public void actionPerformed(ActionEvent e) {
      Button b = (Button) e.getSource();
      if (b == null) return;

      boolean imageThere = checkImage();

      if (imageThere) {
        if (b == originalB) {
          reset(imp, ip);
          filteredB.setEnabled(true);
        } else if (b == filteredB) {
          apply(imp, ip);
        } else if (b == sampleB) {
          reset(imp, ip);
          sample();
          apply(imp, ip);
        } else if (b == stackB) {
          applyStack();
        } else if (b == helpB) {
          IJ.showMessage(
              "Help",
              "Threshold Colour  v1.0\n \n"
                  + "Modification of Bob Dougherty's BandPass2 plugin by G.Landini to\n"
                  + "threshold 24 bit RGB images based on Hue, Saturation and Brightness\n"
                  + "or Red, Green and Blue components.\n \n"
                  + "Pass: Band-pass filter (anything within range is displayed).\n \n"
                  + "Stop: Band-reject filter (anything within range is NOT displayed).\n \n"
                  + "Original: Shows the original image and updates the buffer when\n"
                  + " switching to another image.\n \n"
                  + "Filtered: Shows the filtered image.\n \n"
                  + "Stack: Processes the rest of the slices in the stack (if any)\n"
                  + " using the current settings.\n \n"
                  + "Threshold: Shows the object/background in the foreground and\n"
                  + " background colours selected in the ImageJ toolbar.\n \n"
                  + "Invert: Swaps the fore/background colours.\n \n"
                  + "Sample: (experimental) Sets the ranges of the filters based on the\n"
                  + " pixel value componentd in a rectangular, user-defined, ROI.\n \n"
                  + "HSB RGB: Selects HSB or RGB space and resets all the filters.\n \n"
                  + "Note that the \'thresholded\' image is RGB, not 8 bit grey.");
        }
        updatePlot();
        updateLabels();
        imp.updateAndDraw();
      } else {
        IJ.beep();
        IJ.showStatus("No Image");
      }
      notify();
    }
    void sample() {
      byte[] hsSource, ssSource, bsSource;
      // ImageProcessor ip2;
      // ip2 = imp.getProcessor();
      Rectangle myroi = ip.getRoi();
      int swidth = myroi.width;
      int sheight = myroi.height;
      int sy = myroi.y;
      int sx = myroi.x;
      if (swidth == width && sheight == height) {
        IJ.showMessage("Select a rectangular ROI");
        IJ.beep();
        return;
      }

      IJ.run("Select None");

      int snumPixels = swidth * sheight;

      hsSource = new byte[snumPixels];
      ssSource = new byte[snumPixels];
      bsSource = new byte[snumPixels];

      int[] pixs = new int[snumPixels];
      int[] bin = new int[256];

      int counter = 0, pi = 0, rangePassH = 0, rangeStopH = 0, rangePassL = 0, rangeStopL = 0, i, j;

      for (i = sy; i < sy + sheight; i++) {
        for (j = sx; j < sx + swidth; j++) {
          pixs[counter++] = ip.getPixel(j, i);
        }
      }

      // Get hsb or rgb from roi.
      ColorProcessor cp2 = new ColorProcessor(swidth, sheight, pixs);

      int iminhue = 256, imaxhue = -1, iminsat = 256, imaxsat = -1, iminbri = 256, imaxbri = -1;
      int iminred = 256, imaxred = -1, imingre = 256, imaxgre = -1, iminblu = 256, imaxblu = -1;

      if (isRGB) cp2.getRGB(hsSource, ssSource, bsSource);
      else cp2.getHSB(hsSource, ssSource, bsSource);

      for (i = 0; i < snumPixels; i++) {
        bin[hsSource[i] & 255] = 1;
        if ((hsSource[i] & 255) > imaxhue) imaxhue = (hsSource[i] & 255);
        if ((hsSource[i] & 255) < iminhue) iminhue = (hsSource[i] & 255);
        if ((ssSource[i] & 255) > imaxsat) imaxsat = (ssSource[i] & 255);
        if ((ssSource[i] & 255) < iminsat) iminsat = (ssSource[i] & 255);
        if ((bsSource[i] & 255) > imaxbri) imaxbri = (bsSource[i] & 255);
        if ((bsSource[i] & 255) < iminbri) iminbri = (bsSource[i] & 255);
        // IJ.showMessage("h:"+minhue+"H:"+maxhue+"s:"+minsat+"S:"+maxsat+"b:"+minbri+"B:"+maxbri);
      }

      if (!isRGB) { // get pass or stop filter whichever has a narrower range
        for (i = 0; i < 256; i++) {
          if (bin[i] > 0) {
            rangePassL = i;
            break;
          }
        }
        for (i = 255; i >= 0; i--) {
          if (bin[i] > 0) {
            rangePassH = i;
            break;
          }
        }
        for (i = 0; i < 256; i++) {
          if (bin[i] == 0) {
            rangeStopL = i;
            break;
          }
        }
        for (i = 255; i >= 0; i--) {
          if (bin[i] == 0) {
            rangeStopH = i;
            break;
          }
        }
        if ((rangePassH - rangePassL) < (rangeStopH - rangeStopL)) {
          bandPassH.setState(true);
          bandStopH.setState(false);
          iminhue = rangePassL;
          imaxhue = rangePassH;
        } else {
          bandPassH.setState(false);
          bandStopH.setState(true);
          iminhue = rangeStopL;
          imaxhue = rangeStopH;
        }
      } else {
        bandPassH.setState(true);
        bandStopH.setState(false);
      }

      adjustMinHue(iminhue);
      minSlider.setValue(iminhue);
      adjustMaxHue(imaxhue);
      maxSlider.setValue(imaxhue);
      adjustMinSat(iminsat);
      minSlider2.setValue(iminsat);
      adjustMaxSat(imaxsat);
      maxSlider2.setValue(imaxsat);
      adjustMinBri(iminbri);
      minSlider3.setValue(iminbri);
      adjustMaxBri(imaxbri);
      maxSlider3.setValue(imaxbri);
      originalB.setEnabled(true);
      // IJ.showStatus("done");
    }