47 results about "Line Spread Function" patented technology

The invention relates to a dynamic object modulation transfer function measuring method and a device thereof, pertaining to the optical property measurement field. The invention aims at providing a dynamic object modulation transfer function measuring method and a device thereof which can carry out the dynamic object modulation transfer function measurement under different fields of view, namely, uniform linear motion, uniformly-accelerated rectilinear motion, simple harmonic motion, but also can measure static target modulation transfer function and separate the static target modulation transfer function from whole machine modulation transfer function. The device consists of a light source, a collimating lens, a pupil coupling system and an electro-optical imaging system which are arranged along the ray propagation direction in sequence; the electro-optical imaging system carries out imaging towards the light source moving along the guide rail direction and line spread function is obtained from the image and carried out one-dimensional Fourier transformation so as to obtain the dynamic object modulation transfer function. The method and the device of the invention are not only suitable for static image evaluation field but also for the image evaluation field of dynamic object imaging by a time-delay electro-optical imaging system.

Image ringing noise is reduced by calculating a line spread function value of each pixel's luminance in an input image, dividing the input image into a plurality of blocks, and calculating an average value and a maximum value of the line spread function values for all pixels in each block. Based on the average value and the maximum value of the line spread function values of each block, whether a block is an interfered flat block or a non-interfered block is determined and the pixels in the interfered flat block are set as noisy pixels. Whether each pixel in the non-interfered block is an edge pixel or a non-edge pixel is determined and the non-edge pixels in the non-interfered block are set as noisy pixels. The noisy pixels thus set are smoothed, and the smoothed pixels are combined with the edge pixels for output as an output image.

A measuring method for dynamic object modulation transfer function belongs to the test field of optical properties. The invention aims to provide a measuring method for dynamic object modulation transfer function that can not only remove background vagabond ray and dark current of an image sensor, but also remove nonideal target size and the effect on a measuring result by the diffraction and aberration defect of an optical system. The method first respectively records an interference image, a still image and a dynamic image through imaging under the condition of closing and lightening a point light source, keeping the light source still and moving the light source, respectively uses the still image, the dynamic image and the interference image to do subtraction and obtain an anti-interference still image and an anti-interference dynamic image, extracts and modifies line spread function therein to obtain modified static and dynamic object line spread functions and obtains initial static and dynamic object modulation transfer functions through Fourier transformation. And finally, the method uses the initial dynamic object modulation transfer function to be divided by the initial static object modulation transfer function, thus obtaining the final measuring result of the dynamic object modulation transfer function.

The invention relates to an optical transfer model measuring method in a coding structured light system. The optical transfer model measuring method in the coding structured light system achieves optical transfer modeling of an optoelectronic system for a strip coding structured light system. Firstly, optical transfer modeling of the structured light system is finished theoretically, corresponding measurement legends are designed according to the characteristics of a strip coding light image, measurement of a line spread function of the system is finished through a knife-edge method by using a projected knife edge target, and then Fourier transform is carried out on the line spread function to obtain the optical transfer model of the coding structured light system. The optical transfer model is used for guiding the design of coding structured light, improving the measurement accuracy and expanding the measurement applicability of different reflection surface objects, improves the performance of the coding structured light system, and widens the application range of the structured light technology.

The invention belongs to the field of biomedical engineering and a computer and relates to a modulation transfer function measurement method on the basis of the characteristics of a detector of an X-ray imaging system. The modulation transfer function measurement method comprises the following steps of: placing a knife edge testing instrument to enable the knife edge testing instrument to be clung to the detector, enabling an inclination angle to be formed between a knife edge and the sampling direction of the detector and continuously acquiring a plurality of images; carrying out superposition averaging on a plurality of knife edge images, reducing system noise and then carrying out knife edge boundary detection on an averaged knife edge image to obtain a knife edge boundary line; carrying out Hough transform on a knife edge boundary line graph to obtain a knife edge inclination angle alpha and establishing an oversampling ESF (Extended Superframe Format) curve; using a C spline as a regression spline f for carrying out segmentation fitting on the oversampling ESF curve; carrying out differential operation to obtain a line spread function; carrying out Fourier transform on the line spread function and then carrying out modulus acquisition to obtain a modulation transfer function; and carrying out normalization processing. The modulation transfer function measurement method solves the problem of fitting error generated when the oversampling ESF curve is acquired by a knife edge method; and compared with a conventional knife edge measurement method, the modulation transfer function measurement method can obtain a more accurate MTF (Modulation Transfer Function) curve.

