CN112118433A

CN112118433A - Image display method and laser projection apparatus

Info

Publication number: CN112118433A
Application number: CN201910539226.1A
Authority: CN
Inventors: 郭大勃; 王振
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2019-06-20
Filing date: 2019-06-20
Publication date: 2020-12-22
Anticipated expiration: 2039-06-20
Also published as: CN112118433B

Abstract

The invention relates to an image display method and laser projection equipment, and belongs to the field of projection display. The method comprises the following steps: determining the gain value alpha of each frame of image according to the gray-scale value of each frame of image in a plurality of frames of display images, wherein alpha is more than or equal to 1; adjusting the gray scale value of each frame of image to enable the adjusted gray scale value to be alpha times of the gray scale value before adjustment; adjusting the brightness of the projection light source to enable the adjusted brightness to be 1/alpha of the brightness before adjustment; and displaying each frame of image according to the adjusted gray-scale value and the adjusted brightness, wherein the adjusted brightness corresponding to at least two frames of the displayed images is different. The invention realizes the improvement of the image contrast. The invention is used for adjusting the contrast of the laser projection equipment when displaying images.

Description

Image display method and laser projection apparatus

Technical Field

The invention belongs to the field of projection display, and particularly relates to an image display method and laser projection equipment.

Background

The laser projection display technology is a novel projection display technology in the current market, and laser projection equipment applying the laser projection display technology is gradually attracted by people.

Currently, laser projection devices that employ laser projection display technology typically include an optical imaging system, a video processing system, and a display screen. The video processing system is used for processing the image displayed on the display screen, controlling the optical imaging system to project the processed image onto the display screen, and realizing the display of the image on the display screen through the cooperation of the two systems.

However, the contrast of the current laser projection device is low when displaying images, and therefore, a method for improving the contrast of the images is needed.

Disclosure of Invention

The invention provides an image display method and a laser projection device, which can solve the problem of low contrast ratio of the laser projection device when displaying images, and the technical scheme is as follows:

a first method of providing an image display method, the method comprising:

determining the gain value alpha of each frame of image according to the gray-scale value of each frame of image in a plurality of frames of display images, wherein alpha is more than or equal to 1;

adjusting the gray scale value of each frame of image to enable the adjusted gray scale value to be alpha times of the gray scale value before adjustment;

adjusting the brightness of the projection light source to enable the adjusted brightness to be 1/alpha of the brightness before adjustment;

and displaying each frame of image according to the adjusted gray-scale value and the adjusted brightness, wherein the adjusted brightness corresponding to at least two frames of the displayed images is different.

In a second aspect, there is provided a laser projection apparatus comprising: a display control module, a light source driving circuit, a projection light source and a light modulation device,

the display control module is used for determining the gain value alpha of each frame of image according to the gray-scale value of each frame of image in the multi-frame display image, wherein the alpha is more than or equal to 1;

the display control module is further configured to send a current control signal to the light source driving circuit, and send image display data to the light modulation device, where the current control signal is used to indicate the adjusted brightness of the projection light source, the adjusted brightness is 1/α of the brightness before adjustment, the image display data is used to indicate the adjusted gray scale value of each frame of image, and the adjusted gray scale value is α times of the gray scale value before adjustment, where the adjusted brightness corresponding to at least two frames of the display images is different;

the light source driving circuit is used for outputting current corresponding to the adjusted brightness to the projection light source according to the current control signal;

the projection light source is used for emitting light rays by adopting the adjusted brightness;

the light modulation device is used for modulating the light beam of the projection light source based on the image display data so as to generate an image light beam.

In a third aspect, a laser projection apparatus is provided, comprising:

a processor;

a memory for storing executable instructions of the processor;

wherein the processor is configured to: executing the executable instructions in the memory to implement the image display method of any one of the first aspect.

In a fourth aspect, a computer-readable storage medium is provided, in which instructions are stored, and when the instructions are executed on a processing component, the processing component is caused to execute the image display method according to any one of the first aspect.

The technical scheme provided by the invention can have the following beneficial effects:

according to the image display method and the laser projection equipment provided by the invention, the range of the gray-scale value of each frame of image is expanded according to the gain value, and the brightness of the projection light source is reduced, so that the detailed expression of the image is enhanced, and the contrast of the image is improved, namely the contrast of the laser projection equipment when the image is displayed is improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Drawings

In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in the description of the embodiments will be briefly described below, it being apparent that the drawings in the following description are only some embodiments of the invention, and that other drawings may be derived from those drawings by a person skilled in the art without inventive effort.

Fig. 1 is a schematic structural diagram of a laser projection apparatus provided in an embodiment of the present invention;

FIG. 2 is a graph showing the relationship between the gray level of an input signal and the screen brightness according to an embodiment of the present invention;

FIG. 3 is a graph showing the relationship between the gray level of an input signal and the screen brightness according to an embodiment of the present invention;

FIG. 4 is a graph showing the relationship between the gray level of an input signal and the screen brightness according to an embodiment of the present invention;

FIG. 5 is a flowchart illustrating an image displaying method according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a process for determining a gain value of each frame of image according to a gray-scale value of each frame of image in a plurality of frames of display images according to an embodiment of the present invention;

fig. 7 is a schematic flowchart of determining a target gray scale value according to a gray scale value of each frame of image in a plurality of frames of display images according to an embodiment of the present invention;

FIG. 8 is a statistical histogram provided by an embodiment of the present invention;

FIG. 9 is a schematic diagram of a portion of a laser projection apparatus according to an embodiment of the present invention;

FIG. 10 is a block diagram of a laser projection device provided by an embodiment of the invention;

FIG. 11 is a block diagram of a laser projection device provided by an embodiment of the invention;

fig. 12 is a block diagram of a light source system of a laser projection apparatus according to an embodiment of the present invention;

FIG. 13 is a block diagram of a laser projection device provided by an embodiment of the invention;

fig. 14 is a block diagram of a part of a laser projection apparatus according to an embodiment of the present invention;

fig. 15 is a block diagram of a light source system of a laser projection apparatus according to an embodiment of the present invention;

FIG. 16 is a block diagram of a projection cathode provided by an embodiment of the invention;

fig. 17 is a block diagram of a part of a laser projection apparatus according to an embodiment of the present invention;

fig. 18 is a block diagram of a part of a laser projection apparatus according to an embodiment of the present invention;

fig. 19 is a block diagram of a laser projection apparatus according to an embodiment of the present invention.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The laser projection display technology is a novel projection display technology in the current market, and laser projection equipment applying the laser projection display technology is gradually attracted by people. Referring to fig. 1, a schematic structural diagram of a laser projection apparatus 1 is shown. The laser projection apparatus 1 includes: host computer and display screen. The host includes a video processing system (video processing system)01 and an optical imaging system (optical system) 02. The video processing system 01 is used for processing the image displayed on the display screen and controlling the optical imaging system 02 to project the processed image onto the display screen to realize the display of the image. The video processing system 01 includes a signal input (video input) subsystem 011, a video processing (video process) subsystem 012, and a laser driver (laser driver) subsystem 013. The optical imaging system 02 includes a light source laser subsystem 021, a light modulation subsystem 022, and a projection lens subsystem 023.

The signal input subsystem 011 is configured to receive video input signals in various video formats. The video processing subsystem 012 is configured to convert each frame of image signal in the video input signal received by the signal input subsystem 011 into an image signal in one format, extract an image from the image signal, and perform parameter adjustment processing on the extracted image, for example, the parameter adjustment processing includes adjusting parameters such as brightness, chromaticity, contrast, and sharpness of the image, and the video processing subsystem 012 is further configured to control the light modulation subsystem 022 to perform light beam modulation according to the processed image. The laser driving subsystem 013 is used to control the operation of the light source laser subsystem 021 according to the display requirements of the image.

The light source laser subsystem 021 comprises a laser, a beam shaping and homogenizing module, a wavelength conversion module and the like. The laser is used as a projection light source and can emit light beams with different brightness, and the light beam shaping and homogenizing module and the wavelength conversion module are used for sequentially processing the light beams of the projection light source so as to output the light beams matched with the size of the light modulation device.

The light modulation subsystem 022 includes an interconnected light modulation device for modulating the received light beam to generate an image light beam and an optical engine (optical engine) for driving the light modulation device to move. Among them, the light modulation Device is also called a Micro display chip (display chip), which may be a Digital Micro mirror Device (DMD) or a Liquid Crystal On Silicon (LCOS).

The projection lens subsystem 023 includes a plurality of optical lenses for transmitting, reflecting and/or refracting the image beam before projecting the image beam onto the display screen.

By way of example, the laser projection device may be a laser television comprising a television host and a display screen, wherein the projection lens subsystem in the television host has an ultra-short focus characteristic and supports a close-range setting between the television host and the display screen.

With the development of society, people have higher and higher requirements on the display effect of laser projection equipment, and therefore, higher requirements on a series of parameters (such as contrast ratio) influencing the display effect are also provided. Among them, the contrast of the laser projection apparatus is generally classified into a static contrast and a dynamic contrast. Static contrast generally refers to the contrast calculated by using a contrast algorithm established by the American National Standards Institute (ANSI), which refers to the ratio of the luminance of a white area to the luminance of a black area in a picture (i.e., the same frame of image).

