內存法通過把圖像儲存在內存中進行處理，效率大大高於GetPixel方法，安全性高於指針法。
筆者當初寫圖像處理的時候發現網上多是用GetPixel方法實現，提到內存法的時候也沒有具體實現，所以筆者在這裡具體實現一下- -，望指正。
首先講一下用到的一些方法。
1.LockBits和UnlockBits：使用 LockBits 方法，可在系統內存中鎖定現有的位圖，以便通過編程方式進行更改，每調用LockBits之後都應該調用一次UnlockBits。
2.Scan0：圖像的第一個字節地址。
3.Stride：步幅，掃描寬度，形象的說就是一行的長度。
4.PixelFormat：數據的實際像素格式。
給出原圖：
一、灰度
對每個像素點進行加權平均，（方法不唯一）。
/// <summary>
/// 灰化實現方法
/// </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);//加權平均實現灰化
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("請先打開一張圖片！");
}
}
二、柔化
像素點與周圍像素點差別較大時取平均值。
/// <summary>
/// 柔化實現方法
/// </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;
//處理顏色值溢出
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("請先打開一張圖片！");
}
}
三、銳化
突出顯示顏色值大的像素點。
/// <summary>
/// 銳化實現方法，顯示數值最大像素點
/// </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("請先打開一張圖片！");
}
}
四、浮雕
對圖像像素點的像素值分別與相鄰像素點的像素值相減後加上128, 然後將其作為新的像素點的值。
/// <summary>
/// 浮雕實現方法
/// </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("請先打開一張圖片！");
}
}
五、底片
顏色值取反。
/// <summary>
/// 底片實現方法
/// </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("請先打開一張圖片！");
}
}
六、積木
低像素置0，高像素置255。
/// <summary>
/// 積木實現方法
/// </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("請先打開一張圖片！");
}
}
有些圖片效果看起來不明顯是因為筆者把圖縮小了，其實效果挺明顯的- -。