SFR test equipment and a test method thereof are disclosed. The equipment comprises a target plate, a light source, a base station and an image acquisition system. The target plate is a full field-of-view SFR target plate and is formed by a plurality of inclined black square blocks and a plurality of inclined white square blocks which are intersected. The light source is arranged in front of or behind the target plate. The base station supports a camera module group. The image acquisition system is connected to the camera module group so that an initial image of the target plate is transmittedto the image acquisition system. According to each knife edge inclination angle, an edge spread function (ESF) and a line spread function (LSF) are calculated. And finally, a SFR value of resolutionpower of the camera module group is determined.

The invention belongs to the fields of biomedical engineering and computers, and relates to a knife-edge measuring method of a modulation transfer function (MTF) of a digital X-ray imaging system. The knife-edge measuring method comprises the following steps of: acquiring a plurality of knife-edge images; performing knife-edge boundary detection to obtain a knife-edge boundary straight line; performing Hough conversion on a knife-edge boundary straight line graph to obtain a knife-edge inclination angle; calculating distance from each point close to the knife-edge boundary to the knife-edge straight line, and ordering from small to large according to the distance to form a non-uniformly sampled ERF (Edge Response Function) curve sequence; acquiring an ERF new sequence of a uniform sampling interpolation position by using a center-of-gravity-based Lagrange interpolation method; acquiring a line spread function; and acquiring a normalized modulation transfer function. According to the knife-edge measuring method, an accurate over-sampling ERF curve is constructed, and finally, a more accurate MTF curve compared with that of the conventional knife-edge measuring method can be obtained.

The invention provides a multi-angle automatic MTF estimation method of a remote sensing image. The method comprises the two processes of selecting image blocks and estimating an MTF based on the edge method. The process of selecting the image blocks comprises the steps of rotating an original image by multiple angles to obtain a rotated image, carrying out edge point extraction on the rotated image and the original image to obtain four edge point images, and selecting the image blocks for estimating the MTF with the four edge point images as the reference. The process of estimating the MTF based on the edge method comprises the steps of carrying out edge detection on the obtained image blocks to obtain the positions of edge points, namely, the positions of sub-pixel points of the edge points, fitting the edges of the image blocks through the least square method, carrying out interpolation and average edge spread function extraction on the fit edges of the images blocks, carrying out simple differencing on an average edge spread function to obtain a line spread function, fitting the line spread function through Gaussian distribution, carrying out discrete Fourier transformation on the fit line spread function, and carrying out model extraction on the result to obtain a final MTF series.

The invention provides a television imaging system modulation transfer function test device and method and belongs to the technical field of optical measurement. The television imaging system modulation transfer function test device and method are characterized in that a television imaging system to be tested is placed in an optical collimation system illuminated by an integrating sphere light source, of which the light intensity is adjustable and which is high in space uniformity, and slit targets are arranged in the focal plane of the optical collimation system; the slit targets, after passing through the optical collimation system and the television imaging system to be tested, are imaged to a target surface of the television imaging system; and after an image recording and processing system carries out a series of calculation and processing on the slit images, line spread function distribution of the slit targets and the MTF value are obtained, and thus MTF measurement of the television imaging system is finished.

