Projection geometric correction method and projection equipment

Abstract

The invention discloses a projection geometric correction method and projection equipment, and the method comprises the steps: obtaining the deflection angles of the projection equipment in the X-axis direction, the Y-axis direction and the Z-axis direction when the position of the projection equipment deviates, determining the corresponding pixel offset according to the deflection angles, and compensating the pixel offset through a compensation model, the corrected image is corrected into a rectangular projection image by adopting the compensated pixel offset, then corrected projection coordinates are obtained based on the pixel coordinates of the projection screen frame and the pixel coordinates of the rectangular projection image, and the projection image to be projected is corrected by adopting the corrected projection coordinates; according to the method, when the position of the projection equipment deviates based on the steps, the corrected image is corrected into the rectangular projection image by adopting the relation between the deflection angle and the pixel offset, and then the rectangular projection image is corrected to the projection screen, so that the projection equipment with the deviated position can normally project on the projection screen without adjusting the position; and the operation difficulty of the user is reduced while the watching effect is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of projection display, and in particular, relates to a projection geometry correction method and a projection device. Background Art

[0002] The projection device can project images onto the projection screen. In actual applications, the position of the projection device may change, causing the projection image to be distorted, from a rectangular projection area to an irregular quadrilateral area, and the originally vertical or parallel borders to become tilted, thus affecting the display effect of the projection device.

[0003] Changes in the projected image and the projection area will result in poor effects of the projected image displayed by the projection device. In the prior art, when the position of the projection device changes and causes the projection image to be distorted, the existing method is to restore the position of the projection device manually or automatically. The manual method requires high professionalism and is difficult for ordinary users to complete. The automatic method requires the projection device to be equipped with an automatic adjustment mechanism, which increases the equipment cost and affects the appearance of the projection device. Summary of the invention

[0004] In view of the above-mentioned problems existing in the prior art, the present invention proposes a projection geometry correction method and a projection device. When the position of the projection device changes and causes the projection image to be distorted, the coordinates of the correction transformation are calculated through an algorithm, and the projection device outputs the corrected coordinates, so that a distortion-free projection image can be displayed on the receiving screen without adjusting the position of the projection device.

[0005] The present invention is implemented by the following technical solutions: A projection geometry correction method is proposed, which is applied to a projection device, wherein the projection device is configured with: A posture sensor, used to obtain the three-dimensional position information of the projection device; Correction methods include: Get the three-dimensional position information detected by the attitude sensor; when the three-dimensional position information changes, perform the following steps: Projection correction image; Primary calibration: obtaining a first deflection angle, a second deflection angle and / or a third deflection angle of the projection device according to the three-dimensional position information and the initial position information; determining a first pixel offset, a second pixel offset and / or a third pixel offset based on the first deflection angle, the second deflection angle and / or the third deflection angle; wherein the first deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis, the second deflection angle is an angle at which the projection device deflects relative to the initial position with the Y-coordinate axis as the rotation axis, and the third deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis; Secondary correction: using a compensation model constructed based on the deflection angle and the pixel offset to obtain a pixel offset correction value, and using the pixel offset correction value to compensate for the first pixel offset, the second pixel offset and / or the third pixel offset; Correcting the corrected image into a rectangular projection image using the compensated first pixel offset, second pixel offset and / or third pixel offset; Three corrections: obtaining the pixel coordinates of the projection screen border, and obtaining the corrected projection coordinates based on the pixel coordinates of the projection screen border and the pixel coordinates of the rectangular projection image; The projection image to be projected is corrected using the corrected projection coordinates.

[0006] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the projection geometry correction method proposed in the present invention projects a correction image when the position of the projection device is offset, and uses the three-dimensional position information detected by the attitude sensor to convert the deflection angle of the projection device in the three directions of the X-axis, the Y-axis and the Z-axis, obtains the pixel offset corresponding to the offset angle, uses the compensation model to compensate the pixel offset, uses the compensated pixel offset to correct the correction image into a rectangular projection image, and then obtains the correction projection coordinates based on the pixel coordinates of the projection screen frame and the pixel coordinates of the rectangular projection image, and uses the correction projection coordinates to correct the projection image to be projected; based on the above steps, the present invention uses the relationship between the deflection angle and the pixel offset to first correct the correction image into a rectangular projection image when the position of the projection device is offset, and then corrects the rectangular projection image onto the projection screen, so that the projection device that has been offset can be normally projected on the projection screen without adjusting its position, thereby ensuring the viewing effect while reducing the difficulty of operation for the user.

