CN115719386B - Calibration device and method of laser treatment system based on line scanning - Google Patents
Calibration device and method of laser treatment system based on line scanning Download PDFInfo
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Abstract
The invention provides a calibration device and a calibration method of a laser treatment system based on line scanning, wherein the device comprises the laser treatment system and a calibration camera; the laser treatment system comprises a linear imaging light source, a treatment light source, an imaging galvanometer, a treatment galvanometer and a line camera; the calibration camera is used for shooting calibration camera images generated by the linear imaging light source and the treatment light source; the line camera is used for shooting a line camera image reflected by the line imaging light source through the calibration camera. By introducing the calibration camera, the imaging view field of the line camera is projected on the view field of the calibration camera, so that an accurate calibration image is obtained, the problem of inaccurate striking position caused by view field errors is solved, and the calibration accuracy is greatly improved; by means of the calibration method of the line scanning-based laser treatment system, automatic calibration of the line scanning-based laser treatment system can be achieved, calibration time is shortened, and calibration efficiency and accuracy are improved.
Description
Technical Field
The invention relates to an image processing technology of a laser treatment system, in particular to a calibration device and method of the laser treatment system based on line scanning.
Background
The laser therapeutic apparatus is a system for treating eye fundus diseases by utilizing biological effects generated by laser, and is currently commonly used for treating fundus diseases, eliminating fundus lesion areas or preventing possible fundus diseases. However, conventional laser treatment systems are manual treatments, requiring relatively high demands on the physician and patient, and less and difficult to obtain for a physician with experience with the procedure.
The laser therapeutic apparatus based on line scanning can acquire digital images of eyeground of human eyes in real time by using a line camera to realize automatic laser therapy, thereby solving the problem of low degree of automation of the traditional laser therapeutic apparatus. However, after the line scanning laser therapeutic apparatus changes into digital image, the operation process needs to be controlled by a machine, and a computer needs to obtain a conversion relation between the acquired image and the deflection angle of the therapeutic galvanometer for determining the laser position. The usual calibration method is manual calibration, and the time cost for improving the accuracy is extremely high.
Furthermore, because the coverage range of the imaging view field designed by the line camera in the laser therapeutic apparatus based on the line scanning is larger than the actual irradiation range, errors of the irradiation area exist, the accuracy of the laser irradiation position is definitely reduced, and the calibration accuracy is difficult to guarantee.
Disclosure of Invention
Aiming at the limitation of the limitation, the invention provides a calibration device and a calibration method of a laser treatment system based on line scanning, which can obtain a calibration result more accurately, realize automatic calibration of the line scanning laser treatment system, greatly shorten the calibration time and improve the calibration efficiency and the accuracy compared with the prior art.
To achieve the above object, in one aspect, the present invention provides a calibration device for a laser treatment system based on line scanning, the device including a laser treatment system and a calibration camera; the laser treatment system comprises a linear imaging light source, a treatment light source, an imaging galvanometer, a treatment galvanometer and a line camera; the calibration camera is used for shooting calibration camera images generated by the imaging light source and the treatment light source; the line camera is used for shooting line camera images reflected by the imaging light source through the calibration camera.
In another aspect, the present invention provides a calibration method of a laser treatment system based on line scanning, where the method uses a calibration device of the laser treatment system based on line scanning in the foregoing embodiment, and the method includes: acquiring a calibration camera image generated by an imaging light source shot by a calibration camera and a line camera image reflected by the imaging light source shot by the line camera through the calibration camera; calculating the proportion of dark parts at two sides and a central bright part in the line camera image, and determining a projection area corresponding to the field of view of the line camera image in the calibrated camera image under the proportion according to the size of the line light spot in the calibrated camera image; determining a calibration position corresponding to a pixel point in the line camera image in the projection area in the calibration camera image; and acquiring a calibration camera image with treatment spots, which is generated by an imaging light source and a treatment light source shot by a calibration camera, and adjusting the angle of the treatment galvanometer, so that the treatment spots in the calibration camera image move to the calibration positions, and obtaining the treatment galvanometer angles corresponding to all pixel points in the calibrated line camera image based on the corresponding relation between the angles of all treatment galvanometers and the calibration positions.
Further, after the treatment galvanometer angle corresponding to each pixel point in the calibrated line camera image is obtained, the method further comprises: and (3) moving the imaging galvanometer, and returning to the step of acquiring the calibration camera image generated by the imaging light source shot by the calibration camera until the movable range of the imaging galvanometer is traversed.
