Camera Motion Stabilization
Users of digital cameras may wish to record moving objects against a constant background. Achieving this outcome requires the detection of movement in the background itself, along with the restoration of a stable background behind the moving objects. Existing techniques are inadequate because they can only work with a small number of frames before consuming too much memory. The invention solves this problem by maintaining a cumulative 'mosaic' frame of the background. The resulting procedure can be adapted to produce several effects relying on background detection.
The crux of the invention is a mosaic frame representing a composite assessment of the image background. The mosaic is larger than any individual frame—because it includes older data that now falls outside the margins—but does not include data changeable enough to constitute a foreground object. The background of each new frame is distinguished through comparison to the mosaic. When background elements are identified, the frames can be anchored onto the mosaic. The procedure can then output video in which foreground objects move in front of a fixed composite.
- Compensates for camera movements resulting from shaking by anchoring images according to a reasonable assessment of the background.
- Offsets internal camera effects such as automatic gain control.
- Allows user to customize preferred background changeability and other elements.
- Facilitates video compression by eliminating redundant background data.
- Saves memory relative to earlier techniques assessing the same number of frames.
The patent describes a cycle of operations performed after the input of each new frame. The frame is searched for areas resembling those in the mosaic. This search can use one of many procedures, each of which will yield a different outcome. Once the background elements of the new frame have been defined, the image can be anchored atop the mosaic. The mosaic and input frame modify each other according to criteria set by the user. A threshold for changeability determines the power of the new frame to alter the mosaic and vice-versa. This core procedure can be used to create different outputs.
License - Intellectual PropertyWO2003043348
Determination Motion of a Background