/
frameInterpFlow.m
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/
frameInterpFlow.m
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% Simple flow based frame interpolation
% Forward warp first frame, backwards warp second frame and blend
% Replace parfor with for if the parallel toolbox is not available.
function out = frameInterpFlow(im1, im2, flow, alpha)
%% Setup
im1 = im2double(im1);
im2 = im2double(im2);
[h, w, c] = size(im2);
[mx, my] = meshgrid(1:w,1:h);
%% Forward warp flow
fmx = mx + alpha*flow(:,:,1);
fmy = my + alpha*flow(:,:,2);
flow(:,:,1) = griddata(fmx, fmy, flow(:,:,1), mx, my);
flow(:,:,2) = griddata(fmx, fmy, flow(:,:,2), mx, my);
%% Forward warp im1
im1f = zeros(h,w,c);
parfor i = 1:c
im1f(:,:,i) = griddata(fmx, fmy, im1(:,:,i), mx, my);
end
%% Replace empty pixels
nans=find(isnan(im1f));
im1f(nans)=im1(nans);
%% Backwards warp im2
bmx = mx + (1-alpha)*flow(:,:,1);
bmy = my + (1-alpha)*flow(:,:,2);
im2b = zeros(h,w,c);
parfor i = 1:c
im2b(:,:,i) = interp2(mx, my, im2(:, :, i), bmx, bmy, 'bicubic', NaN);
end
%% Replace empty pixels
nans=find(isnan(im2b));
im2b(nans)=im2(nans);
%% Cap values
im2b = min(im2b,1);
%% Blend images
out = (1-alpha)*im1f + alpha*im2b;