Remote sensing image inter-band registration method based on phase correlation method

Abstract

The invention discloses a remote sensing image inter-band registration method based on a phase correlation method. The remote sensing image inter-band registration method comprises the following steps: S1, partitioning a remote sensing image; s2, separating each wave band of each block of image, selecting one wave band as a reference wave band, and selecting other wave bands as to-be-registered wave bands; s3, converting each block image from a spatial domain to a frequency domain to obtain a frequency spectrogram of a wave band; s4, obtaining correlation and interaction information between wavebands in a frequency domain; s5, obtaining the correlation and the offset degree between the wave band images; s6, calculating the offset between the wavebands; s7, constructing a transformation matrix through the offset, transforming the to-be-registered waveband image, and synthesizing the to-be-registered waveband image in a reference waveband to obtain a registered block image; and S8, splicing the registered block images to obtain a registered integral remote sensing image. According to the method, the sub-pixel level registration between the remote sensing image bands is realized, and the algorithm operation efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of remote sensing data processing and application, and in particular to a remote sensing image band registration method based on a phase correlation method. Background Art

[0002] Remote sensing imaging technology is an important means of obtaining surface information. Remote sensing images have significant advantages in the fields of object recognition and classification and object change monitoring and are widely used. However, due to factors such as wavelength differences between different bands and sensor performance degradation, remote sensing images will produce pixel-level or sub-pixel-level offsets between different bands during imaging. In remote sensing image processing, image registration is a key preprocessing step, which is crucial for subsequent remote sensing image processing, such as image fusion, object recognition and classification, object change monitoring, and image super-resolution. If there is an offset between bands, it will seriously affect the visual effect of the image and the accuracy of subsequent analysis.

[0003] For high-resolution remote sensing images, the accuracy requirements for registration are very strict, and the error must be controlled within 1 pixel to ensure the correctness of the subsequent processing flow. The traditional remote sensing image inter-band registration method mainly relies on feature matching technology, which has limitations in processing efficiency and registration accuracy, especially in the registration problem of sub-pixel level offset. Traditional feature information matching methods usually need to calculate feature points and descriptors, and need to match the extracted features, which has low processing efficiency. At the same time, traditional methods are generally only applicable to situations where the pixel offset between bands is 1 pixel or more. In actual applications, the offset between remote sensing image bands is often at the sub-pixel level, and traditional feature information matching methods cannot achieve good processing results. Summary of the invention

[0004] To solve the above problems, sub-pixel registration can be performed between remote sensing image bands, and the nonlinear offset within the overall image can be converted into a linear offset of the local image for processing, thereby improving the efficiency of image processing. The present invention provides a remote sensing image band registration method based on the phase correlation method, and the specific scheme is as follows: A remote sensing image band registration method based on phase correlation method comprises the following steps: S1, divide the remote sensing image into blocks; S2, separate the bands of each image, select one band as the reference band, and the other bands as the bands to be registered; S3, converting each block image from the spatial domain to the frequency domain to obtain the spectrum of the band; S4, obtain the correlation and interaction information between bands in the frequency domain; S5, obtaining the correlation and offset degree between band images; S6, calculating the offset between bands; S7, constructing a transformation matrix through the offset, transforming the band image to be registered, and synthesizing it with the reference band to obtain the registered block image; S8, stitching the registered block images to obtain the registered overall remote sensing image.

[0005] Preferably, in step S1, the remote sensing image is divided into blocks, and the overall nonlinear offset is converted into a local linear offset for processing.

[0006] Preferably, step S3 performs Fourier transform on the band to be registered and the reference band for each block image, converts the image from the spatial domain to the frequency domain, and obtains a spectrum diagram of the band.

[0007] Preferably, step S4 calculates the cross power spectrum between the band to be registered and the reference band through the acquired spectrum diagram to obtain the correlation and interaction information between the bands in the frequency domain.

[0008] Preferably, step S5 performs a two-dimensional inverse Fourier transform on the cross power spectrum between the bands, transforming the image signal from the frequency domain back to the spatial domain, thereby obtaining a Dirac function to obtain the correlation and offset degree between the band images.

[0009] Preferably, in step S6, the offset between the bands can be obtained by calculating the peak coordinates of the Dirac function.

[0010] The present invention also discloses a computer-readable storage medium, on which a computer program is stored. After the computer program is run, any of the above methods is executed.

[0011] The present invention also discloses a computer system, including a processor and a storage medium, wherein a computer program is stored on the storage medium, and the processor reads and runs the computer program from the storage medium to execute any of the methods described above.

[0012] The beneficial effects of the present invention are: The present invention can realize sub-pixel level pixel offset detection by converting the pixel offset in the spatial domain of remote sensing images to the frequency domain and calculating the phase correlation between bands. A transformation matrix is ​​constructed according to the offset, and the band to be registered is subjected to image transformation to realize the registration of color remote sensing images. The display effect of remote sensing images is greatly enhanced, and the accuracy of subsequent applications such as image fusion and image interpretation is improved.

[0013] The present invention processes large-scale remote sensing images in blocks, converts the nonlinear offset between bands of the overall image into a linear offset within a local block image, and converts the nonlinear transformation into a linear transformation, which greatly reduces the complexity of the image processing algorithm and significantly improves the efficiency of image processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram of the four block images provided by the present invention before registration; Figure 3 This is the processing result after the registration of the four block images provided by the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] The present invention provides a remote sensing image band registration method based on the phase correlation method, which realizes the sub-pixel level registration between remote sensing image bands while greatly improving the efficiency of algorithm operation, so that the remote sensing image maintains a better display effect and the algorithm has better operation performance.

