Authors:
Pol Moreno
and
Felipe Calderero
Affiliation:
Pompeu-Fabra University, Spain
Keyword(s):
Heat Equation, Reverse Diffusion, Sharpness Measures, Deblurring.
Related
Ontology
Subjects/Areas/Topics:
Computer Vision, Visualization and Computer Graphics
;
Features Extraction
;
Image and Video Analysis
;
Image Enhancement and Restoration
;
Image Formation and Preprocessing
Abstract:
The heat equation can be used to model the diffusion process shown in a defocused (blurry) region of a picture
taken with conventional camera lens. The original focused image can be recovered by reverting the heat
equation, that is, by reverse diffusion. However, the main difficulty with this technique is that it becomes
unstable very quickly due to the finite precision of pixel values and the image values blow up. For that reason,
detecting the exact time when the reverse diffusion process should stop is crucial. The goal of this work it to
evaluate the behavior of different non-reference state-of-the-art sharpness measures (that is, when a perfectly
focused image is not available) for the forward and inverse diffusion processes and to propose a robust stop
criterion to reliably detect the moment before each region becomes unstable. To find out a good stop criterion,
we carry out a set of experiments with test and real images. The results in this paper can be valuable not only
to es
timate monocular depth from blur cues, but also to any other image processing fields that require image
deblurring.
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