[0007] In some embodiments of the present invention, the method further comprises a calibration step, comprising: Establish a three-dimensional coordinate system with the center of the projection device as the origin; Taking the X axis as the rotation axis, obtaining a first data set of pixel offsets at different deflection angles; Taking the Y axis as the rotation axis, obtaining a second data set of pixel offsets at different deflection angles; Taking the Z axis as the rotation axis, obtaining a third data set of pixel offsets at different deflection angles; The first data group, the second data group and the third data group are respectively fitted into a first polynomial, a second polynomial and a third polynomial to obtain a corresponding relationship between a first deflection angle and a first pixel offset in the X-axis direction, a corresponding relationship between a second deflection angle and a second pixel offset in the Y-direction, and a corresponding relationship between a third deflection angle and a third pixel offset in the Z-direction.

[0008] In this embodiment, in a three-dimensional coordinate system constructed with the center of the projection device as the origin, data groups of pixel offsets occurring at different deflection angles with the X-axis, Y-axis and Z-axis as the rotation axes are obtained respectively, and each data group is fitted to obtain a polynomial of the relationship between the deflection angle and the pixel offset in the three directions, and this fitting relationship is stored in the projection device. When the position of the projection device changes, after obtaining the three-dimensional position data from the attitude sensor, the deflection angle of the projection device in the three-axis direction can be obtained according to the three-dimensional position data, and then the fitting polynomial is called to calculate the pixel offset corresponding to the deflection angle. The present invention is not limited to obtaining the pixel offset of the projected image in this way, and other technical means for obtaining the corresponding pixel offset at different deflection angles are all within the scope of the present invention, such as obtaining a relationship list by accumulating the relationship between the corresponding pixel offsets at different deflection angles, and obtaining the pixel offset by querying the list after knowing the deflection angle.

[0009] In some embodiments of the present invention, the method further comprises a compensation calibration step, including: Obtaining a compensation data set of the relationship between the deflection angle and the pixel offset at three angles of XYZ; A polynomial regression model is established based on the compensation data set; Use the least squares method to solve for the regression coefficients of the polynomial regression model; Substituting the regression coefficients into the polynomial regression model, the compensation model is obtained.

[0010] In actual calibration and application of the three-axis directions of X, Y, and Z, the offsets on the three-axis angles do not change in a single way, and there is a mutual influence relationship between them. In this embodiment, a compensation data group of the relationship between the deflection angle and the pixel offset on the three angles of X, Y, and Z is then obtained, a polynomial regression model is established according to the compensation data group, the regression coefficient of the regression model is calculated to obtain the compensation model, and the regression coefficient of the polynomial regression model is solved using the least squares method, and the regression coefficient is substituted into the polynomial regression model to obtain the compensation model. When the position of the projection device is offset and the pixel offset is obtained by fitting the relationship, the compensation model is called to compensate for the offsets of the three-axis deflection angles that affect each other, eliminate the mutual influence, and thus improve the correction effect and accuracy.

[0011] In some embodiments of the present invention, before step S5, the method further includes: The deviation between the corrected image and the standard rectangle is determined, and when the deviation is greater than a threshold, steps S2 to S4 are repeated until the corrected image is a rectangular projection image.

[0012] In this embodiment, after the first correction and the second correction are performed, it is determined whether the corrected rectangular projection image meets the standard rectangle. If it does not meet the standard rectangle requirement, the first correction and the second correction are repeated until the corrected rectangular projection image meets the standard rectangle, so as to ensure the accuracy of the three corrections.

[0013] In some embodiments of the present invention, step S5 specifically includes: Get the pixel coordinates of the four vertices of the projection screen border and the pixel coordinates of the four vertices of the rectangular projection image; use Get the corrected projection coordinates; , To correct the projection coordinates, and is the offset of the pixel coordinates of the vertices of the rectangular projection image relative to the pixel coordinates of the vertices of the projection screen border in the x direction and the y direction; x and y are the pixel coordinates of the vertices of the rectangular projection image.

[0014] The present invention also provides a projection device, which is configured with: A posture sensor, used to obtain the three-dimensional position information of the projection device; The projection unit is controlled by the projection controller and projects the image to be projected onto the projection screen; The projection controller is configured with: A sensing unit, used to obtain the three-dimensional position information detected by the posture sensor and determine whether the three-dimensional position information has changed; A projection control unit, used to control the projection unit to project a correction image when the three-dimensional position information changes; A primary correction unit, used for obtaining a first deflection angle, a second deflection angle and / or a third deflection angle of the projection device according to the three-dimensional position information and the initial position information; determining a first pixel offset, a second pixel offset and / or a third pixel offset based on the first deflection angle, the second deflection angle and / or the third deflection angle; wherein the first deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis, the second deflection angle is an angle at which the projection device deflects relative to the initial position with the Y-coordinate axis as the rotation axis, and the third deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis; A secondary correction unit, configured to obtain a pixel offset correction value by using a compensation model constructed based on the deflection angle and the pixel offset, and to compensate the first pixel offset, the second pixel offset and / or the third pixel offset by using the pixel offset correction value; A tertiary correction unit is used to obtain the pixel coordinates of the projection screen border after the projection control unit controls the projection unit to use the compensated first pixel offset, second pixel offset and / or third pixel offset to correct the correction image into a rectangular projection image, and obtain the corrected projection coordinates based on the pixel coordinates of the projection screen border and the pixel coordinates of the rectangular projection image, so that the projection control unit uses the corrected projection coordinates to correct the projection image to be projected.

