Method and system for generating calibration information for an optical imaging touch display device

• US 9,019,241 B2
• Filed: 12/01/2011
• Issued: 04/28/2015
• Est. Priority Date: 02/15/2011
• Status: Expired due to Fees

• Current Assignee: Wistron Corporation
• Original Assignee: Wistron Corporation
• Inventors: Chang, Hsun-Hao
• Primary Examiner(s): Patel, Kumar
• Assistant Examiner(s): ONYEKABA, AMY
• Application Number:
  US13/308,919
• Publication Number:
  US 20120206410A1
• Time in Patent Office: 1,244 Days
• Field of Search: 345173-178, 178/18.01, 382/132, 382/149, 382/164, 382/173, 382/199
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A system for generating calibration information for an optical imaging touch display device includes a calibration tool and a processor. The calibration tool is disposed within an image capturing range of an image capturing unit, and has a surface with mark patterns. Each adjacent pair of the mark patterns defines a pattern boundary. The calibration tool is disposed such that the pattern boundary forms a predefined positional relationship with a corresponding predefined location on the optical imaging touch display device. The processor receives an image frame corresponding to an image of the surface of the calibration tool, performs edge detection on the image frame to determine a position of each of at least one detected pattern edge, and generates the calibration information with reference to the position thus determined and the corresponding predefined location.

Claims

1. A method for generating calibration information for an optical imaging touch display device that includes at least one image capturing unit by utilizing the image capturing unit, a processor and a calibration tool, the calibration tool having a surface that is provided with a plurality of mark patterns, each adjacent pair of the mark patterns defining a pattern boundary therebetween, the calibration tool being disposed such that the pattern boundary between each adjacent pair of the mark patterns forms a predefined positional relationship with a corresponding predefined location on the optical imaging touch display device, a display panel of the optical imaging touch display device having a first side and a second side spaced apart from and parallel to each other, the image capturing unit being disposed at the first side of the display panel, the calibration tool being inclined relative to the second side of the display panel, said method comprising the steps of:

(A) configuring the image capturing unit to capture an image of the surface of the calibration tool when the view of the calibration tool by the at least one image capturing unit is unobscured, so as to generate an image frame;

(B) configuring the processor to perform edge detection on the image frame so as to determine a position of each of at least one detected pattern edge within the image frame; and

(C) configuring the processor to generate the calibration information with reference to the position of each of said at least one detected pattern edge as determined in step (B) and the corresponding predefined location on the optical imaging touch display device, wherein step (C) includes the sub-steps of;

(C-1) configuring the processor to convert the position of each of said at least one detected pattern edge as determined in step (B) into a corresponding mapped location on the optical imaging touch display device; and

(C-2) configuring the processor to generate the calibration information with reference to the mapped location corresponding to each of said at least one detected pattern edge of sub-step (C-1) and the corresponding predefined location on the optical imaging touch display device;

wherein the corresponding mapped locations are defined in a physical coordinate system of the optical imaging touch display device, while the position of each of said at least one detected pattern edge is defined in an image coordinate system;

wherein in sub-step (C-1), the processor converts the position of each of said at least one detected pattern edge as determined in step (B) into the corresponding mapped location on the optical imaging touch display device with reference to an angle included by the calibration tool and the second side of the display panel.

2. The method as claimed in claim 1, wherein step (B) includes the sub-steps of:

(B-1) configuring the processor to obtain a grayscale value for each of a plurality of pixels in the image with reference to the image frame;

(B-2) configuring the processor to determine a gradient value for each of the pixels in a predetermined direction with reference to the grayscale values obtained in sub-step (B-1), wherein the predetermined direction is related to an arrangement of the mark patterns on the surface of the calibration tool; and

(B-3) configuring the processor to obtain, for each of the pixels of the image frame, an edge strength value by comparing the gradient value determined in sub-step (B-2) with a first threshold value; and

(B-4) configuring the processor to determine the position of each of said at least one detected pattern edge with reference to the edge strength values of the pixels as obtained in sub-step (B-3).

3. The method as claimed in claim 2, wherein sub-step (B-4) includes the sub-steps of:

(B-4-1) configuring the processor to perform a summation of the edge strength values of each group of the pixels that are aligned in a direction perpendicular to the predetermined direction so as to obtain a plurality of projection statistic values;

(B-4-2) configuring the processor to determine which of the projection statistic values is greater than a second threshold value;

(B-4-3) configuring the processor to determine the position of said at least one detected pattern edge with reference to result of determination made in sub-step (B-4-2).

4. A system for generating calibration information for an optical imaging touch display device, the optical imaging touch display device including a display panel and at least one image capturing unit, the display panel of the optical imaging touch display device having a first side and a second side spaced apart from and parallel to each other, the image capturing unit being disposed at the first side of the display panel, the system comprising:

a calibration tool to be disposed within an image capturing range of the image capturing unit of the optical imaging touch display device, and having a surface that is provided with a plurality of mark patterns, each adjacent pair of said mark patterns defining a pattern boundary therebetween, said calibration tool being disposed such that said pattern boundary between each adjacent pair of said mark patterns forms a predefined positional relationship with a corresponding predefined location on the optical imaging touch display device, the calibration tool being inclined relative to the second side of the display panel; and

a processor configured for receiving an image frame from the image capturing unit, the image frame corresponding to an image of said surface of said calibration tool as captured by the image capturing unit;

wherein the image frame corresponds to an image of said surface of said calibration tool as captured by the image capturing unit when the view of the calibration tool by the at least one image capturing unit is unobscured; and

wherein said processor performs edge detection on the image frame so as to determine a position of each of at least one detected pattern edge within the image frame, converts the position of each of said at least one detected pattern edge into a corresponding mapped location on the optical imaging touch display device with reference to an angle included by the calibration tool and the second side of the display panel, and generates the calibration information with reference to the mapped location corresponding to each of said at least one detected pattern edge and the corresponding predefined location on the optical imaging touch display device;

wherein the corresponding mapped locations are defined in a physical coordinate system of the optical imaging touch display device, while the position of each of said at least one detected pattern edge is defined in an image coordinate system.

5. The system as claimed in claim 4, wherein said processor obtains a grayscale value for each of a plurality of pixels in the image frame received thereby from the image capturing unit, determines a gradient value for each of the pixels in a predetermined direction with reference to the grayscale values, obtains an edge strength value for each of the pixels of the image frame by comparing the gradient value with a first threshold value, and further determines the position of each of said at least one detected pattern edge with reference to the edge strength values of the pixels thus obtained, the predetermined direction being related to an arrangement of said mark patterns on said surface of said calibration tool.

6. The system as claimed in claim 4, wherein said mark patterns are arranged on said surface of said calibration tool along a predetermined direction.

7. The system as claimed in claim 6, wherein said mark patterns include at least one first mark pattern and at least one second mark pattern different in color from said first mark pattern, said first and second mark patterns being arranged alternatingly along the predetermined direction.

8. The system as claimed in claim 7, wherein said first and second mark patterns differ in color, and are respectively white and black in color.

9. The system as claimed in claim 4, wherein said processor converts the position of each of said at least one detected pattern edge into a corresponding mapped location on the optical imaging touch display device, and generates the calibration information with reference to the mapped location corresponding to each of said at least one detected pattern edge and the corresponding predefined location on the optical imaging touch display device.