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CN-122002014-A - Projector automatic trapezoid correction method, system and medium

CN122002014ACN 122002014 ACN122002014 ACN 122002014ACN-122002014-A

Abstract

The application provides an automatic trapezoidal correction method, system and medium for a projector, wherein the method comprises the following steps: and acquiring the posture information of the projector and the space information of the projector and the projection surface. Under the condition that the optical emission parameters of the projector are known, a projection geometric model is established based on the attitude information and the space information, and transformation parameters for trapezoidal correction of the projector are generated according to the projection geometric model. The projector is controlled to execute one trapezoidal correction action based on the transformation parameters. And controlling the projector to project a preset calibration pattern, acquiring an image of the calibration pattern by adopting the image acquisition device after the trapezoidal correction action is executed, extracting image features, and acquiring geometric parameters corresponding to an actual projection picture based on the image features. And determining a calibration error based on the difference between the geometric parameter and the transformation parameter, and generating a compensation parameter according to the calibration error. The compensation parameters are written to the projector to compensate for the transformation parameters when the projector performs trapezoidal correction. And generating corresponding correction coefficients by the projector through the steps.

Inventors

  • LUO ZHEWEN

Assignees

  • 深圳雅博创新有限公司

Dates

Publication Date
20260508
Application Date
20260123

Claims (10)

  1. 1. An automatic trapezoid correction method for projectors, which is applied to ultra-short focal projectors in the same type production, is characterized by comprising the following steps: acquiring attitude information of the projector and space information of the projector and a projection surface; Establishing a projection geometric model based on the attitude information and the space information under the condition that the optical emission parameters of the projector are known, and generating transformation parameters for trapezoidal correction of the projector according to the projection geometric model; controlling the projector to execute one trapezoidal correction action based on the transformation parameters; controlling the projector to project a preset calibration pattern, acquiring an image of the calibration pattern by adopting an image acquisition device after the trapezoidal correction action is executed, extracting image characteristics, and acquiring geometric parameters corresponding to an actual projection picture based on the image characteristics; determining a calibration error based on a difference between the geometric parameter and the transformation parameter, and generating a compensation parameter according to the calibration error; the compensation parameters are written to the projector to compensate for the transformation parameters when the projector performs trapezoidal correction.
  2. 2. The projector automatic trapezoidal correction method according to claim 1, wherein the step of acquiring the posture information includes: Placing the projector on a horizontal reference plane; acquiring a triaxial acceleration sampling sequence of the inertial measurement unit within a preset sampling time length; respectively averaging the triaxial acceleration sampling sequences to obtain triaxial acceleration offset; and when the subsequent gesture is calculated, a corrected acceleration value is obtained by subtracting the triaxial acceleration offset from the real-time triaxial acceleration value, and the roll angle and the pitch angle are calculated based on the corrected acceleration value.
  3. 3. The projector automatic trapezoidal correction method according to claim 2, wherein the step of acquiring the spatial information includes: obtaining lattice ranging data output by a ranging sensor; Converting the lattice ranging data into a set of spatial points based on field of view parameters of a ranging sensor; Removing points exceeding a preset distance range or invalid ranging from the space point set; the projection plane is fitted to the remaining set of points to obtain plane parameters.
  4. 4. The automatic trapezoidal correction method for a projector according to claim 3, wherein fitting the plane of the projection surface includes the steps of: Selecting at least a preset number of effective points from the space point set; screening outliers by adopting a robust plane fitting strategy to obtain a plane normal vector; The plane normal vector is converted into a coordinate system established by an inertial measurement unit, and a yaw angle is calculated based on the plane normal vector and a horizontal reference direction of the coordinate system.
  5. 5. The projector automatic trapezoidal correction method according to claim 1, wherein the steps of creating a projection geometric model and generating transformation parameters include: Determining a plurality of projection boundary rays corresponding to the display panel boundary based on the optical emission parameters; Calculating the intersection point of the projection boundary light and the projection plane; and determining the intersection point as a boundary characteristic point set of the projection area, and determining a target correction area according to the boundary characteristic point set.
  6. 6. The projector automatic trapezoidal correction method according to claim 5, wherein determining the target correction area includes the steps of: determining a trapezoid boundary by using boundary feature points of the projection area; and obtaining an inscribed rectangle with the largest area in the trapezoid boundary, and taking the vertex of the inscribed rectangle as a characteristic point of the target correction area.
  7. 7. The projector automatic trapezoidal correction method according to claim 5, wherein generating the transformation parameters includes the steps of: establishing a corresponding relation between a reference characteristic point and the characteristic point of the target correction area under a display panel coordinate system; solving a homography transformation matrix based on the corresponding relation; and outputting geometric transformation parameters of the display panel image based on the homography transformation matrix to serve as control parameters of the trapezoid correction action.
  8. 8. The projector automatic trapezoidal correction method according to claim 1, wherein generating the compensation parameter based on the calibration error includes the steps of: Acquiring the calibration error under at least one forward projection attitude and calculating a pitch angle compensation value; respectively acquiring the calibration errors under a plurality of different rotation angle postures and calculating corresponding yaw angle compensation amounts; constructing the rotation angle and the yaw angle compensation amount into a fitting data set, and solving compensation function coefficients for a left-turning working condition and a right-turning working condition respectively; And when the production line is calibrated, adjusting the pitch angle compensation value based on the calibration error of the projector to be calibrated, correcting the constant term of the left-turn compensation function or the right-turn compensation function, and writing the corrected constant term into the projector.
  9. 9. An automatic trapezoidal correction system for a projector, which is applied to the automatic trapezoidal correction method for a projector according to any one of claims 1 to 8.
  10. 10. An automatic trapezoidal correction medium for a projector, which is characterized by being applied to the automatic trapezoidal correction method for a projector according to any one of the claims 1 to 8.

