C#圖片處理之:最簡單的柔化演算法

iDotNetSpace發表於2008-09-24
C#演算法

原文http://blog.csdn.net/ki1381/archive/2007/05/10/1603602.aspx
與銳化相反，柔化是使圖片看起來更柔滑（其實也是模糊的委婉的說法）。柔化的一個最簡單的實現演算法就是取圖片上的每一點（圖片邊緣點忽略），計算它周圍八個點的平均值作為新畫素值。想想也是，之所以看起來模糊，確實是因為周圍的點長的有點像，區別不太明顯。

        // ============================柔化==============================
        /// 
        /// 柔化
        /// 原始圖
        /// 輸出圖
        public static Bitmap KiBlur(Bitmap b)
        {

            if (b == null)
            {
                return null;
            }

            int w = b.Width;
            int h = b.Height;

            try
            {

                Bitmap bmpRtn = new Bitmap(w, h, PixelFormat.Format24bppRgb);

                BitmapData srcData = b.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
                BitmapData dstData = bmpRtn.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

                unsafe
                {
                    byte* pIn = (byte*)srcData.Scan0.ToPointer();
                    byte* pOut = (byte*)dstData.Scan0.ToPointer();
                    int stride = srcData.Stride;
                    byte* p;

                    for (int y = 0; y < h; y++)
                    {
                        for (int x = 0; x < w; x++)
                        {
                            //取周圍9點的值
                            if (x == 0 || x == w - 1 || y == 0 || y == h - 1)
                            {
                                //不做
                                pOut[0] = pIn[0];
                                pOut[1] = pIn[1];
                                pOut[2] = pIn[2];
                            }
                            else
                            {
                                int r1, r2, r3, r4, r5, r6, r7, r8, r9;
                                int g1, g2, g3, g4, g5, g6, g7, g8, g9;
                                int b1, b2, b3, b4, b5, b6, b7, b8, b9;

                                float vR, vG, vB;

                                //左上
                                p = pIn - stride - 3;
                                r1 = p[2];
                                g1 = p[1];
                                b1 = p[0];

                                //正上
                                p = pIn - stride;
                                r2 = p[2];
                                g2 = p[1];
                                b2 = p[0];

                                //右上
                                p = pIn - stride + 3;
                                r3 = p[2];
                                g3 = p[1];
                                b3 = p[0];

                                //左側
                                p = pIn - 3;
                                r4 = p[2];
                                g4 = p[1];
                                b4 = p[0];

                                //右側
                                p = pIn + 3;
                                r5 = p[2];
                                g5 = p[1];
                                b5 = p[0];

                                //右下
                                p = pIn + stride - 3;
                                r6 = p[2];
                                g6 = p[1];
                                b6 = p[0];

                                //正下
                                p = pIn + stride;
                                r7 = p[2];
                                g7 = p[1];
                                b7 = p[0];

                                //右下
                                p = pIn + stride + 3;
                                r8 = p[2];
                                g8 = p[1];
                                b8 = p[0];

                                //自己
                                p = pIn;
                                r9 = p[2];
                                g9 = p[1];
                                b9 = p[0];

                                vR = (float)(r1 + r2 + r3 + r4 + r5 + r6 + r7 + r8 + r9);
                                vG = (float)(g1 + g2 + g3 + g4 + g5 + g6 + g7 + g8 + g9);
                                vB = (float)(b1 + b2 + b3 + b4 + b5 + b6 + b7 + b8 + b9);

                                vR /= 9;
                                vG /= 9;
                                vB /= 9;

                                pOut[0] = (byte)vB;
                                pOut[1] = (byte)vG;
                                pOut[2] = (byte)vR;

                            }

                            pIn += 3;
                            pOut += 3;
                        }// end of x

                        pIn += srcData.Stride - w * 3;
                        pOut += srcData.Stride - w * 3;
                    } // end of y
                }

                b.UnlockBits(srcData);
                bmpRtn.UnlockBits(dstData);

                return bmpRtn;
            }
            catch
            {
                return null;
            }

        } // end of KiBlur

當然這是最簡單的一種，不支援柔化半徑選擇。實際中通常需要自定義模糊的程度，這個下回再談。

來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/12639172/viewspace-462848/，如需轉載，請註明出處，否則將追究法律責任。

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