Posted by
Jason NoSpam on
Nov 17, 2006; 5:04pm
URL: http://imagej.273.s1.nabble.com/Brightness-Contrast-Adjustment-Question-tp3700994p3700996.html
Just so I am sure I understand (I am an imaging newb :) ) this means that for DICOM images, ImageJ loads the "recommended" values for B&C from the DICOM header(metadata)?
Another question, if the DICOM image is 16-bit, does ImageJ "resample/convert" the image to 8-bit to adjust the B&C values?
Thanks so much!
Wayne Rasband <
[hidden email]> wrote: When opening a DICOM, ImageJ set the display range based on the Window
Center (0028,1050) and Window Width (0028,1051) tags. Click "Reset" in
the B&C window and it sets the display range to the minimum and maximum
pixel values. As an example, the File>Open Samples>CT image has a
Window Center of 50 and Window Width of 500, so the display range is
set to -200 to 300 (center-width/2 to center+width/2). Click "Reset"
and the display range is set to -719 to 1402. Press 'h'
Analyze/Histogram) and you will see that the minimum pixel value in the
image is -719 and the maximum is 1402. To display the DICOM tags, press
'i' (Image>Show Info). Press 'r' (File>Revert) to revert to the
original display range.
-wayne
On Nov 17, 2006, at 11:29 AM, Jason K wrote:
> I am using 1.38A imageJ and I noticed something strange with the
> Brightness & Contrast adjustment (Image menu -> Adjust ->
> Brightness/Contrast) when viewing DICOM images.
>
> When you open the B&C window on a DICOM (CT, MRI, or X-ray) the
> sliders for Brightness, Contrast, Minimum,and Maximum are already
> adjusted. Then, if you click the Reset button in this B&C window it
> returns the sliders to a totally different position (likely centered).
>
> Why/How is imageJ starting B&C with the image already adjusted in the
> B&C window? Does ImageJ automatically do a B&C adjustment when a
> DICOM image initially loads?
>
> Thanks in advance,
>
>
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