[0015] In some embodiments of the present invention, the projection device further includes: a calibration unit, for fitting the first data group, the second data group and the third data group into a first polynomial, a second polynomial and a third polynomial respectively, to obtain a corresponding relationship between a first deflection angle and a first pixel offset in the X-axis direction, a corresponding relationship between a second deflection angle and a second pixel offset in the Y-axis direction, and a corresponding relationship between a third deflection angle and a third pixel offset in the Z-axis direction; Among them, the X-axis, Y-axis and Z-axis are used to establish a three-dimensional coordinate system with the center of the projection device as the origin; the first data group is a data group for obtaining pixel offsets at different deflection angles with the X-axis as the rotation axis; the second data group is a data group for obtaining pixel offsets at different deflection angles with the Y-axis as the rotation axis; the third data group is a data group for obtaining pixel offsets at different deflection angles with the Z-axis as the rotation axis.

[0016] In some embodiments of the present invention, the projection device further includes: The compensation calibration unit is used to obtain a compensation data set of the relationship between the deflection angle and the pixel offset at three angles of XYZ; establish a polynomial regression model based on the compensation data set; use the least squares method to solve the regression coefficient of the polynomial regression model; and bring the regression coefficient into the polynomial regression model to obtain the compensation model.

[0017] In some embodiments of the present invention, the projection controller further includes: The rectangle correction judgment unit is used to judge the deviation between the corrected image and the standard rectangle after the first correction and the second correction, and repeat the first correction and the second correction when the deviation is greater than a threshold until the corrected image is a rectangular projection image.

[0018] In some embodiments of the present invention, the tertiary correction unit corrects the projection image to be projected in the following manner: Get the pixel coordinates of the four vertices of the projection screen border and the pixel coordinates of the four vertices of the rectangular projection image; use Get the corrected projection coordinates; , To correct the projection coordinates, and is the offset of the pixel coordinates of the vertices of the rectangular projection image relative to the pixel coordinates of the vertices of the projection screen border in the x direction and the y direction; x and y are the pixel coordinates of the vertices of the rectangular projection image; Wherein, the projection screen frame is calibrated by fluorescent material.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the projection device proposed in the present invention, when the position of the projection device is offset, uses the relationship between the deflection angle and the pixel offset to first correct the correction image into a rectangular projection image, and then corrects the rectangular projection image onto the projection screen, so that the projection device that has been offset can be normally projected on the projection screen without adjusting the position, thereby ensuring the viewing effect and reducing the user's operation difficulty; and in the projection device proposed in the present invention, the attitude sensor adopts tof (time of flight sensor), the calculation accuracy of which can reach the millisecond level, and the speed can reach the hundred frames per second level, which can improve the accuracy and speed of the correction algorithm; the frame of the projection screen is calibrated with fluorescent material, the fluorescent frame is clear, and it is easy to improve the calibration accuracy of the four vertices of the projection screen, thereby improving the algorithm's correction accuracy for the distorted projection image.

[0020] Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 The following is a schematic diagram of the steps of the projection geometry correction method proposed by the present invention; Figure 2 It is a diagram of the three-dimensional coordinate system established in the geometric correction of the present invention; Figure 3 It is a diagram showing the angle deflection of the projection device with the X axis as the rotation axis in the geometric correction of the present invention; Figure 4 It is a diagram showing the angular deflection of the projection device with the Y axis as the rotation axis in the geometric correction of the present invention; Figure 5 It is a diagram showing the angular deflection of the projection device with the Z axis as the rotation axis in the geometric correction of the present invention; Figure 6 The following is a schematic diagram of the steps of the projection geometry correction method proposed by the present invention; Figure 7It is a diagram showing that the correction image in the geometric correction of the present invention is distorted due to the change in the position of the projection device; Figure 8 A rectangular corrected image obtained by the projection geometry correction method provided by the present invention; Fig. 9 for Figure 8 An example of projection after the third correction of the embodiment shown; Fig.10 The figure is a schematic diagram of the functional structure of the projection device proposed in the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The present invention aims to propose a projection geometry correction method, which does not require a position correction device to be configured for a projection device. When the position of the projection device is offset and the projection picture is distorted, the projection picture can be projected onto the projection screen without distortion through the geometry correction method, without manually adjusting the position of the projection device.

[0025] The present invention will now explain in detail the projection geometry correction method by taking an ultra-short-throw laser television as an example of a projection device.

[0026] The first step is to obtain and model the data for the projection geometry correction, such as Figure 1 As shown, the following steps are included: S1: Establish a three-dimensional coordinate system with the center of the projection device as the origin.