Description

Projector automatic trapezoid correction method, system and medium Technical Field The application relates to the field of projection display, in particular to an automatic trapezoidal correction method, system and medium for a projector. Background Automatic keystone correction is a key function of modern projection devices, aimed at compensating for geometrical distortions of the picture (keystone distortion) due to the projection angle by digital image transformation when the projector is not vertically aligned with the projection surface. For an ultra-short focal projector, a large-size picture is projected in an extremely short distance through a special optical design, which makes the optical path and space geometrical relationship more complex than that of a conventional projector. At present, a common scheme for automatic trapezoidal correction of projectors in the industry is mainly a table look-up method based on a preset parameter table. According to the method, a few prototypes are measured in the research and development stage, a lookup table of the gesture, the distance and the correction parameters is established, and the lookup table is solidified in all types of products. However, because of the inability to cover the hardware tolerances unique to each device on the production line, the look-up table provides an "averaging" solution with correction accuracy that is random for individual devices, with an unstable effect, and poor user experience. As the method cannot effectively cope with the individual differences of production, many ultra-short focal length projector products either directly give up the automatic trapezoid correction function or maintain the effect at a lower level, thereby severely restricting the improvement of the usability and the user experience of the products. Therefore, there is a need for a projector automatic trapezoidal correction method that generates corresponding correction coefficients. Disclosure of Invention In view of the foregoing, it is desirable to provide an automatic trapezoidal correction method, system and medium for a projector, so as to solve the above-mentioned problems. The embodiment of the application provides an automatic trapezoidal correction method, system and medium for a projector, which are applied to ultra-short focal projectors in the same-model production, and the method comprises the following steps: acquiring attitude information of the projector and space information of the projector and a projection surface; Establishing a projection geometric model based on the attitude information and the space information under the condition that the optical emission parameters of the projector are known, and generating transformation parameters for trapezoidal correction of the projector according to the projection geometric model; controlling the projector to execute one trapezoidal correction action based on the transformation parameters; controlling the projector to project a preset calibration pattern, acquiring an image of the calibration pattern by adopting an image acquisition device after the trapezoidal correction action is executed, extracting image characteristics, and acquiring geometric parameters corresponding to an actual projection picture based on the image characteristics; determining a calibration error based on a difference between the geometric parameter and the transformation parameter, and generating a compensation parameter according to the calibration error; the compensation parameters are written to the projector to compensate for the transformation parameters when the projector performs trapezoidal correction. In at least one embodiment of the present application, the acquiring the pose information includes the steps of: Placing the projector on a horizontal reference plane; acquiring a triaxial acceleration sampling sequence of the inertial measurement unit within a preset sampling time length; respectively averaging the triaxial acceleration sampling sequences to obtain triaxial acceleration offset; and when the subsequent gesture is calculated, a corrected acceleration value is obtained by subtracting the triaxial acceleration offset from the real-time triaxial acceleration value, and the roll angle and the pitch angle are calculated based on the corrected acceleration value. In at least one embodiment of the present application, the acquiring spatial information includes the steps of: obtaining lattice ranging data output by a ranging sensor; Converting the lattice ranging data into a set of spatial points based on field of view parameters of a ranging sensor; Removing points exceeding a preset distance range or invalid ranging from the space point set; the projection plane is fitted to the remaining set of points to obtain plane parameters. In at least one embodiment of the present application, the fitting the plane of the projection surface includes the steps of: Selecting at least a preset number of effectiv