This paper describes research, conducted at DREV, to make a proof-of-concept implementation of a real-time image stabilization and registration system for airborne long- range imaging sensors. The methods developed could be used for aligning image sequences in real-time or for decreasing bothersome image vibrations in airborne video. This requirement occurs for instance when images come from different sensors and have to be registered prior to applying data fusion methods. In other applications, image observation by human operators and/or computer vision systems is made difficult by the presence of mechanical vibration which mutually offsets sequential frames by either translational or rotational displacements. This may be the case when doing long-range observations with a helicopter-mounted camera where even small motion of the vehicle can result in appreciable image panning. The project had two aims: (1) the development and the optimization of algorithms and methods for image registration at the pixel and sub-pixel levels; and (2) the implementation of these solutions at video rate in hardware. This was accomplished using COTS (commercial-off-the-shelf) hardware on an experimental test bed. Pixel level alignment is done by using and adapting motion-estimation methods based on a block-matching algorithm (a discriminative selection of blocks for optimal motion estimation is done using an interest operator based on texture analysis). Sub-pixel alignment is based on inverse interpolation. In addition, a pyramidal scheme is used as a preprocessing step to improve the robustness and speed of the image- alignment calculations. Description of the hardware implementing the real-time execution of these algorithms is given. Finally, future areas of development and improvement are briefly discussed.
Pixel and subpixel image stabilization at video rate for airborne long-range imaging sensors
Infrared Technology XX ; 1994 ; San Diego,CA,United States
Proc. SPIE ; 2269
1994-10-17
Conference paper
Electronic Resource
English
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