挤压(Pinch)滤镜

Pinch滤镜 Pinch滤镜是通过坐标变换来实现以某个点(cenX,cenY)为中心，某个半径R内图像向其挤压变形的效果。实现这个滤镜的算法很多，主要是数学公式的不同，大家可以自行设计，这里给个代码示例，大家可以直接使用。 代码如下： ~~~ /// <summary> /// Pinch Filter /// </summary> /// <param name="src">Source image.</param> /// <param name="cenX">The X position of sun.</param> /// <param name="cenY">The Y position of sun.</param> /// <returns>The result image.</returns> private Bitmap PinchFilterProcess(Bitmap srcBitmap, int cenX, int cenY) { Bitmap a = new Bitmap(srcBitmap); int w = a.Width; int h = a.Height; int radius = 0; Bitmap dst = new Bitmap(w, h); System.Drawing.Imaging.BitmapData srcData = a.LockBits(new Rectangle(0, 0, w, h), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb); System.Drawing.Imaging.BitmapData dstData = dst.LockBits(new Rectangle(0, 0, w, h), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb); unsafe { byte* pIn = (byte*)srcData.Scan0.ToPointer(); byte* pOut = (byte*)dstData.Scan0.ToPointer(); byte* p = null; int sWidth = srcData.Stride; int stride = sWidth - w * 4; int offsetX = 0, offsetY = 0; int newX = 0, newY = 0; double radian = 0,degree = 10; for (int y = 0; y < h; y++) { for (int x = 0; x < w; x++) { offsetX = x - cenX; offsetY = y - cenY; radian = Math.Atan2(offsetY, offsetX); radius = (int)(Math.Sqrt(offsetX * offsetX + offsetY * offsetY)); radius = (int)(Math.Sqrt(radius) * degree); newX = (int)(radius * Math.Cos(radian)) + cenX; newY = (int)(radius * Math.Sin(radian)) + cenY; newX = Math.Min(w - 1, Math.Max(0, newX)); newY = Math.Min(h - 1, Math.Max(0, newY)); p = pIn + newY * srcData.Stride + newX * 4; pOut[0] = (byte)p[0]; pOut[1] = (byte)p[1]; pOut[2] = (byte)p[2]; pOut[3] = (byte)255; pOut += 4; } pOut += stride; } a.UnlockBits(srcData); dst.UnlockBits(dstData); } return dst; } ~~~ 效果图如下： [](http://www.zealpixel.com/data/attachment/portal/201507/21/221354xqq5q0fkq5fqn0fj.jpg) 原图 [](http://www.zealpixel.com/data/attachment/portal/201507/21/221353y6czmsej4ces55jk.png) Pinch滤镜效果图 最后放上一个完整的C#版程序Demo给大家下载使用：[http://www.zealpixel.com/forum.php?mod=viewthread&tid=55&extra=page%3D1](http://www.zealpixel.com/forum.php?mod=viewthread&tid=55&extra=page%3D1)