WO2019056219A1 - Procédé de correction horizontale de trapèze de projecteur - Google Patents

Procédé de correction horizontale de trapèze de projecteur Download PDF

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Publication number
WO2019056219A1
WO2019056219A1 PCT/CN2017/102490 CN2017102490W WO2019056219A1 WO 2019056219 A1 WO2019056219 A1 WO 2019056219A1 CN 2017102490 W CN2017102490 W CN 2017102490W WO 2019056219 A1 WO2019056219 A1 WO 2019056219A1
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WIPO (PCT)
Prior art keywords
projection
imaging
unit
projector
point
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PCT/CN2017/102490
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English (en)
Chinese (zh)
Inventor
那庆林
麦浩晃
黄彦
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神画科技（深圳）有限公司
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Priority to PCT/CN2017/102490 priority Critical patent/WO2019056219A1/fr
Publication of WO2019056219A1 publication Critical patent/WO2019056219A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]

Definitions

  • the present invention relates to the field of projection technology, and in particular, to a projection image correction technique.
  • the projected image of the projector will exhibit varying degrees of deformation depending on the change in the angle of deflection of the projector relative to the projection plane.
  • the projected image is a standard rectangle; when the optical axis of the projector projection lens is not perpendicular to the projection plane, the optical axis and the projection plane are up and down, or left and right, or up and down
  • the angle of the direction is not a right angle. Therefore, the projected image has a vertical trapezoid as shown in Figure 1), or the left and right trapezoids are as shown in Figure 1 (b), or an irregular quadrilateral. You need to manually adjust the placement of the projector.
  • the optical axis of the projector projection lens is made as perpendicular as possible to the projection screen to improve the deformation of the projected image and obtain a satisfactory image.
  • the manual adjustment of the projector's placement state is not convenient in some application scenarios, and the adjustment is cumbersome, and the adjustment effect is flawed and cannot reach the optimal state.
  • the Chinese invention patent publication No. C N1823523B discloses a method for obtaining a tilt angle of a projection device. The method senses a different point on a projection plane from a distance sensor disposed inside the projection device, and obtains a tilt of the projection device according to the distance. Angle, although the method can correct the left and right trapezoids of the projected image, the distance sensor suitable for the method is expensive and has low practical value. Therefore, there is still no ideal solution for the correction of the left and right ladders of the projector.
  • the technical problem to be solved by the present invention is to provide a correction method for realizing the automatic correction of the left and right trapezoidal deformation of the projected image of the projector in view of the above-mentioned drawbacks of the prior art.
  • the technical problem to be further solved by the present invention is to provide a correction method for the above-mentioned defects of the prior art, which can make the projector achieve lower cost and more practical value for correcting the left and right trapezoids.
  • the present invention provides a left and right trapezoidal correction method for a projector, including the steps of:
  • the step of acquiring the ladder correction parameter according to the actual imaging coordinates of the preset calibration point on the imaging chip of the monitoring unit includes:
  • the mathematical relationship is established by a similar triangle principle, the mathematical relationship further includes coordinates of the preset calibration point in the space coordinate system, and the coordinates are calculated according to the mathematical relationship, according to the The coordinates acquire the trapezoidal correction parameters.
  • the mathematical relationship is established based on a direction vector of the projection light of the projection unit, and the establishing includes the real imaging coordinate of the preset calibration point on the imaging chip of the monitoring unit, and the preset calibration point pre-
  • the steps of setting the value and the mathematical relationship of the projector system parameters include:
  • the projection unit projects a direction vector of the preset calibration point, and obtains the preset calibration point according to the direction vector in the space coordinate system.
  • Vector parameter equation
  • the projector system parameters include a projection unit internal parameter, a monitoring unit internal parameter, and a relative position of the projection unit and the monitoring unit.
  • the preset calibration point includes multiple groups, and the method further includes:
  • the method further includes:
  • the preset calibration point corresponds to a position of the reference calibration point on the projection unit display chip.
  • the step of acquiring the trapezoidal correction parameters according to the actual imaging coordinates of the preset calibration point on the imaging chip of the monitoring unit comprises:
  • the database is a database of mapping relationship between imaging coordinates of each reference calibration point on the imaging chip of the monitoring unit and projection state parameters of the projector;
  • the projector state includes a projection distance of the projector and a deflection angle of the projector;
  • the projector state parameter is a distance from a principal point of the projection unit lens model to a virtual plane where the reference calibration point is located.
  • the database is a database of mapping relationship between imaging coordinates of the reference calibration point group on the imaging chip of the monitoring unit and projection state parameters of the projector;
  • the projector state includes a projection distance of the projector and a deflection angle of the projector;
  • the projector state parameter is a deflection angle of the projection unit optical axis with respect to the projection display surface.