The dynamic contrast refers to a light-dark ratio of the same frame image in the display process, which is related to the brightness of the projection light source in the display process, that is, the brightness ratio of the brightest white area to the darkest black area in the display process of the frame image. For example, as shown in formula (1), the dynamic contrast C satisfies:

L_wthe brightness L of the brightest white area of the frame image during display_BThe brightness of the darkest black area of the image in the frame during the display process.

However, the contrast of the current laser projection apparatus is low, and therefore, a laser projection apparatus with high contrast is needed.

From the above formula of dynamic contrast, when L is_wWhen the maximum value is reached, L can be reduced_BThe dynamic contrast is improved. The actual display brightness of the image of the laser projection device is usually determined by two factors, one factor is the brightness of the projection light source, the other factor is the gray-scale value of the image (i.e. the brightness of the image itself), and the superposition of the two factors can finally determine the actual display brightness of one frame of image, so that the display effect can be optimized by adjusting the ratio of the two factors.

Generally, the brightness of the image itself in the video displayed by the laser projection device is constantly changed based on the content of the image, and for each frame of image, the projection light source can be adjusted according to the brightness of the image itself, so as to adjust the actual display brightness of the image. For example, when one frame of image is a black image, the light source for projection can be reducedSuch that the actual display luminance of the one frame image is lower than its own luminance. In this way, the lower limit value of the actual display luminance of the laser projection apparatus when displaying an image, i.e., the lowest actual display luminance (L) can be reduced by reducing the luminance of the projection light source_B) The dynamic contrast of the laser projection device is improved when the laser projection device displays images. Meanwhile, the brightness of the projection light source is reduced, so that the power consumption of the laser projection equipment is also reduced.

The image display method provided by the embodiment of the invention can improve the dynamic contrast of the laser projection equipment on the basis of not changing the actual display brightness of the image. The principle of the image display method is as follows: the brightness of the projection light source (namely the laser) and the gray-scale value of each frame of image are respectively processed to enhance the detailed expression of the image, so that the brightness of the light source is reduced and the dynamic contrast of the laser projection equipment is improved on the premise of ensuring that the brightness of the displayed image is not changed. For the convenience of the reader to understand, the embodiment of the present invention takes fig. 2 to fig. 4 as an example to explain the image display principle related to the embodiment of the present invention:

as shown in fig. 2 to 4, fig. 2 to 4 show the relationship between the input signal gray-scale value (also called display gray-scale value or image self-brightness) and the screen brightness (i.e. actual display brightness). In fig. 2 to 4, the abscissa represents the input signal gray-scale value, and the ordinate represents the screen brightness. Assuming that the maximum gray-scale value of the image processed by the laser projection apparatus is 256 and the power of the projection light source (since the power of the projection light source is proportional to the brightness of the projection light source, in the embodiment of the present invention, it is assumed that the power of the projection light source is equivalent to the brightness of the projection light source) is a standard quantity (i.e. a reference quantity), for example, a unit of one, then, as shown in fig. 2, the curve (i.e. gamma curve) of the gray-scale value of the input signal of the laser projection apparatus and the brightness of the screen is the solid line in fig. 2. Assuming that the input signal gray-scale value of the currently displayed frame image a is 160, the corresponding screen brightness is 96, and as shown in fig. 3, the input signal gray-scale value of the frame image a is gained by D times, and the frame image a is converted into an image a ', and the screen brightness of the image a' is 192. As shown in fig. 4, image a' may be converted to image a by reducing the power of the projection light source to reduce the screen brightness to 96. Therefore, the larger the display gray scale value range of the image is, the richer the detailed expression of the image is, but the image display method provided by the embodiment of the invention can expand the display gray scale value range of the image, that is, the upper limit value of the display gray scale value is improved, so that the detailed expression of the image is enhanced, and meanwhile, on the premise of ensuring that the actual display brightness of the image A is not changed, the brightness of the projection light source is reduced, the contrast is improved, and the power consumption is reduced.

Referring to fig. 5, an image display method according to an embodiment of the present invention is shown, which can be applied to the above-mentioned laser projection apparatus, as shown in fig. 5, and includes:

step 101, determining a gain value alpha of each frame of image according to the gray-scale value of each frame of image in the multi-frame display image, wherein alpha is larger than or equal to 1.

And 102, adjusting the gray-scale value of each frame of image to enable the adjusted gray-scale value to be alpha times of the gray-scale value before adjustment.

And 103, adjusting the brightness of the projection light source to enable the adjusted brightness to be 1/alpha of the brightness before adjustment.

And 104, displaying each frame of image according to the adjusted gray-scale value and the adjusted brightness. Wherein, the brightness of at least two frames of display images is different after adjustment.

In summary, according to the image display method provided by the embodiment of the invention, the range of the gray-scale value of each frame of image is expanded according to the gain value, and the brightness of the projection light source is reduced, so that the detailed expression of the image is enhanced, and the contrast of the image is improved. On this basis, since the brightness of the projection light source is reduced, the power consumption of the laser projection apparatus is reduced.

An image display method provided in an embodiment of the present invention may be applied to the above-mentioned laser projection apparatus, and the method includes:

step 201, determining a gain value alpha of each frame of image according to the gray-scale value of each frame of image in the multi-frame display image, wherein alpha is larger than or equal to 1.

Wherein the gray scale value of the display image refers to a display gray scale value of the image. The gain value alpha is a coefficient for adjusting the gray-scale value of each frame of image, and the reciprocal of the gain value alpha is a coefficient for adjusting the brightness of the projection light source corresponding to each frame of image.

As shown in fig. 6, the process of determining the gain value α of each frame of image by the laser projection apparatus according to the gray-scale value of each frame of image in the plurality of frames of display images may include:

step 2011, determining a target gray scale value according to the gray scale value of each frame of image in the multi-frame display image.

Because the gray-scale values of the image to be displayed are more, in order to simplify the subsequent operation process, a target gray-scale value for representing the image to be displayed can be determined based on the gray-scale value of the image to be displayed, that is, the target gray-scale value is a representative gray-scale value. As shown in fig. 7, the process of determining the target gray-scale value by the laser projection device according to the gray-scale value of each frame of image in the multiple frames of display images may include:

step 20111, a target set is determined in the gray-scale value sets, and the gray-scale value sets are obtained by sequentially dividing a set gray-scale value range.

The set gray scale value range is a gray scale value range of an image which can be displayed by the laser projection device, for example, 0-255, that is, the laser projection device has 256 levels of gray scales. The plurality of gray-scale value sets may be sets that are divided from a set gray-scale value range, are continuous, are different from each other, and have the same number of gray-scale values, and for example, assuming that the set gray-scale value range is 0 to 255, the plurality of gray-scale value sets are [0.000 to 7.999], [8.000 to 15.999], [16.000 to 23.999]. the. [248.000 to 255.999 ]; the gray-scale value sets may be sets that are divided by a set gray-scale value range and include only one gray-scale value, for example, assuming that the set gray-scale value range is 0-255, the gray-scale value sets are [0.000], [0.001], [0.002]. 255.000 ].

In the embodiment of the present application, the range of the gray scale value of each frame of image needs to be expanded, that is, the upper limit value of the displayed gray scale value needs to be increased to achieve gray scale value amplification, but if the gray scale value of each frame of image is adjusted upwards, the gray scale value of a part of each frame of image may exceed 255 (that is, the gray scale value exceeds 8-bit data), and if the gray scale value of a plurality of pixels in a frame of image exceeds 255, the luminance of the plurality of pixels reaches a saturation state, so that a plurality of details in the frame of image cannot be displayed, and a large loss of image details is caused.

In this embodiment, a designated threshold P may be set, so as to eliminate the image frame to be processed with a larger gray scale value as the gray scale value of more pixels during the subsequent gray scale value enlargement processing. For example, a target set can be determined by setting the designated threshold value P such that the ratio of the number of pixels in each frame of image with gray-scale values falling into the designated gray-scale set to the total number of pixels in each frame of image is greater than or equal to the designated threshold value, the designated gray-scale value set includes gray-scale values 0-W, W is the maximum gray-scale value in the target set, i.e., G/G ≧ P, G is the number of pixels in each frame of image with gray-scale values falling into the designated gray-scale set, and G is the total number of pixels in each frame of image. Therefore, the gray-scale value larger than W in the image frame to be processed can be eliminated, and the gray-scale value larger than W is not amplified in the subsequent process.

The specified threshold value P can reflect the detail loss degree of a frame image to a certain extent, and when P is larger, the detail loss of the frame image is smaller; when P is smaller, the loss of detail of the frame image is greater.

For example, the number of pixels having a gray scale value of no more than W in one frame of image may be set to be 99.5% of the total number of pixels in the frame of image, that is, the threshold P is set to be 99.5%, for example, the total number of pixels in an image is 1920 × 1080, and the number of pixels having a gray scale value of no more than 255 in one frame of image is 1920 × 1080 × 99.5%.

