1. A multimode remote sensing image registration method based on improved RIFT is characterized by comprising the following steps:

step 1, acquiring a reference image and an image to be registered in the same area, and respectively performing phase consistency measurement based on a Log-Gabor filter on the reference image and the image to be registered to obtain phase consistency information corresponding to the reference image and the image to be registered under different angles and different scales;

the reference image and the image to be registered are remote sensing images, and the image to be registered is a real-time image;

step 2, acquiring corresponding maximum moment and minimum moment according to phase consistency information of the reference image and the to-be-registered image under different angles and different scales, and further completing edge point detection and angular point detection to obtain characteristic points of the reference image and the to-be-registered image;

step 3, calculating a maximum index map corresponding to the reference image and a plurality of candidate maximum index maps corresponding to the image to be registered according to the convolution sequence in the phase consistency information of the reference image and the image to be registered;

step 4, respectively calculating the image similarity between one maximum index image corresponding to the reference image and each candidate maximum index image corresponding to the image to be registered, and taking the candidate maximum index image with the maximum similarity as the maximum index image of the image to be registered;

step 5, respectively constructing a GLOH-like feature descriptor of each feature point in the reference image and the to-be-registered image according to the maximum index map of the reference image and the maximum index map of the to-be-registered image;

and 6, performing similarity measurement on the GLOH-like feature descriptors of all feature points of the reference image and the image to be registered by adopting a nearest neighbor measurement algorithm to obtain the final registered homonymous point pairs, and finishing image registration.

2. The improved RIFT-based multimode remote sensing image registration method according to claim 1, wherein in step 1, the specific process of phase consistency measurement based on Log-Gabor filter is as follows:

1.1, for an input image I (x, y), firstly, convolving the image I (x, y) with even symmetric wavelet and odd symmetric wavelet of Log-Gabor filter respectively to obtain response component e at the position of scale s and direction o_so(x, y) and o_so(x,y)：

e_so(x,y)＝I(x,y)*L^even(x,y,s,o)

o_so(x,y)＝I(x,y)*Lo^dd(x,y,s,o)

Wherein L is^even(x, y, s, o) is an even symmetric Log-Gabor wavelet, Lo^dd(x, y, s, o) is an odd symmetric Log-Gabor wavelet;

1.2 computing the amplitude component A of the image I (x, y) at the scale s and direction o_so(x, y) and a phase component phi_so(x,y):

1.3, a noise compensation term T is introduced in consideration of the noise of the image, and the bandwidth and the space width information of the filter and the amplitude of the noise response of the filter are comprehensively considered to be in direct proportion to the bandwidth, so that the obtained final two-dimensional phase consistency model is as follows:

wherein, PC (x, y) is phase consistency information of the image I (x, y), (x, y) represents coordinates of pixel points in the image, w₀(xY) is a weighting factor for a given frequency spread; ζ is a small value in order to prevent the denominator from being zero;the value indicating closure is positive, the result is equal to itself, otherwise zero, Δ φ_so(x, y) is a sensitive phase deviation function; a. the_so(x,y)△φ_so(x, y) is defined as:

in the formula

E (x, y) is a local energy function,

3. the improved RIFT-based multi-mode remote sensing image registration method according to claim 1, wherein in step 2, the maximum moment M and the minimum moment M are calculated according to the following formula:

in the formula, the three intermediate quantities a, b and c are calculated according to the following formula:

wherein, PC (θ)_o) For the image at theta_oPC measure in direction, i.e. phase consistency information.

4. The improved RIFT-based multi-mode remote sensing image registration method according to claim 3, wherein the edge point detection process is as follows: firstly, FAST angular point detection is carried out on the maximum moment M, and then a set number of angular points with highest response intensity are selected as edge points to obtain edge point detection results;

the process of corner detection is as follows: firstly, calculating a Harris response value of each pixel point in the minimum moment m, and then performing non-maximum suppression on each pixel point by taking a neighborhood with a set size to obtain an angular point detection result;

the edge point detection result and the angular point detection result of each image form the characteristic points.