  • the projector state includes a projector projection distance and a projector deflection angle
  • the machine state parameter includes a distance from a principal point of the projection unit lens model to a virtual plane where the reference calibration point is located and a deflection angle of the projection unit optical axis relative to the projection display surface.
  • the step of establishing a mapping relationship between the imaging coordinates of the reference calibration point on the imaging chip of the monitoring unit and the projection state parameter of the projector includes:
  • the set of preset calibration points and the set of reference calibration points respectively comprise two points, and the database is obtained by searching a database of real imaging coordinates on the imaging chip of the monitoring unit according to the preset calibration point.
  • the steps of the projection state parameters corresponding to the real imaging coordinates include:
  • the trapezoidal correction parameter comprises: a right and left deflection angle of the optical axis of the projection unit with respect to the projection display surface.
  • the trapezoidal correction parameter further includes: a coordinate position of the four vertices after the geometric deformation of the projection image on the display unit of the projection unit, the coordinate position is based on a triangular formula, according to the optical axis of the projection unit relative to the projection display surface The left and right deflection angles and the pixel width of the projection unit display chip are calculated.
  • the trapezoidal correction parameter further includes: a projection unit displaying a perspective transformation coefficient of the screen deformation on the chip, the perspective transformation coefficient being solved according to the coordinate position of the four vertices after the geometric distortion of the projection image on the display unit of the projection unit The point corresponds to the equation.
  • the trapezoidal correction parameter further includes: a projection unit displays a point mapping table of the screen deformation on the chip, and the point mapping table is obtained according to a point correspondence equation of the known perspective transformation coefficient.
  • step of projecting at least one set of preset calibration points to the projection display surface by the projection unit Also included before:
  • the preset calibration point corresponds to a position of the reference calibration point on the projection unit display chip.
  • the step of acquiring the ladder correction parameter according to the actual imaging coordinates of the preset calibration point on the imaging chip of the monitoring unit includes:
  • the trapezoidal correction parameter comprises: a coordinate position of the four vertices after the geometric deformation of the projection image on the display unit of the projection unit or a perspective transformation coefficient of the deformation of the screen on the projection unit display chip or a picture on the display unit of the projection unit Deformed point mapping table.
  • the set of preset calibration points and the set of reference calibration points respectively comprise two points, two preset calibration points in the same group or two reference calibration points in the same group are respectively located
  • the projection display surface is within 1/3 of the boundary between the left and right sides.
  • the present invention projects a preset calibration point by the projection unit, the monitoring unit captures the calibration point, and obtains a trapezoidal correction parameter according to the actual position of the calibration point on the imaging chip of the monitoring unit, the calibration point preset value, and the system parameters of the projector. Or pre-establishing a mapping relationship between the position of the reference calibration point on the imaging chip of the monitoring unit and the projection state parameter, and searching for the corresponding projection state parameter according to the actual position on the imaging chip of the monitoring unit corresponding to the preset calibration point, The trapezoidal correction parameter is determined according to the projection state parameter, and finally the image is geometrically deformed by the trapezoidal correction parameter to correct the projected image.
  • the projection image can be automatically adjusted without manual adjustment of the position of the projector, and the adjustment process is more convenient and quick, thereby improving the comfort of the user experience.
  • the monitoring lens used to implement the method is much less expensive than the existing distance sensor, making the projector more competitive in the market.
  • FIG. 1 (a), (b) is a schematic diagram of projection image projection of the projector
  • FIG. 2 is a schematic structural view of a projector of the present invention
  • 3(a) and 3(b) are schematic views showing a first embodiment of the present invention.
  • FIG. 4 is a schematic view of a second embodiment of the present invention.
  • Figure 5 is a schematic view of a third embodiment of the present invention.
  • FIG. 6 is a schematic view of a fourth embodiment of the present invention.
  • 7(a), 7(b), 7(c), 7(d), 7(e), 7(f) are schematic views of a fifth embodiment of the present invention.
  • FIG. 8 is a schematic view of a sixth embodiment of the present invention.
  • 9(a) and 9(b) are schematic views showing a seventh embodiment of the present invention.
  • FIG. 10 is a schematic diagram showing the positional transformation of the left and right trapezoidal correction ⁇ calibration point in the first embodiment of the present invention.
