Calibrate works?

lib/opencv_processing/examples/HueRangeSelection/HueRangeSelection.pde

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+import gab.opencv.*;
+
+PImage img;
+OpenCV opencv;
+Histogram histogram;
+
+int lowerb = 50;
+int upperb = 100;
+
+void setup() {
+  img = loadImage("colored_balls.jpg");
+  opencv = new OpenCV(this, img);
+  size(opencv.width, opencv.height);
+  opencv.useColor(HSB);
+}
+
+void draw() {
+  opencv.loadImage(img);
+  
+  image(img, 0, 0);  
+  
+  opencv.setGray(opencv.getH().clone());
+  opencv.inRange(lowerb, upperb);
+  histogram = opencv.findHistogram(opencv.getH(), 255);
+
+  image(opencv.getOutput(), 3*width/4, 3*height/4, width/4,height/4);
+
+  noStroke(); fill(0);
+  histogram.draw(10, height - 230, 400, 200);
+  noFill(); stroke(0);
+  line(10, height-30, 410, height-30);
+
+  text("Hue", 10, height - (textAscent() + textDescent()));
+
+  float lb = map(lowerb, 0, 255, 0, 400);
+  float ub = map(upperb, 0, 255, 0, 400);
+
+  stroke(255, 0, 0); fill(255, 0, 0);
+  strokeWeight(2);
+  line(lb + 10, height-30, ub +10, height-30);
+  ellipse(lb+10, height-30, 3, 3 );
+  text(lowerb, lb-10, height-15);
+  ellipse(ub+10, height-30, 3, 3 );
+  text(upperb, ub+10, height-15);
+}
+
+void mouseMoved() {
+  if (keyPressed) {
+    upperb += mouseX - pmouseX;
+  } 
+  else {
+    if (upperb < 255 || (mouseX - pmouseX) < 0) {
+      lowerb += mouseX - pmouseX;
+    }
+
+    if (lowerb > 0 || (mouseX - pmouseX) > 0) {
+      upperb += mouseX - pmouseX;
+    }
+  }
+
+  upperb = constrain(upperb, lowerb, 255);
+  lowerb = constrain(lowerb, 0, upperb-1);
+}
+