In an example, the designated threshold P may be a preset fixed threshold, which may be set according to a variety of ways, and may be determined based on a gray-scale value of a test image frame, where the test image frame may be one of a plurality of frames of display images, or may be another image, and after obtaining the test image frame, the gray-scale value threshold and a gain value determined by the gray-scale value threshold may be calculated based on the gray-scale value of the test image frame, and the gray-scale value threshold adjustment process may be performed multiple times, where each gray-scale value threshold adjustment process may include: amplifying the gray scale value which is greater than the gray scale value threshold value in the test image by using the gain value, and determining the number of pixels of which the amplified gray scale value is greater than 255; and when the number of the pixels of which the amplified gray-scale value is larger than 255 is larger than the threshold value of the specified number of pixels, increasing the threshold value of the gray-scale value to obtain an updated threshold value of the gray-scale value, and executing the adjustment process of the threshold value of the gray-scale value again until the number of the pixels of which the amplified gray-scale value is larger than 255 is not larger than the threshold value of the specified number of pixels to obtain a final threshold value W of the gray-scale value. Then, based on W again, the specified threshold P is determined.

The above process of determining a target set from a plurality of gray level value sets may include:

and step A, the laser projection equipment establishes a statistical histogram according to the gray-scale value of each pixel in each frame of image.

The abscissa of the statistical histogram represents an arrangement order of the gray-scale value sets, and the abscissa of the statistical histogram represents a gray-scale value set index, each gray-scale value set index is used for indicating one gray-scale value set of the plurality of gray-scale value sets and reflecting a position of the one gray-scale value set in the plurality of gray-scale value sets, and the ordinate of the statistical histogram represents a number of pixels of the gray-scale value in the corresponding gray-scale value set.

The division manner of the gray scale value sets indicated by the abscissa of the statistical histogram may be the same as that of the above gray scale value sets, and when the gray scale value sets are divided into sets having the same number of gray scale values, which are consecutive to each other (also referred to as overlapping with each other) by the set gray scale value range, for example, it is assumed that the set gray scale value range is 0 to 255, and the gray scale value sets are [0.0 to 7.999], [8.0 to 15.999], [16.0 to 23.999], [248.0 to 255.999], and the gray scale value sets may be 0, 1, and 2 … 31 in this order. When the plurality of gray-scale value sets are sets including only one gray-scale value divided by the set gray-scale value range, for example, assuming that the set gray-scale value range is 0 to 255, the plurality of gray-scale value sets are [0], [1], [2]. the. [255], and the plurality of gray-scale value set labels may be 0, 1, and 2 … 255 in sequence.

The ordinate of the statistical histogram represents the number of pixels of the gray-scale value in the corresponding gray-scale value set, and the number of pixels may be the number of pixels of the maximum gray-scale value of each pixel in each frame of image in the corresponding gray-scale value set. In general, the maximum gray-scale value of the gray-scale values of the primary colors of each pixel may reflect the maximum gray-scale value of each pixel, and thus, the maximum gray-scale value of each pixel may be the maximum gray-scale value of the gray-scale values of the primary colors of each pixel, which may also be referred to as a pixel intensity L ═ MAX (V ═ MAX) (the pixel intensity L may be the maximum gray-scale value of each pixel)_R，V_G，V_B)，V_R、V_GAnd V_BRespectively, the gray scale values of red, green and blue of the same pixel. For example, assuming that the gray-scale values of red, green and blue of a certain pixel are 55, 65 and 75, respectively, the pixel intensity L is 75. Then, the statistical histogram may be established according to the maximum gray-scale value of each pixel in each frame of image.

The range of the number of gray-level value sets is usually: 31-256, for example, the number of gray scale value sets is 32, 112, or 256. Since the more the number of the gray scale value sets, the smaller the gray scale value range of the gray scale value sets divided according to the set gray scale value range, the more accurate the target set obtained subsequently, and the more accurate the gain value calculated by the target set.

For example, please refer to fig. 8, which shows a statistical histogram provided by the embodiment of the present invention. The gray scale value sets represented by the abscissa of the statistical histogram are bin0, bin1, bin2, bin3 … bin30 and bin31, and the gray scale value sets indicated by each gray scale value set reference number are [0.0-7.999], [8.0-15.999], [16.0-23.999], [24.0-31.999]. [240,247.999], [248.0-255.999] in sequence. The number of pixels represented by the ordinate of the statistical histogram is 1280, 3840, 1920, 4800 … 8640, 2880 in this order.

It should be noted that, since the total number of pixels in a frame of image is usually large, each gray-scale value set needs to be set in the process of creating the statistical histogramThe corresponding pixel number is registered, so that the pixel number in each gray-scale value set is usually set by 5 bits (i.e. 2 bits) during data registration due to the limitation of register capacity in the laser projection device⁵I.e., 32) are truncated for granularity, that is, each gray-scale value set is counted in1 count unit of 32 pixels. The number of count units R of the pixel number E for each gray level set is □ E/32, which indicates a round-down (floor) operation.

For example, E-31 and R-0, or E-63 and R-1; as another example, the number R of the count units of the pixel number that can be represented by the ordinate of the statistical histogram shown in fig. 8 is 40, 120, 60, 150 … 270, 90 in this order. Therefore, under the condition that the total number of pixels in one frame of image is large, the counting number can be reduced, the storage space is saved, the process of establishing a statistical histogram is simplified, and the establishing efficiency is improved.

It should be noted that the above statistical histogram may have other forms, for example, the ordinate of the statistical histogram represents a gray scale value set label, and the abscissa represents a histogram of the number of pixels of the gray scale value in the corresponding gray scale value set, that is, the meaning represented by the abscissa and the meaning represented by the ordinate in the above step a are exchanged, and the direction of the corresponding square bar is also adjusted. The embodiment of the present invention does not limit the form of the statistical histogram.

And step B, the laser projection equipment sequentially adds the pixel numbers of the gray scale value sets according to the sequence of the gray scale values corresponding to the gray scale value sets from large to small until the total number of pixels obtained by accumulation is greater than or equal to a threshold value of the total number of pixels, and determines the gray scale value set reached when accumulation is stopped as a target set, wherein the threshold value of the total number of pixels is determined based on the specified threshold value.

The total number of pixels threshold M may satisfy: m is N × (1-P), N is the total number of pixels in each frame image, and then the threshold value of the total number of pixels is equal to the number of pixels of which the gray-scale value exceeds 255 after the gray-scale value of each frame image is subjected to subsequent gray-scale value amplification processing, and M can reflect the detail loss degree of the frame image to a certain extent, and when M is larger, the detail loss of the frame image is larger; when M is smaller, the loss of detail of the frame image is smaller. For example, when P is 99.5%, M may satisfy: m ═ N × (1-99.5%) ═ N × 0.5%. For example, if the total number of pixels of an image is 1920 × 1080, M is 1920 × 1080 × 0.5% ═ 10368.

Since the total number of pixels threshold M satisfies: and if M is N x (1-P), the laser projection equipment sequentially adds the pixel numbers of the multiple gray-scale value sets according to the descending order of the gray-scale values corresponding to the gray-scale value sets, thereby determining the target set.

For example, taking the statistical histogram shown in fig. 8 as an example, the direction of adding the pixel numbers of the plurality of gray-scale value sets may be the X direction shown in fig. 8. Let M be 10368. The number of pixels corresponding to bin31 is 2880, 2880 < 10368, and the number of pixels corresponding to bin31 is added to the number of pixels corresponding to bin30, that is, 2880+8640 is 11520, and 11520 > 10368, and then the gray level set [240,247.999] corresponding to bin30 is determined as the target set.

The total number of pixels threshold M may satisfy: and if M is N × P, the total number of pixels is equal to the number of pixels of which the gray-scale value does not exceed 255 after each frame of image is subjected to subsequent gray-scale value processing. For example, when P is 99.5%, M may satisfy: m ═ N × 99.5%. For example, if the total number of pixels of an image is 1920 × 1080, M is 1920 × 1080 × 99.5% ═ 2063232.

Since the total number of pixels threshold M satisfies: and if M is equal to N multiplied by P, the laser projection equipment sequentially adds the pixel numbers of the multiple gray-scale value sets according to the sequence of the gray-scale values corresponding to the gray-scale value sets from small to large, thereby determining the target set.

For example, continuing with the example of the statistical histogram shown in fig. 8, the direction of adding the pixel numbers of the plurality of gray-scale value sets may be the opposite direction of the X direction shown in fig. 8, and it is understood that the accumulation is stopped from the pixel number corresponding to bin0 until the pixel number corresponding to bin30 is accumulated, and the total number of pixels obtained by the accumulation is greater than or equal to the threshold value of the total number of pixels, and the reached gray-scale value set is the gray-scale value set [240,247.999] corresponding to bin30, and then the gray-scale value set [240,247.999] corresponding to bin30 is determined as the target set.

