How to call "Contrast Enhancer" from Java plugin

[Joachim Wesner]

HI,

I would  like to use the "ContrastEnhancer" class/plugin from my own
plugin.

After some fiddling around I thought the correct call might be

      IJ.runPlugIn(imp, "ij.plugin.ContrastEnhancer", "saturated=.1");

which runs the enhancer plugin up to the dialog window, but does not
process the argument string, but wants the user to enter values and press
OK.

What is the right way to do it? Or is there a more direct way to call the
enhancer class? THANX!

Sincerely

Joachim


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[Wayne Rasband]

  > HI,
  >
  > I would  like to use the "ContrastEnhancer" class/plugin
  > from my own plugin.
  >
  > After some fiddling around I thought the correct call might be
  >
  > IJ.runPlugIn(imp, "ij.plugin.ContrastEnhancer", "saturated=.1");
  >
  > which runs the enhancer plugin up to the dialog window, but
  > does not process the argument string, but wants the user to
  > enter values and press OK.
  >
  > What is the right way to do it? Or is there a more direct way
  > to call the enhancer class? THANX!

Run the Process>Enhance Contrast command with the command recorder
(Plugins>Macros>Record) running and you get this macro call:

      run("Enhance Contrast", "saturated=0.1");

To convert it into a method that can be called from a plugin, change
"run" to "IJ.run" and add an argument that passes an ImagePlus object:

      IJ.run(imp, "Enhance Contrast", "saturated=0.1");

-wayne

[Joachim Wesner]

Hi Wayne,

thanks for the hint, I now understand the difference between IJ.run and
IJ.runPlugIn!

However, this seems to reveal some bug in the contrast enhancer:

If you look in the sourecode of the "B&C" window, you see that the "Auto"
button that I would like to use has it´s own built-in contrast enhancer
which seems to work fine. HOWEVER, it records

      run("Enhance Contrast", "saturated=0.5");

instead! What I find with my data that there seems to be a bug in the true
ContrastEnhancer, the result is NOT the same and depends strongly on the %
value given, for 0.1 there is practically no
effect, while 0.5 percent leads to a strongly asymmetrical  clipping of
much more than 0.5%!

I will send you a test image (float) by personal mail, you should use B&C
Auto and Enhance Contrast 0.5 on it to see the difference!

Sincerely

Mit freundlichen Grüßen / Best regards

Joachim Wesner




                                                                           
             Wayne Rasband                                                
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                                        Re: How to call "Contrast          
                                        Enhancer" from Java plugin        
             08.09.2009 17:59                                              
                                                                           
                                                                           
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  > HI,
  >
  > I would  like to use the "ContrastEnhancer" class/plugin
  > from my own plugin.
  >
  > After some fiddling around I thought the correct call might be
  >
  > IJ.runPlugIn(imp, "ij.plugin.ContrastEnhancer", "saturated=.1");
  >
  > which runs the enhancer plugin up to the dialog window, but
  > does not process the argument string, but wants the user to
  > enter values and press OK.
  >
  > What is the right way to do it? Or is there a more direct way
  > to call the enhancer class? THANX!

Run the Process>Enhance Contrast command with the command recorder
(Plugins>Macros>Record) running and you get this macro call:

      run("Enhance Contrast", "saturated=0.1");

To convert it into a method that can be called from a plugin, change
"run" to "IJ.run" and add an argument that passes an ImagePlus object:

      IJ.run(imp, "Enhance Contrast", "saturated=0.1");

-wayne



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[Wayne Rasband]

> Hi Wayne,
>
> thanks for the hint, I now understand the difference between IJ.run  
> and
> IJ.runPlugIn!
>
> However, this seems to reveal some bug in the contrast enhancer:
>
> If you look in the sourecode of the "B&C" window, you see that the  
> "Auto"
> button that I would like to use has it´s own built-in contrast enhan
> cer
> which seems to work fine. HOWEVER, it records
>
>      run("Enhance Contrast", "saturated=0.5");
>
> instead! What I find with my data that there seems to be a bug in  
> the true
> ContrastEnhancer, the result is NOT the same and depends strongly on  
> the %
> value given, for 0.1 there is practically no
> effect, while 0.5 percent leads to a strongly asymmetrical  clipping  
> of
> much more than 0.5%!

A saturation value of 0.35 seems to produce results closest to what  
you get when clicking on "Auto" in the "B&C" window, so I changed the  
value that gets recorded from 0.5 to 0.35.

-wayne

[Joachim Wesner]

Hi Wayne,

YES, I agree, this is the best compromise. The asymmetry seems to only come
up with higher % values and my special data files with few outliers.

I was a bit puzzled, because I assumed that both cases of contrast
enhancement actually use the very same algorithm (or even class/method
initially) and that the value of 0.5%
might be somehow encoded in the "Auto" code (did not yet really analyze the
source).

Thanks

Joachim Wesner



                                                                           
             Rasband Wayne                                                
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                                        Re: Antwort: Re: How to call      
                                        "Contrast Enhancer" from Java      
             08.09.2009 22:13           plugin                            
                                                                           
                                                                           
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> Hi Wayne,
>
> thanks for the hint, I now understand the difference between IJ.run
> and
> IJ.runPlugIn!
>
> However, this seems to reveal some bug in the contrast enhancer:
>
> If you look in the sourecode of the "B&C" window, you see that the
> "Auto"
> button that I would like to use has it´s own built-in contrast enhan
> cer
> which seems to work fine. HOWEVER, it records
>
>      run("Enhance Contrast", "saturated=0.5");
>
> instead! What I find with my data that there seems to be a bug in
> the true
> ContrastEnhancer, the result is NOT the same and depends strongly on
> the %
> value given, for 0.1 there is practically no
> effect, while 0.5 percent leads to a strongly asymmetrical  clipping
> of
> much more than 0.5%!

A saturation value of 0.35 seems to produce results closest to what
you get when clicking on "Auto" in the "B&C" window, so I changed the
value that gets recorded from 0.5 to 0.35.

-wayne


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