A superpixel-based resolution enhancement method and a scanning controller

Abstract

The application provides a superpixel-based resolution improvement method and a scanning controller, relates to the technical field of image display, and can improve the resolution without increasing the size of a display screen, multiplexes information of adjacent pixels, makes one light-emitting diode participate in imaging of multiple adjacent pixels, and meets the requirements of ultrahigh resolution and refresh rate of a micro display; the method comprises the following steps: S1, performing image processing on an original image; S2, determining the number of frames for separating the original image according to the spatial resolution of the original image; S3, separating the original image into a plurality of frame sub-images according to the number of frames determined in S2 and the row and column positions of each pixel in the original image, and meanwhile adjusting the gray intensity of each pixel color channel according to the separation ratio; S4, expanding the pixels in the sub-image by dividing sub-pixels; and S5, superimposing and merging the plurality of expanded frame sub-images to obtain a high-resolution image.

Description

Technical Field

[0001] This invention relates to the field of image display technology, and in particular to a resolution enhancement method and scanning controller based on superpixels. Background Technology

[0002] Based on the driving method, silicon-based OLED microdisplays are divided into two types: analog driving and digital driving. The grayscale level of the analog driving method is controlled by the amplitude of the current or voltage flowing through the pixel circuit, while the grayscale level of the digital driving method is controlled by the proportion of the light emission time per unit time.

[0003] In analog driving methods, the pixel driving circuit controls grayscale by controlling the charging and discharging process of the capacitor. To address the leakage current problem during charging and discharging, as well as the brightness decay caused by prolonged OLED operation, external circuitry is needed to compensate for leakage current and ensure the stability of OLED light emission. Simultaneously, analog driving methods require an analog-to-digital converter (DAC) to convert the digital video signal into an analog signal corresponding to the grayscale level. Because OLEDs have high luminous efficiency, the required driving current is relatively small. To achieve higher grayscale levels, the voltage or current difference between adjacent grayscale values ​​must be extremely small. Furthermore, as resolution requirements increase, the DAC needs to possess extremely high precision and conversion speed.

[0004] The digital driving method pixel driving circuit has no capacitor and does not require a DAC. All OLED pixels only have two states: bright or dark. When a pixel is in the bright state, the driving current flowing through it is constant. The grayscale is achieved by using digital modulation to control the light emission duty cycle.

[0005] In digital display technology, the most basic unit of a digital image is a single pixel. The quality of a digital image is primarily constrained by pixel density, typically measured by resolution. As technology advances, display panel resolutions are increasing, requiring the size of pixels to continuously shrink. However, due to manufacturing limitations, pixel size cannot be reduced indefinitely, and increasing the number of pixels would exponentially increase the cost of the display, making it unaffordable for both users and manufacturers. Improving display quality while maintaining the total pixel area and manufacturing process (i.e., display size) remains a problem for those skilled in the art.

[0006] Therefore, it is necessary to study a new superpixel scanning method to address the shortcomings of existing technologies and to solve or mitigate one or more of the aforementioned problems. Summary of the Invention

[0007] In view of this, the present invention adopts a digital driving method based on superpixels. The basic principle of superpixels is to utilize the superposition of gray levels, and digital driving, by controlling the emission duty cycle, is more in line with the gray level fusion of superpixels. For the proposed superpixel scanning controller, the traditional digital driving scanning controller is improved by switching scanning between several sub-frames, allowing the same emission scanning element to participate in the imaging process of multiple adjacent pixels. This improves both horizontal and vertical resolution without increasing the display screen size, thereby meeting the requirements of ultra-high resolution and refresh rate for microdisplays.

[0008] The superpixel scanning controller proposed in this invention is primarily designed for color OLED microdisplays. In DMD displays, a square white pixel is typically reflected through a lens and passed through a rotating RGB filter to achieve color display. Therefore, it not only needs to achieve color and grayscale overlay in time but also spatial misalignment. The scanning controller proposed in this invention, designed for a self-designed color silicon-based OLED microdisplay substrate, achieves color without the need for time-based overlay and utilizes elongated pixels to create a more refined image.

[0009] On one hand, the present invention provides a resolution enhancement method based on superpixels, the steps of which include:

[0010] S1. Perform image processing on the original image;

[0011] S2. Determine the number of frames to be separated from the original image based on the spatial resolution of the original image;

[0012] S3. Based on the number of frames determined in S2 and the row and column positions of each pixel in the original image, the original image is separated into several sub-image frames.

