/</mo> <mn>116</mn> </mtd> <mtd> <mi>t</mi> <mo>&lt;</mo> <msup> <mrow> <mo>(</mo> <mn>6</mn> <mo>/</mo> <mn>29</mn> <mo>)</mo> </mrow> <mrow> <mn>1</mn> <mo>/</mo> <mn>3</mn> </mrow> </msup> </mtd> </mtr> </mtable> </mfenced> <mo>;</mo> </mrow> </math>

in the above formula, X_n，Y_n，Z_nThe three stimulus values of the reference illuminants in the laser images are represented, L represents the illuminance of the pixel points, a and b represent opposite dimensions of the pixel points, C represents the saturation of the pixel points, h represents the hue of the pixel points, and t is a variable of a function f (t).

5. The color adjustment method for laser display according to claim 1, wherein in step three, if the number of pixels in a color gamut exceeds 30% of the total number of pixels and is higher than the number of pixels in the remaining color gamut by more than 50% on average, or the number of pixels in a color gamut exceeds 50% of the total number of pixels, the color tone corresponding to the color gamut is recorded as the main color tone of the laser image.

6. The color adjustment method for laser display according to claim 1, wherein in step four, after saturation mapping, the saturation of the pixel is expressed as the following formula:

C*₁－C*₀×P(C*₀×h×L*)×I(h)；

in the formula, C₁Representing the saturation value, C, of the pixel point after saturation mapping₀Representing the saturation value, P (C), of a pixel that has not been mapped to saturation₀Xh × L) represents the tone of the pixel mapped with respect to saturationInfluence function, i (h) a dominant hue influence function representing the dominant hue with respect to saturation mapping.

7. The color adjustment method for laser display according to claim 1, wherein in the fifth step, the tone of the pixel point after tone mapping is expressed by the following formula:

h₁－h₀×e(h₀)；

in the formula, h₁Representing the tone value, h, of the tone-mapped pixel₀Representing tone values of non-tone-mapped pixels, e (h)₀) Representing a tone weight function.

8. The method for adjusting color of laser display according to claim 1, wherein the relationship of the light intensity mapping in the sixth step is expressed by the following formula:

L*₁－L*₀×f(L*₀)；

in the formula, L₁Representing the illuminance, L, of the mapped pixel₀Representing the illumination of the unmapped pixel points, and f (L0) represents an illumination weighting function.

9. A color adjustment device for laser display, comprising:

a format conversion device (1) for converting an original data signal in an RGB format for laser display into a data signal in an L C h format;

an image analysis device (2) for acquiring a dominant hue of an image displayed by the laser;

saturation mapping means (3) connected to the format conversion means (1) and the image analysis means (2), respectively, for performing saturation mapping on the data signal;

tone mapping means (4) connected to said format conversion means (1) and said image analysis means (2), respectively, for tone mapping said data signals;

-illumination mapping means (5) connected to said format conversion means (1) and said image analysis means (2), respectively, for tone mapping said data signals;

and a format reverse conversion device (6) connected to the saturation mapping device (3), the tone mapping device (4), and the illuminance mapping device (5), respectively, for converting the L × C × h format data signal into an RGB format data signal for laser display.