C# 内存法图像处理
内存法通过把图像储存在内存中进行处理，效率大大高于GetPixel方法，安全性高于指针法。
笔者当初写图像处理的时候发现网上多是用GetPixel方法实现，提到内存法的时候也没有具体实现，所以笔者在这里具体实现一下- -，望指正。
首先讲一下用到的一些方法。
1.LockBits和UnlockBits：使用 LockBits 方法，可在系统内存中锁定现有的位图，以便通过编程方式进行更改，每调用LockBits之后都应该调用一次UnlockBits。
2.Scan0：图像的第一个字节地址。
3.Stride：步幅，扫描宽度，形象的说就是一行的长度。
4.PixelFormat：数据的实际像素格式。
给出原图：
一、灰度
对每个像素点进行加权平均，（方法不唯一）。
/// <summary> /// 灰化实现方法 /// </summary> void Image_Ashing() { if (pbshowbox.Image != null) { int Height = this.pbshowbox.Image.Height; int Width = this.pbshowbox.Image.Width; Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format24bppRgb); Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image; BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb); BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb); unsafe { byte* pin = (byte*)(oldData.Scan0.ToPointer()); byte* pout = (byte*)(newData.Scan0.ToPointer()); for (int y = 0; y < oldData.Height; y++) { for (int x = 0; x < oldData.Width; x++) { byte Result = (byte)(pin[0] * 0.1 + pin[1] * 0.2 + pin[2] * 0.7);//加权平均实现灰化 pout[0] = (byte)(Result); pout[1] = (byte)(Result); pout[2] = (byte)(Result); pin = pin + 3; pout = pout + 3; } pin += oldData.Stride - oldData.Width * 3; pout += newData.Stride - newData.Width * 3; } bitmap.UnlockBits(newData); MyBitmap.UnlockBits(oldData); this.pbshowbox.Image = bitmap; } } else { MessageBox.Show("请先打开一张图片！"); } }
二、柔化
像素点与周围像素点差别较大时取平均值。
/// <summary> /// 柔化实现方法 /// </summary> void Image_Soften() { if (pbshowbox.Image != null) { int Height = this.pbshowbox.Image.Height; int Width = this.pbshowbox.Image.Width; Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format32bppRgb); Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image; BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppRgb); BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format32bppRgb); unsafe { byte* pin = (byte*)(oldData.Scan0.ToPointer()); byte* pout = (byte*)(newData.Scan0.ToPointer()); //高斯模板 int[] Gauss = { 1, 2, 1, 2, 4, 2, 1, 2, 1 }; for (int i = 1; i < Width - 1; i++) { for (int j = 1; j < Height - 1; j++) { int r = 0, g = 0, b = 0; int Index = 0; for (int col = -1; col <= 1; col++) { for (int row = -1; row <= 1; row++) { int off = ((j + row) * (Width) + (i + col)) * 4; r += pin[off + 0] * Gauss[Index]; g += pin[off + 1] * Gauss[Index]; b += pin[off + 2] * Gauss[Index]; Index++; } } r /= 16; g /= 16; b /= 16; //处理颜色值溢出 if (r < 0) r = 0; if (r > 255) r = 255; if (g < 0) g = 0; if (g > 255) g = 255; if (b < 0) b = 0; if (b > 255) b = 255; int off2 = (j * Width + i) * 4; pout[off2 + 0] = (byte)r; pout[off2 + 1] = (byte)g; pout[off2 + 2] = (byte)b; } } bitmap.UnlockBits(newData); MyBitmap.UnlockBits(oldData); this.pbshowbox.Image = bitmap; } } else { MessageBox.Show("请先打开一张图片！"); } }
三、锐化
突出显示颜色值大的像素点。
/// <summary> /// 锐化实现方法，显示数值最大像素点 /// </summary> void Image_Sharpen() { if (this.pbshowbox.Image != null) { int Height = this.pbshowbox.Image.Height; int Width = this.pbshowbox.Image.Width; Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format32bppRgb); Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image; BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppRgb); BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format32bppRgb); unsafe { byte* pin = (byte*)(oldData.Scan0.ToPointer()); byte* pout = (byte*)(newData.Scan0.ToPointer()); //拉普拉斯模板 int[] Laplacian = { -1, -1, -1, -1, 9, -1, -1, -1, -1 }; for (int i = 1; i < Width - 1; i++) { for (int j = 1; j < Height - 1; j++) { int r = 0, g = 0, b = 0; int Index = 0; for (int col = -1; col <= 1; col++) { for (int row = -1; row <= 1; row++) { int off = ((j + row) * (Width) + (i + col)) * 4; r += pin[off + 0] * Laplacian[Index]; g += pin[off + 1] * Laplacian[Index]; b += pin[off + 2] * Laplacian[Index]; Index++; } } if (r < 0) r = 0; if (r > 255) r = 255; if (g < 0) g = 0; if (g > 255) g = 255; if (b < 0) b = 0; if (b > 255) b = 255; int off2 = (j * Width + i) * 4; pout[off2 + 0] = (byte)r; pout[off2 + 1] = (byte)g; pout[off2 + 2] = (byte)b; } } bitmap.UnlockBits(newData); MyBitmap.UnlockBits(oldData); this.pbshowbox.Image = bitmap; } } else { MessageBox.Show("请先打开一张图片！"); } }
