im_scale.m

The pattern recognition matlab toolbox

%IM_SCALE Scale all binary images in a datafile to a giving fraction of pixels 'on'
%
%   B = IM_SCALE(A,P)
%   B = A*IM_SCALE([],P)
%
% B is a zoomed in / out version of A such that about a fraction
% P of the image pixels is 'on' (1).
%
% SEE ALSO
% DATASETS, DATAFILES, IM_BOX, IM_CENTER

% 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_scale(a,p)

	prtrace(mfilename);
	
	if nargin < 2 | isempty(p), p = 0.5; end
	
  if nargin < 1 | isempty(a)
    b = mapping(mfilename,'fixed',{p});
    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,{p});
		b = setfeatsize(b,getfeatsize(a));
  elseif isa(a,'double') | isa(a,'dip_image') % here we have a single image
		sca = sqrt(p/mean(a(:)));
		sa = size(a);
		c = imresize(double(a),round(sca*sa),'nearest');
		sc = size(c);
		d = abs(floor((sc - sa)/2));
		if sca < 1
			b = zeros(size(a));
			b(d(1)+1:d(1)+sc(1),d(2)+1:d(2)+sc(2)) = c;	
		else
			b = c(d(1)+1:d(1)+sa(1),d(2)+1:d(2)+sa(2));
		end
	end

return