59 lines
1.5 KiB
Matlab
59 lines
1.5 KiB
Matlab
function y = vl_nnphasesplit( x, dzdy )
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%VL_NNPHASESPLIT CNN phase split the feature plane into 8x8 = 64 DCT mode.
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% Y = VL_NNCROP(X, STRIDE) phase split the input X into 64 DCT phase mode.
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%
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% DZDX = VL_NNCROP(X, DZDY) computes the derivative DZDX of the
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% function projected on the output derivative DZDY. DZDX has the same
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% dimension as X and DZDY the same dimension as Y.
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%
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% dimension must be divided by 8
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assert( rem(size(x,1), 8 ) == 0 & rem( size(x,2), 8) == 0 );
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% Initialize some parameters
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inputSize = [size(x,1) size(x,2) size(x,3) size(x,4)] ;
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outputSize = [size(x,1)/8, size(x,2)/8, 64*size(x,3), size(x,4)];
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% zig zag order
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zzag = zeros(64, 4);
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idx = 1;
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startCh = 1;
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for i = 0:7
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for j = 0:7
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stopCh = startCh + inputSize(3);
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zzag(idx, :) = [ i, j, startCh, stopCh - 1 ];
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idx = idx + 1;
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startCh = stopCh;
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end
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end
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% sampling array
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sy = 1:8:inputSize(1);
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sx = 1:8:inputSize(2);
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if nargin <= 1 || isempty(dzdy)
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% forward function
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if isa( x, 'gpuArray' )
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y = gpuArray.zeros(outputSize, classUnderlying(x)) ;
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else
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y = zeros(outputSize, 'like', x ) ;
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end
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for i = 1:64
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y(:,:,zzag(i,3):zzag(i,4),:) = x(sy + zzag(i,1), sx + zzag(i,2), :, : );
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end
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else
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% backward function
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if isa(dzdy, 'gpuArray')
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y = gpuArray.zeros(inputSize, classUnderlying(dzdy)) ;
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else
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y = zeros(inputSize, 'like', x) ;
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end
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for i = 1:64
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y(sy + zzag(i,1), sx + zzag(i,2), :, : ) = dzdy(:,:,zzag(i,3):zzag(i,4),:);
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end
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end
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