It is noted that when the total number of pixels threshold M satisfies: when M is N × (1-P), although the total number of pixels threshold M is determined based on the specified threshold P, in practical applications, the minimum grayscale value of the target set of a certain frame image determined according to the total number of pixels threshold M may be greater than the grayscale threshold Y, which refers to the minimum grayscale value whose value is greater than 255 after the subsequent gain processing (for example, the grayscale threshold Y may be equal to the grayscale value W). Taking the example of fig. 8 as above, assuming that the gray-scale threshold Y is 247.0, M is N × 0.5, and the number of pixels corresponding to bin31 is 10368, the target set of one frame image determined by M is the gray-scale set [248.000-255.999] corresponding to bin31, which is the set with the largest corresponding gray-scale value among the plurality of gray-scale value sets. The minimum gray-scale value 248 of the target set is greater than 247, which means that the gray-scale values of more pixels in the frame image are larger, and if the frame image is subjected to subsequent gain processing, more gray-scale values in the frame image are larger than 255 (reach a saturation state), so that the detail loss of the frame image is larger. Therefore, when the minimum grayscale value of the target set is greater than the grayscale threshold Y, the laser projection apparatus may directly determine the gain α of the frame image to be 1, or the laser projection apparatus may directly output the frame image without performing subsequent processing on the frame image (i.e., without performing step 20112).

Step 20112, determining a target gray level value of each frame of image according to the target set.

When the minimum gray-scale value of the target set is smaller than the gray-scale value threshold Y, the laser projection device may obtain a target gray-scale value F (also referred to as an intensity correction value F) of each frame image by using a weighted average method according to the statistical histogram, where F satisfies:

wherein N is_ALLTotal number of pixels, N, for each frame image_iRepresenting correspondence of ith gray level setNumber of pixels, L_iAnd representing the gray level value corresponding to the ith gray level value set, wherein i is more than or equal to 0 and less than or equal to x, and the target set is the xth gray level value set. Wherein L is_iThe gray level value corresponding to the ith gray level value set may be a middle value of the ith gray level value set or an average value of the gray level value sets. In general, this L is_iIs the middle value in the ith gray-scale value set. For example, the 1 st set of gray scale values is [0-4 ]]，L₁＝2。

For example, continuing with the statistical histogram shown in fig. 8 as an example, it is assumed that the target set is a gray-scale value set corresponding to bin30, and the total number of pixels of the image is 1920 × 1080. Then

N_ALL＝1920×1080，L₀＝3.999，N₀＝1280，L₁＝12.999，N₁＝3840，L₂＝20.999，N₂＝1920，...，L₃₀＝244.999，N₃₀＝8640。

Alternatively, the laser projection device may first obtain the target gray level L of each initial frame of image by using a weighted average method according to the statistical histogram_MThen using sensitivity dynamic contrast coefficient to the L_MAnd performing more accurate adjustment to obtain a target gray-scale value F which can more accurately represent the gray-scale value of each frame of image, wherein the F satisfies the following conditions:

F＝L_M×k₁+L_X×(1-k₁)，0≤k₁≤1，

wherein N is_ALLTotal number of pixels, N, for each frame image_iIndicates the number of pixels corresponding to the ith gray level set, L_iRepresenting the gray level value corresponding to the ith gray level value set, i is more than or equal to 0 and less than or equal to x, the target set is the xth gray level value set, k₁Is sensitive toCoefficient of sexual dynamic contrast, k₁Usually a constant determined after experimentation. Due to the target gray-scale value L of each frame image_CComparing the target gray level L with each frame of image_MThrough k₁So that, in the subsequent processing, according to the L_CThe gain value alpha is obtained more accurately.

Step 2012, according to the target gray-scale value, the correction table is queried to obtain the gain value α of each frame of image, and the correction table reflects the relationship between the gray-scale value and the gain value α.

Since the laser projection device queries the correction table according to the target gray-scale value to obtain the gain value α of each frame of image, the implementation process of step 2012 is different according to different contents of the correction table, and the following embodiments are described as examples in the embodiment of the present invention.

In the first case, the correction table records the gray-scale values in the set gray-scale value range, and the gain value α corresponding to each gray-scale value.

And the laser projection equipment queries the gain value alpha corresponding to the gray scale value which is equal to the target gray scale value in the correction table according to the target gray scale value.

In the second case, the calibration table records the gray-scale values in the set gray-scale value range and the normalized luminance corresponding to each gray-scale value, and the normalized luminance corresponding to any gray-scale value is obtained by normalizing the luminance corresponding to any gray-scale value.

For example, the brightness value range corresponding to any gray level value is [ B ]_MIN，B_MAX]If the brightness corresponding to any gray level value is x, the corresponding normalization formula is:

norm(x)＝(x-B_MIN)/(B_MAX-B_MIN)；

wherein norm (x) is the normalized luminance corresponding to any one of the gray-scale values.

The normalized luminance is less than or equal to 1. For example, assuming that the value range of the luminance in the gray-scale value range is set to be 0 to 30, the normalized luminance corresponding to any luminance x is x/30.

The laser projection equipment firstly queries a correction table according to a target gray-scale value to obtain normalized brightness Bm corresponding to the gray-scale value equal to the target gray-scale value, and then determines the reciprocal of the normalized brightness as a gain value alpha corresponding to the target gray-scale value, namely alpha is 1/Bm. Since Bm is a number smaller than or equal to 1, the gain value α is a number larger than or equal to 1.

In a third case, the correction table includes a first syndrome table and a second syndrome table, wherein the first syndrome table records gray-scale values in a set gray-scale value range and normalized luminance corresponding to each gray-scale value, and the normalized luminance corresponding to any gray-scale value is obtained by normalizing the luminance corresponding to any gray-scale value. The second syndrome table records the normalized luminance values in the first syndrome table, and a gain value corresponding to each normalized luminance value.

The laser projection equipment firstly queries the first syndrome table according to the target gray-scale value to obtain the normalized brightness corresponding to the gray-scale value equal to the target gray-scale value, and then queries the second syndrome table to obtain the gain value corresponding to the normalized brightness.

It should be noted that there may be other cases in the content recorded in the correction table, as long as the correction table can reflect the relationship between the gray-scale value and the gain value α, which is not limited in the embodiment of the present invention.

Step 202, adjusting the gray level value of each frame of image, so that the adjusted gray level value is alpha times of the gray level value before adjustment.

As can be seen from the above steps, the gain α is a value greater than or equal to 1, and therefore, the gray scale value for adjusting each frame of image is adjusted to be α times of the gray scale value before adjustment, so as to expand the range of the gray scale value for each frame of image, that is, to increase the upper limit value of the gray scale value for each frame of image, so that the brightness of the projection light source is subsequently reduced under the condition that the actual brightness of the displayed image is not changed. Meanwhile, the range of the gray-scale value of each frame of image is expanded, so that the detailed expression of each frame of image is richer.

And step 203, adjusting the brightness of the projection light source to enable the adjusted brightness to be 1/alpha of the brightness before adjustment.

The laser projection equipment adjusts the brightness of the projection light source according to the gain value alpha, and the adjusted brightness is 1/alpha of the brightness before adjustment, so that the lower limit value of the actual display brightness of the laser projection equipment when the laser projection equipment displays the image is reduced and the dynamic contrast of the laser projection equipment when the laser projection equipment displays the image is improved on the premise of ensuring that the actual brightness of the displayed image is not changed. Meanwhile, the brightness of the projection light source is reduced, so that the power consumption of the laser projection equipment is also reduced.

And 204, displaying each frame of image according to the adjusted gray-scale value and the adjusted brightness, wherein the adjusted brightness corresponding to at least two frames of display images is different.

The laser projection equipment can pre-buffer each frame of image, so that each frame of image is delayed for one frame of display compared with the traditional image display method, then the steps are carried out on each frame of image, the adjusted gray-scale value and the adjusted brightness of the projection light source of each frame of image are obtained, and each frame of image is displayed according to the adjusted gray-scale value and the adjusted brightness.

It should be noted that, because each frame of image to be displayed is processed by the image display method, and the gray scale value of the current display image may have a larger difference from the gray scale value of the previous frame of image, the difference between the gain value of the current display image and the gain value of the previous frame of image may also be larger, so that after the gray scale value of the current display image and the corresponding projection light source are adjusted according to the gain values, the actual luminance difference of the two frames of display images is larger, and in the process of switching from the previous frame of image to the current display image, a user may see an obvious luminance change (i.e., flicker), so that the user experience is poorer. Therefore, in order to avoid the above problem, the luminance of the projection light source can be changed at a high speed, that is, the power for driving the projection light source can be changed at a high speed, so that the luminance of the two-frame display image can be changed rapidly. The brightness of the projection light source can be slowly changed, namely, the transition of the brightness of the projection light source is increased, so that the brightness is not easy to be perceived by a user. The high-speed change refers to a change of a change rate larger than a first specified rate threshold, the slow change refers to a change of a change rate smaller than a second specified rate threshold, and the first specified rate threshold is larger than or equal to the second specified rate threshold in a normal condition.

Furthermore, the laser projection equipment can also set an adjusting coefficient to reduce the gain value of the current display image, so that the gain value is smaller, the brightness change of the projection light source is smaller, and the problem of flicker caused by image switching when the brightness difference of two frames of display images is larger is solved.