Further, the calculating the ratio of the dark portions at two sides to the bright portion at the center in the line camera image specifically includes: and vertically and averagely compressing the line camera image into a line, and obtaining the ratio of the width of the dark parts at two sides to the width of the central bright part by utilizing the half-width value of the brightness curve of the line.
Further, the size of the linear light spot in the calibrated camera image is obtained by the following method: transversely and averagely compressing the calibrated camera image into a transverse line, and determining the half-width value of the brightness curve of the transverse line; and longitudinally and averagely compressing the calibrated camera image into a longitudinal line, determining the half-width value of the brightness curve of the longitudinal line, and taking the half-width value of the transverse line and the half-width value of the longitudinal line as the length and the width of the linear light spot respectively.
Further, the determining a projection area corresponding to the line camera image field of view in the scaled camera image according to the size of the line spot in the scaled camera image includes: and expanding the two sides of the linear light spot according to the corresponding proportion to obtain a projection area, wherein the width of the projection area is the width of the linear light spot.
Further, determining a calibration position corresponding to the pixel point in the line camera image in the projection area in the calibration camera image includes: and dividing the projection area into a plurality of image blocks in the transverse direction, wherein the number of the image blocks corresponds to the number of the pixel points in the line camera image, and the centers of the image blocks are respectively used as the positions corresponding to the pixel points in the line camera image in the calibration camera image.
Further, when the angle of the therapeutic vibrating mirror is adjusted and/or the imaging vibrating mirror is moved, a preset jump step is adopted, the corresponding relation between the angle of part of the therapeutic vibrating mirror and each position is obtained, a homography transformation matrix is calculated, and the therapeutic vibrating mirror angle corresponding to each pixel point in the calibrated line camera image is obtained.
Further, the adjusting the angle of the therapeutic galvanometer, so that the therapeutic light spot in the calibration camera image moves to each calibration position, specifically, for each calibration position, includes: determining an initial adjustment direction and an initial adjustment step length based on a preset proportion coefficient, and adjusting the angle of the therapeutic vibrating mirror; and adjusting a scaling factor based on the difference between the position of the therapeutic light spot in the calibration camera image and the position, re-determining an adjusting direction and an adjusting step length, and repeating the steps until the difference between the position of the therapeutic light spot in the calibration camera image and the position meets a preset condition.
In another aspect, the present invention provides a calibration device for a line-scan-based laser treatment system, the device comprising:
the acquisition unit is used for acquiring a calibration camera image generated by an imaging light source shot by the calibration camera and a line camera image reflected by the imaging light source shot by the line camera through the calibration camera; acquiring a calibration camera image with treatment spots, which is generated by an imaging light source and a treatment light source shot by a calibration camera;
the processing unit is used for calculating the proportion of dark parts at two sides and a central bright part in the line camera image, and determining a projection area corresponding to the field of view of the line camera image in the calibrated camera image under the proportion according to the size of the linear light spot in the calibrated camera image; determining a calibration position corresponding to a pixel point in the line camera image in the projection area in the calibration camera image;
the adjusting unit is used for adjusting the angle of the therapeutic vibrating mirror so that the therapeutic light spots in the standard camera image move to the standard positions;
and the data unit is used for obtaining the therapeutic vibrating mirror angle corresponding to each pixel point in the calibrated line camera image based on the corresponding relation between the angle of each therapeutic vibrating mirror and each calibration position.
Compared with the prior art, the invention has the following advantages:
(1) The automatic calibration of the laser treatment system based on line scanning can be realized, the calibration time is shortened, the labor cost is saved, and the calibration efficiency and the accuracy are improved;
(2) By introducing the calibration camera, the imaging view field of the line camera is projected on the view field of the calibration camera, so that an accurate calibration image is obtained, the problem of inaccurate striking position caused by view field errors is solved, and the calibration accuracy is greatly improved;
(3) Specifically, a calibration camera image generated by a linear imaging light source shot by a calibration camera and a linear camera image reflected by the calibration camera by the linear imaging light source shot by the linear camera are obtained; calculating the proportion of dark parts at two sides and a central bright part in the line camera image, and determining a projection area corresponding to the field of view of the line camera image in the calibrated camera image under the proportion according to the size of the line light spot in the calibrated camera image; determining a calibration position corresponding to a pixel point in the line camera image in the projection area in the calibration camera image; the method comprises the steps of obtaining a calibration camera image with treatment light spots, which is generated by an imaging light source and a treatment light source shot by a calibration camera, and adjusting the angle of a treatment galvanometer, so that the treatment light spots in the calibration camera image move to each calibration position, and the treatment galvanometer angle corresponding to each pixel point in the calibrated line camera image is obtained based on the corresponding relation between the angle of each treatment galvanometer and each calibration position, thereby obtaining a more accurate calibration result, and greatly improving the calibration accuracy.