  • the projector of the present invention includes a projection unit 10 for projecting a picture, a monitoring unit 20 for capturing a projection picture, wherein the projection unit 10 includes a projection lens 11 and a display chip 12, and a monitoring unit 20 includes a monitoring lens 21 and an imaging chip 22, the projector further includes an image recognition unit 30 for reading an imaged position of the image captured by the monitoring unit 20 on the imaging chip 22 thereof, and a trapezoidal correction unit for correcting the projected image 40.
  • the method for left and right trapezoidal correction of the projector includes the following steps:
  • [0069] projecting a set of preset calibration points to the projection display surface by the projection unit, that is, projecting a point of the selected position on the projection unit display chip to the projection screen; and adopting the monitoring unit to capture the calibration point on the projection display surface
  • the image recognition unit reads the real imaging coordinates of the calibration point on the imaging chip of the monitoring unit; and obtains a trapezoidal correction parameter according to the actual imaging coordinate of the calibration point on the imaging chip of the monitoring unit; the trapezoidal correction unit according to the trapezoidal correction parameter
  • the projected image is subjected to a corresponding geometric deformation such that the image distortion of the final projection on the projection screen is corrected.
  • multiple sets of preset calibration points may be projected, and a trapezoidal correction parameter is respectively obtained according to the actual imaging coordinates of each set of preset calibration points, and then an average value is obtained for the plurality of trapezoidal correction parameters.
  • the final trapezoidal correction parameters are respectively obtained according to the actual imaging coordinates of each set of preset calibration points, and then an average value is obtained for the plurality of trapezoidal correction parameters.
  • Each set of preset calibration points includes two points, and the larger the distance between the two calibration points in the left-right direction, the smaller the error of the obtained trapezoidal correction parameters, the higher the correction precision, therefore, the two calibration points
  • the position is at the left and right borders of the projection display surface or as close as possible to the two boundaries.
  • the projection display surface is the projection screen ⁇
  • the long side of the projection screen will overflow the projection screen before correction, due to the projected image of the overflow portion and the screen.
  • the projected image is not in a plane (such as a wall or window).
  • the projection screen is close to the display screen of 1/3 of the left and right borders to prevent the calibration point from overflowing the projection screen.
  • the trapezoidal correction parameter may be a left-right deflection angle of the optical axis of the projection unit relative to the projection display surface, or a coordinate position of the four vertices after the geometric distortion of the projection image on the display unit of the projection unit.
  • the projection unit displays a perspective transformation coefficient of the picture deformation on the chip, or the projection unit displays a dot mapping table of the picture deformation on the chip.
  • a trapezoidal correction parameter is obtained by establishing a mathematical relationship, and the projection unit and the monitoring unit are unified into the same spatial coordinate system; the establishment includes a preset calibration point in the monitoring.
  • the above mathematical relationship further relates to a preset value of a preset calibration point and a projector system parameter
  • the preset value of the calibration point is a position coordinate of the calibration point on the display unit of the projection unit, and the calibration point is selected, and the preset The set value is the known amount.
  • the projector system parameters include the internal parameters of the projection unit, the internal parameters of the monitoring unit, and the relative positions of the projection unit and the monitoring unit.
  • the internal parameters of the projection unit include a projection lens focal length, a display chip pixel size and a pixel number specification parameter, and a projection ratio: that is, the projection lens optical axis is perpendicular to Projection display area ⁇ projection unit lens model ratio of the distance from the main point of the projection model to the projection display surface and the ratio of the projection unit lens model main point to the projection display surface and the projection image height, display chip coordinate origin and projection lens light
  • the internal parameters of the monitoring unit include the monitoring lens focal length, the monitoring lens imaging chip pixel size and the pixel
  • the relative position of the monitoring unit and the projection unit includes the projection unit lens model main point and the monitoring unit lens model main The relative position of the point, the relative rotation angle or rotation matrix of the
  • the projector system parameters include, but are not limited to, the above, and the specific parameters required for different embodiments may be selected.
  • the above parameters are known after the projector is finished. Therefore, the trapezoidal correction parameters can be obtained by knowing the actual imaging coordinates of the preset calibration point on the imaging chip of the monitoring unit.
  • the trapezoidal correction parameter is obtained by using a database search method.
  • the imaging coordinates of the reference calibration point on the imaging chip of the monitoring unit and the projector projection state parameter or The mapping relationship database of the trapezoidal correction parameters when the projection image needs to be corrected, the database is searched according to the real imaging coordinates on the imaging unit of the monitoring unit corresponding to the preset calibration point, and the projection state parameter corresponding to the real imaging coordinate is obtained.
  • trapezoidal correction parameters; the trapezoidal correction parameters can be further determined according to the projection state parameters.
