Re: Gamma correction slider?

Posted by dscho on Dec 18, 2009; 5:23pm
URL: http://imagej.273.s1.nabble.com/Gamma-correction-slider-tp3689970p3689973.html

Hi Leonard,

On Fri, 18 Dec 2009, Leonard Sitongia wrote:

> I see a few postings about this subject in the archive, but didn't see a
> reply or resolution.  People around here like the gamma slider on IDL's
> xloadct GUI and I'd like to be able to provide a way of doing this in
> ImageJ as a substitute for IDL.  I found a plug-in which creates a black
> and white LUT with a gamma control (I like how it presents the control
> as a dynamic gamma correction plot) but a slider would be most familiar
> to people.
>
> Is there already a solution for this?

The easiest I can think of is this little Javascript I wrote in response
to your question:

-- snip --
importClass(Packages.ij.WindowManager)
importClass(Packages.ij.gui.GenericDialog)
importClass(Packages.ij.process.ImageProcessor)
importClass(Packages.java.awt.event.AdjustmentListener)

var image = WindowManager.getCurrentImage();
if (image != null) {
        var ip = image.getProcessor();
        ip.snapshot();
       
        var dialog = GenericDialog("Gamma (1.0)");
        dialog.addSlider("gamma", 1, 500, 100);
        dialog.getNumericFields().lastElement().setVisible(false);
        var scrollbar = dialog.getSliders().lastElement();
        dialog.add(scrollbar);
        var listener = new AdjustmentListener ({
                adjustmentValueChanged : function(event) {
                        var value = scrollbar.getValue() / 100.0;
                        dialog.setTitle("Gamma (" + value + ")");
                        ip.reset();
                        ip.snapshot();
                        ip.gamma(value);
                        image.updateAndDraw();
                }
        });
        scrollbar.addAdjustmentListener(listener);
        dialog.showDialog();
        if (dialog.wasCanceled()) {
                ip.reset();
                image.updateAndDraw();
        }
}
-- snap --

In ImageJ, you can copy-paste this into the window you get after
Plugins>New>JavaScript.  In Fiji, you can paste it into the script editor
(File>New>Script, then Language>Javascript), you will even get syntax
highlighting with that.

Ciao,
Johannes