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Topic: Imwrite with colormap
Replies: 4   Last Post: Oct 19, 2012 12:29 PM

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Nicolás

Posts: 11
Registered: 10/18/12
Re: Imwrite with colormap
Posted: Oct 19, 2012 11:08 AM
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"Steve Eddins" wrote in message <k5rf8i$nuh$1@newscl01ah.mathworks.com>...
> On 10/19/2012 5:25 AM, Nicolás wrote:
> > Good morning.
> > I am trying to use imwrite to save a image with a colormap( for example,
> > 'jet'), and with a value of 25 levels, such as this:
> > imwrite(handles.image,handles.colorMap,filename,pathname);
> >
> > However, the image is not saved with the value of levels established
> > previously. Thus the image is saved with a value of 256 leves, instead
> > of 25.
> >
> > Anyone knows do it?
> > Thanks in advance.

>
> The same question came in from a MathWorks training engineer this week.
>
> You didn't say what file format you are using, but I'll assume you are
> writing a TIFF file.
>
> In the TIFF file format spec, it says that the number of colors in the
> colormap is 2^n, where n is the number of bits per sample. (For
> details, see section 5, "Palette-color images," of the TIFF spec.
> http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf)
>
> So it is not possible to make a TIFF file that has a colormap with only
> 25 colors in it.
>
> --
> Steve Eddins
> http://blogs.mathworks.com/steve/



Sorry, but the file format can be jpeg,jpeg 2000,gif,etc,etc, in summary those supported by Matlab.
And another thing. I don't want to save the level of color. What I want to save is the level of intensitiy. When you have a image, you have from 0 to 255 levels of intensity. I want to modify the colormap of the image and then, modifying the level of intensity.

I hope now it is more clear the question.

Thanks you a lot !



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