[0027] A three-dimensional coordinate system is established with the center of the laser TV as the coordinate origin, such as Figure 2 As shown, the horizontal direction is the X-axis, the front-to-back direction is the Y-axis, and the vertical direction is the Z-axis.

[0028] A quadrilateral is used to represent the projection area of ​​the laser TV. When the laser TV is projecting forward, the projected image is a standard rectangle. When the laser TV is deflected, the X, Y and / or Z axes will deviate from the original reference position, causing the laser TV to shift at an angle on the X, Y and / or Z axes. The projected image will be distorted from the original rectangle to an irregular quadrilateral.

[0029] S2: Calibration: Using the X, Y and Z axes as rotation axes, obtain pixel offsets at different deflection angles, and establish a deflection angle and pixel offset data set.

[0030] During the calibration process (pixel offset data measurement), the X, Y and Z axes are used as the rotation axes to rotate the angles. When rotating with the X axis as the axis, the laser TV deflects relative to the Y and Z axes. When rotating with the Y axis as the axis, the laser TV deflects relative to the X and Z axes. When rotating with the Z axis as the axis, the laser TV deflects relative to the X and Y axes. The angle information mentioned later is the angle information in the XYZ three-axis direction obtained based on the change of three-dimensional coordinates.

[0031] (1) Taking the X-axis as the rotation axis, obtain a first data set of pixel offsets at different deflection angles.

[0032] like Figure 3 As shown, with the X axis as the rotation axis, between -10º and 10º ("-" represents counterclockwise rotation, and no sign represents clockwise rotation), more than ten groups of angles are changed at any deflection angle. When the angle is changed each time, the pixel offset of the projection image relative to the standard rectangular projection is recorded to obtain the first data group: [( 1,(x1,y1)), ( 2, (x2, y2))……( i,(xi,yi))……( n,(xn,yn))], where i is the angle of deflection with the X axis as the rotation axis, (xi,yi) is the corresponding pixel offset, and n is the marking amount.

[0033] (2) Taking the Y axis as the rotation axis, obtain a second data set of pixel offsets at different deflection angles.

[0034] Similarly, if Figure 4 As shown, with the Y axis as the rotation axis, between -10º and 10º ("-" represents counterclockwise rotation, and no sign represents clockwise rotation), more than ten groups of angles are changed at any deflection angle. When the angle changes each time, the pixel offset of the projection image relative to the standard rectangular projection is recorded to obtain the second data group: [( 1,(x1,y1)), ( 2, (x2, y2))……( i,(xi,yi))……( m,(xm,ym))], where i is the angle of deflection with the Y axis as the rotation axis, (xi,yi) is the corresponding pixel offset, and m is the marking amount.

[0035] (3) Taking the Z axis as the rotation axis, obtain a first data set of pixel offsets at different deflection angles.

[0036] Similarly, if Figure 5As shown, with the Z axis as the rotation axis, between -10º and 10º ("-" represents counterclockwise rotation, and no sign represents clockwise rotation), more than ten groups of angles are changed at any deflection angle. When the angle is changed each time, the pixel offset of the projection image relative to the standard rectangular projection is recorded to obtain the third data group: [( 1,(x1,y1)), ( 2, (x2, y2))……( i,(xi,yi))……( q, (xq, yq))], where i is the angle of deflection with the Z axis as the rotation axis, (xi,yi) is the corresponding pixel offset, and q is the marking amount.

[0037] S3: The calibration function is obtained by fitting the labeled data.

[0038] (1) Fit the first data set to a first polynomial to obtain the corresponding relationship between the first deflection angle on the X-axis and the first pixel offset:

[0039] ;in, are the polynomial coefficients, is the pixel offset.

[0040] (2) Fitting the second data set to a second polynomial to obtain a corresponding relationship between a second deflection angle on the Y-axis and a second pixel offset.

[0041] ;in, are the polynomial coefficients, is the pixel offset.

[0042] (3) Fitting the third data group to a third polynomial to obtain a corresponding relationship between a third deflection angle on the Z axis and a third pixel offset.

[0043] ;in, are the polynomial coefficients, is the pixel offset.

[0044] As mentioned above, the distance data (d1, d2, d3, d4) of the laser TV from the four vertices of the projection screen are obtained through the tof (time of flight) sensor, and each distance d is converted into a three-dimensional coordinate (x, y, z). By calculating the direction vector of the measuring point relative to the sensor, the geometric relationship between the vectors is found, and the angle information is calculated using trigonometric functions.

[0045] S4: Compensation calibration.

[0046] In practical applications, the deflection in the three directions of X, Y, and Z is not always a single change. When deflection occurs in two or three directions at the same time, , and The corresponding offsets at the three angles affect each other. This step aims to compensate for the offsets that affect each other, thereby eliminating the influence between them and better improving the correction effect.

