最近看了一些Sobel算法，并试了一下，源码如下：
private void Sobel(Bitmap img) {
int width = img.Width;
int height = img.Height;
int[,] Gx = new int[, ]{ {-, , },
{-, , } ,
{-, , } };
int[,] Gy = new int[, ]{ {-,-,-},
{ , , },
{ , , }};
int[,] TotalGx = new int[img.Width, img.Height];
int[,] TotalGy = new int[img.Width, img.Height];
int[,] GTotal = new int[img.Width, img.Height];
Bitmap bitmapTemp = new Bitmap(img.Width, img.Height, PixelFormat.Format24bppRgb);
LockBitmap lockBitmap1 = new LockBitmap(bitmapTemp);
lockBitmap1.LockBits();
LockBitmap lockBitmap = new LockBitmap(img);
lockBitmap.LockBits();
for (int i = ; i < img.Width - ; i++)
{
for (int j = ; j < img.Height - ; j++)
{
Color a = lockBitmap.GetPixel(i - , j - );//[0][0]
Color b = lockBitmap.GetPixel(i - , j); //[0][1]
Color c = lockBitmap.GetPixel(i - , j + );//[0][2]
Color d = lockBitmap.GetPixel(i, j - ); //[1][0]
Color f = lockBitmap.GetPixel(i, j); //[1][1]
Color g = lockBitmap.GetPixel(i, j + ); //[1][2]
Color h = lockBitmap.GetPixel(i + , j - );//[2][0]
Color l = lockBitmap.GetPixel(i + , j); //[2][1]
Color n = lockBitmap.GetPixel(i + , j + ); //[2][2]
TotalGx[i, j] = Gx[, ] * Avg(a) + Gx[, ] * Avg(b) + Gx[, ] * Avg(c)
+ Gx[, ] * Avg(d) + Gx[, ] * Avg(f) + Gx[, ] * Avg(g)
+ Gx[, ] * Avg(h) + Gx[, ] * Avg(l) + Gx[, ] * Avg(n);
//if (TotalGx[i, j] < 0) { TotalGx[i, j] = 0; }
//if (TotalGx[i, j] > 255) { TotalGx[i, j] = 255; }
TotalGy[i, j] = Gy[, ] * Avg(a) + Gy[, ] * Avg(b) + Gy[, ] * Avg(c)
+ Gy[, ] * Avg(d) + Gy[, ] * Avg(f) + Gy[, ] * Avg(g)
+ Gy[, ] * Avg(h) + Gy[, ] * Avg(l) + Gy[, ] * Avg(n);
//if (TotalGy[i, j] < 0) { TotalGy[i, j] = 0; }
//if (TotalGy[i, j] > 255) { TotalGy[i, j] = 255; }
//GTotal[i, j] = TotalGx[i, j] + TotalGy[i, j];
GTotal[i, j] = (int)Math.Sqrt(TotalGx[i, j] * TotalGx[i, j] + TotalGy[i, j] * TotalGy[i, j]);
if (GTotal[i, j] >= )
{ GTotal[i, j] = ; }
if (GTotal[i, j] < )
{ GTotal[i, j] = ; }
//bitmapTemp.SetPixel(i, j, Color.FromArgb(GTotal[i, j], GTotal[i ,j], GTotal[i, j]));
lockBitmap1.SetPixel(i, j, Color.FromArgb(GTotal[i, j], GTotal[i, j], GTotal[i, j]));
}
}
lockBitmap1.UnlockBits();
lockBitmap.UnlockBits();
pictureBox2.Image = lockBitmap1.GetBitmap();
}
public class LockBitmap
{
Bitmap source = null;
IntPtr Iptr = IntPtr.Zero;
BitmapData bitmapData = null; public byte[] Pixels { get; set; }
public int Depth { get; private set; }
public int Width { get; private set; }
public int Height { get; private set; } public LockBitmap(Bitmap source)
{
this.source = source;
} public Bitmap GetBitmap() { return this.source; } /// <summary>
/// Lock bitmap data
/// </summary>
public void LockBits()
{
try
{
// Get width and height of bitmap
Width = source.Width;
Height = source.Height; // get total locked pixels count
int PixelCount = Width * Height; // Create rectangle to lock
Rectangle rect = new Rectangle(, , Width, Height); // get source bitmap pixel format size
Depth = System.Drawing.Bitmap.GetPixelFormatSize(source.PixelFormat); // Check if bpp (Bits Per Pixel) is 8, 24, or 32
if (Depth != && Depth != && Depth != )
{
throw new ArgumentException("Only 8, 24 and 32 bpp images are supported.");
} // Lock bitmap and return bitmap data
bitmapData = source.LockBits(rect, ImageLockMode.ReadWrite,