[0013] S4. Expand the pixels in the sub-image by dividing them into sub-pixels;

[0014] S5. The expanded sub-images are superimposed and merged to obtain a high-resolution image.

[0015] In addition to the aspects described above and any possible implementation, a further implementation is provided in which, in step S3, while separating according to the row and column positions of pixels, the grayscale intensity of each pixel's color channel is adjusted according to the separation ratio.

[0016] In addition to the aspects described above and any possible implementation, a further implementation is provided in which, when the number of frames of the sub-image is 2, the gray intensity of each pixel color channel in the first sub-image is reduced by N compared to the gray intensity of the original image, and the gray intensity of each pixel color channel in the second sub-image is reduced by (100-N)% compared to the gray intensity of the original image; where N is the separation ratio, and its value is an integer between 1 and 100.

[0017] In addition to the aspects described above and any possible implementation, an implementation is further provided in which 45 ≤ N ≤ 55.

[0018] In addition to the aspects and any possible implementations described above, another implementation is provided.

[0019] When the frame rate is 2, the first sub-image contains pixel data of RGB(2i-1,2j) and RGB(2i-1, 2j-1), and the second sub-image contains pixel data of RGB(2i,2j-1) and RGB(2i, 2j), where i is the row, j is the column, and i≥1, j≥1; each pixel is divided into 2*2 sub-pixels;

[0020] When the number of frames is 3, the first sub-image contains RGB(3i-2, 3j-2) pixel data, the second sub-image contains (3i-1, 3j-1) pixel data, and the third sub-image contains RGB(3i, 3j) pixel data, where i is the row, j is the column, and i≥1, j≥1; each pixel is divided into 3*3 sub-pixels;

[0021] When the frame rate is 4, the first sub-image contains RGB (2i-1, 2j-1) pixel data, the second sub-image contains RGB (2i-1, 2j) pixel data, the third sub-image contains RGB (2i, 2j-1) pixel data, and the fourth sub-image contains RGB (2i, 2j) pixel data, where i is the row, j is the column, and i≥1, j≥1; each pixel is divided into 4*4 sub-pixels.

[0022] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the image processing in step S1 includes compensating for the contour of the original image through smoothing processing to improve the recognizability of image edge regions and regions where there are significant gray-scale jumps.

[0023] On the other hand, the present invention provides a superpixel-based scanning controller for implementing any of the resolution enhancement methods described above;

[0024] The scanning controller switches between several sub-frames, allowing the same light-emitting scanning element to participate in the imaging process of multiple adjacent pixels, thereby improving both horizontal and vertical resolution.

[0025] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the scan controller includes:

[0026] Image processing module, including:

[0027] The image smoothing module is used to smooth the original image.

[0028] The frame data extraction module is used to separate pixels in the image based on their row and column positions in the original image; and

[0029] The grayscale data processing module is used to adjust the grayscale intensity of each pixel's color channel according to the separation ratio;

[0030] The data preprocessing module is used to expand and rearrange the bits of the separated pixel data in conjunction with the corresponding timing scanning algorithm, and to perform bit width transformation and data completion according to the transmission bandwidth.

[0031] It also includes a scanning control module, which controls the operation of the light-emitting scanning element array, enabling it to switch between scanning in different sub-images.

[0032] In addition to the aspects and any possible implementations described above, an implementation is further provided in which, when the number of separated frames is 2, the number of scan subfields used is 36 under the condition of a refresh rate of 120Hz.

[0033] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the scanning controller further includes a frame buffer control module for placing the new input image into the storage area while displaying the previous stored image.

[0034] The frame buffer control module includes external and internal storage, and uses two SDRAM external memories to alternate between storage and retrieval.

[0035] Compared with the prior art, one of the above technical solutions has the following advantages or beneficial effects: the scanning method can not only improve the resolution limitation problem, but also be applied to the spatial scanning of micro-displays without increasing the difficulty of device manufacturing process;

[0036] Another technical solution in the above-mentioned technical solution has the following advantages or beneficial effects: the present invention can meet the needs of micro-display equipment for wearable devices in the VR and AR fields.

