C # WinForm color images into gray images, gray, grayscale pictures, fast, Safe,unsafe

Convert color images to gray images, directly using the. NET interface to traverse each pixel point conversion is very inefficient, 800K picture 650,000 pixels My computer takes 5 minutes, and with unsafe, the speed increases thousands of times times, the same picture only uses 0. seconds

A common code for traversing pixel-point conversions

constructor function

C # code < param name= "allowscriptaccess" value= "always" >  

1. Public TPHC ()
2. {
3. InitializeComponent ();
4. this.pictureBox1.ImageLocation = "f:\\ black hair. jpg";
5. }

button click event

C # code

2. Private void button3_click (object sender, EventArgs e)
4. {
6. int Height = this.pictureBox1.Image.Height;
8. int Width = this.pictureBox1.Image.Width;
10. Bitmap Bitmap = new Bitmap (Width, Height);
12. Bitmap Mybitmap = (Bitmap)this.pictureBox1.Image;
14. Color Pixel;
16. For (int x = 0; × < Width; x + +)
18. For (int y = 0; y < Height; y++)
20. {
22. Pixel = Mybitmap.getpixel (x, y);
24. int R, G, B, Result = 0;
26. r = Pixel. R
28. g = pixel. G
30. b = pixel. B
32. //Instance program produces black and white images with weighted average value method
34. int iType = 2;
36. switch (iType)
38. {
40. Case 0://Averaging method
42. Result = ((r + G + B)/3);
44. Break ;
46. Case 1://Max value method
48. Result = r > G? R:g;
50. result = result > b? Result:b;
52. Break ;
54. Case 2://Weighted average value method
56. Result = ((int) (0.7 * R) + (int) (0.2 * g) + (int) (0.1 * b));
58. Break ;
60. }
62. Bitmap. SetPixel (x, Y, Color.FromArgb (result, result, result));
64. }
66. this.pictureBox1.Image = bitmap;
68. }