[0047] include: (1) Obtain a compensation data set of the relationship between the deflection angle and the pixel offset at three angles of XYZ.

[0048] Randomly generate multiple deflections at three angles at the same time, XYZ, and record the pixel offsets at different angles: ;in, It is data points, ( ) is the corresponding pixel offset.

[0049] (2) Establish a polynomial regression model based on the compensated data set.

[0050] Assuming that a polynomial model of order p is used, taking the X direction of the pixel coordinate system as an example, the pixel offset It can be expressed as:

[0051] ;in, is the regression coefficient, is the order of the polynomial and the index of the interaction term, representing the power of each variable in the polynomial. Specifically: is with The relevant power, The number of times it appears in the polynomial; is with The relevant power, The number of occurrences in the polynomial; is with The relevant power, The number of times a polynomial appears.

[0052] Refer to the X direction, and establish the pixel offset in the Y direction in the same way .

[0053] (3) Use the least squares method to solve the regression coefficients of the polynomial regression model.

[0054] Assuming that the design matrix in the least squares solution process is (X) and the offset vector is (y), the regression coefficient (using b as an example) can be obtained by the following formula:

[0055]

[0056] The construction of the design matrix involves converting the input feature (the deflection angle in the present invention) )、( )、( )) and their interaction terms) were converted into matrix form for regression analysis.

[0057] (4) Substitute the regression coefficients into the polynomial regression model to obtain the compensation model.

[0058] All regression coefficients are calculated according to different offset vectors and brought into the constructed polynomial model to eliminate the offset errors caused by mutual influence in the three directions.

[0059] After the data relationship between the position change of the projection device and the corresponding pixel offset is obtained through data collection, fitting and modeling, the data is stored in the storage unit.

[0060] When the projection equipment is in use, Figure 6 As shown, geometric correction is performed according to the following steps.

[0061] S21: Acquire the three-dimensional position information detected by the posture sensor, and determine whether the position of the projection device has changed.

[0062] If the three-dimensional position has not changed, projection can be performed according to the normal projection steps. If the three-dimensional position has changed, step S22 is executed.

[0063] S22: Project the correction image.

[0064] Corrected image as Figure 7 The checkerboard-format correction image is shown. When the checkerboard correction image is projected onto the projection screen, an irregular checkerboard image will appear.

[0065] S23: Obtaining a first deflection angle, a second deflection angle and / or a third deflection angle of the projection device according to the three-dimensional position information and the initial position information.

[0066] The first deflection angle is the angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis, the second deflection angle is the angle at which the projection device deflects relative to the initial position with the Y-coordinate axis as the rotation axis, and the third deflection angle is the angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis. The initial position information is the position at which the projection device can project normally.

[0067] One, two or three of the first deflection angle, the second deflection angle and the third deflection angle may exist at the same time. For example, when the projection device deflects at an angle only with Z as the rotation axis, only the third deflection angle occurs accordingly.

[0068] The attitude sensor is installed at the center of the projection device. Take the TOF sensor as an example, take it as the origin of the coordinate system, first obtain the four distance data D1, D2, D3, and D4 of the four vertices in the distance diagram at the initial projection position of the normal projection, and then convert each distance d into a three-dimensional coordinate and store it. When the position of the projection device changes, by calculating the direction vector of each measurement point relative to the sensor, find the geometric relationship between the vectors and the trigonometric function to calculate the deflection angle. Figure 7 As shown, the green fluorescent frame is the projection screen, the black and white checkerboard is the projection area, the red origin is the array projected by the tof sensor at the initial projection position of normal projection, and the red area is the area where the distorted image needs to be corrected.

[0069] S24: Determine a first pixel offset, a second pixel offset and / or a third pixel offset based on the first deflection angle, the second deflection angle and the third deflection angle.

[0070] The correction function obtained in step S3 is called from the storage unit, and the deflection angle is substituted into the function to obtain the pixel offset. For example, when the projection device deflects with the Z axis as the rotation axis, the correction function corresponding to the Z axis is called, and the third deflection angle is substituted to obtain the third pixel offset.

[0071] S25: using a compensation model constructed based on the deflection angle and the pixel offset to obtain a pixel offset correction value, and using the pixel offset correction value to compensate for the first pixel offset, the second pixel offset and / or the third pixel offset.

[0072] Call the constructed polynomial model, substitute the first deflection angle, the second deflection angle and / or the third deflection angle to obtain a pixel offset correction value, and use the pixel offset correction value to compensate the first pixel offset, the second pixel offset and / or the third pixel offset obtained in step S24 to obtain compensation data.

[0073] S26: Correct the corrected image into a rectangular projection image using the compensated first pixel offset, second pixel offset and / or third pixel offset.

[0074] like Figure 8 Shown is a checkerboard image corrected to a rectangle.

[0075] S27: Obtain pixel coordinates of the projection screen border, and obtain corrected projection coordinates based on the pixel coordinates of the projection screen border and the pixel coordinates of the rectangular projection image.

