Abstract-We will present in this correspondence that for uniformly rotated images, the optimal approximation of the images can be obtained by computing the basis vectors for the discrete cosine transform (DCT) of the original image in polar coordinates, and representing the images as linear combinations of the basis vectors.Index Terms-Discrete cosine transform, Karhunen-Loeve expansion.
Abstract-We present a fast pattern matching algorithm with a large set of templates. The algorithm is based on the typical template matching speeded up by the dual decomposition; the Fourier transform and the Karhunen-Loeve transform. The proposed algorithm is appropriate for the search of an object with unknown distortion within a short period.Patterns with different distortion differ slightly from each other and are highly correlated. The image vector subspace required for effective representation can be defined by a small number of eigenvectors derived by the Karhunen-Loeve transform. A vector subspace spanned by the eigenvectors is generated, and any image vector in the subspace is considered as a pattern to be recognized.The pattern matching of objects with unknown distortion is formulated as the process to extract the portion of the input image, find the pattern most similar to the extracted portion in the subspace, compute normalized correlation between them at each location in the input image, and find the location with the best score. Searching for objects with unknown distortion requires vast computation. The formulation above makes it possible to decompose highly correlated reference images into eigenvectors, as well as to decompose images in frequency domain, and to speed up the process significantly.
W e developed a robot s y s t e m which can play one-onone volleyball games with a h u m a n player. It can n o t only hit a flying ball back t o the player correctly but also have various autonomous functionalities t o interact with h u m a n s necessary for playing games, i.e., it can pick u p a ball of a requested color b y recognizing voice instructions, can locate the players b y recognizing their faces, and can shake hands. This robot performed the entire game sequence over 100 times at a company-sponsored exhibition, where the ball rally continued over 25 t i m e s with a n arbitrary player. In this paper, we mainly describe the real-time visual feedback s y s t e m of the robot which is essential for playing ball games.
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