High resolution zoom: a novel digital zoom for digital video camera

• US 20060125937A1
• Filed: 12/10/2004
• Published: 06/15/2006
• Est. Priority Date: 12/10/2004
• Status: Active Grant

• Current Assignee: Ambarella International LP (Ambarella Incorporated)
• Original Assignee: Ambarella Incorporated
• Inventors: Linzer, Elliot N., LeGall, Didier, Kohn, Leslie D.
• Granted Patent: US 7,688,364 B2
• Time in Patent Office: Days
• US Class Current: 348/240.990
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules
• CPC Class Codes: H04N 23/69 Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements

Abstract

A camera system and a method for zooming the camera system is disclosed. The method generally includes the steps of (A) generating an electronic image by sensing an optical image received by the camera, the sensing including electronic cropping to a window size to establish an initial resolution for the electronic image, (B) generating a final image by decimating the electronic image by a decimation factor to a final resolution smaller than the initial resolution and (C) changing a zoom factor for the final image by adjusting both of the decimation factor and the window size.

Claims

1. A method for zooming a camera, comprising the steps of:

(A) generating an electronic image by sensing an optical image received by said camera, said sensing including electronic cropping to a window size to establish an initial resolution for said electronic image;

(B) generating a final image by decimating said electronic image by a decimation factor to a final resolution smaller than said initial resolution; and

(C) changing a zoom factor for said final image by adjusting both of said decimation factor and said window size.

2. The method according to claim 1, further comprising the step of:

maintaining said final resolution substantially constant throughout said changing.

3. The method according to claim 1, wherein step (C) comprises the sub-step of:

changing a bin ratio of said sensing based on an amount of said electronic cropping.

4. The method according to claim 1, further comprising the step of:

optically zooming said optical image to change said zoom factor.

5. The method according to claim 4, wherein said adjusting varies said zoom factor over a first range and said optically zooming varies said zoom factor over a second range adjoining said first range.

6. The method according to claim 5, wherein said adjusting varies said zoom factor over a third range adjoining said second range and opposite said first range.

7. The method according to claim 1, further comprising the step of:

generating said final image by interpolating said electronic image to said final resolution instead of decimating said electronic image while said window size is smaller than said final resolution.

8. The method according to claim 1, wherein (i) said electronic image comprises a sequence of electronic images, (ii) said final image comprises a sequence of final images and (iii) said adjusting causes a first of said final images to have a different zoom factor than a second of said final images.

9. The method according to claim 1, wherein said decimating comprises a horizontal decimation ratio and a vertical decimation ratio different than said horizontal ratio.

10. A method for zooming a camera, comprising the steps of:

(A) generating an electronic image by sensing an optical image received by said camera; and

(B) generating a final image from said electronic image, wherein (i) a zoom factor for said final image is determined by a combination of an amount of cropping used in generating said electronic image and an optical zooming for said optical image and (ii) said amount of cropping used to achieve said final zoom factor is controllable by a user.

11. The method according to claim 10, wherein said sensing maximizes a utilized area of said optical image.

12. The method according to claim 10, wherein said sensing minimizes a bin ratio used in generating said electronic image.

13. The method according to claim 10, further comprising the step of:

maximize a readout rate of said electronic image by minimizing at least one of said amount of cropping and an amount of a binning.

14. A system comprising:

a sensor array configured to generate a digital signal by sensing an optical signal, said sensing including electronic cropping to a window size to establish an initial resolution in said digital signal; and

a main circuit configured to (i) generate an output signal by decimating said digital signal by a decimation factor to a final resolution smaller than said initial resolution and (ii) change a zoom factor in said output signal by adjusting both of said decimation factor and said window size.

15. The system according to claim 14, wherein said main circuit comprises:

a decimation filter module configured to generate a first intermediate signal from said digital signal;

an interpolation module configured to generate a second intermediate signal by interpolating said digital signal; and

a format module configured to generate said output signal from one of said first intermediate signal and said second intermediate signal.

16. The system according to claim 15, wherein said main circuit further comprises a motor control module configured to control an optical zoom factor in said optical signal.

17. The system according to claim 14, wherein said output signal comprises a video bitstream.

18. A system comprising:

means for generating an electronic image by sensing an optical image received by said apparatus, said sensing including electronic cropping to a window size to establish an initial resolution for said electronic image;

means for generating a final image by decimating said electronic image by a decimation factor to a final resolution smaller than said initial resolution; and

means for changing a zoom factor for said final image by adjusting both of said decimation factor and said window size.

19. A camera comprising:

a sensor array configured to generate a digital signal by sensing an optical signal, said sensing including electronic cropping;

a lens assembly providing an optical zoom for said optical signal;

a main circuit configured to (i) generate an output signal from said digital signal and (ii) change a zoom factor in said output signal by adjusting a combination of said optical zoom and said electronic cropping; and

a user input module commanding said main circuit to establish (i) said zoom factor in said output signal and (ii) a relative contribution of said electronic cropping in said zoom factor.

20. The camera according to claim 19, wherein said user input module is configured to command said main circuit to minimize an amount of photon noise in said final image.

21. The camera according to claim 19, wherein said user input module is configured to command said main circuit to minimize an amount of distortion introduced in said electronic image by said sensor array.

22. The camera according to claim 19, wherein said main circuit is further configured to increase and decrease said zoom factor over time, one direction at a time.

23. A method for zooming a video camera, comprising the steps of:

(A) generating an electronic signal by sensing an optical signal received by said video camera, said sensing including an electronic cropping to a window size;

(B) generating a video signal having a zoom factor from said electronic signal; and

(C) determining based on said window size at least one of (i) a bin ratio for use in generating said electronic signal and (ii) if binning is used in generating said electronic signal.

24. The method according to claim 23, wherein said zoom factor is further determined by an optical zoom of said optical signal.