[0076] In an embodiment of the present invention, fluorescent material is arranged on the frame of the projection screen to form a fluorescent frame. After the distorted image is corrected into a rectangular projection image, the projection area is photographed by a camera to obtain an image including the fluorescent frame.

[0077] In an embodiment of the present invention, before calculating the corrected projection coordinates, it is possible to determine whether the corrected image is a standard rectangle through the captured image, that is, to compare it with the standard rectangle to obtain the deviation between the two. When the deviation is large, the above correction steps are repeated until the corrected rectangular projection image meets the standard rectangle requirements.

[0078] from Figure 8 It can be seen from the figure that after the rectangular correction, the projection area is still outside the projection screen frame and needs to be constrained within the projection screen frame. The present invention can simply and quickly determine the pixel coordinates of the screen frame by detecting the fluorescent frame, calculate the coordinates of the four vertices according to the pixel coordinates of the frame, and calculate the pixel coordinates of the four vertices of the rectangular projection image according to the captured image.

[0079]

[0080] Get the corrected projection coordinates; , To correct the projection coordinates, and is the offset of the pixel coordinates of the vertices of the rectangular projection image relative to the pixel coordinates of the vertices of the projection screen border in the x direction and the y direction, which is calculated according to the coordinates of the four vertices of the fluorescent border and the coordinates of the four vertices of the rectangular projection image; x and y are the pixel coordinates of the vertices of the rectangular projection image.

[0081] The camera can be used to shoot again to determine whether the calibrated projection image has entered the projection screen. If not, the coordinate calculation is repeated.

[0082] S28: Correct the projection image to be projected using the corrected projection coordinates.

[0083] The image file to be projected is written into the display control chip of the projection device. The projection controller controls the display control chip of the device to complete the calibration according to the above steps. The calibrated projection is as follows: Fig. 9 shown.

[0084] Based on the above projection geometry correction method, the present invention also proposes a projection device, such as Fig.10 As shown, including:

[0085] The posture sensor 1 is used to obtain the three-dimensional position information of the projection device.

[0086] The projection unit 2 is controlled by the projection controller 3 and projects the image to be projected onto the projection screen 4 .

[0087] The projection controller is configured with:

[0088] The sensing unit 31 is used to obtain the three-dimensional position information detected by the posture sensor 1 and determine whether the three-dimensional position information has changed.

[0089] The projection control unit 32 is used to control the projection unit 2 to project the correction image when the three-dimensional position information changes.

[0090] The primary correction unit 33 is used to obtain a first deflection angle, a second deflection angle and / or a third deflection angle of the projection device according to the three-dimensional position information and the initial position information; determine a first pixel offset, a second pixel offset and / or a third pixel offset based on the first deflection angle, the second deflection angle and / or the third deflection angle; wherein the first deflection angle is an angle at which the projection device is deflected relative to the initial position with the X-coordinate axis as the rotation axis, the second deflection angle is an angle at which the projection device is deflected relative to the initial position with the Y-coordinate axis as the rotation axis, and the third deflection angle is an angle at which the projection device is deflected relative to the initial position with the X-coordinate axis as the rotation axis.

[0091] The secondary correction unit 34 is used to obtain a pixel offset correction value using a compensation model constructed based on the deflection angle and the pixel offset, and to compensate the first pixel offset, the second pixel offset and / or the third pixel offset using the pixel offset correction value.

[0092] The rectangle correction judgment unit 35 is used to judge the deviation between the corrected image and the standard rectangle after the primary correction and the secondary correction, and repeat the primary correction and the secondary correction when the deviation is greater than a threshold until the corrected image is a rectangular projection image.

[0093] The tertiary correction unit 36 ​​is used to obtain the pixel coordinates of the projection screen border after the projection control unit controls the projection unit to use the compensated first pixel offset, second pixel offset and / or third pixel offset to correct the correction image into a rectangular projection image, and obtain the corrected projection coordinates based on the pixel coordinates of the projection screen border and the pixel coordinates of the rectangular projection image, so that the projection control unit uses the corrected projection coordinates to correct the projection image to be projected. In the embodiment of the present invention, the tertiary correction unit corrects the projection image to be projected in the following manner: obtain the pixel coordinates of the four vertices of the projection screen border and the pixel coordinates of the four vertices of the rectangular projection image; use Get the corrected projection coordinates; , To correct the projection coordinates, and is the offset of the pixel coordinates of the vertices of the rectangular projection image relative to the pixel coordinates of the vertices of the projection screen border in the x direction and the y direction; x and y are the pixel coordinates of the vertices of the rectangular projection image; wherein the projection screen border is calibrated with fluorescent material.

