JPEG-Still Image Compression Standard.ppt

JPEG-Still pression Standard

CSIS Group
BITS-Pilani
Source: Chapter 3 of JPEG—Still pression StandardJPEG2000 Standard for pression: Concepts, Algorithms and VLSI Architecturesby Tinku Acharya and Ping-Sing Tsai
13-Feb-2007
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Topics today…
Introduction
The JPEG Lossless Coding Algorithm
Baseline pression
Progressive DCT-Based Mode
Hierarchical Mode
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EA C473 puting
Introduction
JPEG is the first pression standard for continuous tone still images
Acronym for Joint Photographic Experts Group
Officially referred to as
ISO/IEC IS (International Standard) 10918-1: pression and Coding of Continuous-tone Still Images
ITU-T mendation
13-Feb-2007
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Introduction [2]
Goal of the standard is to support a variety of applications pression of continuous-tone still images of most image sizes in any color space in order to pression performance at or near the state-of-the-art with user-pression ratios and with very good to excellent reconstructed quality
13-Feb-2007
EA C473 puting
Introduction [3]
JPEG defines four modes of operation
Sequential Lossless Mode: Compress the image in a single scan and the decoded image is an exact replica of the original image.
Sequential DCT-based Mode: Compress the image in a single scan using DCT-based pression technique. As a result, the decoded image is not an exact replica, but an approximation of the original image.
Progressive DCT-based Mode: Compress the image in multiple scans and also press the image in multiple scans with each essive scan producing a better-quality image.
Hierarchical Mode: Compress the image at multiple resolutions for display on different devices.
13-Feb-2007
EA C473 puting
Introduction [4]
Modes 2, 3 and 4 are lossy
Mode 1 uses predictive coding with no quantization, hence lossless
Sequential DCT-based JPEG algorithm
In it’s simplest form called baseline JPEG algorithm, which is based on Huffman coding for entropy encoding
The other form is based