Atsushi Morimura

Automatic image stabilizing system by full-digital signal processing

An automatic image-stabilizing system for camcorders and VCRs utilizing only digital signal processing has been developed. New technologies for this system are (1) the BERP (band extract representative point) matching technique with a small-scale circuit, (2) an adaptive system control algorithm to discriminate moving objects, and (3) suppression of motion vectors due to noise. Calculations show that the motion vector detector requires only 11000 gates, the electronic zoom controller requires only 8500 gates, and only one 8-b field memory is required. >

An application of fuzzy set theory for an electronic video camera image stabilizer

An electronic video camera image stabilizer has been developed which eliminates a substantial part of the image instability caused by the involuntary movement of camera holders. For the discrimination between image movement caused by unstable hand-holding and that of moving objects, fuzzy set theory is applied through the following process: 1) dividing the image taken by the camera into four regions, 2) providing two signals to discriminate between the causes of image instability, 3) evaluating these two discriminating signals after they are transformed into reliability values by membership functions, and 4) tuning the membership functions using a simplex method. This image stabilizer has been incorporated into a new compact video camera, and its substantially improved field performance has been confirmed. >

Real-time active range finder using light intensity modulation

We propose a new real-time active range finder system, which operates at a video frame rate. Our system consist of a laser line pattern marker, a rotating mirror, a camera with an optical narrow bandpass filter, and a pipe-lined image signal processor. The vertical laser line pattern is horizontally scanned by the video-synchronized rotating mirror. The pattern is modulated with alternating a monotone decreasing intensity function and a monotone increasing function. The bandpass filter selectively transmits the laser light to decrease the disturbance of background light. Depth images are obtained using the intensity ratio of successive video field images, the coordinates of each pixel, and the baseline length. The intensity ratio specifies a line pattern in a plane. Meanwhile, the coordinates of each pixel specify a line that goes through the pixel position on the CCD and the center of the lens. Depth is calculated as an intersection point on the specified plane and line. The image signal processor can perform the above calculation using LUTs within a video frame. In this paper, we evaluate the measurable range, precision, and color properties of our system. Experimental results show that a two meters measurable range is obtained wit a 50 mW laser power, the standard deviations of the depth images with 5 by 5 median filtering are about 1 percent of the measured depth, and the object color has little effect on the measured depth except when the reflectance of the object is very small.

Scene reconstruction from distorted images using self-calibration of camera parameters

In this paper, we propose a new method for reconstructing a scene from different views through a high-distortion lens camera. Unlike other approaches, no a priori calibrations nor specific test patterns are required. Several pairs of correspondence between input images are used to estimate intrinsic parameters such as focal length and distortion coefficients. From these correspondences, relative movement of the camera between input images is computed as rotation matrices. We assumed radial lens distortion, modeled with a third order polynomial with two distortion coefficients, which covers highly distorted zoom lenses. Since we allow distortion with two coefficients and focal length to be unknown, it is not easy to get these three parameters explicitly from the correspondence alone. To avoid time consumption and the problem of local minima, we take the following steps: uniform searching in the reduced dimension; fitting a function to get a better guess of focal length; and polishing solutions by repeating the uniform search to get the final coefficients of distortion. The total number of evaluations is remarkably reduced by this multistage optimization. Some experimental results are presented, showing that more than 5% of lens distortion is reduced and the rotation of the camera is recovered, and we show a registration of four outdoor pictures.