CN113034372A - Rapid rotation method of underwater image - Google Patents
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- 238000010191 image analysis Methods 0.000 abstract description 5
- 239000013535 sea water Substances 0.000 description 5
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T3/00—Geometric image transformations in the plane of the image
- G06T3/60—Rotation of whole images or parts thereof
- G06T3/608—Rotation of whole images or parts thereof by skew deformation, e.g. two-pass or three-pass rotation
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
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Abstract
The invention discloses a method for rapidly rotating an underwater image, which comprises the following steps: setting the coordinate of one vertex of the original image as a coordinate origin, establishing a coordinate system, and calculating the coordinates of four vertexes of the original image after rotation according to the direction and the angle to be rotated; calculating the number of rows and columns of a new image according to the calculated coordinates of the four vertexes, wherein the new image is a square frame which just covers all pixel points of the original image; traversing all points corresponding to the rows and the columns of the original image, and calculating the row and column indexes of each point in a new image; and assigning the pixel values of all traversed points in the original image to the corresponding row index and column index of each point in the new image to obtain the new image containing the pixel values of all the pixel points of the original image, and setting the rest pixel points in the new image to be white. The method disclosed by the invention can improve the efficiency and accuracy of image analysis.
Description
Technical Field
The invention belongs to the technical field of image analysis, and particularly relates to a rapid rotation method of an underwater image.
Background
In the process of analyzing the underwater sea image, the underwater image is shot to deviate and rotate due to the fluctuation of the sea water, so that the image acquired by the image is an inclined image, and the analysis result of the underwater sea image is influenced. The method for rotating the underwater images of the seawater is necessary for analyzing the underwater images of the ocean and is the core of the current domestic underwater image analysis of the ocean.
In the actual operation process, the measurement of the underwater image of the sea is interfered by the change of the marine environment, the phenomenon is that the image rotates irregularly, and even on the basis of collecting the underwater image of the sea, the underwater image is not the true position of the underwater image. In the underwater image detection process, rotation calculation is performed on an image. For the above reasons, the existing rotation method for detecting the underwater image of the seawater has no real-time property. Therefore, in order to obtain a detection result of a real underwater image of seawater, a rapid rotation method of the underwater image must be found in field measurement, and the position of each pixel point in the image must be determined.
Disclosure of Invention
In order to solve the technical problem, the invention provides a method for rapidly rotating an underwater image so as to achieve the purpose of improving the efficiency and accuracy of image analysis.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for rapidly rotating an underwater image comprises the following steps:
(1) setting the coordinate of one vertex of the original image as a coordinate origin, establishing a coordinate system, and calculating the coordinates of four vertexes of the original image after rotation according to the direction and the angle to be rotated;
(2) calculating the number of rows and columns of a new image according to the calculated coordinates of the four vertexes, wherein the new image is a square frame which just covers all pixel points of the original image;
(3) traversing all points corresponding to the rows and the columns of the original image, and calculating the row and column indexes of each point in a new image;
(4) and assigning the pixel values of all traversed points in the original image to the corresponding row index and column index of each point in the new image to obtain the new image containing the pixel values of all the pixel points of the original image, and setting the rest pixel points in the new image to be white.
In the scheme, the specific method of the step (1) is as follows:
the original image is a square image, the upper left vertex of the original image is set as the origin of coordinates, the original image is rotated around the origin of coordinates, Y is the number of lines of the original image, X is the number of columns of the original image, and Angle is the Angle of rotation, then the X and Y coordinates of the four vertices of the rotated original image are calculated as follows:
lower left vertex:
LeftBottom(x)＝(Y-1)*sin(Angle)；
LeftBottom(y)＝(Y-1)*cos(Angle)；
top left vertex:
LeftTop(x)＝0；
LeftTop(y)＝0；
lower right vertex:
RightBottom(x)＝(X-1)*cos(Angle)+(Y-1)*sin(Angle)；
RightBottom(y)＝-(X-1)*sin(Angle)+(Y-1)*cos(Angle)；
top right vertex:
RightTop(x)＝(X-1)*cos(Angle)；
RightTop(y)＝-(X-1)*sin(Angle)。
in the scheme, the specific method of the step (2) is as follows: the row number of the new image is the maximum row number of the four vertexes minus the minimum row number of the four vertexes, and the column number of the new image is the maximum column number of the four vertexes minus the minimum column number of the four vertexes, and the specific formula is as follows:
Xnew＝max([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])-min([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])；
Ynew＝max([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])-min([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])；
wherein, XnewFor new image column number, YnewThe number of rows for the new image.
