| Summary: | 碩士 === 中華大學 === 資訊工程學系(所) === 98 === This thesis proposes an effective color-difference-based (ECDB) interpolation algorithm for CFA Image demosaicking. A CFA image consists of a set of spectrally selective filters which are arranged in an interleaved pattern such that only one of color component is sampled at each pixel location. To improve the quality of reconstructed full-color images from color filter array (CFA) images, the ECDB algorithm first analyzes the neighboring samples around a green missing pixel to determine suitable samples for interpolating the value of this green missing pixel. After finishing the interpolation operations of all the green missing pixels, a complete green plane (i.e G plane) can be obtained. The ECDB algorithm then makes use of the high correlation between R, G, and B planes to produce the red-green and blue-green color difference planes and further reconstructs the red and the blue planes in successive operations. Because of the green plane provides twice information than red and blue planes, the algorithm exploits the information of green plane more than that of red/blue plane so that the full color image can be reconstructed more accurately. In essence, the ECDB algorithm not only ingeniously combines several up-to-date mainstream interpolation techniques but also designs an effective pixel categorization mechanism to develop a high efficient interpolation mechanism. Compared with other existed methods, the ECDB algorithm contains three main advantages: 1, it peculiarly categories each pixel based on a newly designed geometrical position relationship and then it effectively applies different interpolation mechanisms for different categories; 2, it classifies the pixel variation of a local region in more detail, and designs the effective interpolation mechanism with suitable neighboring pixels and appropriate weighting technique for each kind of pixel variation; and 3, instead of using only the first-order gradient of a certain color, it makes use of the second-order gradient of other color to estimate the missing value of this certain color, because the second-order gradient of other color provides the extra color variation trend which is useful to interpolate the missing color value. The experimental results performed on the well-known Kodak 3-CCD image database demonstrate that the proposed algorithm has outstanding performance
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