第一种方法：
1 public static byte[] GetImagePixel(Bitmap img)
2 {
3 byte[] result = new byte[img.Width*img.Height*3];
4 int n = 0;
5 for (int i = 0; i < img.Height; i++)
6 {
7 for (int j = 0; j < img.Width; j++)
8 {
9 result[n] = img.GetPixel(i ,j).R;
10 result[n+1] = img.GetPixel(i, j).G;
11 result[n+2] = img.GetPixel(i, j).B;
12 n += 3;
13 }
14 }
15 return result;
16 }
第二种方法：
1 using System;
2 using System.Collections.Generic;
3 using System.Text;
4 using System.Drawing;
5 using System.Drawing.Imaging;
6
7 namespace ImageCompare
8 {
9 public unsafe class UnsafeBitmap
10 {
11 Bitmap bitmap;
12
13 // three elements used for MakeGreyUnsafe
14 int width;
15 BitmapData bitmapData = null;
16 Byte* pBase = null;
17
18 public UnsafeBitmap(Bitmap bitmap)
19 {
20 this.bitmap = new Bitmap(bitmap);
21 }
22
23 public UnsafeBitmap(int width, int height)
24 {
25 this.bitmap = new Bitmap(width, height, PixelFormat.Format24bppRgb);
26 }
27
28 public void Dispose()
29 {
30 bitmap.Dispose();
31 }
32
33 public Bitmap Bitmap
34 {
35 get
36 {
37 return (bitmap);
38 }
39 }
40
41 private Point PixelSize
42 {
43 get
44 {
45 GraphicsUnit unit = GraphicsUnit.Pixel;
46 RectangleF bounds = bitmap.GetBounds(ref unit);
47
48 return new Point((int)bounds.Width, (int)bounds.Height);
49 }
50 }
51
52 public void LockBitmap()
53 {
54 GraphicsUnit unit = GraphicsUnit.Pixel;
55 RectangleF boundsF = bitmap.GetBounds(ref unit);
56 Rectangle bounds = new Rectangle((int)boundsF.X,
57 (int)boundsF.Y,
58 (int)boundsF.Width,
59 (int)boundsF.Height);
60
61 // Figure out the number of bytes in a row
62 // This is rounded up to be a multiple of 4
63 // bytes, since a scan line in an image must always be a multiple of 4 bytes
64 // in length.
65 width = (int)boundsF.Width * sizeof(PixelData);
66 if (width % 4 != 0)
67 {
68 width = 4 * (width / 4 + 1);
69 }
70 bitmapData =
71 bitmap.LockBits(bounds, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
72
73 pBase = (Byte*)bitmapData.Scan0.ToPointer();
74 }
75
76 public PixelData GetPixel(int x, int y)
77 {
78 PixelData returnValue = *PixelAt(x, y);
79 return returnValue;
80 }
81
82 public void SetPixel(int x, int y, PixelData colour)
83 {
84 PixelData* pixel = PixelAt(x, y);
85 *pixel = colour;
86 }
87
88 public void UnlockBitmap()
89 {
90 bitmap.UnlockBits(bitmapData);
91 bitmapData = null;
92 pBase = null;
93 }
94 public PixelData* PixelAt(int x, int y)
95 {
96 return (PixelData*)(pBase + y * width + x * sizeof(PixelData));
97 }
98 }
99 public struct PixelData
100 {
101 public byte blue;
102 public byte green;
103 public byte red;
104 }
105 }
106
107
108 public static byte[] GetUnsafeImagePixel(Bitmap img)
109 {
110 byte[] result = new byte[img.Width * img.Height * 3];
111 int n = 0;
112 UnsafeBitmap unsafeBitmap = new UnsafeBitmap(img);
113 unsafeBitmap.LockBitmap();
114 int x = 0, y = 0;
115 do
116 {
117 for (x = 0; x < img.Width; x++)
118 {
119 PixelData pixel = unsafeBitmap.GetPixel(x,y);
120 result[n] = pixel.red;
121 result[n + 1] = pixel.green;
122 result[n + 2] = pixel.blue;
123 n += 3;
124 }
125 y++;
126 } while (y!=img.Height);
127 unsafeBitmap.UnlockBitmap();
128 return result;
129
130 }
第三种速度最快：
1 public static unsafe byte[] ConvertTo8Byte(Bitmap img)
2 {
3 byte[] result = new byte[img.Width*img.Height];
4 int n = 0;
5 BitmapData data = img.LockBits(new Rectangle(0, 0, img.Width, img.Height), ImageLockMode.ReadOnly,
6 PixelFormat.Format24bppRgb);
7 var bp = (byte*)data.Scan0.ToPointer();
8
9 for (int i = 0; i != data.Height; i++)
10 {
11 for (int j = 0; j != data.Width; j++)
12 {
13 result[n] = bp[i * data.Stride + j * 3];
14 n++;
15 //0.3R+0.59G+0.11B
16 //float value = 0.11F * bp[i * data.Stride + j * 3] + 0.59F * bp[i * data.Stride + j * 3 + 1] +
17 // 0.3F * bp[i * data.Stride + j * 3 + 2];
18
19 }
20 }
21 img.UnlockBits(data);
22 //img.Dispose();
23 return result;
24 // ColorPalette palette = bit.Palette;
25 //for (int i = 0; i != palette.Entries.Length; i++)
26 //{
27 // palette.Entries[i] = Color.FromArgb(i, i, i);
28 //}
29 //bit.Palette = palette;
30 //bit.Save(destFile, ImageFormat.Bmp);
31 //img.Dispose();
32 //bit.Dispose();
33 }