Block Truncation coding is a simple and efficient technique for compressing still images. Absolute Moment Block Truncation Coding (AMBTC), an improved form of BTC has been enhanced in this proposed method to achieve better results in terms of PSNR (Peak Signal to Noise Ratio) and bpp (bits per pixel). In BTC and AMBTC based techniques, only two quantizers are used. In the proposed method, four quantizers are used for improving the quality of reconstructed images, by categorizing the blocks based on the distribution of gray levels among the pixels. Adaptive bit-plane patterns are generated to improve the coding efficiency. This method is tested with standard benchmark images such as Lena, Cameraman, Boats, Bridge, Baboon and Kush. For all the images, the proposed method gives better results in terms of bpp and PSNR when compared to that of existing techniques.

AMBTC, bpp, Coding Efficiency, hMean, Image Compression, lMean, PSNR.

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