An application to extract certain regions of an image stream which share the same color.

ColorExtractor.scala

package net.ladstatt.apps

import javafx.scene._

import org.opencv.core._
import org.opencv.imgproc.Imgproc
import javafx.application.{Platform, Application}
import javafx.scene.control._
import javafx.scene.image.ImageView
import javafx.scene.layout.BorderPane
import javafx.stage.Stage
import java.util.ResourceBundle
import javafx.fxml.{FXML, Initializable}
import java.net.URL
import javafx.beans.property.SimpleObjectProperty
import net.ladstatt.jfx._
import org.controlsfx.control.{HsvSlider, RangeSlider}

object ColorExtractor {

  def main(args: Array[String]): Unit = {
    Application.launch(classOf[ColorExtractor], args: _*)
  }

}

class ColorExtractor extends Application with JfxUtils with Initializable with OpenCVUtils {

  val lowerBoundProperty = new SimpleObjectProperty[Scalar](new Scalar(0, 0, 0))

  def setLowerBound(lb: Scalar) = lowerBoundProperty.set(lb)

  def getLowerBound() = lowerBoundProperty.get

  val upperBoundProperty = new SimpleObjectProperty[Scalar](new Scalar(255, 255, 255))

  def setUpperBound(lb: Scalar) = upperBoundProperty.set(lb)

  def getUpperBound() = upperBoundProperty.get

  override def init(): Unit = loadNativeLibs // important to have this statement on the "right" thread

  def colorSpace(conversionMethod: Int = Imgproc.COLOR_BGR2GRAY)(input: Mat): Mat = {
    val colorTransformed = new Mat
    Imgproc.cvtColor(input, colorTransformed, conversionMethod)
    colorTransformed
  }

  def restrain(input: Mat): Mat = {
    val dest = new Mat
    val lb = getLowerBound()
    val ub = getUpperBound()
    Core.inRange(input, lb, ub, dest)
    dest
  }

  def alphaBlend(src: Mat, alpha: Mat): Mat = {
    val channels = new java.util.ArrayList[Mat]()
    Core.split(src, channels)
    channels.add(alpha)
    val merged = new Mat
    Core.merge(channels, merged)
    merged
  }

  @FXML var textFieldLbHue: TextField = _
  @FXML var textFieldLbSaturation: TextField = _
  @FXML var textFieldLbValue: TextField = _

  @FXML var textFieldUbHue: TextField = _
  @FXML var textFieldUbSaturation: TextField = _
  @FXML var textFieldUbValue: TextField = _

  @FXML var hueSlider: HsvSlider = _
  @FXML var saturationSlider: HsvSlider = _
  @FXML var valueSlider: HsvSlider = _

  @FXML var viewPort: ImageView = _

  override def start(stage: Stage): Unit = {
    stage.setTitle("Color Extractor")

    val imageService = new WebcamService

    imageService.setOnSucceeded(
      mkEventHandler(
        event => {
          val imageAsMat = event.getSource.getValue.asInstanceOf[Mat]
          val alphaChannel = restrain(colorSpace(Imgproc.COLOR_BGR2HSV)(imageAsMat))
          viewPort.imageProperty.set(toImage(alphaBlend(imageAsMat, alphaChannel)))
          imageService.restart
        }
      ))

    imageService.start


    val scene = new Scene(mk[BorderPane](mkFxmlLoader("/colorextractor.fxml", this)))
    stage.setScene(scene)
    stage.show

  }

  def initialize(url: URL, resourceBundle: ResourceBundle): Unit = {

    def initRangeSlider(pos: Int, slider: RangeSlider, lowerTextField: TextField, upperTextField: TextField): Unit = {
      slider.lowValueProperty().addListener(mkChangeListener[Number](
        (obVal, oldVal, newVal) => {
          val mutableBounds = getLowerBound.`val`
          mutableBounds(pos) = newVal.doubleValue()
          setLowerBound(new Scalar(mutableBounds))
          lowerTextField.setText("%.2f".format(newVal.doubleValue))
        }
      ))
      slider.highValueProperty().addListener(mkChangeListener[Number](
        (obVal, oldVal, newVal) => {
          val mutableBounds = getUpperBound.`val`
          mutableBounds(pos) = newVal.doubleValue()
          setUpperBound(new Scalar(mutableBounds))
          upperTextField.setText("%.2f".format(newVal.doubleValue))
        }
      ))
    }

    def setRangeSlider(slider: RangeSlider)(range: (Double, Double)) {
      slider.setLowValue(range._1)
      slider.setHighValue(range._2)
    }

    def setHueSlider = setRangeSlider(hueSlider) _
    def setSaturationSlider = setRangeSlider(saturationSlider) _
    def setValueSlider = setRangeSlider(valueSlider) _

    initRangeSlider(0, hueSlider, textFieldLbHue, textFieldUbHue)
    initRangeSlider(1, saturationSlider, textFieldLbSaturation, textFieldUbSaturation)
    initRangeSlider(2, valueSlider, textFieldLbValue, textFieldUbValue)

    setHueSlider((0.0, 179.0))
    setSaturationSlider((0.0, 255.0))
    setValueSlider((0.0, 255.0))

  }

}