Showing papers on "Image compression published in 1976"
10 citations
13 Dec 1976
TL;DR: Analytical results generally indicate that due to the lack of high spatial correlation in the Rayleigh distributed radar surface reflectivity, application of data compression to SAR signals and images under the square difference fidelity criterion may be less effective than its application to images obtained using incoherent illumination.
Abstract: This paper describes some analytical results relative to the effectiveness of applying data compression techniques for efficient transmission of synthetic aperture radar (SAR) signals and images. A Rayleigh target model is assumed in the analysis. It is also assumed that all surface reflectivity information is of interest and needs to be transmitted. Spectral characteristics of radar echo signals and processed images are analyzed. Analytical results generally indicate that due to the lack of high spatial correlation in the Rayleigh distributed radar surface reflectivity, application of data compression to SAR signals and images under the square difference fidelity criterion may be less effective than its application to images obtained using incoherent illumination. On the other hand, if certain random variations in radar images are considered as undesirable, substantial compression ratio may be achieved by removing such variations.
8 citations
09 Jul 1976
TL;DR: A state-of-the-art survey of digital image coding techniques is presented and performance analyses are given for pulse code modulation, statistical, frame replenishment, predictive, interpolative, and transform coding methods.
Abstract: A state-of-the-art survey of digital image coding techniques is presented. Performance analyses are given for pulse code modulation, statistical, frame replenishment, predictive, interpolative, and transform coding methods.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
7 citations
13 Dec 1976
TL;DR: In this paper, an approach is proposed that utilizes modern adaptive estimation and identification theory techniques to learn the picture statistics in real time so that an optimal set of coefficients can be identified as the signal statistics change.
Abstract: Historically, the data compression techniques utilized to process image data have been Unitary Transform encoding or time domain encoding. Recently, these two approaches have been combined into a hybrid transform domain time domain system. The hybrid system incorporates some of the advantages of both concepts and eliminates some of the disadvantages of each. However, the problems of picture statistics dependence and error propagation still exist. This is due to the fact that the transformed coefficients are non-stationary processes, which implies that a constant DPCM coefficient set cannot be optimal for all scenes. In this paper, an approach is suggested that has the potential of eliminating or greatly alleviating these problems. The approach utilizes modern adaptive estimation and identification theory techniques to "learn" the picture statistics in real time so that an optimal set of coefficients can be identified as the signal statistics change. In this way, the dependency of the system on the picture statistics is greatly reduced. Furthermore, by updating and transmitting a new set of predictor coefficients periodically, the channel error propagation problem is alleviated.
5 citations
13 Dec 1976
TL;DR: Research is described which extends transform and linear predictive spatial domain image coding concepts to the coding of frame-to-frame sequences of digital images, and models are developed for transform coefficient and transform coefficient temporal difference variance matrices.
Abstract: This paper describes research which extends transform and linear predictive spatial domain image coding concepts to the coding of frame-to-frame sequences of digital images. The emphasis is directed towards interframe image coding systems that exploit temporal as well as spatial image redundancies. Interframe coder implementations investigated include three-dimensional unitary transform coders and hybrid coders which employ two-dimensional transforms in the spatial domain coupled with first-order DPCM predictive coding in the temporal domain. Based on a statistical image representation, models are developed for transform coefficient and transform coefficient temporal difference variance matrices. Using these models, theoretical MSE performance levels for both coders are determined as a function of spatial subblock size. Results are verified by computer simulation experiments.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
5 citations
TL;DR: The requirements, design, implementation, and flight performance of an on-board image compression system for the lunar orbiting Radio Astronomy Explorer-2 (RAE-2) spacecraft are described.
Abstract: The requirements, design, implementation, and flight performance of an on-board image compression system for the lunar orbiting Radio Astronomy Explorer-2 (RAE-2) spacecraft are described. The image to be compressed is a panoramic camera view of the long radio astronomy antenna booms used for gravity-gradient stabilization of the spacecraft. A compression ratio of 32 to 1 is obtained by a combination of scan line skipping and adaptive run-length coding. The compressed imagery data are convolutionally encoded for error protection. This image compression system occupies about 1000 cm2 and consumes 0.4 W.
4 citations
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TL;DR: A brief review of the state-of-the-art in digital image processing is given in this paper, where the potential for mini-computer and/or special-purpose computers to fill this need is discussed, and features of needed computer architecture are considered.
Abstract: A brief review of the state-of-the-art in digital image processing is given. Wide-spread applications of digital image processing will require maximum computing power at cost less than that of the large-scale computers often used in image processing research. Increased sophistication in processing algorithms will also create a need for even more computing power. The potential for mini-computer and/or special-purpose computers to fill this need is discussed, and features of needed computer architecture are considered.
4 citations
13 Dec 1976
TL;DR: Three modifications of the Constant Area Quantization (CAQ) image bandwidth compression technique have been developed and tested in order to broaden the range of compression ratios obtainable with acceptable image quality.
Abstract: Three modifications of the Constant Area Quantization (CAQ) image bandwidth compression technique have been developed and tested in order to broaden the range of compression ratios obtainable with acceptable image quality. The first modification involved the introduction of an adaptive area threshold, the second was a two-threshold algorithm and the third was a hybrid of the CAQ with a Hadamard transform technique. Using these three algorithms together with the basic CAQ, images spanning the range from 0. 2 to 2 bits per picture element were obtained from an 8 bit original.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
3 citations
15 Sep 1976
TL;DR: The modified gradient operation considered in this report takes the product of four conventional gradient operations in four different directions to provide great improvement in noise reduction and boundary extraction over the conventional gradient operation.
Abstract: : The modified gradient operation considered in this report takes the product of four conventional gradient operations in four different directions Such modified procedure is shown by extensive computer results to provide great improvement in noise reduction and boundary extraction over the conventional gradient operation Furthermore, the procedure is computationally simple and insensitive to rotation of images Computer results of modified gradient operation followed by image compression are also presented (Author)
2 citations
13 Dec 1976
TL;DR: It is hypothesized that a rudimentary measure of human color perception can help define a fidelity measure for color image coding, and a simple visual model is considered, which defines a non-linear transformation of the red, green and blue image components into functions that are more closely related to the perceived colored stimuli.
Abstract: Werner FreiAssistant Professor of Electrical EngineeringImage Processing InstituteUniversity of Southern CaliforniaLos Angeles, California 90007AbstractIt is hypothesized that a rudimentary measure of human color perception can help define a fidelitymeasure for color image coding. A simple visual model is considered, which defines a non -lineartransformation of the red, green and blue image components into functions that are more closely relatedto the perceived colored stimuli. The effects of the transformations on image coding efficiency arediscussed, and an optimal coder, which minimizes the average distortion of these "perceptual" imagefunctions is simulated. Results provide a tentative quality yardstick for actual coders operating at thesame bit rate, but further experiments will be required to substantiate the results.
2 citations
Proceedings Article•
01 Jan 1976
13 Dec 1976
TL;DR: Way in which the image pixels can be permuted before the image is blocked and a special annihilation transform technique to perform the image coding is discussed.
Abstract: In the usual transform compression encoding schemes, an image is divided into regular shaped subimages or blocks, a transform is performed on each block, low energy components thrown away, remaining components encoded and transmitted, and then the received image reconstructed. This paper discusses ways in which the image pixels can be permuted before the image is blocked and a special annihilation transform technique to perform the image coding. Experimental results show the compressed images to have no blocking effects, but a more mottled appearance compared to a discrete cosine transform coding method. The annihilation method on permuted images not only gives reconstructed images better visual quality, but also gives lower RMS error.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.