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executable file 71 lines (57 sloc) 1.983 kB
% [ZOOM] = pixelAxes(DIMS, ZOOM)
%
% Set the axes of the current plot to cover a multiple of DIMS pixels,
% thereby eliminating screen aliasing artifacts when displaying an
% image of size DIMS.
%
% ZOOM (optional, default='same') expresses the desired number of
% samples displayed per screen pixel. It should be a scalar, which
% will be rounded to the nearest integer, or 1 over an integer. It
% may also be the string 'same' or 'auto', in which case the value is chosen so
% as to produce an image closest in size to the currently displayed
% image. It may also be the string 'full', in which case the image is
% made as large as possible while still fitting in the window.
% Eero Simoncelli, 2/97.
function [zoom] = pixelAxes(dims, zoom)
%------------------------------------------------------------
%% OPTIONAL ARGS:
if (exist('zoom') ~= 1)
zoom = 'same';
end
%% Reverse dimension order, since Figure Positions reported as (x,y).
dims = dims(2:-1:1);
%% Use MatLab's axis function to force square pixels, etc:
axis('image');
ax = gca;
oldunits = get(ax,'Units');
if strcmp(zoom,'full');
set(ax,'Units','normalized');
set(ax,'Position',[0 0 1 1]);
zoom = 'same';
end
set(ax,'Units','pixels');
pos = get(ax,'Position');
ctr = pos(1:2)+pos(3:4)/2;
if (strcmp(zoom,'same') | strcmp(zoom,'auto'))
%% HACK: enlarge slightly so that floor doesn't round down
zoom = min( pos(3:4) ./ (dims - 1) );
elseif isstr(zoom)
error(sprintf('Bad ZOOM argument: %s',zoom));
end
%% Force zoom value to be an integer, or inverse integer.
if (zoom < 0.75)
zoom = 1/ceil(1/zoom);
%% Round upward, subtracting 0.5 to avoid floating point errors.
newsz = ceil(zoom*(dims-0.5));
else
zoom = floor(zoom + 0.001); % Avoid floating pt errors
if (zoom < 1.5) % zoom=1
zoom = 1;
newsz = dims + 0.5;
else
newsz = zoom*(dims-1) + mod(zoom,2);
end
end
set(ax,'Position', [floor(ctr-newsz/2)+0.5, newsz] )
% Restore units
set(ax,'Units',oldunits);
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