A method for reducing image ringing noise includes: (a) calculating a line spread function value of each pixel's luminance in an input image; (b) dividing the input image into a plurality of blocks, and calculating an average value and a maximum value of the line spread function values for all the pixels in each of the blocks; (c) based on the average value and the maximum value of the line spread function values for of each of the blocks, determining whether each of the blocks is an interfered flat block or a non-interfered block; (d) setting the pixels in the interfered flat block as a noisy pixels; (e) determining whether each pixel in the non-interfered block is an edge pixel or a non-edge pixel, and setting each the non-edge pixels in the non-interfered block as a noisy pixels; and (f) performing smoothing on each of the noisy pixels thus set, and combining smoothed pixels with the edge pixels for output as an output image.

The invention provides an optical image restoration method based on Kalman filter. The method comprises the following steps of 1, extracting a line spread function; 2, Gaussian fitting the line spread function; 3, generating a high precision line spread function based on the Kalman filter; 4, generating an MTF (modulation transfer function) curve and an MTF matrix; and 5, restoring an image by the MTF matrix. Based on an MTF theory and an image quality degradation theory, the method is used for correcting and measuring interference elements in the line spread function by adopting the Gaussian fitting method and Kalman filter method, thereby obtaining a point spread function which is better and more close to the real imaging performance of an imaging system as the basis of image restoration, and improving the image restoration accuracy from the source. The method can be used for effectively restoring images and improving image quality and the algorithm efficiency is high.

The invention relates to a double-edge scanning measurement method for an infrared focal plane array (IRFPA) modulation transfer function (MTF) and a special device thereof. The method comprises the following steps of: using double edges with adjustable light pass widths as targets and implementing the scanning of the edges by a double parabolic lens reflective 1:1 imaging optical system and a three-dimensional precision displacement mechanism so as to obtain a tool spread function ESF (x); then performing the derivation on the ESF (x) to obtain a line spread function LSF (x); and finally, performing the discrete fourier transform to obtain the MTF. According to the invention, a double-edge scanning mode and a trinomial fermi function are adopted to carry out fitting, so that the defects of the polynomial fitting are overcome. The method has strong applicability and high measurement accuracy; and three short wave infrared, medium wave infrared and long-wave infrared wavebands can be covered.

The invention relates to a slit-method measurement method for a modulation transfer function of a digital X-ray imaging system. The slit-method measurement method comprises the following steps: 1) setting exposure parameters of the digital X-ray imaging system and collecting slit images; 2) carrying out slit position detection through edge detection and obtaining a slit straight line by utilizing line fitting; 3) carrying out Hough transformation on a slit straight line image to obtain slit inclination angle alpha, and constructing an oversampling LSF curve; 4) utilizing an I-spline curve as a regression spline curve f to carry out least square fit on the left and right two parts of the oversampling LSF curve, and meanwhile, meeting constraint conditions, that is, during fitting, guaranteeing that the left part of the LSF curve is a monotone non-decreasing function, and the right part is a monotone non-increasing function, and obtaining a line spread function; and 5) carrying out Fourier transform and then mod operation on the line spread function to obtain a modulation transfer function thereof, and finally, obtaining a normalized modulation transfer function. Compared with the conventional slit measurement method, the method can obtain more accurate MTF curve.

The invention relates to an MTF (Modulation Transfer Function) parameter testing method under the condition of a nonideal target. The method is characterized by comprising the following steps of: (1) establishing a weight map for a special remote sensing image containing margins on the basis of image features; (2) setting a starting point and a terminating point on the margin, and calculating the shortest path from the starting point to the terminating point in the weight map on the basis of dynamic planning; (3) sampling the image grey value to form a margin spread function at a certain distance in the direction vertical to the shortest path, fitting and solving the margin spread function to obtain the line spread function, and carrying out Fourier transform on the line spread function to obtain an MTF curve; (4) repeating the steps 1-3 several times, and taking average values multiple times to reduce error. The invention not only can be used under the ideal conditions of having a target and a margin, but also can extract an MTF parameter by utilizing the targets with irregular shapes, ,thereby enabling the margin selection to be convenient, flexible and accurate.