[0037] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a superpixel formation process provided in one embodiment of the present invention;

[0040] Figure 2 This is a superpixel scanning strategy for color images provided in one embodiment of the present invention;

[0041] Figure 3 This is an implementation flow of a superpixel scanning method provided in one embodiment of the present invention;

[0042] Figure 4 This is a simulation image of the superpixel algorithm provided in one embodiment of the present invention;

[0043] Figure 5 This is a superpixel simulation image with different N values ​​provided in one embodiment of the present invention;

[0044] Figure 6 This is a superpixel scanning process at a refresh rate of 60 MHz provided in one embodiment of the present invention;

[0045] Figure 7 This is a block diagram of a superpixel scanning controller design provided in one embodiment of the present invention;

[0046] Figure 8 This is a flowchart of the image processing module provided in one embodiment of the present invention;

[0047] Figure 9 This is a row and column counter provided in one embodiment of the present invention;

[0048] Figure 10 This is a pixel data preprocessing arrangement structure provided in one embodiment of the present invention;

[0049] Figure 11 This is a data arrangement structure in RAM provided in one embodiment of the present invention;

[0050] Figure 12 This is a data arrangement structure in SDRAM provided in one embodiment of the present invention;

[0051] Figure 13 This is a schematic diagram of scanning and blanking provided in one embodiment of the present invention;

[0052] Figure 14 This is a scanning structure with 256 gray levels, 19 subfields, and 36 subfields provided in one embodiment of the present invention;

[0053] Figure 15 This is a schematic diagram of bit width expansion provided in one embodiment of the present invention;

[0054] Figure 16 This is a gamma correction debugging process provided in one embodiment of the present invention;

[0055] Figure 17 This is a block diagram of a microdisplay driving system provided in one embodiment of the present invention. Detailed Implementation

[0056] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0058] To address the shortcomings of existing technologies, this invention addresses the issue of image scanning algorithms by providing a superpixel scanning algorithm to improve image display quality.

[0059] To address motion sickness in VR applications and improve viewing quality, display refresh rates need to be increased to 120Hz or higher. To meet the ultra-high resolution and refresh rate requirements of microdisplays, a solution is to increase resolution without increasing screen size. This involves reusing information from adjacent pixels, allowing a single LED to participate in the imaging of multiple adjacent pixels, thus creating a larger and denser array of pixels. The basic idea behind superpixel scanning algorithms is that, assuming a small grayscale difference between adjacent pixels, when the resolution is high enough, inaccuracies in the grayscale of some pixels will not affect the visual experience. Figure 1 In (a), a single pixel is divided into 2×2 sub-pixels. Figure 1 In (b), a superpixel is formed by scanning between two pixels, and is represented by the shaded area. Figure 1 In (c), the image is displayed by a 6×6 dot matrix, so that the original one scan constitutes one frame of image. Therefore, if the refresh rate is doubled, the original one scan time can realize two scans. For example, the field 0 scan of Frame0 is performed first, and then the field 1 scan of Frame1 is performed. The scanning switch between field 0 and field 1 improves the resolution in both the horizontal and vertical directions.

[0060] Figure 2The process of implementing a superpixel scanning algorithm for color images is described. Assuming the input color image has a resolution of 10×10×RGB, the image is split into two frames, Frame0 and Frame1, according to "even rows + even columns" and "odd rows + odd columns". During the separation of the input image, the grayscale values ​​of the three color channels are also separated. Furthermore, the grayscale intensity of the three color channels in Frame0 is reduced by N% compared to the grayscale intensity of the input image, and the corresponding grayscale intensity in Frame1 is reduced by (100-N)%, where N is an integer called the separation ratio, ranging from 1 to 100 (N=50% in the figure). When the number of frames is 3, the grayscale intensity of the three color channels in Frame0 is reduced by N% compared to the grayscale intensity of the input image, the grayscale intensity of the three color channels in Frame1 is reduced by M%, and the grayscale intensity of the three color channels in Frame2 is reduced by (1-MN)%, where M and N are integers ranging from 1 to 100. The best effect is achieved when M=N=33.3%. When the frame rate is 4, the grayscale intensity of the three color channels of Frame0 is reduced by N% compared to the grayscale intensity of the input image; the grayscale intensity of the three color channels of Frame1 is reduced by M% compared to the input image; the grayscale intensity of the three color channels of Frame2 is reduced by A% compared to the input image; and the grayscale intensity of the three color channels of Frame3 is reduced by (1-MNA)%. M, N, and A are integers ranging from 1 to 100. The best effect is achieved when M=N=A=25%. The pixels of Frame0 and Frame1 are divided into sub-pixels to expand the image. The expanded Frame0 and Frame1 are then superimposed to obtain the merged image perceived by the human eye. It can be seen that the resolution of the merged image perceived by the human eye is significantly improved compared to Frame0 and Frame1, but the total number of pixels does not increase. A simplified algorithm flow for superpixels is as follows: Figure 3 As shown, the steps include:

[0061] Step 1: Determine the spatial resolution of the input color image;

[0062] Step 2: Perform image processing on the color image;

[0063] Step 3: Separate the image into two frames, Frame0 and Frame1, and simultaneously perform grayscale intensity separation for the corresponding color channels;

[0064] Step 4: Divide the data into sub-pixels and expand Frame0 and Frame1;

[0065] Step 5: Merge Frame0 and Frame1, and display Frame0 and Frame1 at twice the refresh rate.

[0066] Considering that merging the two frames Frame0 and Frame1 will result in uneven grayscale at the edges of the displayed video image, a smoothing filter can be performed after the video source input, i.e., in step 2, to improve the quality of the displayed video.

[0067] Figure 4 The results of the MATLAB simulation experiment show that with a separation ratio of N=50, the image after merging the two frames is very close to the input image. Figure 5 To simulate the results of different separation ratios N, we observed the edge information of the number "a". When the grayscale difference of corresponding pixels in two frames is too large, the edge information of the image becomes more blurred. When N=50, the image edge is the smoothest and the display quality of the image is closest to the original image.

[0068] The superpixel algorithm proposed above will be further optimized below. For example... Figure 6 As shown, the input image can be separated into m (m=2,3,4) frames, and the refresh rate of the microdisplay is 60MHz. The formula below is the mathematical model of the superpixel algorithm at different refresh rates. The left side is the input image, and the first pixel in the upper left corner of the input image is taken as RGB(1,1). When m=2, in order to extract more relevant information of the image, pixel data of RGB(2i-1,2j), RGB(2i-1, 2j-1), RGB(2i, 2j-1), and RGB(2i,2j) (i≥1, j≥1) can be extracted. Frame0 contains pixel information of RGB(2i-1,2j) and RGB(2i-1, 2j-1), and Frame1 contains pixel data of RGB(2i,2j-1) and RGB(2i, 2j). Then, each pixel of Frame0 and Frame1 is divided into 2*2 sub-pixels. The mathematical model is as follows:

[0069] ;

[0070] When m=3, Frame0 extracts RGB(3i-2, 3j-2) pixel data, Frame1 extracts RGB(3i-1, 3j-1) pixel data, and Frame2 extracts RGB(3i, 3j) pixel data. Each frame divides the pixels into 3*3 sub-pixels. The mathematical model is as follows:

[0071] ;

[0072] When m=4, Frame0 extracts RGB(2i-1, 2j-1) pixel data, Frame1 extracts RGB(2i-1, 2j) pixel data, Frame2 extracts RGB(2i, 2j-1) pixel data, and Frame3 extracts RGB(2i, 2j) pixel data. Compared to m=2 and m=3, the spatial movement positions in each frame have changed. Frame1 moves one pixel to the left compared to Frame0, Frame2 moves one pixel down compared to Frame0, and Frame3 moves one pixel to the right and down compared to Frame0. The mathematical model is as follows:

[0073] ;

[0074] Design block diagram of the superpixel scanning controller, as shown below Figure 7 As shown, it mainly includes a video source input module, an image processing module, a data preprocessing module, a frame buffer control module, and a scan control module. None of these modules reside in the clock domain; therefore, the incoming signals need to be synchronized using an asynchronous FIFO. An asynchronous FIFO, as a buffer for cross-domain data transmission, operates as follows: 1. An asynchronous FIFO has two operating clocks: a write clock (wr_clk) and a read clock (rd_clk); 2. An asynchronous FIFO has two sets of data transmission interfaces: a write data interface (wr_data) and a read data interface (q). The wr_data interface operates on the clock wr_clk, and the q interface operates on the clock rd_clk. When the external input write enable (wr_en) is enabled, data is written to the FIFO through the wr_data interface under the synchronization of the wr_clk clock (it is necessary to first check if the FIFO is full). When the external input read enable (rd_en) is enabled, data is output from the FIFO through the q interface under the synchronization of the rd_clk clock (it is necessary to first check if the FIFO is empty); 3. The FIFO operates on a first-input, first-output principle, meaning that data written first is sent first. Simultaneously, the FIFO no longer stores the sent data, and reading and writing can occur simultaneously (the read and write data lines are separate). The following describes each module.