  • a set of reference calibration points must be projected through the projection unit to the projection display surface; the calibration point is captured by the monitoring unit, and the projector is in a different state by multiple experiments, and the calibration point is on the imaging chip of the monitoring unit.
  • the imaging coordinates can be used to establish a database of the correspondence between the imaging coordinates of the reference calibration point on the imaging chip of the monitoring unit and the projection state parameters of the projector or the trapezoidal correction parameters. It should be noted that in this mode, the position of the selected preset calibration point and the reference calibration point selected in the database should be corresponding to the position on the projection unit display chip.
  • This embodiment establishes a mathematical relationship based on the principle of similar triangles.
  • the projection unit imaging lens is simplified into a small hole imaging model, and the small hole is the lens
  • the main point in the small hole imaging model, the main point coincides with the node
  • the 0 point in the figure is the main point of the projection unit lens model.
  • the optical axis direction of the projection unit is the Z axis
  • the projection unit is placed in the X axis
  • the normal direction of the projection unit is the Y axis to construct a spatial coordinate system.
  • the coordinates of the imaging unit imaging lens can also be used as a reference. To build a coordinate system outside of the two shots, simply unify the subsequent calculations into the same spatial coordinate system.
  • the point P1 is a preset calibration point.
  • Pip is the position of the calibration point on the display unit of the projection unit.
  • the position on the display unit of the projection unit is equivalent to the equivalent focal plane S1 of the projection unit, and the position of the point on the equivalent focal plane
  • the distance of the equivalent focal plane from the main point of the projection unit lens model is equal to the distance from the display chip to the main point of the projection unit lens model, that is, the focal length f of the projection unit, therefore, Pip
  • 0'Plp xl
  • the same method can be used to find the Y coordinate of the PI point as (zlxyl) /f. Therefore, the coordinates of the PI point are PI ( (zlxxl) ⁇ , (zlxyl) /f,zl) .
  • the imaging unit imaging lens is simplified into a small hole imaging model, the small hole is the main point of the lens, and the C point is the main point of the monitoring unit lens model; COc is monitoring
  • the optical axis of the unit, the angle between the optical axis and the optical axis of the projection unit is a;
  • the coordinate of the C point is (Xc, Yc, Zc), and the coordinate value can be based on the main point of the projection unit lens model and the main point of the monitoring unit lens model Relative position to determine.
  • the position on the imaging chip is equivalent to the equivalent focal plane S3 of the monitoring unit, and the position of the point on the equivalent focal plane
  • the one-to-one correspondence with the position of the point on the imaging chip of the monitoring unit, and the distance of the equivalent focal plane from the main point of the lens of the monitoring unit is equal to the distance from the imaging chip to the main point of the lens model of the monitoring unit, that is, the focal length fc of the monitoring unit.
  • the image recognition unit can read Pic on the imaging chip coordinates Pic (cxl, cyl). Now with point C Center, rotate the monitoring unit by an oc angle, so that the optical axis COc of the rotating monitoring unit is "parallel to the optical axis of the projection unit 00", and the optical axis COc of the rotating monitoring unit is compared with the equivalent focal plane S4 of the rotating monitoring unit.
  • C0c' fc
  • the focal plane S4 intersects the Pic' point, and the Pic' point coordinates are Plc'(cxl', cyl, fc-Zc).
  • COc is the optical axis of the monitoring unit
  • Pic is the imaging position of the P1 point on the equivalent focal plane S3 of the monitoring unit
  • Ocl is the intersection of the optical axis COc and the equivalent focal plane S3 of the monitoring unit.
  • Bay ljCOcl fc
  • OclPl c cxl.
  • the Y coordinate of the PI point in the OXYZ coordinate system is the coordinate of the point Yc+(zl-Zc) xcyl/fc. Therefore, the PI point coordinate is PI (Xc+(z 1 -Zc)xcx 17fc, Yc+(z 1 -Zc) xcy l/fc,z 1 ).
  • the depth of the calibration point PI that is, the distance z1 from the point P1 to the OXY plane
  • ⁇ ' arctan ((z2'-zl')/(x2'-xl'))
  • This embodiment establishes a mathematical relationship based on the principle of triangulation, that is, the triangle corner formula.
  • the projection unit and the monitoring unit are simplified into a small hole imaging model.
  • the P point is the small hole position of the projection unit, that is, the main point of the projection unit lens model
  • the C point is The position of the small hole of the monitoring unit is the main point of the lens model of the monitoring unit;
  • the point P1 and the point P2 are two preset calibration points on the projection display surface SO, and
  • xl and x2 are respectively P1 and P2 points on the display unit of the projection unit, That is, the position on the equivalent focal plane S1 of the projection unit.