A method for compensating for modulation transfer function of high-resolution satellite images is provided, which relates to the design of MTFC (Modulation Transfer Function Compensation) processing method for domestic high resolution satellite images. The invention solves the problems that the prior image compensation method leads to the degradation of the image signal-to-noise ratio, the noise amplification, the low quality of the restored image, and the high computational complexity in the restoration process. The invention improves from two stages of the point spread function calculation and the image deconvolution restoration. Compared with the traditional pixel-level edge detection method, the precision of sub-pixel edge detection is higher. The high precision can ensure the accuracyof the subsequent edge spread function, line spread function and even the final point spread function. In the process of image deconvolution restoration, for the GPU and multithreaded optimization ofthe maximum likelihood iterative deconvolution algorithm, the windowing radius is calculated according to the point spread function radius, and the ultra-high resolution remote sensing image is windowed and divided into blocks, which effectively removes the influence of boundary ringing and further improves the computational efficiency.

A focus detection system includes a test pattern board, a camera device and a computer. The test pattern has two colors, and a junction is formed between the two colors, and the junction is arranged obliquely. The camera device shoots the test pattern at a focal length to obtain images. The computer performs the following steps: rotate the image so that the image areas at the junction are arranged in the vertical direction; obtain multiple gray scale values ​​of the rotated image in the horizontal direction and draw a gray scale curve, and the relational expression of the gray scale curve is the edge diffusion function ; Differentiate the edge spread function once to obtain the line spread function; perform Fourier transform on the line spread function to obtain the spatial frequency response function and then convert it into a modulation transfer function; then judge whether the focal length of the camera needs to be adjusted, thereby improving efficiency, And a focus detection method is provided for the focus detection system.

The invention discloses a sea surface spilled oil detection method based on spatial frequency characteristics. The method comprises the following steps: (10) sample signal collection: collecting optical signals of a sea surface spilled oil sample to obtain an original image of the sea surface spilled oil; (20) data preprocessing: filtering median of the original image to obtain a target image; (30) edge linear fitting: carrying out edge linear fitting on the target image to obtain a target edge linear equation; (40) image edge spread function preprocessing: removing obvious noise points in the target image; (50) edge spread function stratified resampling: removing other noise signals in the target image to obtain low-noise target signals; (60) line spread function sampling and fitting: carrying out differential fitting on the edge spread function of the low-noise target signals to obtain a line spread function; and (70) modulation transfer function calculation: performing modulation transfer function calculation to obtain spatial frequency characteristic values of the sea surface spilled oil under multiple angles. The method is high in accuracy, good in reliability and high in efficiency.

The current invention presents designs of SPECT gamma cameras without the in-out mechanical motion of the detectors. The elimination of this motion is achieved by the implementation of iterative algorithms, such as Resolution Recovery and / or Wide Beam Reconstruction, which compensate for the Line Spread Function effect due to the collimator characteristics. The use of these methods enables construction of SPECT gamma cameras with a range of novel designs, having their gamma detector (or detectors) orbiting the patient in a predetermined orbit of fixed radius. For example, the radius might be chosen as such that the majority of all patients can be scanned by the system. The advantages of the invention are applicable for gamma cameras with any numbers of detectors.

The invention discloses a high precision grating spectrometer image quality measuring method and device. The device comprises a monochromatic light source which is homogenized by an integrating sphere, a collimator with a slit target, a tested imaging spectrometer and a data processing system. The slit target is controlled by a micro-displacement table to translate along a direction vertical to aslit of the tested spectrometer. The tested spectrometer can receive a signal of the monochromatic light source, wherein the signal passes the slit target. Through analysis and computing of a relationship between light intensity change of certain group of pixels on the spectrometer and slit movement amount, a line spread function of the spectrometer is obtained; influence of width of the slit target on a test result is removed; and through Fourier transform, an MTF of a system spectrum direction is computed. The object slit is rotated for 90 degrees and scanning is carried out, so the MTF of aspace direction can be tested. According to the method, the problem that a transfer function of the spectrum direction of the imaging spectrometer cannot be tested can be solved, and a precise test for image quality of the imaging spectrometer is realized.

