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Mean-Field Theory and Its Applications In Computer Vision3. Gaussian Pairwise Potential. Expensive message passing can be performed by cross-bilateral filtering. Spatial. Range. Cross bilateral filter. output. input. output. input. reproduced from [Durand 02].
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Gaussian Pairwise Potential Expensive message passing can be performed by cross-bilateral filtering Spatial Range
Cross bilateral filter output input output input reproducedfrom [Durand 02]
Efficient Cross-Bilateral Filtering • Based on permutohedral lattice (PLBF)2 • Embed the points on the permutohedral lattice • Apply Gaussian Blurring
Efficient Cross-Bilateral Filtering • Based on permutohedral lattice (PLBF)2 • Embed the points on the permutohedral lattice • Apply Gaussian Blurring • Based on the domain-transform (DTBF)3 • Project the point to lower dimension • Perform filtering in the transformed domain
Efficient Cross-Bilateral Filtering • Based on permutohedral lattice (PLBF)2 • Embed the points on the permutohedral lattice • Apply Gaussian Blurring • Based on the domain-transform (DTBF)3 • Project the point to lower dimension • Perform filtering in the transformed domain • Filtering in frequency domain • Apply fast fourier transform • convolution in (s) domain=multiplication in (f) domain
Permutohedral Lattice based filtering • For each pixel (x, y) • Downsample all the points (dependent on standard deviations)
Embed to the permutohedral lattice • Embed each downsampled points to the lattice
Embed to the permutohedral lattice • Embed each downsampled points to the lattice
Embed to the permutohedral lattice • Embed each downsampled points to the lattice
Embed to the permutohedral lattice • Embed each downsampled points to the lattice
Gaussian blurring • Apply Gaussian blurring along axes
Gaussian blurring • Apply Gaussian blurring along axes
Gaussian blurring • Apply Gaussian blurring along axes
Splatting • Upsample the points
Splatting • Upsample the points
PLBF • Final upsampled points
Domain Transform Filtering • Project points in low-dimension preserving the distance in the high dimension • Filtering performed in low-dimension space • Projecting to the original space
Filtering in high-dimension space Inefficient Spatial Range
Projection in low-dimension space • Project to low-dimension • Maintain geodesic distance high-dimension space
Projection in low-dimension space • Project to low-dimension • Maintain geodesic distance high-dimension space
Projection in low-dimension space • Project to low-dimension • Maintain geodesic distance high-dimension space
Gaussian blurring in low-dimension • Apply Gaussian blurring in low-dimension space
Project • Project the blurred values in the original space
Project • Project the blurred values in the original space
PLBF Vs DTBF • Processing Time: • Both linear in the number of pixels • Filter parameter: • PLBF runtime is inversely proportional to the kernel size defined over space and range • Use PLBF with the relatively large (~10) range • Use DTBF with relatively smaller (~1-2) range
Convergence • Iteration vs. KL-divergence value • In theory: (since parallel update) convergence is not guaranteed • In practice: converges observe a convergence
MSRC-21 dataset • 591 colour images, 320x213 size, 21 object classes
MSRC-21 dataset • 591 colour images, 320x213 size, 21 object classes
PascalVOC-10 dataset • 591 colour images, 320x213 size, 21 object classes
PascalVOC-10 dataset • 591 colour images, 320x213 size, 21 object classes
Long-range connections • Accuracy on increasing the spatial and range standard deviations • On MSRC-21 spatial – 61 pixels, range – 11
Long-range connections • On increasing the spatial and range standard deviations • On MSRC-21 spatial – 61 pixels, range – 11
Long-range connections • Sometimes propagates misleading information
Mean-field Vs. Graph-cuts • Measure I/U score on PascalVOC-10 segmentation • Increase standard deviation for mean-field • Increase window size for graph-cuts method • Both achieve almost similar accuracy
Mean-field Vs. Graph-cuts • Measure I/U score on PascalVOC-10 segmentation • Increase standard deviation for mean-field • Increase window size for graph-cuts method • Time complexity very high, making infeasible to work with large neighbourhood system