  • C, P, Pl, and P2 form two co-edge triangles ACPP1 and ACPP2 on the same side, and the angle P between P 1P2 and CP is the left-right deflection angle of the projection unit optical axis and the projection display surface.
  • ⁇ , where f is the projection The focal length of the element, the xl point is known as the distance xl to F. I xlF I is known, according to the formula otp arctan(
  • Cl, C2 be the imaging position of the point PI and the point P2 on the imaging unit of the monitoring unit, that is, the position on the equivalent focal plane S2 of the monitoring unit.
  • the image recognition unit can calculate ZP1CO' (ie, etc) and ZP2CO' (ie, pc) by reading the positional parameters of Cl and C2 on the imaging chip of the monitoring unit and combining the focal length of the monitoring unit.
  • the length d of the CP in the figure is the distance between the main point of the projection unit lens model and the main point of the monitoring unit lens model in the X-axis direction, and can be determined according to the relative position of the main point of the projection unit lens model and the main point of the monitoring unit lens model. . Therefore, ACPP1 and ACPP2 are known triangles, and the known parameters ⁇ , ⁇ , ac, ⁇ , d are input, and the left and right deflection angle ⁇ of the projection display surface can be calculated. The detailed calculation process is as follows:
  • the optical axis direction of the projection unit is the ⁇ axis, and the projection unit is placed.
  • the X-axis is the X-axis and the normal direction of the projection unit is a Y-axis
  • a coordinate of the two points C and P in the Z-axis direction is equal. If the coordinates of the two points C and P are not equal in the Z-axis direction, the parameters required in the calculation process of the embodiment need to be transformed accordingly. For details, refer to the transformation mode of the first embodiment.
  • This embodiment establishes a mathematical relationship based on the direction vector of the projected ray.
  • the projection unit imaging lens and the monitoring unit monitoring lens are simplified into a small hole imaging model, and the small hole is the main point of the lens, and the 0 point in the figure is the projection unit.
  • the main point of the lens model and point C are the main points of the monitoring unit lens model. Taking 0 point as the origin, the optical axis direction of the projection unit is the Z axis, the projection unit is placed in the X axis, and the normal direction of the projection unit is the Y axis to construct a spatial coordinate system, which is the projection lens coordinate system; similarly,
  • the monitoring lens coordinate system is constructed based on the monitoring unit imaging lens.
  • the coordinates of the two coordinate systems need to be unified to any of the coordinate systems; or the coordinate system is constructed outside the two lenses, as long as the subsequent calculations are unified to the same spatial coordinate system.
  • the following is an example of the subsequent calculation of the unified projection lens coordinate system.
  • the step of constructing the mathematical relationship to obtain the trapezoidal correction parameter in this embodiment includes:
  • P1 is a preset calibration point on the projection display surface SO
  • Pip is the position of the calibration point on the display unit of the projection unit, and the coordinates thereof are
  • the direction vector of the light projected by the projector by the projector can be obtained by the following method: [0115] 1.
  • the direction vector of the light projected by the projector by the preset calibration point can be calculated according to the internal parameters of the projection lens:
  • Formula (3) is a distortion formula of the radial distortion of the projection lens, wherein For radial distortion parameters. According to the above direction vector and formula (3), the direction vector of the actual light projected by the distorted projector lens can be obtained.
  • the direction vector of the light projected by the projector by the preset calibration point can be calculated by actually measuring the projection picture:
  • the direction vector of the actual light projected by the distorted projector lens can be obtained. Since the preset calibration point is a previously set point, the coordinate position on the display unit of the projection unit is displayed.
  • L is the depth of the preset calibration point to the main point of the projection unit lens model.
  • Pic is the position of the calibration point P1 on the imaging chip of the monitoring unit, and the image recognition unit collects the coordinates thereof. It is known that the internal reference matrix MC of the monitoring lens has a parameter definition similar to that of the projection lens.
  • Equation (6) is a distortion formula for monitoring the inverse radial distortion of the lens, where : For radial distortion parameters. According to the above direction vector and formula (6), the direction vector of the ray of the projection point of the undistorted projector in the monitoring lens coordinate system can be obtained. , ⁇
  • the coordinates of the arbitrary point on the real light in the projection lens coordinate system can be expressed as .
  • D is the depth of the preset calibration point to the main point of the monitoring unit lens model.
  • step S1 For the same preset calibration point in the projection lens coordinate system, the coordinates obtained according to step S1 should be consistent with the coordinates obtained according to step S2, therefore:
  • the angle between the projection display screen and the optical axis of the projection lens can be calculated.
