Method and apparatus for stabilizing an image produced in a video camera

• US 5,253,071 A
• Filed: 12/20/1991
• Issued: 10/12/1993
• Est. Priority Date: 12/20/1991
• Status: Expired due to Term

• Current Assignee: Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Corporation Of America (Sony Group Corp.)
• Inventors: MacKay, Michael T.
• Primary Examiner(s): Razavi, Michael T.
• Assistant Examiner(s): GARBER, WENDY RAE
• Application Number:
  US07/811,089
• Time in Patent Office: 662 Days
• Field of Search: 358/222, 358/105, 358/213.11, 358/909, 358/229, 358/225
• US Class Current: 348/208.11
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/687 by shifting the lens or sensor position
• CPC Class Codes: H04N 25/443 by reading pixels from selected 2D regions of the array, e.g. for windowing or digital zooming
• CPC Class Codes: H04N 25/72 using frame transfer [FT]
• CPC Class Codes: H04N 25/73 using interline transfer [IT]
• CPC Class Codes: H04N 25/745 Circuitry for generating timing or clock signals

Abstract

An electronic image stabilization method and apparatus has application for use in hand-held video camcorders. The electronic image stabilization apparatus, contained within the camcorder, comprises a definition television (HDTV) image sensor with photosensitive cells, a gimbaled lens configuration and signal processing circuitry. The lens configuration projects a subject image upon only a portion of the image sensor. As the hand-held camcorder is physically jittered, the lens configuration projects the subject image on a different portion of HDTV image sensor. A scanner circuit reads values from the cells, and a threshold circuit compares the values to a pre-determined threshold value. If the photosensitive cell value is greater, the the projected subject image in the larger HDTV image array is determined, only the photosensitive cells illuminated by the projected subject image extracted from the HDTV image sensor. As a result, jitter in the output image, caused by hand-held shakes, is reduce or eliminated.

Claims

1. An electronic image stabilization apparatus for stabilizing a video image generated from a source image input to a video camera, said electronic image stabilization apparatus comprising:

image sensor means for recording said source image, said image sensor means comprising;

a plurality of photosensitive cells, each of said plurality of photosensitive cells having a surface area and generating a cell value proportional to light intensity incident upon said surface area of said photosensitive cell, and

transferring means for shifting said cell values out of said image sensor;

focusing means for projecting said source image upon said image sensor so as to generate a first image area, said first image area comprising each surface area of said plurality of photosensitive cells illuminated by said source image, said first image area having a total surface area less than said image sensor total surface area by at least one of said cell surface areas;

floating means coupled to said focusing means for moving said first image area within said image sensor such that physical jitter of said video camera results in said source image being projected onto a second image area, said second image area being equal in surface area to said first image area, and said second image area illuminating at least one different photosensitive cell than said first image area in said image sensor, said floating means comprises an outer gimbaled ring and a helical mount, said outer gimbaled ring being coupled to said helical mount, and said helical mount being coupled to said focusing means so as to provide free angular movement for said focusing means in both a horizontal direction and vertical direction with respect to a plane parallel to said image sensor;

scanning means coupled to each of said plurality of photosensitive cells for reading cell values of each of said plurality of photosensitive cells, said scanning means selecting one of said plurality of photosensitive cells and reading a cell value corresponding to said photosensitive cell selected;

threshold means coupled to said scanning means for determining whether said cell value selected is within said second image area, said threshold means having a threshold value and a flagging means wherein said flagging means generates a flag signal when said cell value selected is greater than said threshold value; and

control means coupled to said threshold means and said image sensor means for allowing said transferring means of said image sensor, when said flag signal is present, to transfer out of said image sensor only said cell values within said second image area.

2. An electronic image stabilization apparatus as set forth in claim 1 wherein said image sensor is a high density television (HDTV) charged coupled device (CCD) image sensor.

3. An electronic image stabilization apparatus as set forth in claim 2 wherein said transferring means of said HDTV CCD image sensor is interline transfer.

4. An electronic image stabilization apparatus as set forth in claim 2 wherein said transferring means of said HDTV CCD image sensor is frame transfer.

5. An electronic image stabilization apparatus as set forth in claim 2 wherein said transferring means of said HDTV CCD image sensor is frame interline transfer.

6. An electronic image stabilization apparatus as set forth in claim 1 wherein said transferring means further comprising a plurality of clocking signals, shift register means for conducting said cell values and an output gate, said transferring means applying said clocking signals to said shift register means and said output gate so as to control transfer of said cell values through said shift register means and said output gate.

7. An electronic image stabilization apparatus as set forth in claim 1 wherein said plurality of photosensitive cells of said image sensor are arranged in an array so as to form a top parameter, a bottom parameter, a left parameter and a right parameter of said image sensor, and said scanning means selecting one of said plurality of photosensitive cells by generating a X address and a Y address unique to each of said plurality of photosensitive cells, said X address defining a number of cells in a horizontal direction from said left parameter of said image sensor, and said Y address defining a number of cells in a vertical direction from said top parameter of said image sensor.

8. An electronic image stabilization apparatus as set forth in claim 1 wherein said threshold value is a black noise quiescent charge of a photosensitive element in said image sensor.

