應用矩量保持技術於影像改良,壓縮與分析

Abstract

First, a method of color image sharpening by moment- preserving (MP) is proposed. We develop a new set of color monents. By preserving some color moments of the n*n neighborhood of each pixel, analytic formulas are derived to compute two representative sets of tristimulus color values, and one of them is assign to the pixel as the sharpening result. Second, three image compression methods using MP techniques are proposed. The first method is an improvement of the BTC method. A set of line and edge bit planes are predefined and an adaptive bit plane selection scheme is developed. The second method is a color image compression scheme using MP and BTC techniques. We preserve the new set of color moments mentioned previously to obtain two representative colors and use the Euclidean distance measure to generate a bit-map for each image block. We also present a revised version of the proposed method to obtain a higher compression and good reconstructed image quality. In the third proposed method, a new approach to color quantization using MP thresholding and efficient coding of edge detection results on the bit map are included. Beside, a new approach to subpixel edge detection by mass MP is also proposed. The edge location can estimated directly from analytic formulas with subpixel accuracy. Finally, a method for reduction of color space dimensionality is proposed. After obtaining two representative colors in each image block, we employ the difference vector between the two colors as an axis onto which all the data in the block are projected to reduce the color space into one dimensional. A single spectral image is thus obtained, on which the proposed subpixel edge detection by mass MP is implemented to perform color edge detection. Experimental results are given to show the effectiveness of all the proposed methods.