2009 International Conference on Advances in Recent Technologies in Communication and Computing

Halftoning is the printing technology in which each pixel in halftone image is represented by single bit. Hence halftoning gives 87.5% compression ratio. Modified Huffman encoding technique is used on halftone image for further compression of image data. This algorithm achieves a high compression ratio that ensures optimum utilization of network resources and storage. In our earlier work a small operator of size 3x3 is used, which effectively takes only one tap operation. Floyd-Steinberg operator which takes 5 tap operations has been used. Thus factors, like computational complexity, memory space and image quality, have been considered. The proposed algorithm has been implemented on MATLAB platform and has been tested on various images of size 256x256. The image quality measurement has been done using Mean Square Error and Structural Similarity Index parameters. The proposed technique can be used for storage of images in this hybrid compressed form, and low bit rate data transmission for video conferencing.

Image Compression Using Halftoning and Huffman Coding

Halftone technique is well known for printing where binary data is required. 8:1 compression ratio is achieved by half toning method. To get higher compression ratio the same technique can be used in image processing. In our earlier work different half toning operators are proposed. The half toning operator of size 3X3 which effectively take only one tap operation. Hence the computational complexity and memory space is reduced. For further compression of the image data Vector Quantization technique is used. Vector Quantization technique itself gives very high compression ratio. To avoid time and computational complexity Kekre’s Fast Code Book Generation (KFCG) algorithm is used. In this paper we have used 8, 16, 32, 64, 128 and 256 codebook sizes are used. The pixel group of 2X2 size is used. The experimental results are obtained for various images. For image data compression and image quality measurement, we have used Compression Ratio and Mean Square Error as measuring parameters respectively. We have got result with good Compression Ratio and acceptable image quality. This proposed combination of two compression technique is suitable for video data streaming, where low bit rate for data transmission is the major constraint.

Halftone Image Data Compression Using Kekre's Fast Code Book Generation (KFCG) Algorithm for Vector Quantization

Transmission of audio-video data over internet applications like Multimedia is increasing with fast pace. Biometric, Content Based Image Retrieval (CBIR), CCTV footage applications require huge storage of images in database. For such applications this combination of half tone with Huffman coding is useful. Half toning is lossy technique used in printing industry where binary image is required. Objective of achieving higher Compression Ratio by combining lossy half tone and lossless Modified Huffman coding techniques is used. Apart from standard operator like Floyd-Steinberg and Jarvis operators, Small and South-East operator are used. Halftone and Huffman coding technique is implemented on 10 different color images of size 512x512. For measurement of image quality, Mean Square Error (MSE) and Peak Signal-to-Noise Ratio (PSNR) and Structure Similarity Index (SSIM) are used. This hybrid technique can use for low bit rate video data transmission and mass image storage.

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Image Reconstruction using Fast Inverse Half tone and Huffman Coding Technique

Overhead of data transmission over internet is increasing exponentially every day. Optimization of natural bandwidth is the basic motive by compressing image data to the maximum extend. For the same objective, combination of lossy half tone and lossless Wavelet Transform techniques is proposed so as to obtain low-bit rate video data transmission. Decimal values of bitmapped image are to be converted into either 1 or 0 in half toning process that incur pictorial loss and gives 8:1 compression ratio (CR) irrespective of image. Wavelet Transform is applied on half tone image for higher compression for various levels. An experimental result shows the higher CR, minimum Mean Square Error (MSE). Ten sample images of different people captured by Nikon camera are used for experimentation. All images are bitmap (.BMP) 512 X 512 in size. The proposed technique can be used for video conferencing, storage of movies and CCTV footage etc.

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Data Compression for Video-Conferencing using Half tone and Wavelet Transform

A Fast Inverse Half toning algorithm is used for error diffused halftones. Halftones and other binary images are difficult to process cause several degradations. Jarvis’s halftoning operator is used to obtain sharper halftone image. Color image of 24-bit BMP formats splits image into 8- bit R-G-B planes. Degradation is greatly reduced if the halftone is inverse halftone (converted to gray scale) before scaling, or other processing. At each pixel, the proposed algorithm applies a separable 7 x 7 FIR filter. The filter passes in vertical and horizontal direction separately and computes vertical and horizontal edge strengths from local gradients. It requires entirely local operations and storage of 7 rows. We compare our algorithm with previously reported approaches to show that it delivers comparable subjective quality at a fraction of the computation and memory usage.

Restoration of Color Halftone Image by Using Fast Inverse Half Toning Algorithm

A new approach for removing blocking artifacts in reconstructed block-encoded images is presented in [1].The perceptual quality of video affected by packet losses, low resolution and low bit video coded by the H.264/AVC encoder is studied in [2]. Digital halftoning is a nonlinear system that quantizes a gray level image to one bit per pixel[3]. Halftoning by error diffusion scans the image, quantizes the current pixel, and subtracts the quantization error from neighboring pixels in fixed proportions according to the error filter. The error filter is designed to minimize a local weighted error introduced by quantization.

H. B. Kekre

Papers

Restoration of Color Halftone Image by Using Fast Inverse Half Toning Algorithm

Image data compression using new halftoning operators and run length encoding