110 results about "Nonlinear calibration" patented technology

The invention belongs to the technical field of measured calibration, and relates to a calibration process for solving camera inside and outside parameters by using a single digital camera for shooting a group of images based on LCDs, particularly to a digital camera nonlinear calibration method based on the LCDs, which comprises the following steps: designing and drawing a calibration chart through programming, wherein the calibration chart has round marking points in different sizes; displaying the calibration chart on the screen of a liquid crystal display; then shooting images by a digitalcamera in the mode of rotating around an optical axis; and then computing the camera inside and outside parameters by using the shot images; extracting sub-pixel contour edges in the images by usingthe complete pure flatness of the liquid crystal display and easy detection of centralized positioning height and sub-pixel edge contour of the round marked points, and obtaining a calibration resultof digital camera parameters by a nonlinear optimization method. The calibration method has the advantages of simple and easy operation, small and agile use equipment, good calibration precision, goodquality, strong optimization degree and the like.

The invention discloses a novel calibration method and a system for gas sensors and particulate matter sensors. The method comprises the steps of acquiring cross-over experiment data of parameters with influence on measurement accuracy of the sensors, and inputting a large number of laboratory data of different parameters to an established calibration model, so as to obtain linear and nonlinear calibration parameters of different sensors. The calibration model adopts a universal artificial-intelligence big data algorithm platform in view of different parameters, linear/nonlinear cross corresponding curves, containing different parameters, of temperature, humidity, wind direction, wind speed, atmospheric pressure, interference gas and sensor element aging of the sensors can be automatically extracted and obtained from experimental tank cross-over experiment parameter data through establishing relatively-deep artificial neural network or intelligent gene algorithm models, and random complicated nonlinear calibration model can be mapped, so that the robustness and adaptability are very high.

The invention discloses a phase measuring profilometry system nonlinear correction method combining geometric calibration. According to the phase measuring profilometry system nonlinear correction method combining geometric calibration, a target is scanned through the phase measuring profilometry to obtain an accurate phase, average brightness and brightness modulation, the accurate phase and the average brightness are utilized to calibrate a protector and a camera shooting device respectively, nonlinear response of the projector is obtained according to the accurate phase and a shot structured light image to establish a gray level lookup table, the gray value of the image is pre-compensated by utilizing the gray level lookup table before three-dimensional scanning is carried out on the projected structured light image, and therefore the purpose of carrying out nonlinear correction on a measurement system is achieved. The phase measuring profilometry system nonlinear correction method combining geometric calibration can be used for geometric calibration and nonlinear correction of the phase measuring profilometry system, organically combines geometric calibration of the measurement system and nonlinear correction, and has the advantages of convenient operation, high correction accuracy and high execution efficiency.

The invention relates to a method and a system for nonlinear correction of a radio frequency power amplifier. The method comprises the following steps of: S1. carrying out negative feedback correction on an input signal according to a feedback signal and outputting a negative feedback signal; S2. carrying out pre-distortion correction on the negative feedback signal and outputting the signal subjected to pre-distortion to the radio frequency power amplifier; and S3. collecting the signal amplified through the radio frequency power amplifier, generating the feedback signal and returning to the step S1. The method and the system for nonlinear correction of the radio frequency power amplifier adopt a method of combining the pre-distortion correction and closed-loop negative feedback correction, and are realized in a digital domain; and in comparison with a conventional nonlinear correction method, the correction effect is more accurate, the dependence on a device is smaller and the system is more stable.