Taking two consecutive frames of display images of the laser projection device as an example, it is assumed that the two frames of display images are respectively an nth frame image and an n +1 th frame image. Since the difference between the gray-scale values of the two display images is large when the difference between the luminance values of the two display images is large, the difference between the luminance values of the two display images can be represented by the ratio of the gain values of the two display images. Illustratively, the gain value α when the image of the n +1 th frame is_n+1Gain value alpha with the n-th frame image_nWhen the ratio is in the specified range, the laser projection equipment obtains the adjustment coefficient k₂According to k₂Updating alpha_n+1So that the updated α_n+1Can satisfy the following conditions: alpha is alpha_n+1＝α_n×k₂，0＜k₂< 1, wherein the nth frame image and the (n + 1) th frame image are two adjacent frame display images in the multi-frame display image. The (n + 1) th frame image is a frame image subsequent to the nth frame image. For example, when 5 < (. alpha.)_n+1/α_n) When the luminance difference is less than 9, the difference between the actual luminance displayed by the nth frame image and the actual luminance displayed by the (n + 1) th frame image is considered to be large, and k is obtained₂0.25. Or, when 5 < (. alpha.) > (α)_n/α_n+1) If the difference between the actual brightness displayed by the nth frame image and the actual brightness displayed by the (n + 1) th frame image is larger than 9, k is acquired₂0.5. Note that the adjustment coefficient k is₂May be a fixed value that is set in advance or may be a variable value that is dynamically determined based on display parameters of the laser projection device.

The gain value range may be 1-8, that is, the normalized luminance of each frame image is not lower than 0.13(Bm ═ 1/α ≈ 1/8 ≈ 0.13), because the gain value range is limited by the system performance of the laser projection apparatus. Thus, step 2012 may be replaced by: according to the target gray-scale value, inquiring the correction table to obtain normalized brightness, judging whether the normalized brightness is greater than a specified brightness threshold, when the normalized brightness is greater than the specified brightness threshold, firstly obtaining the gain value alpha of each frame of image according to the normalized brightness, and then continuing to execute the step 103; and when the normalized brightness is not greater than the specified brightness threshold value, displaying each frame of image according to the gray-scale value of each frame of image in the multi-frame display image. Illustratively, the specified brightness threshold is 0.13.

For example, as shown in fig. 9, the image display method provided by the embodiment of the present invention may be applied to the aforementioned video processing subsystem 012, and the video processing subsystem 012 may further be divided into a video format conversion unit 0121, a video processing unit 0122, and a data formatting unit 0123. The video format conversion unit 0121 is configured to convert each frame of image signal in the received video into an image signal in one format, and the video processing unit 0122 is configured to process an image, and transmit the processed image information to the laser driving subsystem 013, so as to control the light source and the laser subsystem to emit light beams with different brightness (that is, to control the brightness of the projection light source), for example, execute the image display method provided in the foregoing embodiment of the present invention. The data formatting unit 0123 is used to control the light modulation device in the optical modulation subsystem 022 to perform light beam modulation according to the processed image.

In the related art, a laser projection apparatus receives a video input signal, converts the video input signal into an image in one format, processes the image, and controls a light modulation device to perform light beam modulation based on the processed image. In this process, the power of the projection light source is not changed, and the brightness of the projection light source is not adjusted.

In the embodiment of the present invention, the signal input subsystem 011 of the laser projection apparatus receives a video input signal and transmits the video input signal to the video format conversion unit 0121, the video format conversion unit 0121 converts the video input signal into an image signal in one format, and transmits the image signal to the video processing unit 0122, and the video processing unit 0122 may extract and buffer the image of the received image signal, so as to perform the image display method for each frame of image. The video processing unit 0122 may include a processor, where the processor determines a corresponding gain value according to a gray level value of each frame of image in a plurality of frames of display images, and then adjusts the brightness of the projection light source according to the gain value, and transmits the adjusted brightness to the laser driving subsystem 013, where the laser driving subsystem 013 controls the light source laser subsystem to emit a light beam with adjusted brightness. The data formatting unit 0123 adjusts the gray level value of each frame image according to the gain value, and then controls the light modulation device in the optical modulation subsystem 022 to perform light beam modulation. And finally, displaying each frame of image according to the adjusted brightness and the adjusted gray-scale value. The process of adjusting the brightness and adjusting the gray level value according to the gain value can be synchronously executed, so that the data processing efficiency is improved.

By way of example, assume that the light modulation device in optical modulation subsystem 022 can be a DMD, which includes a plurality of mirrors. The data formatting unit 0123 first adjusts the gray level of each frame of image according to the gain value, and then controls the deflection time (i.e. the on-off time) of the multiple mirrors of the DMD, so that the light beam of the projection light source is reflected by the deflected mirrors to generate the image light beam with different gray level values, so as to display each frame of image in the following. In the output process of the same frame of display image, the gray-scale value of the frame of display image is improved and the brightness of the projection light source is reduced at the same time, and the superposition effect of the gray-scale value and the brightness of the projection light source keeps the brightness of the whole display image stable, so that the dynamic contrast of the image is improved, and the power consumption of the laser projection equipment is reduced.

The sequence of the steps of the image display method provided by the embodiment of the application can be properly adjusted, and the steps can be correspondingly increased or decreased according to the situation. Any method that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application is covered by the protection scope of the present application, and thus the detailed description thereof is omitted.

In summary, according to the image display method provided by the embodiment of the invention, the range of the gray-scale value of each frame of image is expanded according to the gain value, and the brightness of the projection light source is reduced, so that the detailed expression of the image is enhanced, and the contrast of the image is improved. Further, since the brightness of the projection light source is reduced, the power consumption of the laser projection apparatus is reduced.

The following are embodiments of the apparatus of the present invention that may be used to perform embodiments of the method of the present invention. For details which are not disclosed in the embodiments of the apparatus of the present invention, reference is made to the embodiments of the method of the present invention.

An embodiment of the present invention provides a laser projection apparatus, as shown in fig. 10, including:

a display control module 31, a light source driving circuit 32, a projection light source 33, and a light modulation device 34.

The display control module 31 is configured to determine a gain value α of each frame of image according to a gray-scale value of each frame of image in the multi-frame display image, where α is greater than or equal to 1;

the display control module 31 is further configured to send a current control signal to the light source driving circuit 32, and send image display data to the light modulation device 34, where the current control signal is used to indicate the adjusted brightness of the projection light source 33, the adjusted brightness is 1/α of the brightness before adjustment, the image display data is used to indicate a gray scale value of each frame of image after adjustment, and the gray scale value after adjustment is α times of the gray scale value before adjustment, where the adjusted brightness corresponding to at least two frames of the display images is different;

a light source driving circuit 32 for outputting a current corresponding to the adjusted brightness to the projection light source 33 according to the current control signal;

a projection light source 33 for emitting light with the adjusted brightness;

and a light modulation device 34 for modulating the light beam of the projection light source 33 based on the image display data to generate an image light beam. Alternatively, the light modulation device 34 may be a DMD or an LCOS.

In summary, in the laser projection apparatus provided in the embodiment of the present invention, the display control module expands the range of the gray scale value of each frame of image according to the gain value, and reduces the brightness of the projection light source, so that the detailed expression of the image is enhanced, and the contrast of the image is improved. On this basis, since the brightness of the projection light source is reduced, the power consumption of the laser projection apparatus is reduced.

The laser projection device provided by the embodiment of the invention can be various. The following two realizations are examples of the present invention.

In a first implementation manner, as shown in fig. 11, the light source driving circuit 32 includes a plurality of laser driving circuits 321, the projection light source 33 includes laser components 331 of three primary colors, the plurality of laser components 331 are connected to the plurality of laser driving circuits 321 in a one-to-one correspondence, and the display control module 31 is connected to the plurality of laser driving circuits 321 respectively. The laser assembly 331 includes at least one laser.

The display control module 31 is configured to generate a plurality of enable signals corresponding to three primary colors of each frame of image in the multi-frame display image one to one, transmit the plurality of enable signals to the corresponding laser driving circuits 321, generate a plurality of current control signals corresponding to the three primary colors of each frame of image one to one, and transmit the plurality of current control signals to the corresponding laser driving circuits 321;

each laser driving circuit 321 is configured to provide a driving current corresponding to the laser component 331 connected to the laser driving circuit, where the current control signal corresponding to each laser component 331 has different magnitudes when corresponding to at least two frames of display images;

the laser assembly 331 is configured to emit light under the driving of the corresponding laser driving circuit 321.

Fig. 11 assumes that the primary colors are red, green, and blue, the corresponding enable signals are a red enable signal R _ EN, a green enable signal R _ EN, and a blue enable signal R _ EN, respectively, and the current control signals are a red current control signal R _ PWM, a green current control signal G _ PWM, and a blue current control signal B _ PWM, respectively. For convenience of illustration, the following embodiments are all described by taking the foregoing primary colors as red, green and blue as examples, and when the embodiments of the present invention are actually implemented, the primary colors may have other colors, which is not limited herein.

Because the display control module in the laser projection device can generate a plurality of enable signals corresponding to three primary colors of each frame image in a plurality of frames of display images one by one, the plurality of enable signals are respectively transmitted to the corresponding laser driving circuits, and a plurality of current control signals corresponding to the three primary colors of each frame image one by one are generated, the plurality of current control signals are respectively transmitted to the corresponding laser driving circuits, and each laser driving circuit can provide the driving current corresponding to the laser component for the laser component connected with the laser driving circuit. Because the current control signals corresponding to each laser component have different sizes when corresponding to at least two frames of display images, the laser projection equipment can support the laser components with variable brightness, and the display effect of the laser projection equipment is effectively improved.