The invention discloses a CCD modulation transfer function measuring device and method. The CCD modulation transfer function measuring device comprises a three-dimensional adjusting system, a light source and an optical processing unit. The optical processing unit is fixed to the three-dimensional adjusting system. The optical processing unit comprises a target slit and a microscope objective. The target slit and the microscope objective are arranged on an emergent light path of the light source in sequence. The microscope objective comprises two faces, wherein threads are arranged on one face, the face with the threads is an image space, and the other face is an object space. Emergent light of the light source conducts incidence from the image space and conducts outgoing from the object space. According to the CCD modulation transfer function measuring device and method, the high-imaging-quality target silt with the width smaller than one micron is provided for obtaining of a line spread function, the obtained shrunk high-quality target silt is converged on a measured imaging device array, so that fine sampling is achieved, and the measurement precision is improved.

In an optical system, a color filter mosaic can determine first color pixel locations, second color pixel locations, and third color pixel locations in an array of sensor pixels. The optical system can capture overhead images, which can be subtracted to form a background-subtracted tri-color image of a reflection of sunlight from at least one ground-based curved mirror. A processor can scale color values at the first and second color pixel locations of the tri-color background-subtracted image. The processor can form a single-color background-subtracted image from the scaled color values at the first color pixel locations, the scaled color values at the second color pixel locations, and third color values at the third color pixel locations. The single-color background-subtracted image can correspond to a point spread function or a line spread function of the optical system.

The invention relates to a virtual-reality fusion fuzzy consistency processing method based on a line spread function (LSF) standard deviation. A camera is connected with a computer by a cable; and anHiro square black-white identification card in ARToolkit is arranged in a real scene. The method is characterized in that a real object region that is located at a similar or same depth position as avirtual object in a fusion scene is obtained; an LSF standard deviation of the regional edge is estimated and fuzzy processing is carried out on the virtual object by combining the standard deviationand an image degradation model; and then a fusion scene with the fuzzy consistency between virtual and real objects is generated.

The invention discloses a lens MTF distortion correction method, and relates to the field of lens correction, and the method comprises five steps: firstly following a test point on an image, calculating a distortion correction parameter, then obtaining a distortion correction image, extracting AOI (Area of interest), calculating LSF (Line spread function), carrying out fast Fourier transform, and obtaining an MTF curve. The invention also discloses a lens MTF distortion correction device, which comprises a to-be-tested lens, the to-be-tested lens is a semitransparent chromium layer, one side of the to-be-tested lens is coated with a soda glass coating, the middle part of the to-be-tested lens is provided with a cross slit, and the cross slit is provided with a plurality of linearly distributed test patterns. According to the invention, dynamic distortion compensation correction can be carried out on each specific lens in the lens MTF measurement process, so that the measurement precision can be improved.

A method for reconstructing a high-resolution image in a scattering scene comprises the following steps: S1, for different scattering scenes, measuring a point spread function (PSF) of each scattering scene by using a PSF measuring device, and extracting a line spread function (LSF) in a dimensionality reduction manner according to the measured PSF so as to characterize each scattering scene, and classification of different scattering scenes is realized; and S2, according to the classification result of the scattering scene, carrying out image reconstruction on a one-dimensional signal collected by a calculation ghost imaging system in the scattering scene by adaptively adopting an image reconstruction deep convolutional neural network so as to obtain a high-resolution image, wherein a training set of the reconstruction network comes from one-dimensional data collected in a scattering scene which is most matched with the scattering scene classification features, and self-adaptive high-resolution image reconstruction in different scattering scenes is realized. According to the method, different scattering scenes can be quickly classified, and quick and high-resolution imaging in the different scattering scenes is realized.