5. The improved RIFT-based multi-mode remote sensing image registration method according to claim 1, wherein the acquisition process of a maximum index map corresponding to the reference image is as follows:

3.1 setting the convolution sequence of the Log-Gabor Filter to have N_sA sum of N_oA plurality of directions;

3.2, will be in the same direction N_sA of one dimension_so(x, y) adding to obtain Log-Gabor filter convolution layer A_o(x，y)：

Wherein A is_o(x, y) has N_oThe direction has the same size as the original image;

3.3, A in all directions_o(x, y) is arranged in a direction sequence of 0-150 DEGω is a direction index, ω is 1, 2, …, N_o；

3.4, establishing a blank image MIM with the same size as the reference image;

3.5, for each pixel point (x, y) in MIM, get atIn the same position of N_oA pixel value;

3.6 reaction of N obtained in step 3.5_oThe maximum value of the pixel values beingIs a direction index value omega_maxAs new pixel values at MIM map (x, y);

and 3.7, repeating the steps 3.5-3.6, traversing all pixel points in the MIM to obtain a new MIM, namely the maximum index map.

6. The improved RIFT-based multimode remote sensing image registration method according to claim 5, wherein the obtaining process of the candidate maximum index maps corresponding to the image to be registered is as follows:

for the image to be registered, obtaining a candidate maximum index map according to the steps 3.1-3.7; then, the configuration in step 3.3 is changedWhen A is_o(x, y) the order is such that each change sets up a different layer 1, i.e. 1 st to N_oThe layers being arranged in succession as layer 1, e.g.This in turn generates a setSubscript ω ═ 1, 2, …, N_oThen according toAccording to steps 3.4-3.7, the structure is differentAnd obtaining different candidate maximum index maps.

7. The improved RIFT-based multi-mode remote sensing image registration method according to claim 1, wherein the calculating of the image similarity between one maximum index map corresponding to the reference image and each candidate maximum index map corresponding to the image to be registered is specifically as follows: calculating the gray distribution similarity of the candidate maximum index map corresponding to each image to be registered and a maximum index map corresponding to the reference image by a histogram matching method, namely calculating the gray distribution histogram of the candidate maximum index map corresponding to each image to be registered and a maximum index map corresponding to the reference image respectively, and then calculating the babbit distance between the gray distribution histogram corresponding to each image to be registered and the gray distribution histogram corresponding to the reference image, wherein the smaller the babbit distance, the higher the similarity.

8. The improved RIFT-based multi-mode remote sensing image registration method according to claim 1, wherein the GLOH-like feature descriptor of each feature point in the reference image and the image to be registered is constructed by the following specific process:

firstly, establishing a polar coordinate system by taking the coordinate of a characteristic point as the center on the maximum index maps of a reference image and an image to be registered respectively, and taking a circular area with the radius R as a supporting area;

secondly, dividing each support area into D fan-shaped sub-areas according to D directions; d. d are positive numbers respectively;

and finally, counting the number of each index number in each sub-region, connecting the index numbers into D x D-dimensional description vectors, normalizing the description vectors to obtain normalized description vectors, truncating elements more than 0.2 in the normalized description vectors, and normalizing again to obtain the final GLOH-like feature descriptor.

9. The improved RIFT-based multi-mode remote sensing image registration method according to claim 1, wherein in step 6, the similarity measurement is performed on GLOH-like feature descriptors of all feature points of the reference image and the image to be registered by using a nearest neighbor measurement algorithm, specifically: and measuring the feature descriptors corresponding to each feature point of the reference image and the real-time image by adopting Euclidean distance, namely calculating the ratio of the nearest Euclidean distance to the next nearest Euclidean distance, and if the ratio is smaller than a certain threshold value, considering the two as a matching point pair.

Background

The image registration technology is an important component in the field of image processing, and is widely applied in military and civil fields such as projectile body positioning, aviation guidance, computer vision, mode recognition, remote sensing technology, medicine, climate and the like. The multi-mode image registration technology can make up the defects of a single sensor image in the image registration technology, and is a research hotspot in the field of the current image registration technology. Due to the fact that nonlinear gray level difference and radiation intensity difference exist between multimode remote sensing images, the image registration method based on gray level information is not suitable for the field of multimode remote sensing image registration. The characteristic information is a higher-level description of the image information and can stably exist in the multimode remote sensing images, so that the image registration method based on the characteristic information is commonly used for matching among the multimode remote sensing images and also becomes a main direction for research in the field at home and abroad.

