Method and apparatus for integrating multiple 1-D filters into a digital image stream interface

• US 6,594,399 B1
• Filed: 05/14/1998
• Issued: 07/15/2003
• Est. Priority Date: 05/14/1998
• Status: Expired due to Term

• Current Assignee: Sensar, Inc. (Advent International Corporation)
• Original Assignee: Sensar, Inc. (Advent International Corporation)
• Inventors: Greene, Gary Alan, Kaighn, Kevin Carl, Camus, Theodore A.
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US09/078,767
• Time in Patent Office: 1,888 Days
• Field of Search: 348/222, 382/260, 382/261, 382/299, 382/277, 382/282, 382/265, 382/284, 382/208, 382/205, 382/298, 358/447, 708/308, 708/300, 708/316
• US Class Current: 382/260
• CPC Class Codes: G06T 5/20 using local operators

Abstract

In a method of integrating one or more l-dimensional filters into a digital image stream interface a single digital video input is processed by multiple 1-dimensional digital image filters, especially recursive filters, and combined into a single digital image stream which can be transmitted via a high-speed interface to a host computer'"'"'s memory such that each 1-dimensional filter output can be automatically extracted and placed into its own separate memory buffer for subsequent processing by a secondary image processing device. This additional processing can include the second pass of a two-pass separable filter implemented in software on a general-purpose CPU, and in particular can result in the generation of an image pyramid. This combined hardware and software approach can produce low-cost 2-D digital image filter implementations small enough to be added to existing standard ASIC'"'"'s while still retaining high performance.

Claims

1. A method for producing a filtered digital image comprising:

a. feeding a digital image into an image processing ASIC;

b. performing one-dimensional filtering of the digital image within the ASIC to create single or multiple digital image filter results, the image filter results being at least one partially-pyramided image that is smaller than the digital image;

c. transferring the image filter results through a single image output stream;

d. storing the image output stream in a memory; and

e. filtering at least some portions of the stored image output stream using software in a computer processing unit to produce a filtered image.

2. The method of claim 1 wherein the digital image filter results is transmitted via a high-bandwidth interface to the memory for storage.

3. The method of claim 1 wherein each filter result from the single image output stream is extracted and placed into a separate memory buffer in a host computer'"'"'s memory.

4. The method of claim 1 wherein the filtering in step e is performed in software on a general-purpose CPU.

5. The method of claim 1 wherein step e produces at least one level of a multi-resolution image pyramid.

6. The method of claim 1 also comprising extracting a region of interest from the digital image via a windowing function implemented in hardware on the ASIC prior to filtering.

7. The method of claim 6 also comprising feeding the extracted region through at least one programmable tap filter.

8. The method of claim 1 also comprising computing an average intensity for each filter result in parallel with any further filtering of the result.

9. The method of claim 1 also comprising encrypting the digital image filter results.

10. The method of claim 1 also comprising subsampling the filtered image with programmable phase.

11. The method of claim 1 also comprising performing additional filtering on one of the original digital image and a filtered image in a recursive fashion.

12. The method of claim 11 wherein the additional filtering comprises processing that includes combining the original digital image and a filtered image.

13. The method of claim 12 wherein the additional filtering comprises subtraction of a filtered image from the original digital image.

14. The method of claim 1 wherein the digital image is comprised of video raster lines.

15. The method of claim 14 wherein the raster lines are even raster lines from another image comprised of even raster lines and odd raster lines.

16. The method of claim 14 wherein the raster lines are odd raster lines from another image comprised of even raster lines and odd raster lines.

17. An apparatus for producing a filtered image comprising:

a. a camera which produces a digital image;

b. an ASIC connected to the camera the ASIC configured to perform one dimensional filtering on images received from the camera to produce filtered images comprised of partially pyramided images that are smaller than the received images;

c. at least one memory connected to the ASIC capable of receiving the filtered images from the ASIC, the memory also containing software for performing filtering of the filtered images stored in the at least one memory; and

d. a computer processing unit connected to the at least one memory.

18. The apparatus of claim 17 also comprising a high speed interface connected between the ASIC and the memory.

19. The apparatus of claim 17 wherein the camera and ASIC are connected together in a single camera module and the memory and computer processing unit are a part of a general purpose CPU.

20. The apparatus of claim 17 wherein the ASIC contains at least one programable tap filter.

21. A method for producing a filtered digital image comprising:

a. feeding a digital image into an image processing ASIC;

b. performing one-dimensional filtering of the digital image within the ASIC to create image filter results, the image filter results being at least one partially pyramided image smaller than the digital image; and

c. transferring the image filter results through a single image output stream.