Convolver

[bateman]

Hi all,

I have the following code:

import ij.*;
import ij.process.*;
import ij.gui.*;
import java.awt.*;
import ij.plugin.*;
import ij.plugin.filter.Convolver;
import ij.io.*;

public class Colli_Shots implements PlugIn {
        public void run(String arg) {
       
        OpenDialog od = new OpenDialog("Open.....", null);
        Opener op = new Opener();
        String directory = od.getDirectory();
        String filename = od.getFileName();
       
        ImagePlus imp =  new ImagePlus(directory);
        ImageProcessor ip = imp.getProcessor();
        float[] H = {1,0,1,2,0,2,1,0,1};
        Convolver cv = new Convolver();
        cv.setNormalize(false);
        cv.convolve(ip,H,3,3);
        //imp.updateAndDraw();
                               
        }

}


I just to apply a sobel operator to an image. However when I run the above code,
it compiles but I get a NullPOinterException.

Any ideas why this is?

Thanks for your time

Gary

[Mohamed Tleis]

Hi,

I think this might has to do with creating a new ImagePlus, you are
assigning the directory name to a new imagePlus, maybe you mean new
ImagePlus(directory+ "/" + filename); or whatever separator used.

Best Regards,

On Thu, Apr 19, 2012 at 12:52 PM, Gary <[hidden email]> wrote:

> Hi all,
>
> I have the following code:
>
> import ij.*;
> import ij.process.*;
> import ij.gui.*;
> import java.awt.*;
> import ij.plugin.*;
> import ij.plugin.filter.Convolver;
> import ij.io.*;
>
> public class Colli_Shots implements PlugIn {
>        public void run(String arg) {
>
>        OpenDialog od = new OpenDialog("Open.....", null);
>        Opener op = new Opener();
>        String directory = od.getDirectory();
>        String filename = od.getFileName();
>
>        ImagePlus imp =  new ImagePlus(directory);
>        ImageProcessor ip = imp.getProcessor();
>        float[] H = {1,0,1,2,0,2,1,0,1};
>        Convolver cv = new Convolver();
>        cv.setNormalize(false);
>        cv.convolve(ip,H,3,3);
>        //imp.updateAndDraw();
>
>        }
>
> }
>
>
> I just to apply a sobel operator to an image. However when I run the above
> code,
> it compiles but I get a NullPOinterException.
>
> Any ideas why this is?
>
> Thanks for your time
>
> Gary
>

[Rasband, Wayne (NIH/NIMH) [E]]

On Apr 19, 2012, at 6:52 AM, Gary wrote:

> Hi all,
>
> I have the following code:
>
> import ij.*;
> import ij.process.*;
> import ij.gui.*;
> import java.awt.*;
> import ij.plugin.*;
> import ij.plugin.filter.Convolver;
> import ij.io.*;
>
> public class Colli_Shots implements PlugIn {
> public void run(String arg) {
>
> OpenDialog od = new OpenDialog("Open.....", null);
> Opener op = new Opener();
> String directory = od.getDirectory();
> String filename = od.getFileName();
>
> ImagePlus imp =  new ImagePlus(directory);
> ImageProcessor ip = imp.getProcessor();
> float[] H = {1,0,1,2,0,2,1,0,1};
> Convolver cv = new Convolver();
> cv.setNormalize(false);
> cv.convolve(ip,H,3,3);
> //imp.updateAndDraw();
>
> }

> }
>
> I just to apply a sobel operator to an image. However when I run the above code,
> it compiles but I get a NullPOinterException.
>
> Any ideas why this is?

The ImagePlus constructor requires a full file path:

   ImagePlus imp =  new ImagePlus(directory+filename);

However, an easier way to open the image is to use IJ.openImage(""). Here is an example:

   public void run(String arg) {
      ImagePlus imp = IJ.openImage("");      
      ImageProcessor ip = imp.getProcessor();
      float[] H = {1,0,1,2,0,2,1,0,1};
      Convolver cv = new Convolver();
      cv.setNormalize(false);
      cv.convolve(ip,H,3,3);
      imp.show();
   }

-wayne