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function outImage = BitsPlusPackColorImage(inImage,SPACESCALE,COLORSCALE)
% [outImage,inImage] = BitsPlusPackColorImage(inImage,[SPACESCALE],[COLORSCALE]))
%
% Convert an image for Bits++, assuming it will
% displayed on an even pixel boundary and that
% it has an even number of columns.
%
% Image is resized if SPACESCALE == 1 (default).
% Otherwise scaling is assumed to have been done in advance.
%
% Assume input is in range 0-1 if COLORSCALE == 1 (default).
% Assume input is in range 0-65535 and be integer if COLORSCALE == 0.
%
% If scaling in space, must scale in color, otherwise interpolation
% can violate assumptions of prescaled color (e.g. integer vals).
%
% 8/9/04 dhb Wrote it.
% 18/4/05 ejw Converted it to run with OSX version of Psychtoolbox.
% 26.2.07 mk Bugfix for LSB conversion: Added modulo operation.
% 3/01/07 mk Bugfix for MSB conversion: Added floor operation.
if (nargin < 2 || isempty(SPACESCALE))
SPACESCALE = 1;
end
if (nargin < 3 || isempty(COLORSCALE))
COLORSCALE = 1;
end
if (SPACESCALE && ~COLORSCALE)
error('COLORSCALE must be set if SPACESCALE is.');
end
if (SPACESCALE)
[m,n,p] = size(inImage);
if (rem(n,2) ~= 0)
error('Image must have even number of columns');
end
% imresize is part of the image processing toolbox
% I have recoded to avoid the need for this
%inImage = imresize(inImage,[m n/2],'bilinear');
% halve the horizontal width of the image
% this compensates for the 2:1 aspect ratio for colour++ pixels
inImage = inImage(:,[1:2:n],:);
index = find(inImage < 0);
if (~isempty(index))
inImage(index) = 0;
end
index = find(inImage > 1);
if (~isempty(index))
inImage(index) = 1;
end
else
[m,n,p] = size(inImage);
n = n*2;
end
if (COLORSCALE)
inImage = round(65535*inImage);
end
% Make output image and stuff with high and low bytes
outImage = uint8(zeros(m,n,p));
% First byte is high 8 bits
outImage(:,1:2:end-1,:) = uint8(floor(inImage/256));
% Second byte is low 8 bits
outImage(:,2:2:end,:) = uint8(mod(inImage, 256));
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