Methods and apparatus for one-dimensional signal extraction

• US 9,218,536 B2
• Filed: 12/23/2011
• Issued: 12/22/2015
• Est. Priority Date: 12/23/2011
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Silver, William M.
• Primary Examiner(s): Le, Thien M
• Assistant Examiner(s): Habib, Asifa
• Application Number:
  US13/336,291
• Publication Number:
  US 20130161398A1
• Time in Patent Office: 1,460 Days
• Field of Search: 235/462.09, 235/462.14, 235/462.25, 382/313, 382/181, 382/289
• US Class Current: 1/1
• CPC Class Codes: G06F 2218/02 Preprocessing
• CPC Class Codes: G06K 7/00 Methods or arrangements for sensing record carriers, e.g. for reading patterns methods or arrangements for marking the record carrier in digital fashion G06K1/00; pattern recognition G06F18/00; arrangements for image or video recognition or understanding G06V10/00; character recognition, recognising digital ink or document-oriented image-based pattern recognition G06V30/00
• CPC Class Codes: G06K 7/10 by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/1413 1D bar codes
• CPC Class Codes: G06K 7/1456 determining the orientation of the optical code with respect to the reader and correcting therefore
• CPC Class Codes: G06K 7/146 the method including quality enhancement steps
• CPC Class Codes: G06K 7/1478 adapting the threshold for pixels in a CMOS or CCD pixel sensor for black and white recognition
• CPC Class Codes: G06V 10/242 by image rotation, e.g. by 90 degrees
• CPC Class Codes: G06V 10/44 Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components
• CPC Class Codes: G06V 10/94 Hardware or software architectures specially adapted for image or video understanding
• CPC Class Codes: G06V 30/224 of printed characters having additional code marks or containing code marks

Abstract

Methods and apparatus are disclosed for extracting a one-dimensional digital signal from a two-dimensional digital image along a projection line. Disclosed embodiments provide an image memory in which is stored the digital image, a working memory, a direct memory access controller, a table memory that holds a plurality of transfer templates, and a processor. The processor selects a transfer template from the table memory responsive to an orientation of the projection line, computes a customized set of transfer parameters from the selected transfer template and parameters of the projection line, transmits the transfer parameters to the direct memory access controller, commands the direct memory access controller to transfer data from the image memory to the working memory as specified by the transfer parameters, and computes the one-dimensional digital signal using at least a portion of the data transferred by the direct memory access controller into the working memory.

Claims

1. A digital electronic apparatus for extracting from a two-dimensional digital image a one dimensional digital signal along a projection line, comprising:

an image memory in which is stored the digital image;

a working memory which receives a portion of the digital image from the image memory;

a direct memory access controller configured to receive a set of transfer parameters for transferring data from the image memory to the working memory as specified by the set of transfer parameters;

a table memory that holds a plurality of transfer templates, wherein one of the plurality of transfer templates corresponds to an orientation relative to a pixel grid of the two-dimensional digital image, and from which can be derived a set of transfer parameters, wherein the set of transfer parameters;

are customized for the projection line;

can be used to obtain pixels corresponding to the projection line having the orientation; and

comprise a plurality of count values and at least one pitch value; and

wherein the orientation is one of a set of allowable orientations, the set of allowable orientations including a plurality of orientations that are not parallel to the pixel grid and are not diagonal to the pixel grid; and

wherein the plurality of transfer templates comprises information that can be used to derive transfer parameters for any one of the plurality of allowable orientations;

a processor connected to the working memory, the direct memory access controller, and the table memory, which operates so as to;

select the one of the plurality of transfer templates from the table memory responsive to the orientation;

compute a customized set of transfer parameters responsive to the selected transfer template and to parameters of the projection line, wherein the customized set of transfer parameters define a set of pixels in the two-dimensional digital image corresponding to the projection line having the orientation;

transmit the customized set of transfer parameters to the direct memory access controller;

command the direct memory access controller to transfer data from the image memory to the working memory as specified by the customized set of transfer parameters, wherein the data comprises the set of pixels corresponding to the projection line; and

compute the one-dimensional digital signal using at least a portion of the data transferred by the direct memory access controller into the working memory.

2. The apparatus of claim 1, wherein the processor computes the one-dimensional signal by fetching pixels from the working memory in a different order than the order of the transfer from image memory to working memory.

3. The apparatus of claim 1, wherein the set of transfer parameters describes a three dimensional transfer.

4. The apparatus of claim 1, wherein the image memory is a dynamic random access memory, and the working memory is a static random access memory of the processor.

5. The apparatus of claim 1, wherein the processor further computes a second one-dimensional signal from data previously transferred into the working memory, and wherein the transfer of data from the image memory to the working memory overlaps with the processor computing the second one-dimensional signal.

6. The apparatus of claim 1 wherein the one of the plurality of transfer templates is selected such that unneeded pixels are minimized.

13. The apparatus of claim 1, wherein the parameters of the projection line comprise a starting point of the projection line and a length of the projection line.

15. The apparatus of claim 1, wherein the one of the plurality of transfer templates comprises dimensions of the set of pixels corresponding to the projection line.

16. The apparatus of claim 1, wherein the one of the plurality of transfer templates is predetermined off-line.

7. A method for extracting a one dimensional digital signal along a projection line from a two-dimensional digital image, the method comprising:

storing the two-dimensional digital image in an image memory;

storing in a table memory a plurality of transfer templates, wherein one of the plurality of transfer templates corresponds to an orientation relative to a pixel grid of the two-dimensional digital image, and from which can be derived a set of transfer parameters, wherein the set of transfer parameters;

are customized for the projection line;

can be used to obtain pixels corresponding to the projection line having the orientation; and

comprise a plurality of count values and at least one pitch value; and

wherein the orientation is one of a set of allowable orientations, the set of allowable orientations including a plurality of orientations that are not parallel to the pixel grid and are not diagonal to the pixel grid; and

wherein the plurality of transfer templates comprises information that can be used to derive transfer parameters for any one of the plurality of allowable orientations;

selecting the one of the plurality of transfer templates from the table memory responsive to the orientation;

computing a customized set of transfer parameters responsive to the selected transfer template and to parameters of the projection line, wherein the customized set of transfer parameters define a set of pixels in the two-dimensional digital image corresponding to the projection line having the orientation;

transmitting the customized set of transfer parameters to a direct memory access controller;

transferring, using the direct memory access controller, at least a portion of the digital image from the image memory to a working memory as specified by the customized set of transfer parameters, wherein the data comprises the set of pixels corresponding to the projection line; and

computing the one-dimensional digital signal using at least a portion of the data transferred by the direct memory access controller into the working memory.

8. The method of claim 7, further comprising computing the one-dimensional signal by fetching pixels from the working memory in a different order than the order of the transfer from image memory to working memory.

9. The method of claim 7, wherein the set of transfer parameters describes a three dimensional transfer.

10. The method of claim 7, wherein the image memory is a dynamic random access memory, and the working memory is a static random access memory.

11. The method of claim 7, further comprising computing a second one-dimensional signal from data previously transferred into the working memory, and wherein transferring data from the image memory to the working memory overlaps with computing the second one-dimensional signal.

12. The method of claim 7, wherein the one of the plurality of transfer templates is selected such that unneeded pixels are minimized.

14. The method of claim 7, wherein the parameters of the projection line comprise a starting point of the projection line and a length of the projection line.

17. The method of claim 7, wherein the one of the plurality of transfer templates comprises dimensions of the set of pixels corresponding to the projection line.

18. The method of claim 7, wherein the one of the plurality of transfer templates is predetermined off-line.