(4) In addition, a homography transformation matrix is adopted to obtain the therapeutic galvanometer angle corresponding to each pixel point in the calibrated line camera image, and when only partial points are calibrated, the result of the non-calibrated points can be estimated through the matrix; when all points are calibrated, the error points with larger deviation can be calibrated through matrix correction, so that the problem of inaccurate position of partial areas caused by calculation errors of a few points is solved, and the calibration accuracy is improved.
(5) By adopting the method and the device, the calibration precision can be further improved. In an embodiment of the invention, the minimum time unit required for each operation to be performed depends on the time interval between two frames of images of the line camera, i.e. the frame rate. At present, the most widely used simple manual calibration mode is usually used for calibrating only 3 and 4 points, and when the method is actually used, hundreds of points are usually calibrated automatically in a short time, so that the stability of a calibration result is improved by hundreds of times, and the laser light source characteristic is improved by improving the performance of a laser, so that the area of a light spot is further reduced, and the calibration precision is further improved.
(6) The invention has wide application scene, is suitable for various treatment systems, such as ophthalmic or endoscopic laser treatment systems, and has good application prospect.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention, as well as the preferred embodiments thereof, together with the following detailed description of the invention, given by way of illustration only, together with the accompanying drawings.
Drawings
FIG. 1 is a schematic diagram of a calibration apparatus of a line-scan-based laser treatment system according to an embodiment of the present invention;
FIG. 2 is a flow chart of a calibration method of a laser treatment system based on line scanning according to an embodiment of the present invention;
FIG. 3 is a line camera image schematic;
FIG. 4 is a schematic view of a projected area in a calibration camera image;
fig. 5 is a schematic diagram of a scanning bow-type movement of a laser spot according to another embodiment of the present invention.
Detailed Description
Other advantages and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, by way of illustration, is to be read in connection with certain specific embodiments, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. For a further understanding of the present invention, the present invention will be described in further detail with reference to the following preferred embodiments.
The invention is characterized by comprising a laser treatment system based on line scanning and a calibration system for calibrating a camera, wherein the laser treatment system comprises a linear imaging light source, a treatment light source, an imaging galvanometer, a treatment galvanometer and a line camera; the calibration camera is used for shooting calibration camera images generated by the imaging light source and the treatment light source; the line camera is used for shooting a line camera image reflected by the imaging light source through the calibration camera to accurately realize automatic calibration of the laser of the line scanning laser treatment system, and the specific method comprises the steps of obtaining a calibration camera image generated by the imaging light source shot by the calibration camera and a line camera image reflected by the imaging light source shot by the line camera through the calibration camera; calculating the proportion of dark parts at two sides and a central bright part in the line camera image, and determining a projection area corresponding to the field of view of the line camera image in the calibrated camera image under the proportion according to the size of the line light spot in the calibrated camera image; determining a calibration position corresponding to a pixel point in the line camera image in the projection area in the calibration camera image; the method comprises the steps of obtaining a calibration camera image with treatment light spots, which is generated by an imaging light source and a treatment light source shot by a calibration camera, and adjusting the angle of a treatment galvanometer, so that the treatment light spots in the calibration camera image move to each calibration position, and the treatment galvanometer angle corresponding to each pixel point in the calibrated line camera image is obtained based on the corresponding relation between the angle of each treatment galvanometer and each calibration position, thereby obtaining a more accurate calibration result, greatly improving the calibration accuracy, and solving the problem that the calibration accuracy is influenced due to the inherent defects of the line camera of the line scanning laser treatment system in the prior art.
Example 1
Referring to fig. 1, an embodiment of the present invention provides a calibration apparatus for a line-scan based laser treatment system, the apparatus including a laser treatment system and a calibration camera; the laser treatment system is a photocoagulation instrument and comprises a linear imaging light source, a treatment light source, an imaging galvanometer, a treatment galvanometer and a line camera; the calibration camera is used for shooting calibration camera images generated by the linear imaging light source and the treatment light source; the line camera is used for shooting line camera images reflected by the imaging light source through the calibration camera.
