diff --git a/src/imagefilters/ImageFilters.scala b/src/imagefilters/ImageFilters.scala
index aa4ac71..b3e0552 100644
--- a/src/imagefilters/ImageFilters.scala
+++ b/src/imagefilters/ImageFilters.scala
@@ -59,4 +59,13 @@ object ImageFilters {
       Math.sqrt(dx*dx + dy*dy).toInt
     }
   })
+
+  def sobel(a: Array[Array[Int]], intensityFactor: Double): Array[Array[Int]] = filter(a, (value, x, y, width, height) => {
+    if (x == 0 || x == width - 1 || y == 0 || y == height - 1) value
+    else {
+      val dx: Int = a(y-1)(x+1) + 2*a(y)(x+1) + a(y+1)(x+1) - a(y-1)(x-1) - 2*a(y)(x-1) - a(y+1)(x-1)
+      val dy: Int = a(y+1)(x-1) + 2*a(y+1)(x) + a(y+1)(x+1) - a(y-1)(x-1) - 2*a(y-1)(x) - a(y-1)(x+1)
+      (Math.sqrt(dx*dx + dy*dy)*intensityFactor).toInt
+    }
+  })
 }
diff --git a/src/imagefilters/ImageProcessingApp.scala b/src/imagefilters/ImageProcessingApp.scala
index 7568f3c..5e3eb0e 100644
--- a/src/imagefilters/ImageProcessingApp.scala
+++ b/src/imagefilters/ImageProcessingApp.scala
@@ -4,7 +4,7 @@ import isc.graphics.ImageGraphics
 
 object ImageProcessingApp extends App {
 
-	val imageFile = "./res/collins_eileen.png"
+	/*val imageFile = "./res/collins_eileen.png"
 	val org = new ImageGraphics(imageFile, "Original", -500, -250)
 	val dest = new ImageGraphics(imageFile, "Duplicate", 0, -250)
 	val thresh = new ImageGraphics(imageFile, "Threshold", -500, 250)
@@ -22,5 +22,19 @@ object ImageProcessingApp extends App {
 	mean2.setPixelsBW(ImageFilters.mean(mean2.getPixelsBW(), 4))
 
 	val edges = new ImageGraphics("./res/rice.jpg", "Edges", 500, 250)
-	edges.setPixelsBW(ImageFilters.edges(edges.getPixelsBW()))
+	edges.setPixelsBW(ImageFilters.edges(edges.getPixelsBW()))*/
+
+	val imageFile: String = "./res/grace_hopper.jpg"
+	val org = new ImageGraphics(imageFile, "Original", -768, -512)
+	val bw = new ImageGraphics(imageFile, "Black & White", -256, -512)
+	val threshold = new ImageGraphics(imageFile, "Threshold", 256, -512)
+	val blur = new ImageGraphics(imageFile, "Blurred", -768, 0)
+	val edges = new ImageGraphics(imageFile, "Edge detection", -256, 0)
+	val sobel = new ImageGraphics(imageFile, "Sobel", 256, 0)
+
+	bw.setPixelsBW(ImageFilters.duplicate(org.getPixelsBW()))
+	threshold.setPixelsBW(ImageFilters.threshold(org.getPixelsBW(), 128))
+	blur.setPixelsBW(ImageFilters.mean(org.getPixelsBW(), 3))
+	edges.setPixelsBW(ImageFilters.edges(org.getPixelsBW()))
+	sobel.setPixelsBW(ImageFilters.sobel(org.getPixelsBW(), 0.3))
 }