四、浮雕
对图像像素点的像素值分别与相邻像素点的像素值相减后加上128, 然后将其作为新的像素点的值。
/// <summary> /// 浮雕实现方法 /// </summary> void Image_Relief() { if (this.pbshowbox.Image != null) { int Height = this.pbshowbox.Image.Height; int Width = this.pbshowbox.Image.Width; Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format24bppRgb); Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image; BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb); BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb); unsafe { byte* pin_1 = (byte*)(oldData.Scan0.ToPointer()); byte* pin_2 = pin_1 + (oldData.Stride); byte* pout = (byte*)(newData.Scan0.ToPointer()); for (int y = 0; y < oldData.Height - 1; y++) { for (int x = 0; x < oldData.Width; x++) { int b = (int)pin_1[0] - (int)pin_2[0] + 128; int g = (int)pin_1[1] - (int)pin_2[1] + 128; int r = (int)pin_1[2] - (int)pin_2[2] + 128; if (r < 0) r = 0; if (r > 255) r = 255; if (g < 0) g = 0; if (g > 255) g = 255; if (b < 0) b = 0; if (b > 255) b = 255; pout[0] = (byte)(b); pout[1] = (byte)(g); pout[2] = (byte)(r); pin_1 = pin_1 + 3; pin_2 = pin_2 + 3; pout = pout + 3; } pin_1 += oldData.Stride - oldData.Width * 3; pin_2 += oldData.Stride - oldData.Width * 3; pout += newData.Stride - newData.Width * 3; } bitmap.UnlockBits(newData); MyBitmap.UnlockBits(oldData); this.pbshowbox.Image = bitmap; } } else { MessageBox.Show("请先打开一张图片！"); } }
五、底片
颜色值取反。
/// <summary> /// 底片实现方法 /// </summary> void Image_Negative() { if (pbshowbox.Image != null) { int Height = this.pbshowbox.Image.Height; int Width = this.pbshowbox.Image.Width; Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format24bppRgb); Bitmap MyBitmap = (Bitmap)this.pbshowbox.Image; BitmapData oldData = MyBitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb); BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb); unsafe { byte* pin = (byte*)(oldData.Scan0.ToPointer()); byte* pout = (byte*)(newData.Scan0.ToPointer()); for (int y = 0; y < oldData.Height; y++) { for (int x = 0; x < oldData.Width; x++) { pout[0] = (byte)(255 - pin[0]); pout[1] = (byte)(255 - pin[1]); pout[2] = (byte)(255 - pin[2]); pin = pin + 3; pout = pout + 3; } pin += oldData.Stride - oldData.Width * 3; pout += newData.Stride - newData.Width * 3; } bitmap.UnlockBits(newData); MyBitmap.UnlockBits(oldData); this.pbshowbox.Image = bitmap; } } else { MessageBox.Show("请先打开一张图片！"); } }
六、积木
低像素置0，高像素置255。
/// <summary> /// 积木实现方法 /// </summary> private void Image_Block() { if (this.pbshowbox.Image != null) { int Height = this.pbshowbox.Image.Height; int Width = this.pbshowbox.Image.Width; Bitmap bitmap = new Bitmap(Width, Height); Bitmap Mybitmap = (Bitmap)this.pbshowbox.Image; BitmapData oldData = Mybitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb); BitmapData newData = bitmap.LockBits(new Rectangle(0, 0, Width, Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb); unsafe { byte* pin = (byte*)(oldData.Scan0.ToPointer()); byte* pout = (byte*)(newData.Scan0.ToPointer()); for (int y = 0; y < oldData.Height; y++) { for (int x = 0; x < oldData.Width; x++) { int avg = (pin[0] + pin[1] + pin[2]) / 3; if (avg > 128) { pout[0] = 255; pout[1] = 255; pout[2] = 255; } else { pout[0] = 0; pout[1] = 0; pout[2] = 0; } pin = pin + 3; pout = pout + 3; } pin = pin + oldData.Stride - oldData.Width * 3; pout = pout + newData.Stride - newData.Width * 3; } bitmap.UnlockBits(newData); Mybitmap.UnlockBits(oldData); this.pbshowbox.Image = bitmap; } } else { MessageBox.Show("请先打开一张图片！"); } }
有些图片效果看起来不明显是因为笔者把图缩小了，其实效果挺明显的- -。
