Focusing at a moving object accurately is difficult and important to take photo of the target successfully in a digital
camera. Because the object often moves randomly and changes its shape frequently, position and distance of the target
should be estimated at real-time so as to focus at the objet precisely.
We propose a new method of real-time object tracking to do auto-focus for moving target in digital camera. Video
stream in the camera is used for the moving target tracking. Particle filter is used to deal with problem of the target
object’s random movement and shape change. Color and edge features are used as measurement of the object’s states.
Parallel processing algorithm is developed to realize real-time particle filter object tracking easily in hardware
environment of the digital camera.
Movement prediction algorithm is also proposed to remove focus error caused by difference between tracking result
and target object’s real position when the photo is taken.
Simulation and experiment results in digital camera demonstrate effectiveness of the proposed method. We embedded
real-time object tracking algorithm in the digital camera. Position and distance of the moving target is obtained
accurately by object tracking from the video stream. SIMD processor is applied to enforce parallel real-time processing.
Processing time less than 60ms for each frame is obtained in the digital camera with its CPU of only 162MHz.
We present a new method to make virtual environment by using a sphere for reference. Images taken with digital camera or video camera are projected to the sphere. Relative orientation of adjacent images is determined by a linear transform and directions of all the images relative to the sphere are determined by multiplying the linear transform and directions of all the images relative to the sphere are determined by multiplying the linear transform matrix. Images are dynamically composed and projected back at a selected viewing direction without using an environment map. We have derived mathematical formula of the transform matrix. To improve the back projection speed, we also make environment maps by projecting images from the sphere to equator plane by setting projection center at southern or northern pole of the sphere. 3D scene can be projected to two circles in almost uniform pixel density without singularity at the poles. Distortion of lens causes large accumulated registration error. We developed a method for calibrating and correcting the distortion using matched corresponding points of adjacent images. A pyramid-based image matching method is also developed to reduce accumulated registration error.
A new computer generated hologram (CGH) zone-plate common path interferometer which can be used for testing an aspherical mirror with large aperture is presented. A CGH zone- plate made by laser beam drawing is used as the null optical element and its diffraction of (0, 0) and (+1, +1) orders are used as reference light and test light, respectively. Therefore, stigmatic points can be formed so as to use spatial filter effectively to get rid of extraneous light. As a result, fringes with high S/N can be obtained.
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