In the above scheme, the specific method of step (3) is as follows:
Yn＝1+round(-indexX*sin(Angle)+indexY*cos(Angle))+round(abs(min([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])))；
Xn＝round(indexX*cos(Angle)+indexY*sin(Angle))+round(abs(min([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])))+1；
wherein, YnFor any point's row index in the new image, XnFor any point in the new image, index is the column index, Y is the number of lines in the original image, X is the number of columns in the original image, Y is the column index of the original imageoFor any point in the line index of the original image, XoFor any point in the row index of the original image, Angle is the rotation Angle, abs is the absolute value, min is the minimum value, and round is the integer.
Through the technical scheme, the rapid rotation method of the underwater image provided by the invention is not limited by accumulation time and marine environment interference, can rapidly identify the true position of the pixel point in the seawater underwater image, and achieves the purpose of improving the efficiency and accuracy of underwater image analysis.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
FIG. 1 is a schematic flow chart of a fast rotation method for underwater images according to an embodiment of the present invention;
FIG. 2 illustrates an image rotation process according to an embodiment of the present invention.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
The embodiment of the invention provides a method for rapidly rotating an underwater image, which comprises the following steps as shown in figure 1:
(1) setting the coordinate of one vertex of the original image as a coordinate origin, establishing a coordinate system, and calculating the coordinates of four vertexes of the original image after rotation according to the direction and the angle to be rotated;
in the present embodiment, as shown in fig. 2, the acquired underwater image is a single-channel grayscale image with a width of 640 pixels and a height of 480 pixels; the upper left corner of the original image is O (0, 0); the lower left corner is a (479, 0); c (0, 639) at the upper right corner, B (479, 639) at the lower right corner, 480 pixels in row number Y, and 640 pixels in column number X; if required by 30. Angle is 30; sin (30) ═ 0.5; cos (30) ═ 0.866; after rotation, the x, y coordinates of the four vertices are calculated as follows:
lower left vertex a':
LeftBottom(x)＝(Y-1)*sin(Angle)＝479*0.5＝239.5；
LeftBottom(y)＝(Y-1)*cos(Angle)＝479*0.866＝414.814；
upper left vertex O:
LeffTop(x)＝0；
LeftTop(y)＝0；
lower right vertex B':
RightBottom(x)＝(X-1)*cos(Angle)+(Y-1)*sin(Angle)
＝639*0.866+479*0.5＝792.874；
RightBottom(y)＝-(X-1)*sin(Angle)+(Y-1)*cos(Angle)
＝-639*0.5+479*0.866＝95.314；
upper right vertex C':
RightTop(x)＝(X-1)*cos(Angle)＝639*0.866＝553.374；
RightTop(y)＝-(X-1)*sin(Angle)＝-639*0.5＝-319.5。
(2) calculating the number of rows and columns of a new image according to the calculated coordinates of the four vertexes, wherein the new image is a square frame (a dotted frame surrounded by DEGF in fig. 2) which just covers all pixel points of the original image; the specific method comprises the following steps:
line number Y of new imagenewColumn number X of new image by subtracting the minimum number of rows of four vertices from the maximum number of rows of four verticesnewThe number of columns with the four vertices being the largest minus the number of columns with the four vertices being the smallest is given by the following formula:
Xnew＝max([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])-min([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])
＝max(239.5，0，792.874，553.374)-min(239.5，0，792.874，553.374)
＝792.874-0
＝792.874
＝793；
Ynew＝max([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])-min([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])
＝max(414.814，0，95.314，-319.5)-min(414.814，0，95.314，-319.5)
＝414.814-(-319.5)
＝734.314
＝734；
therefore, a new image after rotation is obtained as an image of 734 rows and 793 columns.
(3) Traversing all points corresponding to the rows and the columns of the original image, and calculating the row and column indexes of each point in a new image;
in this embodiment, the original image is 640 x 480, so that after 640 columns are traversed, each column traverses 480 rows again, i.e., from the (0, 0) point to the (639, 479) point.
