An efficient zonal sampling method for contour extraction and image compression using DCT transform

Three different algorithms of contour extraction and image compression using low-pass filter (LPF) and high-pass filter (HPF) is presented and compared with the traditional zonal sampling algorithm of low-pass and high-pass filters in this paper. The proposed algorithms are applied in spectral domain using Discrete Cosine Transform (DCT). Effectiveness of the contour extraction for different classes of images is evaluated. In the paper the main idea of the proposed procedure for both contour extraction and image compression are performed. To compare the results, the mean square error, signal-to-noise ratio criterions , and compression ratio (bit per pixel) were used. The simplicity to obtain compressed image and extracted contours with accepted level of the reconstruction is the main advantage of the proposed algorithms.