Image coding/compression EE5364 DSP Project Pradeep Suthram, David Hemmert, Tammo Heeren All Mathcad files [MCD/PDF] can be found on: http://webpages.acs.ttu.edu/theeren

Overview Quantization Compression Linear quantization Adaptive quantization Compression DCT JPEG Wavelet

Linear Quantization Image intensities are quantized into equidistant quantization steps [Mathcad 2001 File]

Linear Quantization results 1 Bit 8 Bit

Linear Quantization error

Linear Quantization SNR 6.2dB per grayscale bit

Adaptive Quantization Quantization steps are scaled by the characteristic image probability density function [Mathcad 2001 File]

Adaptive Quantization results Linear quantization

Adaptive Quantization error (adaptive vs. linear)

Adaptive Quantization SNR 5.6dB per grayscale bit for adaptive quantization [red] 6.2dB per grayscale bit for linear quantization [blue]

JPEG Algorithm Lenna BMP file used 8x8 pixel block DCT Level-shift Quantizer Encoder Data Lenna BMP file used Gray scale image level-shifted by –128 for n = 8, 2^(n-1) = 128

using a typical normalization matrix JPEG Algorithm Quantization using a typical normalization matrix [ 16 11 10 16 24 40 51 61 12 12 14 19 26 58 60 55 14 13 16 24 40 57 69 56 14 17 22 29 51 87 80 62 18 22 37 56 68 109 103 77 24 35 55 64 81 104 113 92 49 64 78 87 103 121 120 101 72 92 95 98 112 100 103 99 ] Encoding Zig-Zag Pattern Huffman Coding Run-length Coding Tables DC Size | Amplitude AC Run/Size | Amplitude

To come: Compression DCT JPEG decompression Wavelet

References: Rafael C. Gonzalez, Richard E. Wood, “Digital Image Processing”, Addison Wesley, 1993 Geoffrey M. Davis, Aria Nosratinia, “Wavelet-based Image Coding: An Overview”, http://www.geoffdavis.net/ Subhasis, Saha, “Image Compression - from DCT to Wavelets : A Review”, http://www.acm.org/crossroads/xrds6-3/sahaimgcoding.html Weidong Kou, “Digital Image Compression Algorithms and Standards,” Kluwer Academic Publishers, 1995. “Selected Papers on Image Coding and Compression,” Majid Rabbani, Ed., Brian J. Thompson, Gen. Ed., SPIE Milestone Series, Vol MS-48, SPIE Optical Engineering Press, 1992. “Fractal Image Compression Theory and Application,” Yuval Fisher, Ed., Springer-Verlag New York, 1995. Bernd Jaehne, “Digital Image Processing”, Third Edition, Springer-Verlag, New York 1995