[0075] Image processing module, such as Figure 8 As shown, it comprises three parts: an image smoothing module, a frame data extraction module, and a grayscale data processing module. After superpixel processing, the image edges and contours become blurred, requiring contour compensation to improve the recognizability of edge regions and areas with significant grayscale jumps. Many commonly used image smoothing methods exist, including Gaussian filtering and neighborhood weighted averaging. Common smoothing kernels include 3x3, 4x4, and 5x5 kernels; the 3x3 smoothing kernel is as follows:

[0076] ;

[0077] The 4x4 smoothing kernel is:

[0078] ;

[0079] The 5x5 smoothing kernel is:

[0080] .

[0081] For 3x3 and 5x5 smoothing kernels, the superpixel generation position is in the middle. For 4x4 smoothing kernels, the superpixel generation position is as follows:

[0082] , where RGB(r, c) represents the superpixel generation location.

[0083] The generation of grayscale data for two frames of images can be achieved by counting the rows and columns of each input frame of the image based on timing control signals such as clock (CLK), line synchronization (HS), frame synchronization (VS), and input valid signal (DE). Figure 9 As shown, this extracts the data DIN_odd (odd rows, odd columns) and DIN_even (even rows, even columns). In the grayscale processing module, grayscale data is separated according to a separation ratio.

[0084] The data preprocessing module expands and rearranges the bits of the incoming pixel data using a corresponding timing scan algorithm, performs bit-width transformation and data padding based on the transmission bandwidth, and then stores the rearranged data in internal memory in preparation for input to SDRAM. Figure 10 As shown, the data bit width of the XXX microdisplay is designed to be 64 bits. The rearranged pixel data does not have the concept of individual pixels; the 64 bits of data can be considered as a single transmission unit. Data of the same bit width is divided into 8 bit planes for processing, and the data arrangement order of a single pixel in each bit plane is R, G, B.

[0085] The frame buffer control module's function is to store new images in the memory area when they are input, while simultaneously displaying the previously stored image frame. Here, "one frame of data" refers to the input frame of data, including DIN_odd and DIN_even. To ensure continuous data transmission, the frame buffer module is divided into external and internal storage, using two SDRAM external memories for alternating storage and retrieval. To fully buffer the pixel data of one frame of image, the internal storage uses RAM to cache data up to the SDRAM's burst length. Figure 11 It is a data arrangement structure stored in RAM. Data is stored in bits, with a data width of 64 bits and a depth of 240 (8 bits × 30). Figure 12It uses the external SDRAM data arrangement structure, which also stores data in bits, with each row of memory storing one row of image data. To improve system brightness, a "ping-pong operation" is used, writing the data for the next frame while illuminating the current frame.

[0086] The scanning control module is the core of the digital drive display. The scanning method typically starts from the top-left pixel of the screen and scans pixel by pixel from left to right. Once all rows have been scanned, frame synchronization is achieved using the VS (frame synchronization signal). The algorithm employed must satisfy grayscale voltage requirements without placing excessive pressure on data transmission bandwidth, while also minimizing display quality issues such as low-gray flicker and dynamic false outlines. Current research employs various methods, such as increasing the number of data bits, using different arrangement methods, and dividing the data into more sub-frames. Two commonly used algorithms are: one divides the grayscale into sub-frames of equal duration, which means that N grayscale levels require... For each subframe, adding one bit of grayscale requires a significant increase in storage bandwidth and speed; another algorithm weights the data based on grayscale values, incorporating sorting algorithms and lookup tables to configure data weights and grayscale levels, offering advantages such as low noise, high image quality, high grayscale levels, and rich colors. For example... Figure 13 The row scanning order of the microdisplay driver panel is from left to right, and the column scanning order is from top to bottom. The first row is scanned until the last column of pixels in the first row is lit, then the scanning of all columns in the second row begins. For example, when using a 19-subfield scanning sequence 1 / 16, 1 / 8, 1 / 4, 1 / 2, 1, 2, 4, 8 to achieve 256 levels of grayscale scanning, for a weight of 1 / 2, the scan starts from the first row and proceeds row by row to the nth row. At this point, n is half the value of N, and the illumination time of the pixels in the first row is the time required to scan half the screen. When scanning row n+a, the illuminated pixels in row a are turned off. When the weight is 2, the scan is repeated once more based on the previous scan, accumulating over time until the pixel brightness reaches the corresponding weight value.

