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- % [PYR, INDICES] = buildWpyr(IM, HEIGHT, FILT, EDGES)
- %
- % Construct a separable orthonormal QMF/wavelet pyramid on matrix (or vector) IM.
- %
- % HEIGHT (optional) specifies the number of pyramid levels to build. Default
- % is maxPyrHt(IM,FILT). You can also specify 'auto' to use this value.
- %
- % FILT (optional) can be a string naming a standard filter (see
- % namedFilter), or a vector which will be used for (separable)
- % convolution. Filter can be of even or odd length, but should be symmetric.
- % Default = 'qmf9'. EDGES specifies edge-handling, and
- % defaults to 'reflect1' (see corrDn).
- %
- % PYR is a vector containing the N pyramid subbands, ordered from fine
- % to coarse. INDICES is an Nx2 matrix containing the sizes of
- % each subband. This is compatible with the MatLab Wavelet toolbox.
- % Eero Simoncelli, 6/96, based on original lisp code from 1987.
- function [pyr,pind] = buildWpyr(im, ht, filt, edges)
- if (nargin < 1)
- error('First argument (IM) is required');
- end
- %------------------------------------------------------------
- %% OPTIONAL ARGS:
- if (exist('filt') ~= 1)
- filt = 'qmf9';
- end
- if (exist('edges') ~= 1)
- edges= 'reflect1';
- end
- if isstr(filt)
- filt = namedFilter(filt);
- end
- if ( (size(filt,1) > 1) & (size(filt,2) > 1) )
- error('FILT should be a 1D filter (i.e., a vector)');
- else
- filt = filt(:);
- end
- hfilt = modulateFlip(filt);
- % Stagger sampling if filter is odd-length:
- if (mod(size(filt,1),2) == 0)
- stag = 2;
- else
- stag = 1;
- end
- im_sz = size(im);
- max_ht = maxPyrHt(im_sz, size(filt,1));
- if ( (exist('ht') ~= 1) | (ht == 'auto') )
- ht = max_ht;
- else
- if (ht > max_ht)
- error(sprintf('Cannot build pyramid higher than %d levels.',max_ht));
- end
- end
- if (ht <= 0)
- pyr = im(:);
- pind = im_sz;
- else
- if (im_sz(2) == 1)
- lolo = corrDn(im, filt, edges, [2 1], [stag 1]);
- hihi = corrDn(im, hfilt, edges, [2 1], [2 1]);
- elseif (im_sz(1) == 1)
- lolo = corrDn(im, filt', edges, [1 2], [1 stag]);
- hihi = corrDn(im, hfilt', edges, [1 2], [1 2]);
- else
- lo = corrDn(im, filt, edges, [2 1], [stag 1]);
- hi = corrDn(im, hfilt, edges, [2 1], [2 1]);
- lolo = corrDn(lo, filt', edges, [1 2], [1 stag]);
- lohi = corrDn(hi, filt', edges, [1 2], [1 stag]); % horizontal
- hilo = corrDn(lo, hfilt', edges, [1 2], [1 2]); % vertical
- hihi = corrDn(hi, hfilt', edges, [1 2], [1 2]); % diagonal
- end
- [npyr,nind] = buildWpyr(lolo, ht-1, filt, edges);
- if ((im_sz(1) == 1) | (im_sz(2) == 1))
- pyr = [hihi(:); npyr];
- pind = [size(hihi); nind];
- else
- pyr = [lohi(:); hilo(:); hihi(:); npyr];
- pind = [size(lohi); size(hilo); size(hihi); nind];
- end
- end
-
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