Description of slapplyfilterband

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slapplyfilterband

PURPOSE

SLAPPLYFILTERBAND Applies filter band to filter images in batch

SYNOPSIS

function fimgs = slapplyfilterband(imgs, filterband, filtersize, varargin)

DESCRIPTION

SLAPPLYFILTERBAND Applies filter band to filter images in batch

 $ Syntax $
   - fimgs = slapplyfilterband(imgs, filterband, filtersize, ...)

 $ Arguments $
   - imgs:         The images to be filtered
   - filterband:   The set of filter band
   - filtersize:   The spec of filter size
   - fimgs:        The filtered images

 $ Description $
   - fimgs = slapplyfilterband(imgs, filterband, filtersize, ...) applies 
     a set of filterbands to images in batch. Suppose there are k filters, 
     imgs is an array of size h0 x w0 x n1 x n2 x ... x nm, then fimgs is
     an array of size h x w x n1 x n2 x ... x nm x k, here h and w are
     respectively the height and width of the filtered image.
     You can further specify the following properties:
       - 'roi':    The ROI in original image (default = 'full')
                   'full'|'confined'|[t, b, l, r]
                   Please refer to slpixneighbors for details on ROI.
       - 'fbform': The form of filterband (default = 'normal')
                   - 'normal':  normal form
                   - 'vec':     vectorized form
     
 $ History $
   - Created by Dahua Lin, on Sep 2nd, 2006

CROSS-REFERENCE INFORMATION

This function calls:

• slfiltersize SLFILTERSIZE Extracts information from filtersize
• slpixneighbors SLPIXNEIGHBORS Extracts the neighborhood of pixels from an image
• slvecfilters SLVECFILTERS Vectorizes the filter band
• raise_lackinput RAISE_LACKINPUT Raises an error indicating lack of input argument
• slparseprops SLPARSEPROPS Parses input parameters

This function is called by:

• slbenchmark_batchfilter SLBENCHMARK_BATCHFILTER Compares the efficiency of batch filter

SUBFUNCTIONS

• function fimg = filter_oneimg(img, roi, vfb, filtersize, h, w, k)

SOURCE CODE

0001 function fimgs = slapplyfilterband(imgs, filterband, filtersize, varargin)
0002 %SLAPPLYFILTERBAND Applies filter band to filter images in batch
0003 %
0004 % $ Syntax $
0005 %   - fimgs = slapplyfilterband(imgs, filterband, filtersize, ...)
0006 %
0007 % $ Arguments $
0008 %   - imgs:         The images to be filtered
0009 %   - filterband:   The set of filter band
0010 %   - filtersize:   The spec of filter size
0011 %   - fimgs:        The filtered images
0012 %
0013 % $ Description $
0014 %   - fimgs = slapplyfilterband(imgs, filterband, filtersize, ...) applies
0015 %     a set of filterbands to images in batch. Suppose there are k filters,
0016 %     imgs is an array of size h0 x w0 x n1 x n2 x ... x nm, then fimgs is
0017 %     an array of size h x w x n1 x n2 x ... x nm x k, here h and w are
0018 %     respectively the height and width of the filtered image.
0019 %     You can further specify the following properties:
0020 %       - 'roi':    The ROI in original image (default = 'full')
0021 %                   'full'|'confined'|[t, b, l, r]
0022 %                   Please refer to slpixneighbors for details on ROI.
0023 %       - 'fbform': The form of filterband (default = 'normal')
0024 %                   - 'normal':  normal form
0025 %                   - 'vec':     vectorized form
0026 %
0027 % $ History $
0028 %   - Created by Dahua Lin, on Sep 2nd, 2006
0029 %
0030 
0031 %% parse and verify input
0032 
0033 if nargin < 2
0034     raise_lackinput('slapplyfilterband', 2);
0035 end
0036 
0037 imgsiz = size(imgs);
0038 
0039 if ndims(imgs) == 2
0040     n = 1;
0041 else
0042     n = prod(imgsiz(3:end));
0043 end
0044 
0045 [filtsiz, bmg] = slfiltersize(filtersize);
0046 fh = filtsiz(1);
0047 fw = filtsiz(2);
0048 
0049 
0050 opts.roi = 'full';
0051 opts.fbform = 'normal';
0052 opts = slparseprops(opts, varargin{:});
0053 
0054 if ischar(opts.roi)
0055     switch opts.roi
0056         case 'full'
0057             h = imgsiz(1); w = imgsiz(2);
0058         case 'confined'
0059             h = imgsiz(1) - bmg(1) - bmg(2);
0060             w = imgsiz(2) - bmg(3) - bmg(4);
0061         otherwise
0062             error('sltoolbox:invalidarg', ...
0063                 'Invalid ROI option: %s', opts.roi);
0064     end
0065 elseif isnumeric(opts.roi)
0066     h = opts.roi(2) - opts.roi(1) + 1;
0067     w = opts.roi(4) - opts.roi(3) + 1;
0068 else
0069     error('sltoolbox:invalidarg', 'Invalid ROI parameter');
0070 end
0071 
0072 fimgs = [];
0073 if h <= 0 || w <= 0
0074     return;
0075 end
0076 
0077 if ~ismember(opts.fbform, {'normal', 'vec'})
0078     error('sltoolbox:invalidarg', 'Invalid fbform: %s', opts.fbform);
0079 end
0080 
0081 %% Main
0082 
0083 % prepare vectorized filterband
0084 
0085 switch opts.fbform
0086     case 'normal'
0087         if size(filterband, 1) ~= fh || size(filterband, 2) ~= fw
0088             error('sltoolbox:sizmismatch', ...
0089                 'The size of filterband is not consistent.');
0090         end
0091         vfb = slvecfilters(filterband);
0092     case 'vec'
0093         vfb = filterband;
0094 end
0095 k = size(vfb, 1);
0096 
0097 % do filtering
0098 
0099 if n == 1
0100     fimgs = filter_oneimg(imgs, opts.roi, vfb, filtersize, h, w, k);
0101 else
0102     fsiz = [h, w, imgsiz(3:end), k];
0103     chsiz = [h, w, 1, k]; 
0104     fimgs = zeros(h, w, n, k);
0105     for i = 1 : n
0106         curimg = imgs(:,:,i);
0107         curf = filter_oneimg(curimg, opts.roi, vfb, filtersize, h, w, k);        
0108         fimgs(:,:,i,:) = reshape(curf, chsiz);
0109     end
0110     fimgs = reshape(fimgs, fsiz);
0111 end
0112 
0113 
0114 
0115 %% Core function
0116 
0117 function fimg = filter_oneimg(img, roi, vfb, filtersize, h, w, k)
0118     
0119 NBs = slpixneighbors(img, filtersize, 'roi', roi, 'output', 'cols');
0120 fimg = vfb * NBs;  % k x npix
0121 fimg = fimg';     % npix x k
0122 fimg = reshape(fimg, [h, w, k]);
0123 
0124 
0125 
0126             
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