In order to obtain a multimode remote sensing image registration result with strong robustness and high accuracy, stable characteristic information needs to be extracted. The most basic feature information in an image is a point feature and a line feature. The point features have wide application in image matching and stereo scene matching. The currently commonly used Feature extraction algorithms include Scale-Invariant Feature Transform (SIFT), Speeded-Up Robust Features (SURF), orb (organized FAST and rotaed brief), and some improved SIFT algorithms, however, these methods usually use intensity information or gradient information to detect and describe Features, and these algorithms fail because there may be some radiation distortion in the remote sensing image, and it is difficult to obtain stable registration effect.

Disclosure of Invention

Aiming at the problems of the traditional point Feature algorithm based on intensity information or gradient information in the multi-mode remote sensing image registration, the invention aims to provide a multi-mode remote sensing image registration method based on improved RIFT (radial-Invariant Feature Transform), which uses Phase Consistency (PC) information of an image to replace the intensity information and the gradient information of the image to detect Feature points, and uses a Maximum Index Map (Maximum Index Map, MIM) of the respective Phase consistency amplitudes of a reference image and a real-time image to perform Feature description.

In order to achieve the purpose, the invention is realized by adopting the following technical scheme.

A multi-mode remote sensing image registration method based on improved RIFT comprises the following steps:

step 1, acquiring a reference image and an image to be registered in the same area, and respectively performing phase consistency measurement based on a Log-Gabor filter on the reference image and the image to be registered to obtain phase consistency information corresponding to the reference image and the image to be registered under different angles and different scales;

the reference image and the image to be registered are remote sensing images, and the image to be registered is a real-time image;

step 2, acquiring corresponding maximum moment and minimum moment according to phase consistency information of the reference image and the to-be-registered image under different angles and different scales, and further completing edge point detection and angular point detection to obtain characteristic points of the reference image and the to-be-registered image;

step 3, calculating a maximum index map corresponding to the reference image and a plurality of candidate maximum index maps corresponding to the image to be registered according to the convolution sequence in the phase consistency information of the reference image and the image to be registered;

step 4, respectively calculating the image similarity between one maximum index image corresponding to the reference image and each candidate maximum index image corresponding to the image to be registered, and taking the candidate maximum index image with the maximum similarity as the maximum index image of the image to be registered;

step 5, respectively constructing a GLOH-like feature descriptor of each feature point in the reference image and the to-be-registered image according to the maximum index map of the reference image and the maximum index map of the to-be-registered image;

and 6, performing similarity measurement on the GLOH-like feature descriptors of all feature points of the reference image and the image to be registered by adopting a nearest neighbor measurement algorithm to obtain the final registered homonymous point pairs, and finishing image registration.

Compared with the prior art, the invention has the beneficial effects that:

according to the method, the characteristic information of the image is obtained by utilizing the PC information of the image, and because the radiation difference and the gray level difference exist between the multimode remote sensing images, the phase consistency information is not influenced by the gray level difference, the radiation difference and the illumination difference, so that the method has strong robustness and is more significant for the characteristic representation of the image. And (3) obtaining a maximum index map pair with highest similarity by judging the similarity between a Maximum Index Map (MIM) constructed by the initial convolution sequence of the reference image and the maximum index maps constructed by different convolution sequences of the real-time images, and realizing rotation invariance. Secondly, the GLOH-like descriptor of each feature point is constructed based on the maximum index graph, the dimensionality of the descriptor can be reduced, and the time complexity of an algorithm is reduced. And finally, carrying out similarity measurement by using an algorithm based on nearest neighbor registration to obtain the finally matched homonymous point pairs.

Drawings

The invention is described in further detail below with reference to the figures and specific embodiments.

FIG. 1 is a flow chart of the implementation of the method of the present invention

FIG. 2 is a diagram illustrating exemplary phase consistency in accordance with an embodiment of the present invention; wherein (a) is an original image, and (b) is a phase consistency result graph of the original image;

FIG. 3 is a diagram illustrating exemplary feature detection according to an embodiment of the present invention; wherein, (a) the original image, (b) is a minimum moment graph, (c) is a maximum moment graph, and (d) the characteristic point detection graph;

FIG. 4 is a diagram illustrating a maximum index map structure according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a descriptor architecture according to an embodiment of the present invention;

FIG. 6 shows the result of the registration of the SAR image and the visible light image according to the embodiment of the present invention; wherein (a) is a registration result connecting line graph, (b) is a fusion graph, and (c) is a checkerboard splicing graph;

FIG. 7 illustrates the registration of an infrared image and a visible image according to an embodiment of the present invention; wherein (a) is a registration result connecting line graph, (b) is a fusion graph, and (c) is a checkerboard splicing graph;

fig. 8 is a result of registration of a SAR image and a SAR image according to an embodiment of the present invention; wherein (a) is a registration result connecting line graph, (b) is a fusion graph, and (c) is a checkerboard splicing graph.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention.