[0094] The projection device also includes: The calibration unit 5 is used to fit the first data group, the second data group and the third data group into the first polynomial, the second polynomial and the third polynomial respectively, to obtain the corresponding relationship between the first deflection angle and the first pixel offset in the X-axis direction, the corresponding relationship between the second deflection angle and the second pixel offset in the Y-direction, and the corresponding relationship between the third deflection angle and the third pixel offset in the Z-direction; wherein the X-axis, the Y-axis and the Z-axis are three-dimensional coordinate systems established with the center of the projection device as the origin; the first data group is a data group with the X-axis as the rotation axis, and the pixel offset at different deflection angles is obtained; the second data group is a data group with the Y-axis as the rotation axis, and the pixel offset at different deflection angles is obtained; the third data group is a data group with the Z-axis as the rotation axis, and the pixel offset at different deflection angles is obtained.

[0095] The compensation calibration unit 6 is used to obtain a compensation data set of the relationship between the deflection angle and the pixel offset at three angles of XYZ; establish a polynomial regression model based on the compensation data set; use the least squares method to solve the regression coefficient of the polynomial regression model; and bring the regression coefficient into the polynomial regression model to obtain a compensation model.

[0096] According to the projection geometry correction method given above, when the position of the projection device is offset, the relationship between the deflection angle and the pixel offset is used to first correct the correction image into a rectangular projection image, and then the rectangular projection image is corrected onto the projection screen, so that the projection device that has been offset can be normally projected on the projection screen without adjusting its position, thereby ensuring the viewing effect and reducing the user's operating difficulty; and in the projection device proposed by the present invention, the attitude sensor adopts tof (time of flight sensor), the calculation accuracy of which can reach the millisecond level, and the speed can reach the hundred frames per second level, which can improve the accuracy and speed of the correction algorithm; the frame of the projection screen is calibrated with fluorescent material, the fluorescent frame is clear, and it is easy to improve the calibration accuracy of the four vertices of the projection screen, thereby improving the correction accuracy of the algorithm for the distorted projection image.

[0097] It should be noted that, in the specific implementation process, part of the above-mentioned method can be implemented by a hardware processor executing computer execution instructions in software form stored in a memory, which will not be elaborated here, and the programs corresponding to the actions executed can be stored in the computer-readable storage device of the system in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0098] The computer-readable storage device mentioned above may include a volatile memory, such as a random access memory; it may also include a non-volatile memory, such as a read-only memory, a flash memory, a hard disk or a solid-state drive; it may also include a combination of the above types of memory.

[0099] The processor mentioned above may also be a general term for multiple processing elements. For example, the processor may be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, field programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc., or may be a dedicated processor.

[0100] It should be pointed out that the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A projection geometry correction method, applied to a projection device, wherein the projection device is configured with: A posture sensor, used to obtain the three-dimensional position information of the projection device; It is characterized in that Correction methods include: Get the three-dimensional position information detected by the attitude sensor; when the three-dimensional position information changes, perform the following steps: Projection correction image; Primary calibration: obtaining a first deflection angle, a second deflection angle and / or a third deflection angle of the projection device according to the three-dimensional position information and the initial position information; determining a first pixel offset, a second pixel offset and / or a third pixel offset based on the first deflection angle, the second deflection angle and / or the third deflection angle; wherein the first deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis, the second deflection angle is an angle at which the projection device deflects relative to the initial position with the Y-coordinate axis as the rotation axis, and the third deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis; Secondary correction: using a compensation model constructed based on the deflection angle and the pixel offset to obtain a pixel offset correction value, and using the pixel offset correction value to compensate for the first pixel offset, the second pixel offset and / or the third pixel offset; Correcting the corrected image into a rectangular projection image using the compensated first pixel offset, second pixel offset and / or third pixel offset; Three corrections: obtaining the pixel coordinates of the projection screen border, and obtaining the corrected projection coordinates based on the pixel coordinates of the projection screen border and the pixel coordinates of the rectangular projection image; The projection image to be projected is corrected using the corrected projection coordinates.

2. The projection geometry correction method according to claim 1, characterized in that: The method further comprises a calibration step, comprising: Establish a three-dimensional coordinate system with the center of the projection device as the origin; Taking the X axis as the rotation axis, obtaining a first data set of pixel offsets at different deflection angles; Taking the Y axis as the rotation axis, obtaining a second data set of pixel offsets at different deflection angles; Taking the Z axis as the rotation axis, obtaining a third data set of pixel offsets at different deflection angles; The first data group, the second data group and the third data group are respectively fitted into a first polynomial, a second polynomial and a third polynomial to obtain a corresponding relationship between a first deflection angle and a first pixel offset in the X-axis direction, a corresponding relationship between a second deflection angle and a second pixel offset in the Y-direction, and a corresponding relationship between a third deflection angle and a third pixel offset in the Z-direction.

