Video camera with major functions implemented in host software

• US 20050162531A1
• Filed: 03/25/2005
• Published: 07/28/2005
• Est. Priority Date: 06/30/1999
• Status: Abandoned Application

• Current Assignee: Logitech Europe S A (Logitech International SA)
• Original Assignee: Logitech Europe S A (Logitech International SA)
• Inventors: Li, Wei, Zimmermann, Remy, Billerbeck, Bryed, Maggi, Sergio, Labrousse, Jean-Michel Junien, Hsu, Mark, Norcross, Mitchell, Sanchez, George, Auberger, Georges
• Application Number:
  US11/090,762
• Publication Number:
  US 20050162531A1
• Time in Patent Office: Days
• US Class Current: 348/222.100
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 21/4143 embedded in a Personal Computer [PC]
• CPC Class Codes: H04N 2201/001 Sharing resources, e.g. processing power or memory, with a connected apparatus or enhancing the capability of the still picture apparatus
• CPC Class Codes: H04N 23/661 Transmitting camera control signals through networks, e.g. control via the Internet
• CPC Class Codes: H04N 23/80 Camera processing pipelines; Components thereof
• CPC Class Codes: H04N 25/61 the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4"
• CPC Class Codes: H04N 25/68 applied to defects

Abstract

A low cost camera by implementing the major functions in host software is provided. This is accomplished by sending raw, digitized data from the camera directly to the host. The increased volume of raw data is handled by either an improved compression/decompression scheme using lossless compression, using lossy compression or using a shared bus with higher bandwidth. By moving such functions as color processing and scaling to the host, the pixel correction can also be moved to the host. This in turn allows the elimination of the frame buffer memory from the camera. Finally, the camera can use a low cost lens by implementing vignetting, distortion, gamma or aliasing correction with a correction value stored in a register of the camera for later access by the host to perform corrections.

Claims

1-6. -6. (canceled)

7. A video camera system comprising:

(a) a video camera having an image sensor, and

an analog to digital converter coupled to said image sensor;

(b) an interface coupled to said video camera, said interface being a shared interface capable of concurrent use by other peripheral devices; and

(c) a processing unit for receiving video digital data from said interface, said processing unit being configured to perform on said video digital data

anomalous pixel correction by comparison of pixel brightness with surrounding pixels, without the need to store pixel defects in a defective pixel memory in said video camera, and

color processing;

such that anomalous pixel correction and color processing circuitry is not needed in said video camera, and said anomalous pixel correction is performed prior to said color processing.

8. The system of claim 7 wherein said video camera further includes a processing device for compressing digital data from said analog to digital converter.

9. A method for decoding a Huffman compressed data stream in a processor having instructions for operating on multiple pixels in a register in parallel, comprising:

duplicating a group of bits from said data stream to provide duplicates in multiple positions in a first register; and

performing an operation between values in a second register and said duplicates in parallel, with a different value being used for each duplicate.

10. The method of claim 9 further comprising:

using a result of said operation in an indexing operation to index a table of Huffman decoded values.

11. A video camera comprising:

a low cost lens having a defect;

an image sensor;

an analog to digital converter coupled to said image sensor;

a memory element for holding a value corresponding to a correction factor for said defect in said inexpensive lens, said value being transferable to a remote host; and

an interface, coupled to said analog to digital converter and said memory element, for establishing communication with said remote host.

12. The camera of claim 11 wherein said value is a lens vignetting value.

13. A method of detecting and correcting defective pixels in raw data taken from an image sensor used to obtain a digitized image, wherein said raw data includes normal pixels and defective pixels, said method comprising the steps of:

(a) receiving a raw data signal for each pixel in said image;

(b) computing for each pixel received from said image sensor a brightness value;

(c) computing for each pixel received from said image sensor a local brightness value;

(d) computing for each pixel received from said image sensor a local brightness deviation of said brightness value from said local brightness value;

(e) setting a deviation threshold;

(f) comparing for each pixel received from said image sensor, its local brightness deviation to said deviation threshold and designating pixels having local brightness deviations greater than said deviation threshold as defective pixels;

(g) recording the location of said defective pixels in a statistical database;

(h) recording the frequency of occurrence of said defective pixels in said statistical database; and

(i) correcting the brightness value of said defective pixels, provided said correcting is warranted by trends from said statistical database.

14. A method for operating a video camera comprising the steps of:

reading image data from an image sensor array;

processing said image data in a video digital signal processor (DSP), said processing including performing image compression;

providing processed image data to a bus; and

providing a clock signal to said image sensor array to transfer image data from said image sensor array at a rate corresponding to a data transfer rate over said bus, such that a frame buffer memory for storing an entire frame of said image is not needed.