Referring to fig. 1, the invention provides a multimode remote sensing image registration method based on improved RIFT, comprising the following steps:

step 1, acquiring a reference image and an image to be registered in the same area, and respectively performing phase consistency measurement based on a Log-Gabor filter on the reference image and the image to be registered to obtain phase consistency information corresponding to the reference image and the image to be registered under different angles and different scales;

the reference image and the image to be registered are remote sensing images, and the image to be registered is a real-time image;

the two-Dimensional Log-Gabor Function (2Dimensional Log-Gabor Function, 2D-LGF) is defined as:

where (ρ, θ) is a logarithmic polar coordinate; s and o are the scale and orientation of the 2D-LGF, respectively; (ρ)_s，θ_(s，o)) Is the center frequency of the 2D-LGF; sigma_ρAnd σ_θThe bandwidths are expressed in ρ and θ, respectively.

The 2D-LGF is a frequency filter whose corresponding spatial domain filter is obtained by inverse Fourier transform, i.e. the

L(x，y，s，o)＝L^even(x，y，s，o)+iL^odd(x，y，s，o)

In the formula, the real part L^even(x, y, s, o) is an even symmetric Log-Gabor wavelet, and an imaginary part L^odd(x, y, s, o) is an odd symmetric Log-Gabor wavelet. The spatial domain filter is the Log-Gabor filter of the invention.

In two-dimensional space, an input image I (x, y) is given, and as shown in FIG. 2(a), the image I (x, y) is first convolved with even symmetric wavelets and odd symmetric wavelets of a Log-Gabor filter to obtain a response component e at a position of a scale s and a direction o_so(x, y) and o_so(x, y), which is defined as follows:

e_so(x，y)＝I(x，y)*L^even(x，y，s，o)

o_so(x，y)＝I(x，y)*L^odd(x，y，s，o)

based on the above-mentioned convolution response components, the amplitude component A of the image I (x, y) at the scale s and direction o can be obtained_so(x, y) and a phase component phi_so(x, y), which is defined as follows:

considering the noise of the image and the analysis results of each scale and each direction, a noise compensation term T needs to be introduced, and at this time, the information such as the bandwidth and the spatial width of the filter needs to be considered comprehensively, and the amplitude of the response of the filter to the noise is generally directly proportional to the bandwidth thereof, so according to the above conclusion, the definition of the final two-dimensional phase consistency model can be obtained:

the exact PC map is calculated by the above equation, as shown in FIG. 2 (b). Where PC (x, y) is the phase consistency information of the image I (x, y), (x, y) represents the coordinates of the pixel points in the image, w₀(x, y) is a weighting factor for a given frequency spread; ξ is a small value to prevent the denominator from being zero;the operator is to prevent that the result is negative, i.e. the result equals itself when the enclosed value is positive, otherwise it is zero. Delta phi_so(x, y) is a sensitive phase deviation function. A. the_so(x，y)Δφ_so(x, y) is defined as:

in the formula

E (x, y) is a local energy function whose two parts are obtained by convolving the signal with a pair of orthogonal filters, i.e.

Step 2, acquiring corresponding maximum moment and minimum moment according to phase consistency information of the reference image and the to-be-registered image under different angles and different scales, and further completing edge point detection and angular point detection to obtain characteristic points of the reference image and the to-be-registered image;

after phase consistency information of the reference image and the image to be registered at different angles and different scales is calculated through a PC model, the minimum moment M and the maximum moment M of the reference image and the image to be registered can be calculated through the following formulas, and therefore the angular point and the edge point of each image are detected respectively.

In the formula, the three intermediate quantities a, b and c are calculated as follows:

wherein, PC (θ)_o) For the image at theta_oPC measure in direction, i.e. phase consistency information.

