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Motion blur can significantly degrade image quality, often resulting from object motion, camera translation, or rotation. This guide explores the Point Spread Function (PSF), convolution models, and de-blurring techniques to recover sharp images. We assume pure translation of the camera, no object motion during exposure, and minimal parallax for the ideal scenario. Experimental validation using DSLR hand-held shots demonstrates the application of these techniques, including the use of known kernels for effective deconvolution. Regularization methods are discussed to manage noise and stabilize results.
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Sources of blur • Object motion
Sources of blur • Object motion • Translation of camera
Sources of blur • Object motion • Translation of camera • Rotation of camera
Sources of blur • Object motion • Translation of camera • Rotation of camera • Defocus • Internal camera distortions
PSF = Point Spread Function (PSF) Assume: • Point light source
B = KL + N Convolution model motivation • Assume: • No image plane rotation • No object motion during the exposure • No significant parallax (depth variation) Camera motion is Pure Translation!!! • Violation of assumption:
B = KL + N Convolution model motivation • Assume: • No image plane rotation • No object motion during the exposure • No significant parallax (depth variation) Camera motion is Pure Translation!!! • Experimental validation: 8 subjects handholding DSLR with 1 sec exposure Close-up of dots
Generation rule:B = KL + N Convolution Model • Notations • L: original image • K: the blur kernel (PSF) • N: sensor noise (white) • B: input blurred image +
Fourier Convolution Theorem! How can the image be recovered? Assumptions: • Known kernel (PSF) • Constant kernelfor the whole image • No noise Goal: • Recover Ls.t.: B = KL
De-blur using Convolution Theorem Convolution Theorem:
Recovered Example: Blurred Image PSF
Deconvolution is unstable Example: Noisy case:
FT of original signal Original signal Convolved signals w/w noise FT of convolved signals Reconstructed FT of the signal 1D example: Regularization is required
51 151 191 Regularizing by window Window size: