IMAGE REGISTRATION USING N-FOLD BLUR REMOVAL

CONTENTS

• Introduction• Objective• Existing system• Proposed system• Block diagram• Formulae• Output

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INTRODUCTION• The original method works for unknown blurs,

assuming the blurring point-spread function(PSF) exhibits an N-fold rotational symmetry.

• This makes registration algorithm well-suited in applications where blurred image registration must be used as a preprocess step.

• This leads to an improvement of the image registration performance.

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OBJECTIVE• To improve the performance of image registration and

reduce the error occurrence, we implement the N-fold blur removal.

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EXISTING SYSTEMS.no Title Algorithm Drawback Performance

1. Automatic image registration for applications in remote sensing

Edge-based Selection of the control points

Feature inconsistance

Accuracy is 76.5%

2. Blur invariant translational image registration for N-fold symmetric blurs

Global based blur invariant

PSF has no symmetry

Computational speed is 170 seconds

3. Combined invariants to similarity transformation and to blur using orthogonal zernike moments

Orthogonal zernike moments

Not adaptive for order invariance(only even order invariance)

Accuracy 92%

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Cond…S.no Title Algorithm Drawback Performance

4. Moment forms invariant to rotation and blur in arbitrary number of dimensions

Moment forms invariant

Degraded performance of boundary effect

Accuracy 83%

5. Blur Invariant Phase Correlation in X-Ray DigitalSubtraction Angiography

splineimage warping

Not support for motion artifacts

Registration error is 0.9

6. Multichannel blind deconvolution of spatially misaligned images

Maximum a posteriori probability (MAP)

Inaccurate registration of channels

Better performance and high SNR

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Cond…S.no Title Algorithm Drawback Performance

7. Wavelet-domain blur invariants for image analysis

Spatial-Domain Blur Invariants(SDBI)

Failed in asymmetric blur registration task

Accuracy is 75%

8. Degraded image analysis: An invariant approach

Combined invariants

Focused only on combined invariants not on image rotation andaffine transform.

SNR value is lower than 10 db

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PROPOSED SYSTEM• Registration method designed specifically for registering

blurred images.

• Registration of blurred images requires special methods because general registration methods usually do not perform well on blurred images.

• Global based blur invariant approach of phase correlation.

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BLOCK DIAGRAM

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Image Blurred image PSF estimation

N-fold blur removal(3-fold and 6-fold)Deblurred image

Image taken with camera having shutter with four blades and shape of the PSF can

be clearly viewed in the out-of-focus background. PSF has 4-fold

rotational symmetry

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Reference image Blurred sensed image

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PSF’s of three common compact cameras

9-fold 6-fold 4-fold

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Registration of two images

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formulaeRecalling the original method g⟹ blurred sensed image f⟹ reference image h⟹ point spread function Δ⟹ shift x⟹ number of pixels h⟹ h(r,θ) = h(r, θ+2πj/N) N⟹ number of folds

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g(x) = (f * h)(x - Δ)

Cond…Projection operators ⟹Used to eliminate the blur

= F(u) / F(u) ; j=1,………,N F(u) F{f}(u) is the Fourier transform of f(x) Rju Rotation of frequency coordinates by the angle 2⟹ πj/N Rju= 2*pi*j/N

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Cond…Blur Invariant Operators ⟹ To calculate reflection operator S(x) =

S(x)⟹ Reflection operator 𝛼 ⟹ Angle b/w reflection line and horizontal axis

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Cond… ⟹ To calculate the Fourier Transform for original image and

dihedral blurred image

f Original image⟹ Df Dihedral blurred⟹ image

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F{f} / F{Df}

Cond… ⟹ To calculate the invariants to dihedral blur

= F{f} / F{ ; j=1,………,N

F{f} Fourier transform of original image⟹

F{ Rotational symmetry(Cyclic groups,Cf)⟹

L = F{f} / F{ ; j=1,………,N

F{ Rotational and Reflectional symmetry (Dihedral groups, ⟹Df)

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Cond…Image registration algorithm

⟹used to design a robust blur-invariant registration method

To calculate the normalized cross-power spectra

Cj = ; j=1,…N (Rotation)

│ │ Bj = │ │ ; j=1,…N (Rot+Ref)

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Cond…Inverse Fourier Transform of Cj

{Cj }(x) = 𝛿(x +Δ - Δ)

Inverse Fourier Transform of Bj

{Bj }(x) = 𝛿(x +Δ - S Δ)

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Two images acquired by a hand-held camera with different

focus settings and shift

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Two frames from a video sequence taken with different focus settings

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Original image

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Blurred image

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Rgb to gray converted image

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Psf for Dihedral blurred image

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dihedral blurred image

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Psf for blurred image

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Registration of 3-fold and 6-fold

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PerformanceN-Folds

Mis-Registration (%) MSE PSNR(dB)

Only fold Fold+ dihedral

3-Folds 31% 20% 0.005 33 dB

6-Folds 22.5% 12% 0.0019 38.5 dB

Thank you

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