1. EEC-693/793 Applied Computer Vision with Depth Cameras
Lecture 19
Wenbing Zhao

2. Outline Emgu CV Software installation
Configure a new project with Emgu CV
Working with Emgu CV images

3. Software Needed OpenCV does not support C#: cannot use it directly
We will be using Emgu CV: a cross platform .Net wrapper for OpenCV
Due to unknown reason, later version of EmguCV does not work on x64 Windows platform
Latest version that worked for me is:

4. Configuration with EmguCV
It is tricky to use EmguCV in Visual Studio
You must add the following EmguCV dll files as references
Emgu.CV.dll
Emgu.CV.UI.dll 
Emgu.Util.dll  
Furthermore, you must copy at least the following OpenCV dlls to your project’s bin/Debug or bin/Release directory
opencv_core220.dll    
opencv_imgproc220.dll
Infrared data: 16 bits per pixel at 640x480 at 30 FPS

5. Configuration with EmguCV
Alternatively, you can add opencv dlls as files into your project. For each dll, right click and select properties. Then choose “copy always”. The dll will be copied to the output directory for you.
More one critical step. Right click your project name in the “Solution Explorer” pane, and select properties. Then, choose the “Build” tab and change the platform target to “x64”

6. Configuration with EmguCV

7. Working with EmguCV Images
EmguCV Image Class
Creating Image
Getting/setting pixels
Drawing objects on image
5/12/2019
EEC492/693/793 - iPhone Application Development

8. Generic Parameters for EmguCV Images
Image<TColor, TDepth>
Depth: number of bits used to represent the color of a single pixel
Color: type of color representation. Emgu CV supports
Supported TDepth types:
Byte
SByte
Single (float)
Double
UInt16
Int16
Int32 (int)
Supported TColor types:
Gray
Bgr (Blue Green Red)
Bgra (Blue Green Red Alpha)
Hsv (Hue Saturation Value)
Hls (Hue Lightness Saturation)
Lab (CIE L*a*b*)
Luv (CIE L*u*v*)
Xyz (CIE XYZ.Rec 709 with D65 white point)
Ycc (YCrCb JPEG)
Image<Gray, Byte> image = new Image<Gray, Byte>( width, height);

9. Creating EmguCV Images
Creating a new image
No background
With blue background
Creating an image from an existing file
Creating an image from bitmap
Image<Bgr, Byte> img1 = new Image<Bgr, Byte>(480, 320);
Image<Bgr, Byte> img1 = new Image<Bgr, Byte>(480, 320, new Bgr(255, 0, 0));
Image<Bgr, Byte> img1 = new Image<Bgr, Byte>("MyImage.jpg");
Image<Bgr, Byte> img = new Image<Bgr, Byte>(bmp);
5/12/2019
EEC492/693/793 - iPhone Application Development

10. Accessing Image Data (Pixels)
Direct access to Image
//Color Image
My_Image[0, 0] = new Bgr(Color.Red);
//Gray Image
gray_image[0, 0] = new Gray(200);
//Color Image
Bgr my_Bgr = My_Image[0, 0];
//Gray Image
Gray my_Gray = gray_image[0, 0];

11. Accessing Image Data (Pixels)
Access via Image.Data property
Must respect the image depth when accessing the Data property
A grayscale image has a depth of one (i.e., 1 bit)
[x,y,0]
RGB color image has a depth of 3 (i.e., 23 bits or one Byte)
[x,y,0], [x,y,1], [x,y,2] represent the blue, green, and red spectrums
//Color Image Color
R = Color.Red;
My_Image.Data[0,0,2] = R.R; //Write to the Red Spectrum My_Image.Data[0,0,1] = R.G; //Write to the Green Spectrum My_Image.Data[0,0,0] = R.B; //Write to the Blue Spectrum
//Gray Image gray_image[0, 0] = new Gray(200);

12. Accessing Image Data: Examples
Using column per row access:
private void settingPixelsSlow(Image<Bgr, Byte> img) {
Stopwatch evaluator = new Stopwatch();
int repetitions = 100;
Bgr color = new Bgr(100, 40, 243);
evaluator.Start();
for (int run = 0; run < repetitions; run++) {
for (int j = 0; j < img.Cols; j++) {
for (int i = 0; i < img.Rows; i++){
img[i, j] = color; }
evaluator.Stop();
Console.WriteLine("Average execution time for {0} iteration \n using column per row access: {1}ms\n", repetitions, evaluator.ElapsedMilliseconds / repetitions);

13. Accessing Image Data: Examples
Using Data property
private void settingPixelsFaster(Image<Bgr, Byte> img) {
Stopwatch evaluator = new Stopwatch();
int repetitions = 100;
evaluator.Start();
for (int run = 0; run < repetitions; run++) {
for (int j = 0; j < img.Cols; j++) {
for (int i = 0; i < img.Rows; i++) {
img.Data[i, j,0] = 100;
img.Data[i, j, 1] = 40;
img.Data[i, j, 2] = 243; }
evaluator.Stop();
Console.WriteLine("Average execution time for {0} iteration \n using Data property: {1}ms\n", repetitions, evaluator.ElapsedMilliseconds / repetitions);

14. Accessing Image Data: Examples
Using Data property outside the loop:
private void settingPixelsFastest(Image<Bgr, Byte> img) {
Stopwatch evaluator = new Stopwatch();
int repetitions = 100;
byte[, ,] data = img.Data;
evaluator.Start();
for (int run = 0; run < repetitions; run++) {
for (int j = 0; j < img.Cols; j++) {
for (int i = 0; i < img.Rows; i++) {
data[i, j, 0] = 100;
data[i, j, 1] = 40;
data[i, j, 2] = 243; }
evaluator.Stop();
Console.WriteLine("Average execution time for {0} iteration \n using Data property smartly: {1}ms\n", repetitions, evaluator.ElapsedMilliseconds / repetitions);

15. Automatic Garbage Collection
The Image<TColor, TDepth> class automatically take care of the memory management and garbage collection
Once the garbage collector decided that there is no more reference to the Image<TColor, TDepth> object, it will call the Disposed method, which release the unmanaged IplImage structure
using (Image<Gray, Single> image =
new Image<Gray, Single>(1000, 800)) {
... //do something here in the image
} //The image will be disposed here and memory freed

16. First EmguCV WPF App Basic image type is: Image<Rgb,byte>
It is a wrapper for IplImage class in OpenCV
Image<> offers many constructors
public Image(Bitmap bmp);
public Image(string fileName);
public Image(int width, int height);
public Image(int width, int height, TColor value);
public Image(int width, int height, int stride, IntPtr scan0);
In the app, we will create a new Image object, draw “Hello world”, and display via WPF image control
TColor value: image color

17. First EmguCV WPF App Create a new WPF project
Add emgu cv dlls and opencv dlls
Add System.Drawing reference
Change platform target to x64
Add one image control in MainWindow
Draw “Hello world” using EmguCV Image<>
Convert the image to BitmapSource using the provided helper function
Set the BitmapSource as the WPF image control source

18. First EmguCV WPF App Add the following namespaces: using Emgu.CV;
using Emgu.CV.CvEnum;
using Emgu.CV.Structure;
// for Image to BitmapSource conversion
using System.IO;
using System.Runtime.InteropServices;
using System.Drawing;
using System.Drawing.Imaging;
// for Stopwatch
using System.Diagnostics;

19. First EmguCV WPF App public MainWindow() { InitializeComponent();
//Create an image of 400x200 of Blue color
Image<Bgr, Byte> img =
new Image<Bgr, byte>(400, 200, new Bgr(255, 0, 0));
MCvFont f = new MCvFont(FONT.CV_FONT_HERSHEY_COMPLEX, 1.0, 1.0); //Create the font
//Draw "Hello, world." on the image using the specific font
img.Draw("Hello, world", ref f, new System.Drawing.Point(10, 80),
new Bgr(0, 255, 0));
BitmapSource imgsource=ToBitmapSource(img);
image1.Source = imgsource; }

20. First EmguCV WPF App
// taken from:
[DllImport("gdi32")]
private static extern int DeleteObject(IntPtr o);
public BitmapSource ToBitmapSource(IImage image) {
using (System.Drawing.Bitmap source = image.Bitmap) {
IntPtr ptr = source.GetHbitmap(); //obtain the Hbitmap
BitmapSource bs = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
ptr, IntPtr.Zero, Int32Rect.Empty, System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
DeleteObject(ptr); //release the HBitmap
return bs; }}

21. Have a little more fun
EmguCV Image also provides a number of drawing methods
Draw a Circle of the specific color and thickness
// thickness: If thickness is less than 1, the circle is filled up
void Draw(CircleF circle, TColor color, int thickness);
// others
void Draw(Ellipse ellipse, TColor color, int thickness);
void Draw(IConvexPolygonF polygon, TColor color, int thickness);
void Draw(LineSegment2D line, TColor color, int thickness);
void Draw(Rectangle rect, TColor color, int thickness);
PointF pt = new PointF(50, 50);
CircleF circ = new CircleF(pt, 50);
img.Draw(circ, new Bgr(0, 255, 0), 2);

22. Accessing Pixels in Image
Try out the three ways of accessing pixels in the image
Draw more customized patterns in the image