It should be noted that, in the linear imaging light source of the laser treatment system in this embodiment, a point light source generally forms a linear light source after passing through a cylindrical lens, and an imaging field of view of the linear light source after passing through an imaging galvanometer scanning may cover a surface, and a planar image is obtained after synchronizing with a line camera. Because of the confocal nature, line scanning is better in resolution than general area scanning. The calibration camera is placed at the light outlet of the laser treatment system, after the linear imaging light source of the linear scanning laser treatment system is turned on, the calibration camera can shoot a bright thin line, namely a frame of calibration camera image generated by the linear imaging light source shot on the calibration camera, and the line camera shoots and obtains a frame of line camera image reflected by the calibration camera through the surface reflection of the frame of calibration camera image. In this embodiment, the imaging galvanometer selects a one-dimensional galvanometer, the treatment galvanometer selects a two-dimensional galvanometer, and two one-dimensional galvanometers may be provided to control the deflection in the X direction and the Y direction respectively.
According to the embodiment, the imaging view field of the line camera is projected on the view field of the calibration camera through introducing the calibration camera, so that an accurate calibration camera image is obtained, and the treatment galvanometer angle corresponding to each pixel point in the calibrated line camera image is obtained according to the projection relation, so that the problem of inaccurate striking position caused by view field errors is solved, and the laser calibration accuracy of the laser treatment system based on line scanning is greatly improved. The specific calibration method is as follows:
referring to fig. 2, an embodiment of the present invention provides a calibration method of a laser treatment system based on line scanning, the method includes:
step S10, obtaining a calibration camera image generated by an imaging light source shot by a calibration camera and a line camera image reflected by the imaging light source shot by the line camera through the calibration camera;
step S20, calculating the proportion of dark parts at two sides and a central bright part in the line camera image, and determining a projection area corresponding to the field of view of the line camera image in the calibrated camera image under the proportion according to the size of the linear light spot in the calibrated camera image;
step S30, determining the corresponding calibration position of the pixel point in the line camera image in the projection area in the calibration camera image;
and S40, obtaining a linear imaging light source shot by a calibration camera and a calibration camera image with treatment light spots generated by the treatment light source, and adjusting the angle of the treatment galvanometer so that the treatment light spots in the calibration camera image move to the calibration positions, and obtaining the treatment galvanometer angles corresponding to the pixel points in the calibrated line camera image based on the corresponding relation between the angles of the treatment galvanometers and the calibration positions.
It should be noted that, after step S40, step S50 is further included, after the therapeutic galvanometer angle corresponding to each pixel point in the calibrated line camera image is obtained, the imaging galvanometer is moved at this time, and step S10 of obtaining the calibrated camera image generated by the line imaging light source captured by the calibration camera is returned, and the process is circulated until the movable range of the imaging galvanometer is traversed.
That is, in this embodiment, the therapeutic galvanometer angle corresponding to each pixel point in the line camera image is marked, but only one line is actually shot by the line camera, after the line is marked, the imaging galvanometer will move to the next line, and the therapeutic galvanometer angle corresponding to each pixel point in the next line is marked. After the imaging galvanometer traversal is finished, the line camera image obtained each time can be spliced into a whole image according to the position relation, the position relation is obtained according to the parameters of the imaging galvanometer movement, and finally, each pixel point in the whole image has a corresponding therapeutic galvanometer angle, namely a calibration result.
The specific mobile calibration process may refer to the schematic diagram of the bow-type scanning calibration process shown in fig. 5, and specifically includes:
firstly, starting scanning from a first pixel point on the left side of a first line shot by a line camera as a calibrated initial position, adjusting a treatment galvanometer, moving a treatment light spot in a positive direction according to a transverse coordinate axis until the treatment light spot moves to a calibrated position corresponding to a last pixel point on the right side of the first line, and then completing calibration of the angle of the treatment galvanometer corresponding to each pixel point on the first line; then, moving the imaging galvanometer to the next line, adjusting the treatment galvanometer by adopting the laser calibration method from the step S10 to the step S40 in sequence, enabling the treatment light spot in the calibrated camera image to move to the calibration position corresponding to the rightmost pixel point of the next line, then adjusting the treatment galvanometer to move the treatment light spot according to the negative direction of the transverse coordinate axis, and completing the calibration of the treatment galvanometer angle corresponding to each pixel point on the next line shot by the line camera; and (3) circulating until each pixel point in the final whole image has a corresponding therapeutic galvanometer angle, namely a calibration result.
In this embodiment of the present application, the calibration camera image is an image on the field of view of the calibration camera, and the image is located in a calibration range, where the calibration range should enable the therapeutic light spot obtained when the therapeutic light source moves in any manner not to move out.
