12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182 |
- % [PYR, INDICES] = buildGpyr(IM, HEIGHT, FILT, EDGES)
- %
- % Construct a Gaussian pyramid on matrix IM.
- %
- % HEIGHT (optional) specifies the number of pyramid levels to build. Default
- % is 1+maxPyrHt(size(IM),size(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. Default = 'binom5'. 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.
- function [pyr,pind] = buildGpyr(im, ht, filt, edges)
- if (nargin < 1)
- error('First argument (IM) is required');
- end
- im_sz = size(im);
- %------------------------------------------------------------
- %% OPTIONAL ARGS:
- if (exist('filt') ~= 1)
- filt = 'binom5';
- 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
- max_ht = 1 + 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 (exist('edges') ~= 1)
- edges= 'reflect1';
- end
- %------------------------------------------------------------
- if (ht <= 1)
- pyr = im(:);
- pind = im_sz;
- else
- if (im_sz(2) == 1)
- lo2 = corrDn(im, filt, edges, [2 1], [1 1]);
- elseif (im_sz(1) == 1)
- lo2 = corrDn(im, filt', edges, [1 2], [1 1]);
- else
- lo = corrDn(im, filt', edges, [1 2], [1 1]);
- lo2 = corrDn(lo, filt, edges, [2 1], [1 1]);
- end
-
- [npyr,nind] = buildGpyr(lo2, ht-1, filt, edges);
- pyr = [im(:); npyr];
- pind = [im_sz; nind];
-
- end
-
|