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Home > Archive > Radiology > September 2004 > Optical density to grayscale values
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Optical density to grayscale values
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| Hi,
I am trying to use a VIDAR VXR Film Digitizer and 32-bit TWAIN for
windows to make a .tif file which is an absolute faithful conversion
of all the optical densities on a radiographic film into grayscale
values.
The reason is that I want to make distance measurements on my .tif
file from a point of particular optical density to another point of
optical density - not from one physical structure to another.
I know that the software can do clever things to improve contrast or
brighten a dark area but in this case I just want my .tif file to look
exactly like the radiographic film with no enhancements.
What settings in the TWAIN software and the scanner (digitizer) should
I use to achieve this.
For example, I have the option of using Translation tables:
Histogram-equalized
Linear histogram-based
Linear histogram independent
Linear optical density
etc.
Other options include 'dark enhance' and resolution.
Any advice is greatly appreciated,
Chris.
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| What do you mean by normalize the images? We monitor the film
processing and I think this is consistant. I am happy with the fims
and just need a way to be certain that my .tif image has the same
relative darkness / lightness as the original film
Thanks.
"John Chewter" <john@LESS_SPAMchewter.f9.co.uk> wrote in message news:<chl42o$db5$1@sparta.btinternet.com>...[vbcol=seagreen]
> You will have trouble unless you normalize the images
>
> The spread on film processing is quite large - too large
>
> "Chris" <c_g_taylor2000@yahoo.co.uk> wrote in message
> news:33598cff.0409070821.69603c12@posting.google.com...
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