For example: a point (3, 5) with rows and columns of 3 and 5 respectively in the original image, indexX being 5 and indexY being 3; its gray value is 3, calculate the row index and column index of the point in the new image:
Yn＝1+round(-indexX*sin(Angle)+indexY*cos(Angle))+round(abs(min([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])))
＝1+round(5*0.5+3*0.866)+round(abs(min(414.814，0，95.314，-319.5)))
＝1+roung(2.5+2.598)+round(319.5)
＝1+5+320；
＝326；
Xn＝round(indexX*cos(Angle)+indexY*sin(Angle))+round(abs(min([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])))+1
＝round(5*0.866+3*0.5)+round(abs(min(239.5，0，792.874，553.374)))+1
＝round(5.83)+0+1；
＝7；
wherein, YnFor the line index of the point in the new image, XnThe column index of the point in the new image, index, Y the number of lines of the original image, X the number of columns of the original image, YoFor the line index of the point in the original image, XoThe column index of the point in the original image, Angle is the rotation Angle, abs is the absolute value, min is the minimum value, and round is the rounding.
Thus, point (3, 5) corresponds to the rotated position of 326 rows, 7 columns, i.e., point (326, 7).
(4) And assigning the pixel values of all traversed points in the original image to the row and column indexes of each point in the new image to obtain the new image containing the pixel values of all the pixel points of the original image, and setting the rest pixel points in the new image to be white.
In this embodiment, the rotated new image is an image in 734 rows and 793 columns, the original image covers the pixels corresponding to the new image, and the remaining pixels are all initial values, white, and the pixel value is 255.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (4)
1. A method for rapidly rotating an underwater image is characterized by comprising the following steps:
(1) setting the coordinate of one vertex of the original image as a coordinate origin, establishing a coordinate system, and calculating the coordinates of four vertexes of the original image after rotation according to the direction and the angle to be rotated;
(2) calculating the number of rows and columns of a new image according to the calculated coordinates of the four vertexes, wherein the new image is a square frame which just covers all pixel points of the original image;
(3) traversing all points corresponding to the rows and the columns of the original image, and calculating the row and column indexes of each point in a new image;
(4) and assigning the pixel values of all traversed points in the original image to the corresponding row index and column index of each point in the new image to obtain the new image containing the pixel values of all the pixel points of the original image, and setting the rest pixel points in the new image to be white.
2. The fast rotation method of underwater images according to claim 1, characterized in that the specific method of step (1) is as follows:
the original image is a square image, the upper left vertex of the original image is set as the origin of coordinates, the original image is rotated around the origin of coordinates, Y is the number of lines of the original image, X is the number of columns of the original image, and Angle is the Angle of rotation, then the X and Y coordinates of the four vertices of the rotated original image are calculated as follows:
lower left vertex:
LeftBottom(x)＝(Y-1)*sin(Angle)；
LeftBottom(y)＝(Y-1)*cos(Angle)；
top left vertex:
LeftTop(x)＝0；
LeftTop(y)＝0；
lower right vertex:
RightBottom(x)＝(X-1)*cos(Angle)+(Y-1)*sin(Angle)；
RightBottom(y)＝-(X-1)*sin(Angle)+(Y-1)*cos(Angle)；
top right vertex:
RightTop(x)＝(X-1)*cos(Angle)；
RightTop(y)＝-(X-1)*sin(Angle)。
3. the fast rotation method of underwater images as claimed in claim 1, characterized in that the specific method of step (2) is as follows: the row number of the new image is the maximum row number of the four vertexes minus the minimum row number of the four vertexes, and the column number of the new image is the maximum column number of the four vertexes minus the minimum column number of the four vertexes, and the specific formula is as follows:
Xnew＝max([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])-min([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])；
Ynew＝max([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])-min([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])；
wherein, XnewFor new image column number, YnewThe number of rows for the new image.
4. The fast rotation method of underwater images as claimed in claim 1, characterized in that the specific method of step (3) is as follows:
Yn＝1+round(-indexX*sin(Angle)+indexY*cos(Angle))+round(abs(min([LeftTop(y)，LeftBottom(y)，RightTop(y)，RightBottom(y)])))；
Xn＝round(indexX*cos(Angle)+indexY*sin(Angle))+round(abs(min([LeftTop(x)，LeftBottom(x)，RightTop(x)，RightBottom(x)])))+1；
wherein, YnFor any point's row index in the new image, XnFor any point in the new image, index is the column index, Y is the number of lines in the original image, X is the number of columns in the original image, Y is the column index of the original imageoFor any point in the line index of the original image, XoFor any point in the row index of the original image, Angle is the rotation Angle, abs is the absolute value, min is the minimum value, and round is the integer.
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| 杜冬: "自动几何校正中摄像机的自动校正方法", 《中国民航飞行学院学报》 * |
| 王小芳等: "基于图像转置算法的研究", 《电脑知识与技术》 * |
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