The invention discloses a binary phase shifting pattern based three-dimensional measurement method, which is characterized in that focused projection equipment and a camera shooting device are utilized, a plurality of groups of binary pattern sequences coded by spatial square waves are projected to a measured objected by using the projection equipment, each group of patterns is provided with a specific spatial frequency, the spatial frequency of one of the groups of patterns is 1, adjacent patterns in each group of patterns have a fixed phase shifting amount therebetween, the total phase shifting amount is a cycle, corresponding pattern sequences are recorded by using the camera shooting device, a phase calculation formula of phase measuring profilometry is applied to image groups with different frequencies respectively so as to acquire a fundamental frequency phase and a plurality of high frequency truncation phases, an absolute phase is acquired according to a temporal phase unwrapping method, and three-dimensional coordinates of the measured object are determined according to the phases and system calibration parameters. The method disclosed by the invention can be applied to high-speed and high-precision three-dimensional measurement. The binary phase shifting pattern based three-dimensional measurement method has the advantages of ability of being free of nonlinear correction, high scanning speed, simple system calibration, and ability of accurately measuring scenes with great depth variations.

The invention relates to an on-orbit radiation nonlinear calibration method of a Fourier transform infrared spectrometer, and belongs to the technical field of on-orbit calibration methods of infraredloads. The method comprises the following steps of: step 1, closing the temperature control after the temperature control of an inner blackbody on a satellite reaches the balance of a highest temperature control point, wherein an instrument is periodically aligned with the inner blackbody and a cold space for observation during the inner blackbody temperature control, inner blackbody free temperature reduction and inner blackbody balancing periods, step 2, screening remote sensing data packets observed by the inner blackbody and downloaded by the satellite to obtain a plurality of inner blackbody observation remote sensing data; step 3, calculating uncalibrated spectral digital quantity and spectral radiance observed in the inner blackbody and the cold space; step 4; carrying out least square fitting on every channel in spectral band to obtain nonlinear calibrated coefficients; step 5, calculating target spectral brightness of earth observation by the instrument. The method can determine the nonlinear response relation of the Fourier transform spectrometer and improve the calibration precision and the data inversion accuracy.

The invention relates to an image full-screen anti-aliasing method and a device for head-up display characters and belongs to the technical field of image processing. The low-frequency flat area of an image and the high-frequency marginal area of the image are differentiated based on the correlation of adjacent pixels. The high-frequency marginal area of the image is selectively subjected to the anti-aliasing treatment based on a weighted Gaussian filtering function. In this way, the uniformity of displayed image lines is ensured, while the defect that an overall image is darker and lower in contrast ratio based on the traditional non-content-based anti-aliasing algorithm can be overcome. Moreover, based on the fact that the images of head-up display characters are rich in high-frequency components and severe in gray discretization, the contrast ratio is improved based on a nonlinear calibration curve. According to the invention, the phenomenon that lines in an original image of a head-up display character are poor in uniformity and the edge of the image is twisted can be effectively improved. The display effect of the overall image of the head-up display character is improved and the real-time performance is high. The entire processing process is shorter than three thousandths of the duration of a whole-frame image. The influence of the system delay is small. The method is simple and easy in hardware implementation.

The invention discloses a method for increasing the contrast of an OLED display screen, which comprises: firstly, determining the maximum value of the monochromatic brightness total values of a display signal; secondly, calculating the ratios of the maximum value to the monochromatic brightness reference values of all pixels, and dividing the obtained ratios into four ratio intervals which are divided in advance; thirdly, processing the ratios by using different nonlinear calibration modes according to different intervals; and finally, outputting the processed display signal to the OLED display screen for display. By increasing the brightness of the low-light part of a dark field and the brightness of the high-light part of a bright field, the method of the invention improves the detail display of the OLED display screen and increases image contrast, so that the OLED display screen can clearly display image frames in high light.

The invention relates to a ps-grade time frequency measurement circuit and a measurement method thereof. The measurement circuit comprises a circuit channel, an ECL logic control circuit, deltat1 and deltat2 extracting circuits, an integrating-sampling circuit, an ADC converting circuit, an integrating capacitor, a constant-current-source circuit, an FBGA circuit, a single-chip microcomputer control circuit, a keyboard, a display circuit, etc. The measurement method is improved based on simulation of an inner difference method. Through performing unification calibration, device nonlinear calibration, temperature drift calibration, imbalance voltage current calibration, system triggered error calibration and the like on two channels, the calibration method of each system parameter is designed through long-term statistics operation, and the calibration methods are called as system statistics calibration in total. Finally stable and accurate ps-grade time frequency measurement is realized.

