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


From: Geordie McBain
Subject: Re: Anybody have a prgram to write a .bmp file?
Date: Thu, 01 Feb 2007 15:12:02 +1100

On Wed, 2007-01-31 at 19:44 -0800, Robert A. Macy wrote:
> Is there another way?
> 
> cat comes back as undefined.

Yes, you can use reshape ([r, g, b], [(size (r)), 3]); e.g.

---
octave:25> n=3; m=5; r = rand (n, m); g = rand (n, m); b = rand (n, m);
octave:26> all ((reshape ([r, g, b], [(size (r)), 3]) == cat (3, r, g,
b)) (:))
ans =  1
---

> 
> On Wed, 31 Jan 2007 21:06:09 -0500
>  Paul Kienzle <address@hidden> wrote:
> > 
> > On Jan 30, 2007, at 10:01 PM, Robert A. Macy wrote:
> > 
> > > However, it has the same flaw that all the image
> > functions
> > > are doing:
> > >>> r=ones(256,1)*(0:255)/255;
> > >>> g=.5*ones(256,256);b=.5*ones(256,256);
> > >>> [X,map]=rgb2ind(r,g,b);
> > >>> bmpwrite(X,map,"Xtest.bmp");
> > > when opened the square is not gradually changing color
> > as
> > > expected, but a solid green square.
> > 
> > bmpwrite is expecting values in 0-255.  Try the
> > following:
> > 
> >    r=ones(256,1)*(0:255)/255;
> >    g=.5*ones(256,256);b=.5*ones(256,256);
> >    bmpwrite(cat(3,r,g,b)*256,'Xtest.bmp');
> > 
> > - Paul
> > 
> 
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-- 
Geordie McBain
www.aeromech.usyd.edu.au/~mcbain




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