By utilizing the technical scheme of the embodiment, the projection area corresponding to the line camera image view field is determined according to the size of the line light spot in the calibration camera image by calculating the proportion of the dark parts at two sides and the central bright part in the line camera image, the line camera imaging view field range is accurately established, the view field error problem caused by the fact that the line camera imaging view field range is larger than the actually-illuminated range is eliminated, and the determination of the projection area lays a firm and beneficial foundation for improving the laser calibration accuracy; furthermore, the corresponding calibration position of the pixel point in the line camera image in the projection area in the calibration camera image can be accurately determined; and then adjusting the angle of the therapeutic galvanometer so that the therapeutic light spots in the standard camera image move to the corresponding standard positions of the pixel points in the line camera image in the projection area, and obtaining the therapeutic galvanometer angles corresponding to the pixel points in the calibrated line camera image based on the corresponding relation between the angle of each therapeutic galvanometer and the standard positions. Thereby obtaining a more accurate calibration result and greatly improving the accuracy of laser calibration.
Example two
On the basis of the first embodiment, as a preferred implementation manner, in this embodiment, the calculating ratio of the dark portions at the two sides to the bright portion at the center in the line camera image uses step S200: and vertically and averagely compressing the line camera image into a line, and obtaining the ratio of the width of dark parts at two sides to the width of the central bright part in the line camera image by utilizing the half-width value of the line brightness curve.
Specifically, referring to fig. 3, the line camera image 200 is a light beam, and there are dark portions on the left and right sides, and since the edges of the light beam are not flat and the bright and dark portions are gradually transited, the boundary line is not as obvious as shown in the figure, it is inconvenient to directly acquire the width of the light beam. In this embodiment, the entire image is compressed longitudinally into a line, the brightness curve of the line is obtained, the half-width value of the brightness curve is calculated and used as the width of the central bright portion, and the widths of the left dark portion area and the right dark portion area are obtained. Assuming that the width of the left dark portion 22 is d1, the width of the right dark portion 21 is d2, and the width of the middle bright portion 20 is d0, a ratio of the width of the two dark portions to the width of the center bright portion in the line camera image is proportional=d1/d 0, and proportional=d2/d 0, respectively, is obtained.
The full width at half maximum (FWHM, full width at half maximum) is the distance between points half the peak value among the peaks. Specifically, a tangent line L at the bottom of the peak is formed, parallel lines of L are formed at a position of half the peak height, and the width between two points where the parallel lines and the peak intersect is half-width.
In addition, the ratio of the dark portions at the two sides to the bright portion at the center in the line camera image is preferably not limited to the above-mentioned method of vertically and averagely compressing the line camera image into one line, and according to practical situations, the line camera image may not be vertically and averagely compressed into one line, but the half-width value of the brightness curve of each line in the horizontal direction in the line camera image may be directly calculated, and then the average value may be obtained.
Example III
On the basis of the first embodiment and the second embodiment, as a preferred implementation manner, in the calibration camera image in this embodiment, the size of the line light spot is obtained through step S202: transversely and averagely compressing the calibrated camera image into a transverse line, and determining the half-width value of the brightness curve of the transverse line; and longitudinally and averagely compressing the calibrated camera image into a longitudinal line, determining the half-width value of the brightness curve of the longitudinal line, and taking the half-width value of the transverse line and the half-width value of the longitudinal line as the length and the width of the linear light spot respectively.
Further, according to the size of the linear light spot in the calibrated camera image, and according to the ratio of the width of the dark parts at two sides in the linear camera image to the width of the central bright part in the embodiment II, ratio=d1/d 0 and ratio=d2/d 0, the two sides of the linear light spot are expanded, and a projection area is obtained, wherein the width of the projection area is the width of the linear light spot; the length of the projection area extended to the left is the length of the linear light spot, the length extended to the right is the length of the linear light spot, and the total length of the projection area is (1+ratio+ratio).
Specifically, fig. 4 shows a calibration camera image, wherein the projection area 100 is wide as the line spot 10, and has a left expansion portion 12 and a right expansion portion 11 on both sides in the length direction of the line spot, the length of the left expansion portion is the length of the line spot, and the length of the right expansion portion is the length of the line spot, so that the length of the projection area is (1+ratio+ratio).
It should be noted that, before the line spot size is obtained in step S202, step S201 is further included: if the calibration camera image may rotate due to the camera placement or the system itself, hough transformation may be performed on the calibration camera image first, to determine the rotation direction of the line light spot.