Fig. 3(a) is an original image, and for the minimum moment graph m, as shown in fig. 3(b), the Harris response value of each pixel point is calculated first, and then the non-maximum suppression is performed on each pixel point by taking a neighborhood of 3 × 3 to obtain a corner point detection result.

For the maximum moment graph M, as shown in fig. 3(c), FAST corner detection is performed first, and then 2500 corners with the highest response intensity are selected as edge points, so as to obtain an edge point detection result.

The corner points and edge points of each image are combined as the final feature points, and the feature point detection result is shown in fig. 3 (d).

Step 3, calculating a maximum index map corresponding to the reference image and a plurality of candidate maximum index maps corresponding to the image to be registered according to the convolution sequence in the phase consistency information of the reference image and the image to be registered;

the maximum index map is the convolution sequence of Log-Gabor filter-amplitude A_so(x, y) constructed, N_sA sum of N_oIn one direction (the invention takes N_s＝4，N_o6) first in the same direction N_sA of one dimension_so(x, y) adding to obtain Log-Gabor filter convolution layer A_o(x, y) as shown in the following formula:

A_o(x, y) has 6 directions, and has the same direction as the original imageThe same size, as shown in FIG. 4, will be A_o(x, y) are arranged in the direction sequence (0-150 DEG)ω is a direction index, ω is 1, 2, …, N_o. Firstly, a blank image MIM with the same size as the original image is established, and for each pixel point (x, y) in the MIM, the blank image MIM can be obtainedThe 6 pixel values of the same position in the image are obtained, and then the maximum value of the 6 pixel values is locatedIs a direction index value omega_maxTraversing all pixel points as new pixel values at the MIM (x, y) graph to obtain the MIM, wherein the pixel values are index values, namely 1-N_o。

(3.1) for reference image I_ADirect structuring of MIM_A。

(3.2) for real-time images I_BChanging the structureWhen A is_oThe sequence of (x, y) is that different 1 st layers are set every time, namely, the 1 st to 6 th layers are sequentially set as the 1 st layer. E.g. group 1In (0 °, 30 °, 60 °, 90 °, 120 °, 150 °) with indices of (1, 2, 3, 4, 5, 6), group 2Then the sets are ordered by (30 °, 60 °, 90 °, 120 °, 150 °, 0 °) with indices of (1, 2, 3, 4, 5, 6), thus generating sets in turnSubscript ω 1, 2, …, N_oThen according toTo make a difference

Step 4, respectively calculating the image similarity between one maximum index image corresponding to the reference image and each candidate maximum index image corresponding to the image to be registered, and taking the candidate maximum index image with the maximum similarity as the maximum index image of the image to be registered;

according to the invention, the real-time image obtained in step 3There always exists a certain oneAnd MIM_ASimilarly, by calculatingEach of which isAnd MIM_AThe similarity of the gray distribution is selected from the MIM_AHighest similarityAs the maximum index map ultimately required for real-time images.

Here calculated by means of histogram matchingEach of which isAnd MIM_AThe similarity of the gray distribution of (a). Specifically, each is calculated separatelyAnd MIM_AThen, the babbitt distance of the two histograms is calculated, and a pair of maximum index maps with the minimum babbitt distance is selected as a final required maximum index map pair.

Step 5, respectively constructing a GLOH-like feature descriptor of each feature point in the reference image and the to-be-registered image according to the maximum index map of the reference image and the maximum index map of the to-be-registered image;

because the original RIFT algorithm adopts a construction method similar to SIFT descriptors, the calculated amount is large, and in order to improve the calculation speed and the uniqueness of the descriptors, the invention adopts an affine concentric circle supporting area similar to GLOH to construct the descriptors. As shown in fig. 5, a polar coordinate system is established on the maximum index map with the coordinates of the feature points as the center, and a circular region with a radius R of 48 is taken as a support region, and the circular support region has better rotation invariance compared with a rectangular support region₁＝0.25R，r₂＝0.5R，r₃0.75R, the radius is taken as a circular region, the region where R < 0.25R is left as a circle, and 8 directions are equally taken to divide the circular region into sector-shaped sub-regions, for a total of 19 sub-regions. And counting the number of each index number in each sub-region, then connecting the index numbers into a description vector with 19 x 8 and 152 dimensions, normalizing the description vector to obtain a normalized description vector, truncating elements more than 0.2 in the normalized description vector, and finally normalizing again to obtain the final GLOH-like feature descriptor.