[0087] Because the superpixel algorithm processes the separated Frame0 and Frame1 using a scanning algorithm, the number of subfields is reduced due to grayscale separation. Previously, at a refresh rate of 60Hz, there were 19 subfields; the superpixel algorithm, at a refresh rate of 120Hz, uses 36 subfields. Figure 14 As shown. The algorithm theoretically improves image display quality. In addition to outputting frame data, it also outputs the data signals and clock signals required by the display screen, thereby enabling control of the microdisplay substrate circuitry.

[0088] Since the human visual system's perception of brightness is non-linear, segmented adjustment based on actual light emission conditions allows for higher correction in low-brightness areas to adapt to gamma characteristics, resulting in more pronounced grayscale changes after correction and better meeting the needs of human visual perception. Digital modeling of the display system's gamma characteristics is performed to calculate the corrected video drive data, which is pre-stored in memory. During display, a lookup table method is used to implement gamma correction of the image.

[0089] Nonlinear correction requires completing the nonlinear mapping from input data to output data, which necessitates bit-width expansion of the output data, such as... Figure 15 The intermediate code value of low-bit-width input data can correspond to the intermediate code values ​​of multiple high-bit-width data. By adjusting the increment of the input data to correspond to the increment of the output data, a non-linear mapping is achieved. The more bits wide the input data is extended, the smoother the output curve becomes, but the amount of data also increases.

[0090] The input data is 8 bits, representing a grayscale value range of 0~255. In the preceding timing scan, gamma correction expands the bit width to 18 bits to represent finer grayscale levels. A lookup table is used to map the low-bit-width input data to the high-bit-width output data, thereby improving image contrast. The gamma curve can be fitted using multiple points (n=31, the larger n is, the more accurate the fit). The curve between two adjacent points is approximately a straight line, resulting in a 30-segment function. Since the maximum and minimum values ​​(maximum luminous intensity) of the 18-bit data obtained through bit expansion are already determined, only the middle 29 points need to be set to control the shape of the gamma curve. Because the human eye is sensitive to grayscale changes in low-brightness environments, more points are selected in the low grayscale region and fewer points in the high grayscale region. After the chip is fabricated, the shape of the gamma curve can be adjusted according to the actual luminous conditions of the XXX microdisplay to achieve better display results. The output values ​​corresponding to the above 29 intermediate gray levels are obtained through LUT operations; while for the gray levels between two adjacent points, it is first necessary to determine which two points the point is located between, and then obtain the output through linear interpolation. The calculation formula is as follows:

[0091] ;

[0092] in For 8-bit input data of the R / G / B three color channels, To expand the output data bit width, and for The input grayscale values ​​of two adjacent points and These are the output values ​​for the corresponding two points.

[0093] Because the superpixel scanning driving method proposed in this invention requires a higher refresh rate, a higher refresh rate corresponds to a higher number of subfields, and a higher number of subfields is achieved by gamma correction. Therefore, gamma correction is needed to make the display effect of the microdisplay more in line with the human eye's perception requirements.

[0094] The specific debugging process for gamma correction is as follows: Figure 16 As shown, the steps include:

[0095] Step 1: Measure the maximum brightness corresponding to 255 gray levels;

[0096] Step 2: Based on the principle of gamma correction, obtain the relationship between the gray levels perceived by the brain and the original video data;

[0097] Step 3: Select the positions of these 29 points on the gamma curve based on the values ​​of the internal registers configured on the SPI bus;

[0098] Step 4: Measure the luminance of the intermediate gray level and compare it with the standard luminance table.

[0099] The substrate chip architecture of the superpixel microdisplay mainly consists of three parts: row and column driving circuits and pixel circuits. Figure 17 This is a block diagram of the overall driving system for the microdisplay. The input image data is 24 bits, with a frame rate of 120Hz, achieving 256×RGB grayscale display. The column driving circuit mainly consists of a shift register, a latch, and a buffer. First, the image data signal is input into the column driving circuit within one row scan time. Then, driven by the row synchronization signal HS, the latch stores one row of data from the shift register, allowing the shift register and latch to work in parallel. The row driving circuit decodes the address lines into row signals and drives them to the pixel circuits. Only when both the row and col signals are valid will the pixel unit at that intersection light up. According to the row-scanning-column-driving scanning strategy, pixels are selected and lit from top to bottom row by row. Based on the characteristics of human vision, a complete visual image can be formed.

