Some General Study on Image Restoration.
Date of Submission
December 1992
Date of Award
Winter 12-12-1993
Institute Name (Publisher)
Indian Statistical Institute
Document Type
Master's Dissertation
Degree Name
Master of Technology
Subject Name
Computer Science
Department
Electronics and Communication Sciences Unit (ECSU-Kolkata)
Supervisor
Ray, Kumar Sankar (ECSU-Kolkata; ISI)
Abstract (Summary of the Work)
Image restoration is a well known problem of image processing. Several works have been developed in this direction by several researchers [1] [2] [3] [4]. But one drawback of all these works is that they have not considered the nonnegativity constraint of the restored gray level value. The negative values in the gray level value implies an absurdity of negative intensities of radiant energy in the original object distribution.Another drawback some of the said works, where of certain optimal conditions are tested, is that there is no explicit test for sufficiency of optimality of the restoration. In addition to this sometimes the necessary extreme point of restoration, is shifted heuristically to achieve nonnegative value of the gray levels of the restored image.Considering all these drawbacks of the existing image restoration methods , in this dissertation, we represent an pproach for unconstrained and constrained image restoration sethods using Quadratic Programming Technique. Along with the suitable constraint equations, needed for improving the quality of the restored image, we consider the non-negativity constraints of the restored gray level image. We also consider the necessary and sufficient conditions of optimality of the objective function.The image represented by a vector of order (n x 1) is degraded due to defocusing and additive noise. The obtained image , represented by a vector of order (m x 1) is formed by the relation g = Hf + 1, where H is the degraded matrix of order (m x n). H is formed by the concept of point spread function [2] [4] and 7 of order (m x 1) is uncorrelated random noise. In the absence of any knowledge about our object isto minimize Z(f) (g Hf) (g - hf) (1) subject to the condition ft≤ 0.To further improve the quality of image add the we following constraint equations,Vf ≤ p where is the vector formed by the second derivative of the given image ‘g’ and V’ is the smoothing matrix [1].We also propose a method to estimate the degradation matrix H on the basis of sample values of original image 'f and degraded image ‘g’.
Control Number
ISI-DISS-1992-171
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
DOI
http://dspace.isical.ac.in:8080/jspui/handle/10263/6339
Recommended Citation
kanrar, Asit, "Some General Study on Image Restoration." (1993). Master’s Dissertations. 180.
https://digitalcommons.isical.ac.in/masters-dissertations/180
Comments
ProQuest Collection ID: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqm&rft_dat=xri:pqdiss:28843201