Image processing system and method using subsampling with constraints such as time and uncertainty constraints

• US 5,995,648 A
• Filed: 03/18/1997
• Issued: 11/30/1999
• Est. Priority Date: 03/18/1997
• Status: Expired due to Term

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Drisko, Robert, Bachelder, Ivan A.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): MEHTA, BHAVESH M
• Application Number:
  US08/819,876
• Time in Patent Office: 987 Days
• Field of Search: 382/298, 382/299, 382/141, 382/151, 382/149, 382/188, 382/282, 382/152, 382/153, 382/147, 382/148, 382/145, 364/570, 364/550, 364/728, 358/88, 356/394, 395/125, 362/32, 348/126
• US Class Current: 382/147
• CPC Class Codes: G06T 2207/30141 Printed circuit board [PCB]
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/30 Determination of transform parameters for the alignment of images, i.e. image registration
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

An automated object inspection system involving locating an object in an input image obtains a digital representation of an image including the object. Expected geometric parameters representing expected geometric features of the object are obtained. A set of pixels required for input to an object locating process is selected. A subsampling factor is defined based upon at least the expected geometric parameters. The subsampling factor defines a reduction in resolution of the set of pixels. The set of pixels is subsampled in accordance with the defined subsampling factor. The object locating process is run on the subsampled set of pixels. In defining the subsampling factor based upon at least the expected geometric parameters, the system takes into account constraints such as time an uncertainty constraints.

Claims

1. In an automated object inspection system involving locating an object in an input image, an image processing method comprising:

obtaining a pixel representation of an input image including said object;

obtaining expected geometric parameters representing certain expected geometric features of said object;

selecting from said pixel representation a set of pixels required for input to an object locating process;

defining, after said selecting said set of pixels and after said obtaining said expected geometric parameters, a subsampling factor based upon at least said expected geometric parameters, said subsampling factor defining a reduction in resolution of said set of pixels;

subsampling said set of pixels in accordance with the defined subsampling factor; and

running said object locating process on the subsampled set of pixels;

wherein said defining a subsampling factor comprises estimating a time value indicative of a time said object locating process requires to complete operations on said subsampled set of pixels, and defining said subsampling factor so said time value falls within a desired processing time range.

2. The method according to claim 1, wherein said object comprises a surface mounted device (SMD).

3. Computer-readable media tangibly embodying a program of instructions executable by the machine to perform functions including:

obtaining a pixel representation of a input image including said object;

obtaining expected geometric parameters representing certain expected geometric features of said object;

selecting from said pixel representation a set of pixels required for input to an object locating process;

defining, after said selecting said set of said pixels and after said obtaining said expected geometric parameters, a subsampling factor based upon at least said expected geometric parameters, said subsampling factor defining a reduction in resolution of said set of pixels;

subsampling said set of pixels in accordance with the defined subsampling factor; and

running said object locating process on the subsampled set of pixels;

wherein said defining a subsampling factor comprises estimating a time value indicative of a time said object locating process requires to complete operations on said subsampled set of pixels, and defining said subsampled factor so said time value falls within a desired processing time range.

4. The method according to claim 3, wherein said object comprises a surface mounted device (SMD).

5. An automated object inspection system involving locating an object in an input image, said system comprising:

means for obtaining a pixel representation of an input image including said object;

means for obtaining expected geometric parameters representing certain expected geometric features of said object;

means for selecting from said pixel representation a set of pixels required for input to an object locating process;

means for defining, after said set of pixels is selected and after said expected geometric parameters are obtained, a subsampling factor based upon at least said expected geometric parameters, said subsampling factor defining a reduction in resolution of said set of pixels;

means for subsampling said set of pixels in accordance with the defined subsampling factor; and

means for running said object locating process on the subsampled set of pixels;

wherein said means for defining a subsampling factor comprise means for estimating a time value indicative of a time said object locating process requires to complete operations on said subsampled set of pixels, and means for defining said subsampling factor so said time value falls within a desired processing time range.

6. The system according to claim 5, wherein said object comprises a surface mounted device (SMD).