Referring to fig. 12, a partial structural schematic diagram of an exemplary light source system (i.e., the aforementioned projection light source 23) of the laser projection apparatus according to the embodiment of the invention is shown. As shown in fig. 12, the light source system generally includes a laser light source, two dichroic mirrors, a reflecting mirror 30, a condensing lens 40, a diffusion wheel 50, and a light rod 60. The laser light source includes a red laser assembly 101 for emitting red laser light, a green laser assembly 102 for emitting green laser light, and a blue laser assembly 103 for emitting blue laser light. The red laser light emitted from the red laser assembly 101 may be transmitted to the condensing lens 40 through a dichroic mirror 201. The green laser light emitted from the green laser assembly 102 may be reflected to another dichroic mirror 202 through the reflecting mirror 30, then reflected to one dichroic mirror 201 through the another dichroic mirror 202, and then reflected to the condensing lens 40 through the one dichroic mirror 201. The blue laser light emitted from the blue laser module 103 may be transmitted to one dichroic mirror 201 through another dichroic mirror 202, and then reflected to the condenser lens 40 through the one dichroic mirror 201. The laser light applied to the condensing lens 40 is condensed by the condensing lens 40 and then applied to the diffusion wheel 50. The laser irradiated on the diffusion wheel 50 is irradiated into the light bar 60 after being homogenized by the diffusion wheel 50, and a three-color light source is realized under the action of the homogenized light of the light bar 60. Wherein the laser assembly comprises at least one laser.

Wherein each laser driving circuit 321 may include: the driving chip, the voltage output circuit and the light source switch circuit are used for being connected with a laser component;

the driving chip is used for receiving a current control signal corresponding to the laser component and providing a driving current of the corresponding laser component to the light source switching circuit based on the current control signal;

the driving chip is also used for receiving an enabling signal corresponding to the laser component and controlling the lighting time length of the corresponding laser component driven by the light source switching circuit through the switch control signal based on the enabling signal;

the voltage output circuit is used for providing rated voltage of the laser component for the light source switching circuit;

and the light source switch circuit is used for conducting when the switch control signal is an effective potential and providing the corresponding driving current of the laser component to the connected laser component under the rated voltage.

Optionally, the driving chip includes a first pin, a second pin, and a third pin, where the first pin is used to output a switch control signal;

the light source switching circuit includes: a current sensing resistor and a first switching transistor.

One end of the current detection resistor is connected with the rated voltage output end and the second pin of the voltage output circuit respectively, the other end of the current detection resistor is connected with the anode and the third pin of the laser component respectively, the source electrode of the first switch transistor is connected with the cathode of the laser component, the grid electrode of the first switch transistor is connected with the first pin, and the drain electrode of the first switch transistor is connected with the low potential.

The driving chip is used for detecting the current loaded on the current detection resistor through the second pin and the third pin and adjusting the current loaded on the current detection resistor to the driving current corresponding to the laser component.

Optionally, the driving chip is configured to adjust a value of the current control signal, so as to adjust a current loaded on the current detection resistor to a driving current of the corresponding laser component;

and/or the current detection resistor is an adjustable resistor, and the driving chip is used for adjusting the resistance value of the resistor detection resistor so as to adjust the current loaded on the current detection resistor to the driving current of the corresponding laser component.

Optionally, the current control signal is a PWM signal, and the laser driving circuit 321 further includes:

and the repeater is connected with the driving chip and used for receiving the current control signal corresponding to the laser component and outputting the current control signal with the amplitude equal to the rated amplitude voltage to the driving chip.

Optionally, the repeater includes: the circuit comprises a first resistor, a second resistor and an operational amplifier.

The resistance values of the first resistor and the second resistor are equal, the same-direction input end of the operational amplifier is connected with one end of the first resistor, one end of the first resistor is an input end of a current control signal, the reverse-direction input end of the operational amplifier is connected with one end of the second resistor and a second signal output end, the output end of the operational amplifier is connected with the other end of the second resistor and the driving chip, and the rated voltage of the operational amplifier is amplitude voltage.

Optionally, the voltage output circuit is a voltage boost circuit, and the voltage boost circuit is configured to boost the input voltage to a rated voltage of the laser component, and load the rated voltage for the light source switching circuit.

Optionally, the boost circuit includes: the inductor, the second switching transistor, the diode, the capacitor, the fifth resistor, the sixth resistor and the seventh resistor;

one end of the inductor is connected with the supply end of the input voltage, the other end of the inductor is respectively connected with the anode of the diode and the source electrode of the second switching transistor, and the cathode of the diode is the output end of the rated voltage;

one end of the capacitor is connected with the output end of the rated voltage, the other end of the capacitor is connected with a fourth signal output end, the fourth signal output end is used for outputting level signals lower than the rated voltage, and for example, the fourth signal output end is used as a reference ground;

the fifth resistor and the sixth resistor are connected in series between the output end of the rated voltage and a fifth signal output end, the fifth signal output end is used for outputting a level signal lower than the rated voltage, and for example, the fifth signal output end is used as a reference ground;

the seventh resistor is connected in series between the drain of the second switching transistor and a sixth signal output terminal for outputting a level signal of a voltage lower than the drain, for example, the sixth signal output terminal is a reference ground.

Alternatively, as shown in fig. 13, the display control module 31 includes: the laser light modulation device comprises an algorithm processor 311 and a control processing module 312, wherein the algorithm processor 311 is connected with the control processing module 312, and the control processing module 312 is further connected with a laser driving circuit 321 and the light modulation device 34 respectively.

The algorithm processor 311 may be implemented by a Field-Programmable Gate Array (FPGA).

The algorithm processor 311 is configured to determine a gain value α of each frame of image according to a gray-scale value of each frame of image in the multi-frame display image, where α is greater than or equal to 1. The image display data of each frame of image may reflect the basic distribution and the basic tone of the color of each frame of image, and when the image display data is 4K data, the 4K data may be input to the algorithm processor 311 in the form of a V-by-One (a digital interface standard developed for image transmission).

The algorithm processor 311 is further configured to send image display data and current control signals corresponding to the laser assemblies to the control processing module 312, where each of the current control signals is used to indicate an adjusted brightness of the corresponding laser assembly, the adjusted brightness is 1/α of the brightness before adjustment, the image display data is used to indicate a gray level value of each frame of image after adjustment, and the gray level value after adjustment is α times the gray level value before adjustment.

The control processing module 312 is used for sending image display data to the light modulation device 34 and sending a current control signal corresponding to the laser component to the laser driving circuit 321.

And the light modulation device 34 is used for modulating the light beams of the laser light source based on the image display data to generate image light beams, and projecting the image light beams onto the display screen to realize the display of each frame of image. It should be noted that the laser projection apparatus may further include a plurality of optical lenses, which are located between the light modulation device 34 and the display screen, and are used for projecting the image beam onto the display screen after transmitting, reflecting and/or refracting the image beam.

In the embodiment of the present invention, the display control module may adjust the brightness of the laser light source in real time based on the gain value α of each frame of image, that is, the change of each frame of image, so as to implement the dynamic contrast. In the light source switch circuit of the laser driving circuit, when the first switch transistor is an MOS transistor, such as an NMOS transistor, the on-off time of the light source switch circuit reaches ns (nanosecond) level, and the on-off time of the laser driving circuit reaches mus (microsecond) level, so that the current response speed of the laser component is high, the precision is high, namely the laser driving circuit can quickly and accurately respond to the change of the brightness of each pixel of an image, the brightness of the laser component can be randomly adjusted from 0 to the brightness corresponding to a rated current value, the image quality problem of serious color mixing of various basic color lights caused by the slow reaction speed of the laser driving circuit is solved, and the driving circuit is the basis for realizing high dynamic contrast, namely supports the dynamic brightness adjustment of the laser projection equipment on hardware.

Optionally, the control processing module includes: a master control processor and a slave control processor, wherein the algorithm processor is respectively connected with the master control processor and the slave control processor, the master control processor is also respectively connected with the laser driving circuit and the optical modulation device, the slave control processor is also connected with the optical modulation device,

the algorithm processor 311 is configured to determine a gain value α of each frame of image according to the gray-scale value of each frame of image, where α is greater than or equal to 1;

the algorithm processor 311 is further configured to send a current control signal and first sub-data to the master controller, and send second sub-data to the slave controller, where the first sub-data and the second sub-data constitute image display data, each current control signal is used to indicate an adjusted brightness of a corresponding laser component, the adjusted brightness is 1/α of the brightness before adjustment, the image display data is used to indicate a gray scale value of each frame of image after adjustment, and the adjusted gray scale value is α times of the gray scale value before adjustment;

a main control processor for sending a current control signal and an enable signal to the laser driving circuit and sending first sub data to the optical modulation device 34;

a slave processor for transmitting the second sub data to the light modulation device 34;

and the light modulation device 34 is used for modulating the light beam of the laser light source based on the first sub data and the second sub data to generate an image light beam.