As a preferred embodiment, in step S30, determining a calibration position corresponding to a pixel point in the line camera image in the projection area includes step S301: and dividing the projection area into a plurality of image blocks in the transverse direction, wherein the number of the image blocks corresponds to the number of the pixel points in the line camera image, and the centers of the image blocks are respectively used as the corresponding calibration positions of the pixel points in the line camera image in the calibration camera image.
Specifically, n pixels in the transverse direction of the line camera (the image shot by the line camera corresponds to a line, so the longitudinal direction of the line camera can be regarded as the same point) are obtained according to the resolution of the line camera, the extended line light spot image projection area is divided into n parts, and the center point position of each small part of image block is obtained, and is used as the projection position of the corresponding pixel point of the line camera image on the calibration camera image.
As a preferred embodiment, in step S40, the angle of the therapeutic galvanometer is adjusted so that the therapeutic spot in the calibration camera image moves to each of the calibration positions, specifically, for each of the calibration positions, the method includes step S401: determining an initial adjustment direction and an initial adjustment step length based on a preset proportion coefficient, and adjusting the angle of the therapeutic vibrating mirror; and adjusting a scaling factor based on the difference between the position of the therapeutic light spot in the calibration camera image and the calibration position, re-determining an adjusting direction and an adjusting step length, and repeating the steps until the difference between the position of the therapeutic light spot in the calibration camera image and the calibration position meets a preset condition.
It should be noted that, in this embodiment, the scaling factor refers to a relationship between a position offset in an image and an offset of a galvanometer, that is, the position offset in the image is multiplied by the scaling factor to obtain the offset of the galvanometer, where the scaling factor may be adjusted in real time according to an actual situation, for example, a distance between a treatment light spot in a known image and a next calibration position is based on a preset scaling factor K1, and it is assumed that an initial adjustment direction and an initial adjustment step determined after calculation are: the X direction rotates clockwise by 5 degrees, the position of the therapeutic light spot in the calibrated camera image is observed to approach the direction of the calibrated position, but the approaching distance only reaches one half of the expected distance, the adjustment direction can be judged to be basically correct, the adjustment step length can be doubled, the adjustment is carried out based on the numerical value of the comparison proportion coefficient K1 to become K2 (if the position of the therapeutic light spot in the calibrated camera image is observed to be far away from the direction of the calibrated position, the sign of K2 is opposite to that of K1), then the adjustment direction and the adjustment step length of the next step can be redetermined based on the proportion coefficient K2, and the steps are repeated until the difference between the position of the therapeutic light spot in the calibrated camera image and the calibrated position meets the preset condition, and the preset condition in the implementation is that the position of the therapeutic light spot coincides with the calibrated position or the distance is smaller than 2 pixels.
The treatment galvanometer is rotated to enable the centroid of the treatment light spot to be continuously close to the center of the image pixel block until the distance between the centroid of the treatment light spot and the center of the image pixel block is zero or smaller than a preset threshold value, the centroid coordinate of the treatment light spot at the moment is calculated, and the centroid coordinate of the treatment light spot and the coordinates of the treatment galvanometer are recorded;
the calculation method of the barycenter coordinates of the therapeutic light spots in the embodiment is calculated by a barycenter method, and the specific calculation mode is as follows:
i, j are the abscissa and ordinate, respectively, of the image, I i,j For pixel brightness at (i, j), and (x, y) for centroid coordinates of the spot.
As a preferred implementation mode, when adjusting the angle of the therapeutic vibrating mirror and/or moving the imaging vibrating mirror, a preset jump step is adopted to obtain the corresponding relation between the angle of part of therapeutic vibrating mirror and each calibration position, and a homography transformation matrix is calculated to obtain the therapeutic vibrating mirror angle corresponding to each pixel point in the calibrated line camera image. The scheme of setting the jump step length can simplify the calibration step, further shorten the calibration time and improve the efficiency.
The transformation matrix in this embodiment is a homography transformation matrix of 3*3, and is calculated by a singular value decomposition method.
Specifically, a matrix is providedThe barycenter coordinates of the laser spots in the calibration conversion table are (X) i ，Y i ) The therapeutic galvanometer coordinate is (X i '，Y i '), a system of linear equations of order can be constructed:
and solving the solution of the homogeneous linear equation set by a singular value decomposition method.
Note that, in this embodiment, whether a partial correspondence or a complete correspondence is obtained, a homography matrix (homography matrix) may be calculated as a calibration result. When only partial points are calibrated, the result of the un-calibrated points can be estimated through a matrix, and when all the points are calibrated, the error points with larger deviation can be calibrated through matrix correction.
