Re: Anybody have a prgram to write a .bmp file?

[Robert A. Macy]

Paul,

IT WORKED!

Thanks.  That's EXACTLY what I needed. 

       - Robert -

On Tue, 6 Feb 2007 22:06:40 -0500
 Paul Kienzle <address@hidden> wrote:
> 
> On Feb 6, 2007, at 11:19 AM, Robert A. Macy wrote:
> 
> > Paul,
> >
> > I don't understand what you said.
> >
> > The X index matrix is square, the same siaxe as the
> r,g,b
> > matrices, and consists of integers going from one up to
> the
> > total size of the matrix: rows*columns
> >
> > The map is the similar size of
> >   rows*columns by 3
> > and the values in the matrix are between 0 and 1
> 
> yes
> 
> > colourmap appears to be 64 by 3 no matter what I do,
> even
> > if I clear the thing, it comes back after
> >>> [X,map]=rgb2ind(r,g,b);
> 
> yes
> 
> > It sounds like you're trying to limit the color from 24
> bit
> > down to 256 color, but how do I do that using these
> > functions?
> 
> When you do bmpwrite(X,map,'file') it is trying to
> use a map of length 65536, but bmpwrite only
> supports a map of length 256.
> 
> You can:
> 
> (a) detect if the map is of length greater than 256
> and write a truecolor image instead,
> 
> (b) backport the bmpwrite from octave-forge CVS so
> that you can writing truecolor rgb maps directly, or
> 
> (c) fix rgb2ind so that it finds the best map of
> length 256 with which to represent the colors.  I
> suggested using a perceptual quantization rather than
> an rgb quantization to make better use of the map.
> 
> I've implemented option (a) in the attached file.
> 
> - Paul
>