im_box.m

The pattern recognition matlab toolbox

%IM_BOX Find rectangular image in datafile enclosing a blob (0/1 image)
%
%   B = IM_BOX(A)
%   B = A*IM_BOX
%
% If A is a 0/1 image then B is the same image with all empty (0) border
% columns and rows removed.
%
%   B = IM_BOX(A,N)
%
% If A is a 0/1 image then B is the same image, but having in each direction
% N empty (0) columns and rows around the object (1).
%
%   B = IM_BOX(A,[NX1 NX2 NY1 NY2])
%
% If A is a 0/1 image then B is the same image, but having NX1, NX2 empty 
% columns (0) left, respectively right of the object (1) and NY1, NY2 empty
% rows (0) above, respectively below the object(1).
%
%   B = IM_BOX(A,N,ALF)
%
% Adds as many empty (0) columns or rows such that the aspect ratio of
% images (height/width) equals ALF. For ALF == 1, square images are returned.
% For ALF == 0, images are taken as they are and N rows and columns are
% added.
%
% SEE ALSO
% DATASETS, DATAFILES

% Copyright: R.P.W. Duin, [e-mail]
% Faculty EWI, Delft University of Technology
% P.O. Box 5031, 2600 GA Delft, The Netherlands

function b = im_box(a,n,alf)

	prtrace(mfilename);
	
	if nargin < 3, alf = []; end
	if nargin < 2 | isempty(n), n= []; end
	
  if nargin < 1 | isempty(a)
    b = mapping(mfilename,'fixed',{n,alf});
    b = setname(b,'Image bounding box');
	elseif isdataset(a)
		error('Command cannot be used for datasets as it may change image size')
	elseif isdatafile(a)
		isobjim(a);
    b = filtim(a,mfilename,{n,alf});
		b = setfeatsize(b,getfeatsize(a));
  elseif isa(a,'double') | isa(a,'dip_image') % here we have a single image
		if isa(a,'dip_image'), a = double(a); end
		if isempty(n)
			jx = find(sum(a,1) ~= 0);
			jy = find(sum(a,2) ~= 0);
			b = a(min(jy):max(jy),min(jx):max(jx));
		else
    	if (~isempty(alf) & alf == 0) 
				c = a;
			else
				c = feval(mfilename,a); 
			end
    	[my,mx] = size(c);
    	if length(n) == 1
        	n = [n n n n];
    	elseif length(n) ~= 4
        	error('Second parameter should be scalar or vector of length 4')
    	end
    	b = zeros(my+n(3)+n(4),mx+n(1)+n(2));
    	b(n(3)+1:n(3)+my,n(1)+1:n(1)+mx) = c;
		end
		if ~isempty(alf) & alf ~= 0
			[m,k] = size(b);
			r = round(m*alf) - k;
			if r == 0
				;
			elseif r >= 1 % add r columns
				c = zeros(m,k+r);
				c(:,ceil(r/2):ceil(r/2)+k-1) = b;
				b = c;
			else % add rows
				r = round(k/alf) - m;
				c = zeros(m+r,k);
				c(ceil(r/2):ceil(r/2)+m-1,:) = b;
				b = c;
			end
		end	 
	end

return