The invention relates to an attitude adjustment and nonlinear calibration method for imaging in the identical region of a heterogeneous scene. The attitude adjustment and nonlinear calibration method comprises the following steps: calculating an initial drift angle of satellite imaging and adjusting a satellite yaw angle, transferring into a calibration mode of imaging in the same region of the heterogeneous scene; accurately calculating an image drift size by adopting a top-down time interface step length in an imaging process of the calibration mode, controlling an accurate push-sweeping direction of imaging of a linear array CCD (Charge Coupled Device) through adjusting the satellite yaw angle to ensure that the linear array CCD can be used for sequentially imaging the identical region; and determining whether the obtained image data meets the condition of nonlinear calibration, and if being met, establishing a nonlinear calibration mapping relationship table on the basis of histogram matching histogram matching, and if not, re-determining an imaging scene to continuously execute on-tract calibration so that more image data is obtained. The attitude adjustment and nonlinear calibration method is low in requirement for a ground scene without a more uniform scene; a non-uniform scene can meet a calibration task, each track of satellite operating can realize calibration, with high calibration frequency.

Calibration could be implemented in several stages during the color rendering processes. One possible and efficient place to put the calibration to work is in the screen table itself. In order to make the screen intelligent enough to adjust the factor results from output device characteristics, such as the dot gain, toner characteristics, etc., the method is introduced to create a gamma function with normalized gradation curve. Some color balance adjustment features (contrast, brightness, saturation and color strength) also have been taken into consideration.

The invention discloses a three-dimensional measurement method based on a pulse width modulation fringe. The three-dimensional measurement method consists of three key parts of pulse fringe encoding, pulse fringe defocusing and three-dimensional reconstructing. A pulse fringe is generated from a computer and then moderately defocused through a projector to generate a sine fringe on a reference face for three-dimensional measurement. The invention is advantageous in that (1) as the pulse fringe is a binary fringe, the grayscale value thereof can only be two values (0 and 1), so the measurement is quick; (2) since the nonlinear gamma of the projector can be eliminated simply by slight defocusing the projector, phase errors can be reduced without complex nonlinear calibration; and (3) thanks to less reduction in fringe contrast after the pulse fringe is slightly defocused, the measurement depth problem is overcome.

The invention discloses a beat frequency signal nonlinear correction method in an FMCW distance measurement system, solves the problem of low signal-to-noise ratio caused by influence of frequency modulation nonlinearity on nonlinear correction by means of phase comparison of an auxiliary interferometer in the prior art, and belongs to the technical field of signal processing. The method comprisessteps that S1, Hilbert transform of signals of an auxiliary interferometer is carried out to acquire phase information of the signals of the auxiliary interferometer, the phase information is utilized to acquire an orthogonal basis used for nonlinear correction, and the orthogonal basis comprises frequency modulation nonlinear information; and S2, a measurement interferometer signal is sampled, and the measurement interferometer signal is converted by utilizing the orthogonal basis in the step S1 to finish nonlinear correction. According to the invention, the auxiliary interferometer is usedfor sampling the light source signal, the signal of the auxiliary interferometer is used as the orthogonal basis used in the spectral analysis method to replace the original linear phase orthogonal basis to carry out spectral analysis on the measurement path signal, and the influence caused by frequency modulation nonlinearity and light source mode hopping can be effectively eliminated.

The invention discloses a monitoring method of lane space occupancy based on videos, comprising the following concrete steps: step 1: arranging an effective monitoring field of view, and acquiring basic data; step 2: carrying out nonlinear correction of a lane: calibrating the lane, computing the gradients of the upper bottom and the lower bottom of a calibrated trapezoid, computing the weight of each row in the calibrated trapezoid, carrying out curve fitting on the corrected weight, iterating and optimizing weight corrected parameters, and computing the actual length of the corrected calibrated trapezoid region lane, the fitting actual length obtained after curve fitting and the height of a triangle capable of being expressed by the inclination angles of the upper bottom and the lower bottom of the calibrated trapezoid region; and step 3: computing the space occupancy of the lane to obtain the actual value of the lane space occupancy. The method of the invention can effectively reduce the computing error of the lane occupancy since vehicles are big in a near place and are small in a far place in traffic video monitoring.