In the second implementation manner, as shown in fig. 14, the projection light source 33 includes a laser light source 332, a display control module 31, a light source driving circuit 32, and the laser light source 332 connected in sequence. Illustratively, the laser light source 332 may be a monochromatic laser light source, such as a red laser light source or a blue laser light source.

The display control module 31 is configured to generate N first current control signals corresponding to each frame of image in multiple frames of display images, select an effective second current control signal from the N first current control signals, and transmit the second current control signal to the light source driving circuit 32, where the N first current control signals include a single-color current control signal and a mixed-color current control signal corresponding to M primary colors of each frame of image, N is an integer greater than 2, and M is a positive integer;

a light source driving circuit 32 for controlling the laser light source 332 to emit light based on the received second current control signal;

the second current control signals corresponding to at least two frames of display images are different in size.

The display control module can generate N first current control signals corresponding to each frame of image in multiple frames of display images, select effective second current control signals from the N first current control signals, and transmit the second current control signals to the light source driving circuit, so that the light source driving circuit controls the laser light source to emit light.

Referring to fig. 15, a partial structural schematic diagram of an exemplary light source system of a laser projection apparatus according to an embodiment of the present invention is shown. The light source system includes: the projection light source 33, the optical engine 35 and the projection lens 36 are arranged in sequence along the light beam transmission direction. The projection light source 33 is configured to emit a light beam, the optical engine 35 is configured to modulate the light beam to generate an image light beam when being irradiated by the light beam emitted from the projection light source 33, and the projection lens 36 is configured to project the image light beam onto the projection screen 40.

For example, the projection light source 33, the optical engine 35 and the projection lens 36 may be applied to a laser projection device such as a laser television, and the projection light source may include: at least one laser, the projection light source is used for emitting laser light of at least one color. For example, the projection light source may be a monochromatic projection light source (i.e., including one laser emitting laser light of one color) or a bichromatic projection light source (i.e., including a plurality of lasers emitting laser light of two colors in common).

Illustratively, as shown in fig. 16, the projection light source 33 includes at least a fluorescent wheel 110, a color filter wheel 120, a blue laser light source 130, a light combining part 140, a beam shaping part 150, and a light collecting part 160. The blue laser light source 130, the beam shaping unit 150, the light combining unit 140, the fluorescent wheel 110, the color filter wheel 120, and the light collecting unit 160 are sequentially arranged along the transmission direction of the blue laser light. The blue laser light source 130 is configured to emit blue laser light. The beam shaping unit 150 is configured to perform a reducing process on the blue laser beam emitted from the blue laser source 130 to obtain a reduced collimated blue laser beam, and transmit the collimated blue laser beam to the light combining unit 140. The light combining part 140 is configured to transmit the received blue laser light to the fluorescent wheel 110, the light combining part 140 is further configured to transmit the blue laser light transmitted by the fluorescent wheel 110 to the color filter wheel 120, the blue laser light is the blue laser light transmitted by the transmission area after the blue laser light irradiates the transmission area, and the light combining part 140 is further configured to transmit the fluorescent light emitted by the fluorescent wheel 110 to the color filter wheel 120, and the fluorescent light is generated by the blue laser light irradiating the fluorescent area. The color filter wheel 120 is configured to output red light, blue light, and green light in a time-sequential manner when the color filter wheel 120 rotates, where the red light and the green light are obtained by filtering the fluorescent light by the color filter wheel 120, and the blue light is obtained by transmitting blue laser light by the color filter wheel 120. The light collection member 160 is used to homogenize the red, blue and green light.

The light-emitting process of the projection light source is as follows: the blue laser emitted from the blue laser source 130 is shaped by the beam shaping device 150, and then emitted to the light combining part 140 and transmitted to the fluorescent wheel 110; the fluorescent wheel 110 rotates in sequence, when the blue laser beam irradiates the transmission region on the fluorescent wheel 110, the blue laser beam transmits from the fluorescent wheel 110, passes through the relay circuit optical path of the blue laser beam (referring to the optical path circuit in fig. 16 in which the blue laser beam is transmitted from the fluorescent wheel 110 to the light combining part 140), then passes through the light combining part 140 again, passes through the color filter wheel 120, and enters the light collecting part 160; when the blue laser irradiates the fluorescent region of the fluorescent wheel 110, the phosphor on the fluorescent region is excited to emit fluorescent light of at least one color, and the excited fluorescent light is transmitted in a reverse direction, reflected to the color filter wheel 120 by the light combining part 140, and then enters the light collecting part 160. After the light of the three colors (three color light for short) passes through the light collection component 160, the light is modulated by the optical machine 35 to generate an image light beam, and the image light beam is transmitted to the projection lens 36, so as to finally realize the image output of the three color light.

Optionally, as shown in fig. 17, the display control module 31 includes: a processing module 311, a signal generator 312 and a data selector 313, wherein the processing module 311 is connected with the data selector 313. It should be noted that the processing module 311 may also generally control the signal generation of the signal generator 312, and therefore may also be connected to the signal generator 312.

The processing module 311 is configured to generate N first current control signals and M enable signals corresponding to each frame of image in the multi-frame display image, and transmit the N first current control signals and the M enable signals to the data selector 313. In fig. 17, it is assumed that N is 4, M is 3, and both the monochrome current control signal and the color mixture current control signal are PWM signals. The 4 first current control signals are a red PWM signal R _ PWM, a green PWM signal G _ PWM, a blue PWM signal B _ PWM, and a color-mixed PWM signal Y _ PWM, respectively. The M enable signals are a red enable signal R _ EN, a green enable signal G _ EN, and a blue enable signal B _ EN, respectively. For example, the amplitude voltage of the color-mixed PWM signal Y _ PWM is 3.3V, the frequency is 18.3kHZ, and the duty ratio is 50%.

The signal generator 312 is configured to generate the duty control signal LD _ duty and output the duty control signal LD _ duty to the light source driving circuit 32. The duty control signal LD _ duty is used to control the turning on and off of the laser light source. Illustratively, when the duty control signal LD _ duty is at a high level, the laser light source is turned on; when the duty control signal LD _ duty is low, the laser light source is turned off. When the laser light source is a monochromatic light source, the laser projection apparatus needs to ensure that the monochromatic laser light source is normally open during the image display process, so the duty control signal LD _ duty is usually a continuous high-level signal during the operation of the laser projection apparatus.

The data selector 313 selects the second current control signal T _ PWM among the N first current control signals based on the M enable signals, and transmits the second current control signal T _ PWM to the light source driving circuit 32. The second current control signal T _ PWM is matched to a signal at an active potential among the M enable signals.

The light source driving circuit 32 is configured to adjust the current of the laser light source 332 based on the received second current control signal T _ PWM, and control the laser light source 332 to turn on or off based on the duty control signal LD _ duty.

In the embodiment of the present invention, the signal generator 312 may generate the duty ratio control signal LD _ duty in various ways. In an alternative implementation, the signal generator 312 directly generates a duty control signal LD _ duty that is continuously high; in another alternative implementation, the signal generator 312 synthesizes the duty ratio control signal LD _ duty based on the M enable signals. The processing module 311 is also connected to a signal generator 312. A processing module 311, further configured to transmit the M enable signals to the signal generator 312; and a signal generator 312 for synthesizing the duty ratio control signal based on the M enable signals.

Optionally, N is 4, M is 3, the data selector has a data input terminal for receiving 4 first current control signals, a logic pin for receiving 3 enable signals, and an output pin for outputting a second current control signal;

the data selector is used for outputting a first current control signal corresponding to a certain primary color as a second current control signal from the output pin when the enable signal corresponding to the certain primary color is an effective potential and the enable signals corresponding to other primary colors are not effective potentials; and when the enable signals corresponding to at least two primary colors are effective potentials, outputting the mixed-color current control signal as a second current control signal from the output pin.

Optionally, the processing module is further connected to the signal generator, and the processing module is further configured to transmit the M enable signals to the signal generator;

and a signal generator for synthesizing the duty ratio control signal based on the M enable signals.

Optionally, M is 3, the signal generator includes: a first or gate and a second or gate;

the two input ends of the first or gate are used for respectively receiving two enable signals in the 3 enable signals, one input end of the second or gate is connected with the output end of the first or gate, the other input end of the second or gate is used for receiving the other enable signals except the two enable signals in the 3 enable signals, and the output end of the second or gate is used for outputting the duty ratio control signal.

Optionally, the light source driving circuit includes: the device comprises a voltage output circuit, a driving chip and a peripheral circuit;

the voltage output circuit is used for providing rated voltage of the laser light source for the peripheral circuit;

the driving chip is used for receiving the second current control signal, providing current corresponding to the second current control signal for the peripheral circuit, receiving the duty ratio control signal and controlling the on-off of the peripheral circuit based on the duty ratio control signal;

and the peripheral circuit is respectively connected with the driving chip and the laser light source and is used for providing the laser light source with current corresponding to the second current control signal under the rated voltage when the peripheral circuit is conducted.

