Abstract

Abstract Image de-blurring is an inverse problem whose intent is to recover an image from the image affected badly with different environmental conditions. Usually, blurring can happen in various ways; however, de-blurring from a motion problem with or without noise can pose an important problem that is difficult to solve with less computation task. The quality of the restored image in iterative methods of blind motion de-blurring depends on the regularization parameter and the iteration number, which can be automatically or manually stopped. Blind de-blurring and restoration employing image de-blurring and whiteness measures are proposed in this paper to automatically decide the number of iterations. The technique has three modules, namely image de-blurring module, whiteness measures module, and image estimation module. New whiteness measures of hole entropy and mean-square contingency coefficient have been proposed in the whiteness measures module. Initially, the blurred image is de-blurred by the employment of edge responses and image priors using point-spread function. Later, whiteness measures are computed for the de-blurred image and, finally, the best image is selected. The results are obtained for all eight whiteness measures by employing evaluation metrics of increase in signal-to-noise ratio (ISNR), mean-square error, and structural similarity index. The results are obtained from standard images, and performance analysis is made by varying parameters. The obtained results for synthetically blurred images are good even under a noisy condition with ΔISNR average values of 0.3066 dB. The proposed whiteness measures seek a powerful solution to iterative de-blurring algorithms in deciding automatic stopping criteria.

Highlights

  • Image blurring is one of the prime causes of poor image quality in digital imaging

  • The results are obtained for all eight whiteness measures by employing evaluation metrics of increase in signal-to-noise ratio (ISNR), mean-square error, and structural similarity index

  • The maximum ISNR obtained is for iteration number 22, which is shown in the graph of ISNR vs. iteration, which matches with the selection of iteration number based on whiteness measure by maximizing already existing whiteness measures such as covariance, weighted co-variance entropy, block covariance, block weighted co-variance, and block entropy, and by minimizing newly proposed mean-square contingency coefficient and holoentropy

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Summary

Introduction

Image blurring is one of the prime causes of poor image quality in digital imaging. Two main causes of blurry images are out-of-focus shots and camera shake. The image recovery problem is to estimate an image from the blurred image by use of various methods [7]. The iterations have to be manually stopped when a good image estimate with high increase in signal-to-noise ratio (ISNR) value is obtained. Stein’s unbiased risk estimate-based [11, 12] approaches are not useful in BID, as it requires full knowledge of the degradation model, but is useful in NBID. It provides an estimate of the mean-square error (MSE), by assuming knowledge of the noise distribution and requiring an accurate estimate of its variance [26].

Review of Related Works
Contribution of the Paper
Image De-blurring Module
W hiteness Measures Module
Image Estimation Module
Results and Discussion
Simulation Results
Performance Analysis
Conclusion
Full Text
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