9. An electronic image stabilization apparatus as set forth in claim 7 wherein said control means comprises calculation means and gating means, said calculation means being coupled to said X address and said Y address of said scanning means for providing four disabling distances, a first horizontal disabling distance being equal to a number of photosensitive cells between said left parameter of said image sensor and said X address corresponding to said cell value selected, a second horizontal disabling distance being equal to a number of cells between said right parameter of said image sensor and said X address corresponding to said cell value selected plus a number of cells contained within said second image area in a horizontal direction, a first vertical disabling distance being equal to a number of cells between said top parameter of said image sensor and said Y address corresponding to said cell value selected, and a second vertical disabling distance being equal to a number of cells between said bottom parameter of said image sensor and said Y address corresponding to said cell value selected plus a number of cells contained within said second image area in a vertical direction, said gating means being coupled to said transferring means and said calculation means for disabling said output gate of said transferring means, said gating means disabling said clocking signal to said output gate when said cell values are located within any of said four disabling distances.

10. An electronic image stabilization apparatus for stabilizing a video image generated from a source image input to a video camera, said electronic image stabilization apparatus comprising:

an image sensor for recording said source image, said image sensor comprising;

a plurality of photosensitive cells, each of said plurality of photosensitive cells having a surface area and generating a cell value, said plurality of photosensitive cells being arranged in an array so as to form a top parameter, a bottom parameter, a left parameter and a right parameter of said image sensor, said cell value being proportional to light intensity incident upon said surface area of said photosensitive cells, and

a transferring device for shifting said cell values out of said image sensor, said transferring device having clocking signals, shift registers for conducting said cell values and an output gate, said transferring device applying said clocking signals to said shift registers and said output gate so as to control transfer of said cell values through said shift registers and said output gate;

a lens for projecting said source image upon said image sensor so as to generate a first image area, said first image area comprising each surface area of said plurality of photosensitive cells illuminated by said source image, said first image area having a total surface area less than said image sensor total surface area by at least one of said cell surface areas;

a gimbaled configuration coupled to said lens for moving said first image area within said image sensor such that physical jitter of said video camera results in said source image being projected onto a second image area, said second image area being equal in surface area to said first image area, and said second image area illuminating at least one different photosensitive cell than said first image area in said image sensor said gimbaled configuration comprises an outer gimbaled ring and a helical mount, said outer gimbaled ring being coupled to said helical mount, and said helical mount being coupled to said lens so as to provide free angular movement for said lens in both a horizontal direction and vertical direction with respect to a plane parallel to said image sensor;

a scanning circuit for reading said cell value of each of said plurality of photosensitive cells, said scanning circuit being coupled to each of said cell values of said image sensor, said scanning circuit selecting one of said plurality of photosensitive cells and reading a cell value corresponding to said photosensitive cell selected by generating a X address and a Y address unique to each of said plurality of cells, said X address defining a number of cells in a horizontal direction from said left parameter of said image sensor, and said Y address defining a number of cells in a vertical direction from said top parameter of said image sensor;

a threshold circuit coupled to said scanning circuit for determining whether said cell value selected is within said second image area, said threshold circuit having a threshold value and a comparator wherein said comparator generates a flag signal when said cell value selected is greater than said threshold value; and

a control circuit coupled to said comparator of said threshold circuit for allowing said transferring device of said image sensor to transfer out of said image sensor, when said flag signal is present, only said cell values within said second image area, said control circuit comprising;

a counter circuit coupled to said X address and said Y address of said scanning circuit for providing four disabling distances, a first horizontal disabling distance being equal to a number of photosensitive cells between said left parameter of said image sensor and said X address corresponding to said cell value selected, a second horizontal disabling distance being equal to a number of cells between said right parameter of said image sensor and said X address corresponding to said cell value selected plus a number of cells contained within said second image area in a horizontal direction, a first vertical disabling distance being equal to a number of cells between said top parameter of said image sensor and said Y address corresponding to said cell value selected, and a second vertical disabling distance being equal to a number of cells between said bottom parameter of said image sensor and said Y address corresponding to said cell value selected plus a number of cells contained within second said image area in a vertical direction, and

a gating circuit coupled to said transferring device and said counter circuit for disabling said output gate of said transferring device, said gating circuit disabling said clocking signal to said output gate when said cell values are located within any of said four disabling distances.

11. An electronic image stabilization apparatus as set forth in claim 10 wherein said image sensor is a high density television (HDTV) charged coupled device (CCD) image sensor.

12. An electronic image stabilization apparatus as set forth in claim 11 wherein said transferring device of said HDTV CCD image sensor is interline transfer.

13. An electronic image stabilization apparatus as set forth in claim 11 wherein said transferring device of said HDTV CCD image sensor is frame transfer.

14. An electronic image stabilization apparatus as set forth in claim 11 wherein said transferring device of said HDTV CCD image sensor is frame interline transfer.

15. An electronic image stabilization apparatus as set forth in claim 10 wherein said threshold value is a black noise quiescent charge of a photosensitive element in said image sensor.

16. A method of electronic image stabilization for stabilizing a video image generated from a source image input to a video camera, said electronic image stabilization method comprising the steps of:

providing an image sensor having a plurality of photosensitive cells and a transferring means, each of said plurality of photosensitive cells having a surface area and generating a cell value proportional to light intensity incident upon said surface area of said photosensitive cell, said transferring means shifts said cell values out of said image sensor;

focusing said source image upon said image sensor so as to generate a first image area, said first image area comprising each surface area of said plurality of photosensitive cells illuminated by said source image, said first image area having a total surface area less than said image sensor total surface area by at least one of said cell surface areas;

floating said source image within said image sensor such that physical jitter of said video camera results in said source image being projected onto a second image area, said second image area being substantially equal in surface area to said first image area, and said second image area illuminating at least one different photosensitive cell than said first image area in said image sensor;

selecting a cell value from said plurality of photosensitive cells;

determining whether said cell value selected is within said second image area; and

controlling said transferring means in said image sensor when said selected cell value is within said second image so as to shift out only said cells values within said second image area.