The present invention provides one simple and convenient LED display screen nonlinearity correcting method and device. The technological scheme includes the following steps: constituting nonlinearity correcting curve; forming nonlinearity correcting data; forming nonlinearity memory list storing in nonlinearity memory, reading grey data and scanning; and sending corrected grey data to display screen. The device includes R, G and B grey input unit, R, G and B grey output unit and nonlinearity correcting chip in between.

The invention discloses an intelligent test system based on a TEDS sensor and a matrix switch technology and a test method thereof. The test process of the test system comprises the following steps that (1) sensor TEDS information is read; (2) a conditioning module group is automatically configured; (3) automatic switching of channels is acquired; (4) sensor data are nonlinearly corrected; and (5) the data are parsed. The detection process is simple without artificial input of the sensor information or artificial replacement of the conditioning module and switching of the test channels so that detection efficiency is greatly enhanced. The intelligent test system is suitable for automatic conditioning and automatic testing of sensor output signals after intelligent reconstruction.

The invention provides a digital projector gray nonlinearity correction method, a storage medium and a projection system. The method comprises the following steps: generating an ideal grayscale image sequence by using a computer, collecting grayscale images by using a camera, solving an actual grayscale mean value Ik by using N groups of actual grayscale images, drawing a grayscale mean value curve comprising a linear part and a nonlinear part, and fitting the grayscale mean value curve to obtain a mapping relation between an ideal projection grayscale and a corrected ideal grayscale, obtaining a value table of actual gray under different current values, establishing a two-dimensional corrected ideal gray correction lookup table taking the ideal gray before current correction as a variable, and generating a sine curve by using the corrected ideal gray value and projecting the sine curve. According to the method, nonlinear correction can be directly carried out on the projection image of the projector, and the method is also suitable for changing the brightness of the projector, so that the accuracy of collecting the gray scale of the stripe image is improved, and the solving accuracy of phase information is greatly improved.

The embodiment of the invention relates to a mobile data calibration method and device, electronic equipment and a storage medium. The method comprises the following steps: receiving historical mobiledata and historical positioning data acquired by a measurement terminal in a historical time period, wherein the historical mobile data comprises historical IMU data collected by the measurement terminal; fitting the historical movement data and the historical positioning data to obtain a nonlinear calibration function after fitting; sending the fitted nonlinear calibration function to a terminalto be calibrated, wherein the fitted nonlinear calibration function is used for indicating the to-be-calibrated terminal to calibrate initial mobile data acquired by the to-be-calibrated terminal byusing the fitted nonlinear calibration function, so as to obtain calibrated mobile data and the initial mobile data comprises initial IMU data of the terminal to be calibrated. By adopting the method,the calculation complexity can be reduced, and the calibration cost can be saved.

The invention relates to a nonlinear function generator, a function transformer and a general nonlinear corrector, belonging to the technical fields of signal transformation and automatic control and measurement. The nonlinear function generator has the following types: an easy type and a synthetic type, inverted and inphase broken line types, inverted and inphase triangular wave synthesis types and a sine-wave synthesis type, and the like. The function transformer comprises the nonlinear function generator and an input and output gain controller which adopts a bipolar adjustable-gain amplifier, the nonlinear corrector has three types, i.e. a direct feed type, a feedback type and a combined type and comprises a weighted combiner, the function transformer and an output synthesizer, the general nonlinear corrector comprises a zero-bit adjustment circuit and the nonlinear corrector, and a (general) nonlinear corrector of a high impedance type adopts the (general) nonlinear corrector of a pre-voltage follower.