Example IV
The embodiment provides a calibration device of a laser treatment system based on line scanning, which comprises:
the acquisition unit is used for acquiring a calibration camera image generated by an imaging light source shot by the calibration camera and a line camera image reflected by the imaging light source shot by the line camera through the calibration camera; acquiring a calibration camera image with treatment spots, which is generated by an imaging light source and a treatment light source shot by a calibration camera;
the processing unit is used for calculating the proportion of dark parts at two sides and a central bright part in the line camera image, and determining a projection area corresponding to the field of view of the line camera image in the calibrated camera image under the proportion according to the size of the linear light spot in the calibrated camera image; determining a calibration position corresponding to a pixel point in the line camera image in the projection area in the calibration camera image;
the adjusting unit is used for adjusting the angle of the therapeutic vibrating mirror so that the therapeutic light spots in the standard camera image move to the standard positions;
and the data unit is used for obtaining the therapeutic vibrating mirror angle corresponding to each pixel point in the calibrated line camera image based on the corresponding relation between the angle of each therapeutic vibrating mirror and each calibration position.
As one example, the methods of the present invention may be implemented in software and/or a combination of software and hardware, e.g., using an Application Specific Integrated Circuit (ASIC), a general purpose computer, or any other similar hardware device.
The method of the present invention may be implemented in the form of a software program that is executable by a processor to perform the steps or functions described above. Likewise, the software programs (including associated data structures) may be stored on a computer readable recording medium, such as RAM memory, magnetic or optical drive or diskette and the like.
In addition, some steps or functions of the methods described herein may be implemented in hardware, for example, as circuitry that cooperates with the processor to perform various steps or functions.
Furthermore, portions of the methods described herein may be implemented as a computer program product, such as computer program instructions, which when executed by a computer, may invoke or provide methods and/or techniques in accordance with the present application by way of operation of the computer. Program instructions for invoking the methods of the invention may be stored in fixed or removable recording media and/or transmitted via a data stream in a broadcast or other signal bearing medium and/or stored within a working memory of a computer device operating according to the program instructions.
The processor of the embodiment of the invention is configured to execute the steps of the automatic calibration method of the laser treatment system laser based on the line scanning in the embodiment by executing the executable instructions, so that any pixel point on an image imaged according to fundus can be ensured, the angle of deflection of the treatment vibrating mirror for treating the laser can be known, the laser light spot can accurately appear on the selected pixel position, the accuracy and precision of operation planning implementation are greatly improved, the use is convenient, the safety and the rapidness are realized, the intelligent automatic calibration is realized, and the calibration time is greatly shortened.
It should be noted that, for simplicity of description, the foregoing method embodiments are all expressed as a series of action combinations, but it should be understood by those skilled in the art that the present application is not limited by the order of actions described, as some steps may be performed in other order or simultaneously in accordance with the present application. Further, those skilled in the art will also appreciate that the embodiments described in the specification are all alternative embodiments, and that the acts and modules referred to are not necessarily required in the present application.
Finally, it is pointed out that in the present document relational terms such as first and second, and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or terminal device comprising the element.
The present invention is not limited to the above-mentioned embodiments, but is intended to be limited to the following embodiments, and any modifications, equivalents and modifications can be made to the above-mentioned embodiments without departing from the scope of the invention.
Claims (8)
1. A calibration device of a laser treatment system based on line scanning, which is characterized by comprising a laser treatment system and a calibration camera;
the laser treatment system comprises a linear imaging light source, a treatment light source, an imaging galvanometer, a treatment galvanometer and a line camera;
the calibration camera is used for shooting calibration camera images generated by the linear imaging light source and the treatment light source;
the line camera is used for shooting the line camera image reflected by the line imaging light source through the calibration camera, and projecting the imaging view field of the line camera image shot by the line camera and reflected by the calibration camera onto the calibration camera view field to obtain an accurate calibration image.