  • the steps of performing distortion and anti-distortion calculation are omitted; if the optical axes of the monitoring lens and the projection lens are parallel, the above-described steps of performing vector transformation according to the rotation matrix may be omitted, or the rotation amount may be modified in other forms to simplify the model. .
  • a mapping relationship between the imaging coordinates of the reference calibration point on the imaging chip of the monitoring unit and the projection state parameter of the projector is established in advance. Firstly, the reference calibration point is selected, and the calibration point is projected onto the projection display surface by the projection unit; the calibration point is taken by the monitoring unit, and the projector is recorded at different projection distances and different deflections with respect to the projection display surface through multiple experiments.
  • the projection state parameter of the crucible is the distance from the main point of the projection unit lens model to the virtual plane where the reference calibration point is located.
  • the virtual plane where the reference calibration point is located is a plane perpendicular to the projection optical axis of the projection unit through the calibration point.
  • the preset calibration point used by the actual calibration of the projector corresponds to the reference calibration point selected in the database.
  • the monitoring unit is located on the right side of the projection unit, and the P point and the C point are respectively the main point of the projection unit lens model and the main point of the monitoring unit lens model;
  • the distance ZA of the virtual plane S5 of the projection unit lens model main point P to the point A can be found according to the X coordinate value Xa of the A point on the imaging chip;
  • the X coordinate value Xb on the chip can be used to find the distance ZB of the virtual plane (not shown) of the projection point lens model main point P to B. Since the coordinates XPA and XPB of the preset calibration point on the equivalent focal plane SI of the projection unit are known values, according to the similar triangle principle, it can be concluded that:
  • the deflection angle ⁇ of the projection unit optical axis and the projection display surface can be calculated:
  • a mapping relationship between the imaging coordinates of the reference calibration point on the imaging chip of the monitoring unit and the projection state parameters of the projector is established in advance.
  • a set of reference calibration points is selected, and the calibration points are projected onto the projection display surface by the projection unit; and the calibration points are captured by the monitoring unit, and the projection distance of the projector relative to the projection display surface is recorded by multiple experiments, Different deflection angles ⁇ , the imaging coordinates of the above-mentioned calibration points on the imaging chip of the monitoring unit; finally establishing the correspondence between the imaging coordinates of the reference calibration point group on the imaging chip of the monitoring unit and the deflection angle of the optical axis of the projection unit with respect to the projection display surface Relational database, the projection state parameter of this unit is the deflection angle of the optical axis of the projection unit relative to the projection display surface.
  • the preset calibration point used for the actual calibration of the projector corresponds to the reference calibration point selected in the database.
  • FIGS. 7(a) to 7(f) point P is the projection unit lens model main point, and C is the monitoring unit lens model main point.
  • Figure 7 (b) is a schematic diagram of the projection unit optical axis with no deflection ⁇ relative to the projection display surface. The uppermost rectangle in the figure is the projection picture S0, and Al and Bl are two preset calibration points projected on the projection display surface. The rectangle in the lower right corner is the imaging diagram of the imaging chip 22 of the monitoring unit. Cl and D1 are the positions of the two preset calibration points of Al and Bl on the imaging chip, and their coordinates can be read.
  • FIG. 7(a) is based on FIG. 7(b), in which the projection display surface SO is deflected with respect to the optical axis of the projection unit, and the projection screen becomes a trapezoidal image having a small left and right. Since the projected image is distorted, the positions of the two preset calibration points on the projection display surface are moved to ⁇ and ⁇ , and the positions of the two calibration points on the monitoring lens imaging chip 22 are moved to C1' and D1'. In the rectangle in the lower right corner of Figure 7 (a), the two dotted circles are the imaging positions of Figure 7 (b) ,. When the projection display surface is deflected by the ⁇ , the two calibration points move toward the center of the imaging chip, and the corresponding ones are different. The deflection angle, the two calibration points are also different on the imaging chip.
  • FIG. 7(c) is based on FIG. 7(b), the projection display surface SO is reversed with respect to the optical axis of the projection unit, and the projection screen becomes a trapezoidal image with a small left and a large right.
  • the positions of the two preset calibration points on the projection display surface are moved to ⁇ and ⁇ , and the positions of the two calibration points on the monitoring unit imaging chip 22 are also changed to C1" and Dl".
  • the two dotted circles are the imaging positions of Figure 7 (b)
  • the change rule is:
  • the two calibration points are toward the edge of the imaging chip. Moving, and corresponding to different deflection angles, the two calibration points are also different on the imaging chip.
  • FIG. 7(e) is based on FIG. 7(b), the projection display surface SO is not deflected, and the projection display surface is moved closer.