3. The projection geometry correction method according to claim 2, characterized in that: The method further comprises the step of compensation calibration, comprising: Obtaining a compensation data set of the relationship between the deflection angle and the pixel offset at three angles of XYZ; A polynomial regression model is established based on the compensation data set; Solve for the regression coefficients of the polynomial regression model using the least squares method; Substituting the regression coefficients into the polynomial regression model, the compensation model is obtained.

4. The projection geometry correction method according to claim 1, characterized in that: Before step S5, the method further includes: The deviation between the corrected image and the standard rectangle is determined, and when the deviation is greater than a threshold, steps S2 to S4 are repeated until the corrected image is a rectangular projection image.

5. The projection geometry correction method according to claim 1, characterized in that: Step S5 specifically includes: Get the pixel coordinates of the four vertices of the projection screen border and the pixel coordinates of the four vertices of the rectangular projection image; use Get the corrected projection coordinates; where x ′ ,y ′ To correct the projection coordinates, Δx and Δy are the offsets of the pixel coordinates of the vertices of the rectangular projection image relative to the pixel coordinates of the vertices of the projection screen border in the x direction and the y direction; x and y are the pixel coordinates of the vertices of the rectangular projection image.

6. A projection device, comprising: A posture sensor, used to obtain the three-dimensional position information of the projection device; The projection unit is controlled by the projection controller and projects the image to be projected onto the projection screen; It is characterized in that The projection controller is configured with: A sensing unit, used to obtain the three-dimensional position information detected by the posture sensor and determine whether the three-dimensional position information has changed; A projection control unit, used to control the projection unit to project a correction image when the three-dimensional position information changes; A primary correction unit, used for obtaining a first deflection angle, a second deflection angle and / or a third deflection angle of the projection device according to the three-dimensional position information and the initial position information; determining a first pixel offset, a second pixel offset and / or a third pixel offset based on the first deflection angle, the second deflection angle and / or the third deflection angle; wherein the first deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis, the second deflection angle is an angle at which the projection device deflects relative to the initial position with the Y-coordinate axis as the rotation axis, and the third deflection angle is an angle at which the projection device deflects relative to the initial position with the X-coordinate axis as the rotation axis; A secondary correction unit, configured to obtain a pixel offset correction value by using a compensation model constructed based on the deflection angle and the pixel offset, and to compensate the first pixel offset, the second pixel offset and / or the third pixel offset by using the pixel offset correction value; A tertiary correction unit is used to obtain the pixel coordinates of the projection screen border after the projection control unit controls the projection unit to use the compensated first pixel offset, second pixel offset and / or third pixel offset to correct the correction image into a rectangular projection image, and obtain the corrected projection coordinates based on the pixel coordinates of the projection screen border and the pixel coordinates of the rectangular projection image, so that the projection control unit uses the corrected projection coordinates to correct the projection image to be projected.

7. The projection device according to claim 6, characterized in that: The projection device also includes: a calibration unit, for fitting the first data group, the second data group and the third data group into a first polynomial, a second polynomial and a third polynomial respectively, to obtain a corresponding relationship between a first deflection angle and a first pixel offset in the X-axis direction, a corresponding relationship between a second deflection angle and a second pixel offset in the Y-axis direction, and a corresponding relationship between a third deflection angle and a third pixel offset in the Z-axis direction; Among them, the X-axis, Y-axis and Z-axis are used to establish a three-dimensional coordinate system with the center of the projection device as the origin; the first data group is a data group for obtaining pixel offsets at different deflection angles with the X-axis as the rotation axis; the second data group is a data group for obtaining pixel offsets at different deflection angles with the Y-axis as the rotation axis; the third data group is a data group for obtaining pixel offsets at different deflection angles with the Z-axis as the rotation axis.

8. The projection device according to claim 7, characterized in that: The projection device also includes: The compensation calibration unit is used to obtain a compensation data set of the relationship between the deflection angle and the pixel offset at three angles of XYZ; establish a polynomial regression model based on the compensation data set; use the least squares method to solve the regression coefficient of the polynomial regression model; and bring the regression coefficient into the polynomial regression model to obtain the compensation model.

9. The projection device according to claim 6, characterized in that: The projection controller also includes: The rectangle correction judgment unit is used to judge the deviation between the corrected image and the standard rectangle after the first correction and the second correction, and repeat the first correction and the second correction when the deviation is greater than a threshold until the corrected image is a rectangular projection image.

10. The projection device according to claim 6, characterized in that: The three-time correction unit corrects the projection image to be projected in the following manner: Get the pixel coordinates of the four vertices of the projection screen border and the pixel coordinates of the four vertices of the rectangular projection image; use Get the corrected projection coordinates; where x ′ ,y ′ To correct the projection coordinates, Δx and Δy are the offsets of the pixel coordinates of the vertices of the rectangular projection image relative to the pixel coordinates of the vertices of the projection screen border in the x direction and the y direction; x and y are the pixel coordinates of the vertices of the rectangular projection image; Wherein, the projection screen frame is calibrated by fluorescent material.

Images