2. A method for calibrating a line scan-based laser therapy system, comprising:
obtaining a calibration camera image generated by a linear imaging light source shot by a calibration camera and a linear camera image reflected by the calibration camera by the linear imaging light source shot by the linear camera;
calculating the ratio of dark parts at two sides to a central bright part in the line camera image, namely, longitudinally and averagely compressing the line camera image into a line, and obtaining the ratio of the width of the dark parts at two sides to the width of the central bright part by utilizing the half-width value of the brightness curve of the line; determining a projection area corresponding to the line camera image view field in the calibrated camera image under the proportion according to the size of the line light spot in the calibrated camera image;
the determining a calibration position corresponding to the pixel point in the line camera image in the projection area in the calibration camera image specifically comprises the following steps: dividing the projection area into a plurality of image blocks in the transverse direction, wherein the number of the image blocks corresponds to the number of the pixel points in the line camera image, and the centers of the image blocks are respectively used as the corresponding calibration positions of the pixel points in the line camera image in the calibration camera image;
and obtaining a linear imaging light source shot by a calibration camera and a calibration camera image with treatment light spots generated by the treatment light source, and adjusting the angle of the treatment galvanometer, so that the treatment light spots in the calibration camera image move to each calibration position, and obtaining the treatment galvanometer angles corresponding to each pixel point in the calibrated line camera image based on the corresponding relation between the angle of each treatment galvanometer and each calibration position.
3. The method according to claim 2, further comprising, after obtaining the therapeutic galvanometer angle corresponding to each pixel point in the calibrated line camera image: and (3) moving the imaging galvanometer, and returning to the step of acquiring the calibration camera image generated by the imaging light source shot by the calibration camera until the movable range of the imaging galvanometer is traversed.
4. The method of claim 2, wherein the nominal camera image line spot size is obtained by:
transversely and averagely compressing the calibrated camera image into a transverse line, and determining the half-width value of the brightness curve of the transverse line; and longitudinally and averagely compressing the calibrated camera image into a longitudinal line, determining the half-width value of the brightness curve of the longitudinal line, and taking the half-width value of the transverse line and the half-width value of the longitudinal line as the length and the width of the linear light spot respectively.
5. The method of claim 2, wherein determining the projection area in the scaled camera image corresponding to the line camera image field of view based on the size of the line spot in the scaled camera image comprises:
and expanding the two sides of the linear light spot according to the corresponding proportion to obtain a projection area, wherein the width of the projection area is the width of the linear light spot.
6. A method according to claim 2 or 3, wherein when the angle of the therapeutic galvanometer is adjusted and/or the imaging galvanometer is moved, a preset jump step is adopted to obtain the corresponding relation between the angle of part of the therapeutic galvanometer and each calibration position, and a homography transformation matrix is calculated to obtain the therapeutic galvanometer angle corresponding to each pixel point in the calibrated line camera image.
7. The method according to claim 2, wherein said adjusting the angle of the treatment galvanometer such that the treatment spot in the nominal camera image is moved to each of said nominal positions, in particular, comprises, for each of said nominal positions:
determining an initial adjustment direction and an initial adjustment step length based on a preset proportion coefficient, and adjusting the angle of the therapeutic vibrating mirror;
and adjusting a scaling factor based on the difference between the position of the therapeutic light spot in the calibration camera image and the calibration position, re-determining an adjusting direction and an adjusting step length, and repeating the steps until the difference between the position of the therapeutic light spot in the calibration camera image and the calibration position meets a preset condition.
8. A calibration device for a line-scan-based laser treatment system, comprising:
the acquisition unit is used for acquiring a calibration camera image generated by an imaging light source shot by the calibration camera and a line camera image reflected by the imaging light source shot by the line camera through the calibration camera; acquiring a calibration camera image with treatment spots, which is generated by an imaging light source and a treatment light source shot by a calibration camera;
the processing unit is used for calculating the ratio of the dark parts at two sides to the central bright part in the line camera image, specifically, the line camera image is longitudinally and averagely compressed into a line, and the half-width value of the line brightness curve is utilized to obtain the ratio of the width of the dark parts at two sides to the width of the central bright part respectively; determining a projection area corresponding to the line camera image view field in the calibrated camera image under the proportion according to the size of the line light spot in the calibrated camera image; the determining a calibration position corresponding to the pixel point in the line camera image in the projection area in the calibration camera image specifically comprises the following steps: dividing the projection area into a plurality of image blocks in the transverse direction, wherein the number of the image blocks corresponds to the number of the pixel points in the line camera image, and the centers of the image blocks are respectively used as the corresponding calibration positions of the pixel points in the line camera image in the calibration camera image;
the adjusting unit is used for adjusting the angle of the therapeutic vibrating mirror so that the therapeutic light spots in the standard camera image move to the standard positions;
and the data unit is used for obtaining the therapeutic vibrating mirror angle corresponding to each pixel point in the calibrated line camera image based on the corresponding relation between the angle of each therapeutic vibrating mirror and each calibration position.
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