source.PixelFormat); // create byte array to copy pixel values
int step = Depth / ;
Pixels = new byte[PixelCount * step];
Iptr = bitmapData.Scan0; // Copy data from pointer to array
Marshal.Copy(Iptr, Pixels, , Pixels.Length);
}
catch (Exception ex)
{
throw ex;
}
} /// <summary>
/// Unlock bitmap data
/// </summary>
public void UnlockBits()
{
try
{
// Copy data from byte array to pointer
Marshal.Copy(Pixels, , Iptr, Pixels.Length); // Unlock bitmap data
source.UnlockBits(bitmapData);
}
catch (Exception ex)
{
throw ex;
}
}
/// <summary>
/// Get the color of the specified pixel
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <returns></returns>
public Color GetPixel(int x, int y)
{
Color clr = Color.Empty; // Get color components count
int cCount = Depth / ; // Get start index of the specified pixel
int i = ((y * Width) + x) * cCount; if (i > Pixels.Length - cCount)
throw new IndexOutOfRangeException(); if (Depth == ) // For 32 bpp get Red, Green, Blue and Alpha
{
byte b = Pixels[i];
byte g = Pixels[i + ];
byte r = Pixels[i + ];
byte a = Pixels[i + ]; // a
clr = Color.FromArgb(a, r, g, b);
}
if (Depth == ) // For 24 bpp get Red, Green and Blue
{
byte b = Pixels[i];
byte g = Pixels[i + ];
byte r = Pixels[i + ];
clr = Color.FromArgb(r, g, b);
}
if (Depth == )
// For 8 bpp get color value (Red, Green and Blue values are the same)
{
byte c = Pixels[i];
clr = Color.FromArgb(c, c, c);
}
return clr;
} /// <summary>
/// Set the color of the specified pixel
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="color"></param>
public void SetPixel(int x, int y, Color color)
{
// Get color components count
int cCount = Depth / ; // Get start index of the specified pixel
int i = ((y * Width) + x) * cCount; if (Depth == ) // For 32 bpp set Red, Green, Blue and Alpha
{
Pixels[i] = color.B;
Pixels[i + ] = color.G;
Pixels[i + ] = color.R;
Pixels[i + ] = color.A;
}
if (Depth == ) // For 24 bpp set Red, Green and Blue
{
Pixels[i] = color.B;
Pixels[i + ] = color.G;
Pixels[i + ] = color.R;
}
if (Depth == )
// For 8 bpp set color value (Red, Green and Blue values are the same)
{
Pixels[i] = color.B;
}
} //public Color GetPixel(int x, int y)
//{
// unsafe
// {
// byte* ptr = (byte*)Iptr;
// ptr = ptr + bitmapData.Stride * y;
// ptr += Depth * x / 8;
// Color c = Color.Empty;
// if (Depth == 32)
// {
// int a = ptr[3];
// int r = ptr[2];
// int g = ptr[1];
// int b = ptr[0];
// c = Color.FromArgb(a, r, g, b);
// }
// else if (Depth == 24)
// {
// int r = ptr[2];
// int g = ptr[1];
// int b = ptr[0];
// c = Color.FromArgb(r, g, b);
// }
// else if (Depth == 8)
// {
// int r = ptr[0];
// c = Color.FromArgb(r, r, r);
// }
// return c;
// }
//} //public void SetPixel(int x, int y, Color c)
//{
// unsafe
// {
// byte* ptr = (byte*)Iptr;
// ptr = ptr + bitmapData.Stride * y;
// ptr += Depth * x / 8;
// if (Depth == 32)
// {
// ptr[3] = c.A;
// ptr[2] = c.R;
// ptr[1] = c.G;
// ptr[0] = c.B;
// }
// else if (Depth == 24)
// {
// ptr[2] = c.R;
// ptr[1] = c.G;
// ptr[0] = c.B;
// }
// else if (Depth == 8)
// {
// ptr[2] = c.R;
// ptr[1] = c.G;
// ptr[0] = c.B;
// }
// }
//} //return data[((width * y) + x) * 4 + i];
}
效果如下：
总结：用自带的图片处理性能低下，建议使用指针或者其他图像库处理，比如OpenCV的.NET库。