  • the positions of the two preset calibration points on the projection display surface are moved to A2 and B2, and the positions of the two calibration points on the monitoring unit imaging chip 22 are also changed to C2 and D2, respectively.
  • the two dashed circles are the imaging positions of Figure 7 (b) ,. Comparing Figure 7 (e) with Figure 7 (b), when the projection display surface moves closer to ⁇ The position of the two calibration points on the imaging chip of the monitoring unit also changes - the positions of the two calibration points on the imaging chip move to the right.
  • FIG. 7(d) is a schematic diagram showing the smoothing of the projection display surface relative to the optical axis of the projection unit on the basis of FIG. 7(e), the positions of the two preset calibration points on the projection display surface are moved to A2' and B2', the position of the two calibration points on the monitoring unit imaging chip 22 also changes to C2' and D2'.
  • Figure 7 (f) is a schematic diagram of the reverse deflection of the projection display surface relative to the optical axis of the projection unit based on Figure 7 (e), the position of the two preset calibration points on the projection display surface is moved to A2" and B2", the position of the two calibration points on the monitoring unit imaging chip 22 also changes to C2" and D2".
  • a database of correspondence between the imaging coordinates of the reference calibration point group on the imaging chip of the monitoring unit and the deflection angle of the optical axis of the projection unit with respect to the projection display surface is established in advance, and the imaging point on the monitoring unit can be performed according to the preset calibration point.
  • the real coordinate finds the deflection angle of the optical axis of the projection unit relative to the projection display surface.
  • a mapping relationship between the imaging coordinates of the reference calibration point on the imaging chip of the monitoring unit and the projection state parameter of the projector is established in advance.
  • a set of reference calibration points is selected, and the calibration points are projected onto the projection display surface by the projection unit; and the calibration points are captured by the monitoring unit, and the projection distance of the projector relative to the projection display surface is recorded by multiple experiments, Different deflection angles ⁇ , the above criteria
  • the imaging coordinates are fixed on the imaging chip of the monitoring unit; finally, two databases are established, which are respectively the first database: the imaging coordinates of each reference calibration point on the imaging chip of the monitoring unit and the entrance point of the projection unit to the virtual plane where the reference calibration point is located
  • the correspondence database between the distances, and the second database the projector is at the same projection distance, any two different deflection angles ⁇ , and the difference between the imaging coordinates of any reference calibration point on the imaging chip of the monitoring unit is opposite to the optical axis of the projection unit
  • the projection state parameter of the crucible includes the distance from the main point of the projection unit lens model to the virtual plane where the reference calibration point is located, and the deflection angle of the optical axis of the projection unit relative to the projection display surface.
  • the virtual plane where the reference calibration point is located is a plane perpendicular to the projection optical axis of the projection unit.
  • the preset calibration point used by the actual calibration of the projector corresponds to the reference calibration point selected by the database.
  • the monitoring unit is located on the right side of the projection unit, and the P point and the C point are respectively the main point of the projection unit lens model and the main point of the monitoring unit lens model;
  • the X-axis coordinate value on the chip the position of the preset calibration point on the virtual plane S5 where the A point is located, that is, the ideal projection position ⁇ ' of the point;
  • the above embodiments 1 to 5 describe in detail how to obtain the trapezoidal correction parameter of the deflection angle of the optical axis of the projection unit with respect to the projection display surface. In actual use, this can also be based on the input requirements of the trapezoidal correction unit.
  • the trapezoidal correction parameters are converted to other trapezoidal correction parameters. The specific conversion process is as follows
  • the projection unit lens model main point 0 is the coordinate origin, the projection horizontal direction is the X axis, the projection vertical direction is the ⁇ axis, and the optical axis direction is the ⁇ axis to establish the projection lens coordinate system.
  • the length is equal to the length of ⁇ 2.
  • the projection distance is based on the projection scale relationship
  • the length of the L ⁇ projection base is TL, and the coordinates of P can be obtained as
  • W is the number of pixels in the width direction of the projected DMD.
  • ⁇ is the number of pixels in the height direction of the projected DMD.
  • the projection unit displays any point on the chip.
  • the point map table of the screen deformation on the display unit display chip can be obtained by sequentially storing in the mapping table.
  • a deflection angle of the optical axis of the projection unit relative to the projection display surface a coordinate position of the four vertices after the geometric distortion of the projection image on the display unit of the projection unit, a perspective transformation coefficient of the deformation of the screen on the projection unit display chip, and a projection unit
  • the dot map showing the screen distortion on the chip can be selected as the input parameters of the trapezoidal correction unit, and is selected according to actual needs.