[0018] like Figure 1 , a remote sensing image band registration method based on phase correlation method, comprising the following steps: S1. Divide large-size remote sensing images into blocks and convert the overall nonlinear offset into local linear offset for processing.

[0019] S2. Separate the bands of each image, select one of the bands as the reference band, and the other bands as the bands to be registered.

[0020] S3, for each block image, the registration band and the reference band are Fourier transformed to convert the image from the spatial domain to the frequency domain, that is, for a two-dimensional image with M rows and N columns Perform Fourier transform to obtain the spectrum of the band , where and are variables in the frequency domain, corresponding to the horizontal frequency and the vertical frequency, and are variables in the spatial domain, corresponding to the horizontal position and vertical position respectively, and are the number of rows and columns of the image, respectively. is an imaginary unit, satisfying , is a constant used to convert frequency to radians;

[0021] S4. Calculate the cross power spectrum between the band to be registered and the reference band through the obtained spectrum diagram , to obtain the correlation and interaction information between bands in the frequency domain, where and is the spectrum diagram of the band to be aligned and the reference band, and are the amplitudes of the reference band and the band to be registered, respectively. and are variables in the frequency domain, corresponding to the horizontal frequency and the vertical frequency respectively;

[0022] S5. Cross-power spectrum between bands Perform a two-dimensional inverse Fourier transform to transform the image signal from the frequency domain back to the spatial domain to obtain the Dirac function , to obtain the correlation and offset between band images, where and are variables in the frequency domain, corresponding to the horizontal frequency and the vertical frequency, and are variables in the spatial domain, corresponding to the horizontal position and vertical position respectively, and are the number of rows and columns of the image, respectively. is an imaginary unit, satisfying , is a constant used to convert frequency to radians;

[0023] S6. Calculate the peak coordinates of the Dirac function to obtain the linear offset between the block image bands. and , where To obtain the maximum value of the function, is the Dirac function obtained in step S5;

[0024] S7. Construct a transformation matrix using the offset , transform the band image to be registered and synthesize it with the reference band to obtain the registered block image, where and is the pixel coordinate of the original block image, and is the pixel offset, and is the pixel coordinate of the output block image;

[0025] S8. Stitching the registered block images to obtain the registered overall remote sensing image.

[0026] The present invention can realize sub-pixel level pixel offset detection by converting the pixel offset in the spatial domain of remote sensing images to the frequency domain and calculating the phase correlation between bands. A transformation matrix is ​​constructed according to the offset, and the band to be registered is subjected to image transformation to realize the registration of color remote sensing images. The display effect of remote sensing images is greatly enhanced, and the accuracy of subsequent applications such as image fusion and image interpretation is improved.

[0027] At the same time, the present invention performs block processing on large-size remote sensing images, converts the nonlinear offset between bands of the overall image into a linear offset within the local block image, and converts the nonlinear transformation into a linear transformation, which greatly reduces the complexity of the image processing algorithm and significantly improves the efficiency of image processing.

[0028] The present invention also discloses a computer-readable storage medium and a computer system. A computer-readable storage medium stores a computer program, and after the computer program is run, the method described above is executed. A computer system includes a processor and a storage medium, wherein the storage medium stores a computer program, and the processor reads and runs the computer program from the storage medium to execute the method described above.

[0029] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0030] The various illustrative logic blocks, modules, and circuits described in conjunction with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0031] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0032] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0033] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

[0034] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A remote sensing image band registration method based on phase correlation method, characterized in that: The following steps are involved: S1, divide the remote sensing image into blocks; S2, separate the bands of each image, select one band as the reference band, and the other bands as the bands to be registered; S3, converting each block image from the spatial domain to the frequency domain to obtain the spectrum of the band; S4, obtain the correlation and interaction information between bands in the frequency domain; S5, obtaining the correlation and offset degree between band images; S6, calculating the offset between bands; S7, constructing a transformation matrix through the offset, transforming the band image to be registered, and synthesizing it with the reference band to obtain the registered block image; S8, stitching the registered block images to obtain the registered overall remote sensing image.

2. The method according to claim 1, characterized in that: In step S1, the remote sensing image is divided into blocks, and the overall nonlinear offset is converted into a local linear offset for processing.

3. The method according to claim 1, characterized in that: In step S3, for each block image, Fourier transform is performed on the band to be registered and the reference band, and the image is converted from the spatial domain to the frequency domain to obtain a spectrum diagram of the band.

4. The method according to claim 1, characterized in that: Step S4 calculates the cross power spectrum between the band to be registered and the reference band through the acquired spectrum diagram to obtain the correlation and interaction information between the bands in the frequency domain.

5. The method according to claim 1, characterized in that: Step S5 performs a two-dimensional inverse Fourier transform on the cross power spectrum between the bands, transforming the image signal from the frequency domain back to the spatial domain, thereby obtaining a Dirac function to obtain the correlation and offset degree between the band images.

6. The method according to claim 5, characterized in that: In step S6, the offset between the bands can be obtained by calculating the peak coordinates of the Dirac function.

7. A computer-readable storage medium, characterized in that: A computer program is stored on the medium, and after the computer program is run, the method according to any one of claims 1 to 6 is executed.

8. A computer system, characterized in that: The method comprises a processor and a storage medium, wherein a computer program is stored in the storage medium, and the processor reads and runs the computer program from the storage medium to execute the method as claimed in any one of claims 1 to 6.

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