Image PyramidsImage Pyramids

• Pre-filter images to collect information Pre-filter images to collect information at different scalesat different scales

• More efficient computation, allowsMore efficient computation, allowslarger motionslarger motions

Image PyramidsImage Pyramids

SzeliskiSzeliski

Pyramid CreationPyramid Creation

• ““Gaussian” PyramidGaussian” Pyramid

• ““Laplacian” PyramidLaplacian” Pyramid– Created from GaussianCreated from Gaussian

pyramid by subtractionpyramid by subtractionLLii = G = Gii – expand(G – expand(Gi+1i+1))

SzeliskiSzeliski

Octaves in the Spatial DomainOctaves in the Spatial Domain

Bandpass ImagesBandpass Images

Lowpass Images

SzeliskiSzeliski

BlendingBlending

• Blend over too small a region: seamsBlend over too small a region: seams

• Blend over too large a region: ghostingBlend over too large a region: ghosting

Multiresolution BlendingMultiresolution Blending

• Different blending regions for different Different blending regions for different levels in a pyramid [Burt & Adelson]levels in a pyramid [Burt & Adelson]– Blend low frequencies over large regions Blend low frequencies over large regions

(minimize seams due to brightness (minimize seams due to brightness variations)variations)

– Blend high frequencies over small regions Blend high frequencies over small regions (minimize ghosting)(minimize ghosting)

Pyramid BlendingPyramid Blending

SzeliskiSzeliski

Minimum-Cost CutsMinimum-Cost Cuts

• Instead of blending high frequencies Instead of blending high frequencies along a straight line, blend along line of along a straight line, blend along line of minimum differences in image minimum differences in image intensitiesintensities

Minimum-Cost CutsMinimum-Cost Cuts

Moving object, simple blending Moving object, simple blending blur blur

[Davis 98][Davis 98]

Minimum-Cost CutsMinimum-Cost Cuts

Minimum-cost cut Minimum-cost cut no blur no blur

[Davis 98][Davis 98]