Re: Enhance Contrast Question

Posted by Avital Steinberg on Jan 14, 2015; 6:09am
URL: http://imagej.273.s1.nabble.com/Re-Enhance-Contrast-Question-tp5011209p5011210.html

Thanks, Michael - I asked the same question about a day ago and solved it
in the way you described. Getting the min and max values in java works like
this:

double min=ip.getMin();
double max=ip.getMax();

or if it's a macro, use this:

*getMinAndMax(min, max)*
Returns the minimum and maximum displayed pixel values (display range). See
the DisplayRangeMacros
<http://rsb.info.nih.gov/ij/macros/DisplayRangeMacros.txt> for examples.

Avital

On Tue, Jan 13, 2015 at 11:53 PM, Michael Schmid <[hidden email]>
wrote:

> Hi Fatima,
>
> if you have the lowest and highest pixel value of the range to display
> between black and white (c and d in your case, I call them 'min' and 'max'
> here:
> In a Macro use
>   setMinAndMax(min, max);
> and in Java
>   ip.setMinAndMax(min, max);
> where ip is the ImageProcessor. You can get it for the current image via
>   ImagePlus imp = WindowManager.getCurrentImage();
>   ImageProcessor ip = imp.getProcessor();
>
> Michael
> ________________________________________________________________
> On Jan 13, 2015, at 21:54, fmerchant wrote:
>
> > Using the site below the description for Contrast Stretching in the
> Enhance
> > Contrast menu item is as follows
> >
> > http://homepages.inf.ed.ac.uk/rbf/HIPR2/stretch.htm
> >
> > For example for 8-bit graylevel images the lower and upper limits might
> be 0
> > and 255. Call the lower and the upper limits a and b respectively.
> >
> > The simplest sort of normalization then scans the image to find the
> lowest
> > and highest pixel values currently present in the image. Call these c
> and d.
> > Then each pixel P is scaled using the following function:
> >
> >    Pout = (Pin - c) (b-a/d-c) + a
> >
> > Values below 0 are set to 0 and values about 255 are set to 255.
> >
> > How do I call Enhance Contrast, with user-defined values for c and d in
> the
> > formula above?
> >
> > Thanks,
> > Fatima
> >
> >
> >
> >
> > --
> > View this message in context:
> http://imagej.1557.x6.nabble.com/Enhance-Contrast-Question-tp5011207.html
> > Sent from the ImageJ mailing list archive at Nabble.com.
> >
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>
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