[0100] Superpixel scanning can achieve high image resolution while maintaining low cost. Therefore, superpixel scanning can be combined with digital scanning to achieve high resolution without changing the microdisplay substrate chip process cost, making it suitable for the low-cost, high-resolution, and high-refresh-rate requirements of virtual reality applications.

[0101] The foregoing has provided a detailed description of a resolution enhancement method and scanning controller based on superpixels, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and its core ideas; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0102] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system including said element. "Substantially" means within an acceptable margin of error, indicating that a person skilled in the art can resolve the technical problem and substantially achieve the technical effect within a certain margin of error.

Claims

1. A resolution enhancement method based on superpixels, characterized in that, Includes the following steps: S1. Perform image processing on the original image; S2. Determine the number of frames to be separated from the original image based on the spatial resolution of the original image; S3. Based on the number of frames determined in S2 and the row and column positions of each pixel in the original image, the original image is separated into several sub-image frames. While separating according to the row and column positions of the pixels, the gray intensity of the color channel of each pixel is adjusted according to the separation ratio. S4. Expand the pixels in the sub-image by dividing each pixel into 2×2 sub-pixels; S5. Overlay and merge the expanded sub-images to obtain a high-resolution image; When the number of frames in a sub-image is 2, the gray intensity of each pixel color channel in the first sub-image is reduced by N compared to the gray intensity of the original image, and the gray intensity of each pixel color channel in the second sub-image is reduced by (100-N)% compared to the gray intensity of the original image; where N is the separation ratio, which is an integer between 1 and 100. When the number of frames is 2, the first sub-image contains pixel data of RGB(2i-1,2j) and RGB(2i-1, 2j-1), and the second sub-image contains pixel data of RGB(2i,2j-1) and RGB(2i, 2j), where i is the row, j is the column, and i≥1, j≥1; each pixel is divided into 2*2 sub-pixels; When the number of frames is 3, the first sub-image contains RGB(3i-2, 3j-2) pixel data, the second sub-image contains (3i-1, 3j-1) pixel data, and the third sub-image contains RGB(3i, 3j) pixel data, where i is the row, j is the column, and i≥1, j≥1; each pixel is divided into 3*3 sub-pixels; When the frame rate is 4, the first sub-image contains RGB (2i-1, 2j-1) pixel data, the second sub-image contains RGB (2i-1, 2j) pixel data, the third sub-image contains RGB (2i, 2j-1) pixel data, and the fourth sub-image contains RGB (2i, 2j) pixel data, where i is the row, j is the column, and i≥1, j≥1; each pixel is divided into 4*4 sub-pixels.

2. The resolution enhancement method based on superpixels according to claim 1, characterized in that, 45≤N≤55。 3. The resolution enhancement method based on superpixels according to claim 1, characterized in that, The image processing in step S1 includes compensating for the contour of the original image through smoothing to improve the recognizability of image edge areas and areas where there are significant gray-scale jumps.

4. A scanning controller based on superpixels, characterized in that, The scanning controller is used to implement the resolution enhancement method as described in any one of claims 1-3; The scanning controller switches between several sub-frames, allowing the same luminescent scanning element to participate in the imaging process of multiple adjacent pixels, thereby improving both horizontal and vertical resolution. The scanning controller includes: Image processing module, including: The image smoothing module is used to smooth the original image. The frame data extraction module is used to separate pixels in the image based on their row and column positions in the original image; and The grayscale data processing module is used to adjust the grayscale intensity of each pixel's color channel according to the separation ratio; The data preprocessing module is used to expand and rearrange the bits of the separated pixel data in conjunction with the corresponding timing scanning algorithm, and to perform bit width transformation and data completion according to the transmission bandwidth. It also includes a scanning control module, which controls the operation of the light-emitting scanning element array, enabling it to switch between scanning in different sub-images.

5. The superpixel-based scanning controller according to claim 4, characterized in that, When the number of separated frames is 2, the number of scan subfields used is 36 under the condition of a refresh rate of 120Hz.

6. The superpixel-based scanning controller according to claim 4, characterized in that, The scanning controller also includes a frame buffer control module, which is used to put the new input image into the storage area and display the previous stored image. The frame buffer control module includes external and internal storage, and uses two SDRAM external memories to alternate between storage and retrieval.

Images