  • This embodiment is a further solution based on the fifth embodiment.
  • a database of correspondence between the imaging coordinates of the reference calibration point group on the imaging chip of the monitoring unit and the deflection angle of the optical axis of the projection unit relative to the projection display surface is established in advance, and the monitoring unit can be in accordance with the preset calibration point.
  • the real coordinate on the imaging chip finds the deflection angle of the optical axis of the projection unit relative to the projection display surface.
  • the seventh embodiment if the deflection angle of the optical axis of the projection unit relative to the projection display surface is known, the coordinate position of the four vertices after the geometric deformation of the projection image on the display unit of the projection unit and the projection unit can be obtained.
  • Other keystone correction parameters such as a perspective transformation coefficient of the screen distortion on the chip and a dot map of the screen deformation of the projection unit on the chip are displayed. Therefore, it is also possible to establish in advance a database of mapping relationship between the imaging coordinates of the reference calibration point on the imaging chip of the monitoring unit and several other trapezoidal correction parameters.
  • This embodiment is directed to the case where the projector may perform multiple corrections after performing trapezoidal correction. For example, in the case where the projected image has the left and right trapezoids and the upper and lower trapezoidal deformations (ie, the irregular quadrilateral), it may be necessary. First perform up and down keystone correction and then perform left and right keystone correction; or the projector is in use If the mid-projection state, for example, the deflection angle is changed again, it is necessary to perform the left and right keystone correction again when the left and right trapezoidal correction has been performed. In this case, the relevant parameters of the preset calibration point need to be transformed.
  • the present embodiment is a method of processing a projection image of a projector that has undergone trapezoidal correction on the basis of the third embodiment and the seventh embodiment.
  • the coordinates on the display unit of the projection unit before the trapezoidal correction is performed are
  • the preset calibration points can be transformed by perspective: , 3 ⁇ 4 + . 3 ⁇ 4 +: € I ⁇ + f, ' , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
  • the preset of the calibration point is preset.
  • the value needs to be the coordinates of the transformed chip on the display chip.
  • the angle between the projection display surface and the optical axis of the projection lens can be calculated.
  • the corresponding new trapezoidal correction parameter can be calculated by the seventh embodiment.
  • the upper and lower trapezoidal corrections are performed first, and the left and right trapezoidal corrections are taken as an example for description.
  • ⁇ 1 and ⁇ in the figure are the upper and lower trapezoids.
  • the projection unit displays the working area of the chip, and A2 and A2' are respectively the working area of the imaging chip of the monitoring unit before and after the upper and lower trapezoid correction, and Sl and S2 are respectively two reference calibration points.
  • the position C1 on the imaging chip of the monitoring unit before the upper and lower trapezoidal correction can be calculated to obtain the preset calibration point S2' corresponding to S2 and the corresponding calibration point corresponding to the imaging unit on the monitoring unit before the upper and lower trapezoidal correction is performed.
  • the location of C2. Using the C1 coordinate value corresponding to the preset calibration point SI' and the C2 coordinate value corresponding to the preset calibration point S2', the database is searched to obtain the trapezoidal correction parameters of the left and right trapezoidal correction, and the left and right trapezoidal correction of the projected image is completed.
  • the position of the calibration point on the display chip is fixed, that is, the selected preset calibration point is corrected, and the reference calibration point selected by the database is established.
  • the position on the display unit of the projection unit is the same; the actual imaging coordinates of the preset calibration point used on the imaging unit on the imaging unit of the monitoring unit are used.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Transforming Electric Information Into Light Information (AREA)
  • Projection Apparatus (AREA)

Abstract

L'invention concerne un procédé de correction horizontale de trapèze d'un projecteur, consistant à : une unité de projecteur (10) projette au moins un ensemble de points fixes prédéfinis sur une surface de projection; une unité de surveillance (20) capture les points fixes et lit les coordonnées d'image sur la puce d'imagerie (22) de l'unité de surveillance (20); obtenir, selon les coordonnées d'image en temps réel sur la puce d'imagerie (22) de l'unité de surveillance (20), des paramètres de correction de calcul de clé; effectuer, selon les paramètres de correction de calcul de clé, une distorsion géométrique correspondante sur l'image projetée. De cette manière, il n'est pas nécessaire de régler manuellement l'emplacement de placement du projecteur et le réglage automatique de l'image projetée peut être obtenu. Le processus de réglage est pratique et rapide, et améliore l'expérience utilisateur.
PCT/CN2017/102490 2017-09-20 2017-09-20 Procédé de correction horizontale de trapèze de projecteur WO2019056219A1 (fr)

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