Optionally, the laser light source is a laser component, also called a bank light source (bank is a packaging method), and the voltage output circuit is a voltage reduction circuit; alternatively, the Laser light source is a multi-chip Laser (MCL), and the voltage output circuit is a booster circuit.

Optionally, the display control module further includes: and the digital-to-analog converter is positioned between the processing module and the data selector and is used for receiving the N first current control signals in the form of digital signals, respectively converting the received N first current control signals into the N first current control signals in the form of analog signals and transmitting the converted N first current control signals to the data selector.

Optionally, as shown in fig. 18, the processing module 311 includes: the light modulation device comprises an algorithm processor 311a and a control processing module 311b, wherein the algorithm processor 311a is connected with the control processing module 311b, and the control processing module 311b is further connected with a data selector 313 and the light modulation device 34 respectively.

The algorithm processor 311a is configured to determine a gain value α of each frame image according to the gray-scale value of each frame image, where α is greater than or equal to 1. The algorithm processor may be implemented using an FPGA.

The image display data of each frame of image may reflect the basic distribution and the basic tone of the color of each frame of image, and when the image display data is 4K data, the 4K data may be input to the algorithm processor 311a in the form of 8 VBO (full V-by-One, a digital interface standard developed for image transmission) signals.

The algorithm processor 311a is further configured to send the N first current control signals, the M enable signals, and the image display data to the control processing module 311 b.

Optionally, the control processing module includes: a master control processor and a slave control processor, the algorithm processor is respectively connected with the master control processor and the slave control processor, the master control processor is also respectively connected with the data selector and the optical modulation device, the slave control processor is also connected with the optical modulation device,

the algorithm processor is used for determining the gain value alpha of each frame image according to the gray-scale value of each frame image, and alpha is more than or equal to 1;

the algorithm processor is further used for sending N first current control signals and first subdata to the master control processor, and sending second subdata to the slave control processor, wherein the first subdata and the second subdata form image display data, each current control signal is used for indicating the adjusted brightness, the adjusted brightness is 1/alpha of the brightness before adjustment, the image display data is used for indicating the gray-scale value of each frame of image after adjustment, and the adjusted gray-scale value is alpha times of the gray-scale value before adjustment;

the main control processor is used for receiving the N first current control signals, generating M enabling signals, transmitting the N received first current control signals and the M enabling signals to the data selector, and sending first subdata to the optical modulation device;

the slave control processor is used for sending the second subdata to the optical modulation device;

and the light modulation device is used for modulating the light beam of the laser light source based on the first subdata and the second subdata to generate an image light beam.

In the embodiment of the present invention, the display control module may adjust the brightness of the laser light source in real time based on the gain value α of each frame of image, that is, the change of each frame of image, so as to implement the dynamic contrast. In the light source switch circuit of the laser series circuit, when the first switch transistor is an MOS transistor, such as an NMOS transistor, the on-off time of the light source switch circuit reaches ns (nanosecond) level, and the on-off time of the laser series circuit reaches mus (microsecond) level, so that the current response speed of the laser light source is high, and the precision is high.

Optionally, as shown in fig. 19, the laser projection apparatus further includes: the memory 37, the mirror driving circuit 381, the mirror 382, and the power module 39, wherein the memory 37 is connected to the display control module 31 and is used for storing image display Data, that is, storing the adjusted gray level value of each frame of image, for example, the memory is a Double Data Rate (DDR) memory; the galvanometer driving circuit 381 is respectively connected with the display control module 31 and the galvanometer 382 and is configured to drive the galvanometer 382 to vibrate under the control of the display control module 31, for example, the galvanometer 382 may be a 4-dimensional galvanometer, that is, capable of vibrating in 4 directions, and by arranging the galvanometer driving circuit 381 and the galvanometer 382, image superposition display may be performed, so that detail expressive force is increased, which is equivalent to resolution enhancement; the power module 39 is used to supply power to the electric components, and is connected to each electric component in the laser projection apparatus, and fig. 19 illustrates an example in which the power module 39 is connected to the light source driving circuit 32.

It is worth mentioning that the laser projection apparatus may further include as shown in fig. 12: at least one of the two dichroic mirrors, the reflecting mirror 30, the condensing lens 40, the diffusion wheel 50, and the light stick 60, or the laser projection apparatus may further include, as shown in fig. 15: the optical machine 35 and the projection lens 36, and at least one of the fluorescent wheel 110, the color filter wheel 120, the blue laser light source 130, the light combining part 140, the beam shaping part 150, and the light collecting part 160 shown in fig. 16, the functions of each element may refer to fig. 12, fig. 15, and fig. 16, and are not described again in the embodiments of the present invention.

An embodiment of the present invention provides a laser projection apparatus, including: a processor;

a memory for storing executable instructions of the processor;

wherein the processor is configured to: executable instructions in the memory are executed to implement any of the image display methods provided by the embodiments of the present invention described above.

An embodiment of the present invention provides a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and when the instructions are executed on a processing component, the processing component is enabled to execute any one of the image display methods provided in the embodiments of the present invention.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims

1. An image display method, characterized in that the method comprises:

2. The method according to claim 1, wherein the determining the gain value α of each frame of image in the multi-frame display image according to the gray-scale value of each frame of image comprises:

determining a target gray-scale value according to the gray-scale value of each frame of image in the multi-frame display image;

and inquiring a correction table to obtain the gain value alpha of each frame of image according to the target gray-scale value, wherein the correction table reflects the relationship between the gray-scale value and the gain value alpha.

3. The method of claim 2, wherein determining the target gray-scale value according to the gray-scale value of each frame of image in the plurality of frames of display images comprises:

determining a target set in a plurality of gray-scale value sets, wherein the gray-scale value sets are obtained by sequentially dividing a set gray-scale value range;

determining a target gray-scale value of each frame of image according to the target set;

the ratio of the number of pixels of which the gray-scale values in each frame of image fall into a specified gray-scale set to the total number of pixels in each frame of image is greater than or equal to a specified threshold, wherein the specified gray-scale value set comprises gray-scale values 0-W, and W is the maximum gray-scale value in the target set.

4. The method of claim 3, wherein determining a target set among a plurality of gray scale value sets comprises:

establishing a statistical histogram according to the gray-scale value of each pixel in each frame of image, wherein the abscissa of the statistical histogram represents the arrangement sequence of gray-scale value sets, and the ordinate of the statistical histogram represents the number of pixels of the gray-scale value in the corresponding gray-scale value set;

and sequentially adding the pixel numbers of the plurality of gray scale value sets according to the descending order of the gray scale values corresponding to the gray scale value sets until the total number of pixels obtained by accumulation is greater than or equal to a pixel total number threshold value, determining the gray scale value set reached when accumulation is stopped as a target set, and determining the pixel total number threshold value based on the specified threshold value.

5. The method according to claim 3, wherein the minimum gray-scale value of the target set is less than a gray-scale value threshold, and the target gray-scale value F of each frame of image satisfies:

wherein N is_ALLTotal number of pixels, N, of each frame of image_iIndicates the number of pixels corresponding to the ith gray level set, L_iRepresenting the gray level value corresponding to the ith gray level value set, wherein i is more than or equal to 0 and less than or equal to x, and the target set is the xth gray level value set;

or, the target gray-scale value F of each frame image satisfies:

F＝L_M×k₁+L_X×(1-k₁)，0≤k₁≤1，

wherein k is₁For sensitive dynamic contrast factor, N_ALLTotal number of pixels, N, of each frame of image_iIndicates the number of pixels corresponding to the ith gray level set, L_iAnd representing the gray level value corresponding to the ith gray level value set, wherein i is more than or equal to 0 and less than or equal to x, and the target set is the xth gray level value set.

6. The method of claim 1, further comprising:

when the gain value alpha of the n +1 frame image_n+1Gain value alpha with the n-th frame image_nWhen the ratio of (a) is within a specified range, updating the alpha_n+1So that the updated α_n+1Satisfies the following conditions:

updated alpha_n+1＝α_n×k₂，0＜k₂＜1，

Wherein the nth frame image and the (n + 1) th frame image are two adjacent frame display images in the multi-frame display image.

7. The method according to claim 4, wherein the creating a statistical histogram according to the gray-scale value of each pixel in each frame of image comprises:

and establishing a statistical histogram according to the maximum gray-scale value of each pixel in each frame of image, wherein the maximum gray-scale value of each pixel is the maximum gray-scale value in the gray-scale values of the primary colors of each pixel.

8. The method according to claim 2, wherein the calibration table records gray-scale values in a set gray-scale value range and normalized luminance corresponding to each gray-scale value, and the normalized luminance corresponding to any gray-scale value is obtained by normalizing the luminance corresponding to any gray-scale value.

9. A laser projection device, comprising: a display control module, a light source driving circuit, a projection light source and a light modulation device,

10. The laser projection device of claim 9, wherein the light source driving circuit comprises a plurality of laser driving circuits, the projection light source comprises laser components of three primary colors, the plurality of laser components are connected with the plurality of laser driving circuits in a one-to-one correspondence, and the display control module is connected with the plurality of laser driving circuits respectively;

or, the projection light source comprises a laser light source, the display control module, the light source driving circuit and the laser light source are connected in sequence.