And 6, performing similarity measurement on the GLOH-like feature descriptors of all feature points of the reference image and the image to be registered by adopting a nearest neighbor measurement algorithm to obtain the final registered homonymous point pairs, and finishing image registration.

And measuring the characteristic descriptors corresponding to each characteristic point of the reference image and the real-time image by adopting Euclidean distance. And calculating the ratio of the nearest Euclidean distance to the next nearest Euclidean distance, and if the ratio is smaller than a certain threshold value, considering the nearest Euclidean distance and the next nearest Euclidean distance as a matching point pair.

In particular, assume thatAnd (3) taking the characteristic point set of the reference image as p and the characteristic point set of the image to be registered as q, and calculating the distance between each point in the characteristic point set p and each point in the characteristic point set q one by one to obtain a distance set D between the characteristic points. Sequencing the elements in the distance set D to obtain the nearest distance D_minAnd a next nearest neighbor distance d_n-min。

The nearest neighbor metric algorithm distinguishes correct matching pairs from incorrect matching pairs by judging the ratio of nearest neighbor distance to next nearest neighbor distance:

thus, for a correct matching pair, its nearest neighbor distance d_minIs much smaller than the next nearest neighbor distance d_n-minI.e. Dis tan ceRatio < 1; but the nearest neighbor distance d of the wrong matched pair_minAnd a next nearest neighbor distance d_n-minThe difference is not large, i.e. Dis tan ceRatio ≈ 1. A threshold value Tresh e (0, 1) of the distance ratio can be taken to distinguish between correctly matched pairs and incorrectly matched pairs. When the pair of feature points is a correct matching point pair, the distance ratio is concentrated in a region having a smaller value, and when the pair is a wrong matching point pair, the distance ratio is concentrated in a region having a larger value. In the invention, when rejecting all matching points with distance ratio larger than 0.75, nearly 90% of wrong matching points can be rejected, and only less than 5% of correct matching points are lost, namely:

dis tan percentage > Tresh, rejecting matched pair

Dis tan ceRatio is less than or equal to Tresh, and the received matching pair is a candidate matching pair.

Simulation experiment

The effect of the present invention is further explained by simulation experiments.

(1) Simulation conditions

And carrying out registration simulation analysis by utilizing the measured data of the SAR images and the visible light images, and comparing the measured data with the simulation result of the traditional SIFT algorithm. The simulation parameters are shown in table 1:

TABLE 1 registration data specific information

Fig. 6(a) is a registration connection line diagram of the SAR image and the visible light image in the experimental data, and it can be seen that under the condition that the scenes of the two images are complex and the SAR image is interfered by noise, the number of the homonymous points which can be matched is large. Fig. 6(b) and 6(c) are respectively a fusion map and a checkerboard mosaic obtained based on the registration result, and it can be seen that the registration accuracy is high through the fusion map and the checkerboard mosaic.

Fig. 7(a) is a registration connection line diagram of an infrared image and a visible light image in experimental data, and it can be seen that the number of matched homonymous points is large under the condition that the two images have gray level difference and radiation difference. Fig. 7(b) and 7(c) are respectively a fusion map and a checkerboard mosaic obtained based on the registration result, and it can be seen that the registration accuracy is high through the fusion map and the checkerboard mosaic.

Fig. 8(a) is a registration connecting line diagram of the SAR image and the SAR image in the experimental data, and it can be seen that the number of the matched homonymous points is large under the condition that the two images have a large rotation angle and the imaging quality is poor. Fig. 8(b) and 8(c) are respectively a fusion map and a checkerboard mosaic obtained based on the registration result, and it can be seen that the registration accuracy is high through the fusion map and the checkerboard mosaic.

The method can realize accurate registration of the multimode remote sensing images which have large radiation difference, poor imaging quality, rotation angle difference, large gray level difference and complex scene, because the phase consistency of the images has strong robustness to the radiation difference, illumination change and gray level difference among the images. The method has the advantages that the method is high in stability of feature detection and feature description based on the phase consistency of the image, so that similar information between the same-name points can be extracted more easily, the accuracy of a registration result is improved to a great extent, and a more accurate registration result is obtained.

Although the present invention has been described in detail in this specification with reference to specific embodiments and illustrative embodiments, it will be apparent to those skilled in the art that modifications and improvements can be made thereto based on the present invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.