MATLAB: Error while changing image bit depth in MATLAB

retag

I'm trying to convert RGB image with some bit depth to BMP image of bit depth 8. here is my code
    a = imread('DSC01684_5.bmp');
    [x,map] = rgb2ind(a,32); 
    imwrite(x,map,'C:\Documents and Settings\Home\Desktop    \DSC01684_5.bmp.','bitdepth', 8);
and I'm getting error like
    ??? Error using ==> imformats>find_in_registry at 507
    Format specifier must be a 1-D character array.
    Error in ==> imformats at 114
        varargout{1} = find_in_registry(fmts, varargin{1});
    Error in ==> imwrite>get_format_from_filename at 550
    fmt_s = imformats(ext);
    Error in ==> imwrite at 389
    format = get_format_from_filename(filename);
is the error in imwrite function or in changing bit depth?
However if i use
    output_filename = 'C:\Documents and Settings\Home\Desktop\DSC01684_5.bmp.'
    imwrite(x, map, output_filename, 'bmp', 'bitdepth', 8);
I'm getting error like
    ??? Error using ==> imagesci\private\writebmp
     Too many input arguments
     Error in ==> imwrite at 429 
     feval(fmt_s.write, data, map, filename, paramPairs{:});

Best Answer

The first error is caused by the trailing dot in "DSC01684_5.bmp.", such that omitting it allows to recognize the file type by the extension.
Because RGB2IND replies an UINT8 for 32 colors, you do not have to specify the bitdepth explicitly:
file = 'C:\Documents and Settings\Home\Desktop\DSC01684_5.bmp'
imwrite(x, map, file);
imfinfo(file)
% >> ... BitDepth: 8
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