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	Sun, 02 Apr 2006 13:15:58 EDT
Date: Sun, 2 Apr 2006 13:15:58 -0400 (EDT)
From: David Scriven <davidwriter@yahoo.com>
Subject: Re: [Tiff] 16-bit TIFF to 8-bit BMP/TIF ???
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Status:   

Chris,

There are quite a few packages, depending on your platform,
that display 16bit images without conversion. NIH Image (Mac)
ImageJ (all platforms) ImageMagic (Linux, maybe others) 
ScionImage (Windows). I'm sure there are others. Some
packages require that you 'import' 16 bit images rather
'open' them to view them. 

I'm not sure why you have the need to convert the images
to 8-bit to analyse them, as the whole point of 16 bit
is increased dynamic range and finer granularity. Conversion
to 8-bit removes that, and may distort the intensity relationships.
For example, taking the square root will not result in the same
values as dividing by 256 (say).

libtiff handles 16 bit images as easily as 8 bit and once
you've extracted the data, the analysis protocols should
be the same.

David
> Hi,
> 
> Sorry for the late reply. What I am getting with most
> software packages is an entirely black image. Is there
> a way of veiwing the data form teh 16-bit unsigned
> TIFF without libtiff automatically converting to 8-bit
> i.e. view 16-bit data? I can manually convert all
> values using a square root (changing into the desired
> 8-bit 0-255 whilst keeping proportions).
>    This may be a slow memory inefficient method but at
> this stage I would like this functionality.
> 
> Kind Regards,
>    Chris


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