The invention belongs to the technical field of remote sensing, and particularly relates to an MTF-based remote sensing image quality evaluation method. The method comprises the following steps: step1, selecting a calculation area; step 2, carrying out straight line fitting on the step edge of the image; 3, fitting an edge spread function; 4, performing deriving to obtain a line spread function;and step 5, performing Fourier transform to obtain an MTF. The method solves the problem of objective evaluation of the remote sensing image. According to the method, the remote sensing image can be objectively evaluated, and the problems that a subjective evaluation method depends on testers to manually interpret the remote sensing image, time and labor are wasted, and automatic interpretation ofmassive remote sensing data is not facilitated are solved. In the actual application of remote sensing image processing, a reference image corresponding to a distorted image cannot be obtained, and areference evaluation method is not suitable, so that the reference-free evaluation method based on MTF has greater application advantages and wider application range.

Optical systems utilize waveplates to simultaneously encode information for increasing image depth of field and for providing a depth map of the imaged object or sample. These waveplates are configured to result in a focus-invariant point spread function in one focal region, and to result in point spread functions that vary as a function of range within the imaged object in a different focal region. For example, a basic compound microscope might have a specially shaped waveplate inserted at the back aperture plane of the microscope objective to manipulate the phase of the wavefront. An image formed on one side of the plane of best focus is focus invariant, and is brought into focus by a restoring algorithm. An image formed on the other side of the plane of best focus captures point spread functions comprising rings that vary with depth within the imaged object.

The invention discloses focus X-ray precision testing equipment used for the field of industrial radiation testing, more specially relates to an X-ray focus tester based on slit method, and belongs to the field of nondestructive automatic testing equipment. The X-ray focus tester based on slit method comprises a microfocus X-ray source, a radiation image receiver, an X-ray emission source, a multi-angle rotation three-dimensional testing device of the radiation image receiver, a four-axis moving platform of samples to be tested, and a computer and hierarchical control system. According to the X-ray focus tester, sizes of X-ray spots are determined via slit grating imaging, the line spread function and modulation transfer function (MTF) of the light source are obtained via slit imaging, and then the light spot size of the light source is determined based on a spatial frequency corresponding to MTF of 0.5. The X-ray focus tester based on slit method is nondestructive testing equipment of a new generation, is especially used for testing of electronic products and production testing of a plurality of medical facilities, and can be used in the fields of medical treatment, spaceflight, military, and industry.

The invention discloses a method for measuring the MTF (Modulation Transfer Function) of an imaging system based on distance weighting, which comprises the following steps: (1) an appropriate edge region in an image obtained by shooting is selected, and the image data is linearized by using a photoelectric conversion function of a sensor to obtain an edge image to be measured; (2) in the edge image obtained in the step 1, the edge position of the edge is obtained by finding the median point of the ESF (Edge Spread Function) of each line successively; (3) an edge position function is obtained by carrying out least square fitting on the edge position of the edge obtained in step 2; (4) the distance from each pixel on the image to the edge is calculated, and the ESF with equidistant samplingis obtained according to the distance weighting; (5) derivation is performed on the ESF obtained in step 4 to obtain a LSF (Line Spread Function), and Fourier transform is performed on the LSF to obtain the MTF of the imaging system. The invention realizes MTF measurement of images containing edge regions, and has the advantages of not being limited by edge angles, good noise resistance, accuratecalculation, good stability, etc.

In an optical system, a color filter mosaic can determine first color pixel locations, second color pixel locations, and third color pixel locations in an array of sensor pixels. The optical system can capture overhead images, which can be subtracted to form a background-subtracted tri-color image of a reflection of sunlight from at least one ground-based curved mirror. A processor can scale color values at the first and second color pixel locations of the tri-color background-subtracted image. The processor can form a single-color background-subtracted image from the scaled color values at the first color pixel locations, the scaled color values at the second color pixel locations, and third color values at the third color pixel locations. The single-color background-subtracted image can correspond to a point spread function or a line spread function of the optical system.