美颜之漫画滤镜算法

漫画滤镜

所谓漫画滤镜就是通过复杂的算法来模拟漫画的特点，从而使真实照片呈现出漫画的风格。图玩智能科技为企业提供更优质更稳定的美颜产品，欢迎随时咨询www.toivan.com。要实现漫画的效果，首先要了解漫画的特点，漫画具有几个比较明显的特点如下：

1，颜色泛用

漫画中，使用的颜色比较单一，一般不会超过7种颜色，不像真实照片那样，具有丰富的颜色种类；

2，边缘较强

漫画中，所有事物都有比较明显的黑色边缘，给人一种分割分明且突出的感觉；

3，形象夸张，内容概括

漫画中，一般描述的人物表情，效果等等都十分夸张，而且内容高度概括，让人浮想联翩；

以上3点就是漫画的特点，其中，第三点是由漫画的本质决定的，这一点，我们真实的照片是无法实现的，因此，这一点我们在这里不用考虑。对于1和2两点，我们均可以使用相应的图像算法，来模拟实现，具体如下：

对于颜色泛用，表现在图像算法中，实际上就是减少颜色的种类，对颜色种类进行降维，这一点，我们可使用颜色聚类算法，双边滤波算法等等，其中，双边滤波在使颜色平坦的同时，还可以保留边缘信息。

对于边缘保留，我们可以使用边缘算子来实现，比如拉普拉斯算子，Sobel，Roberts，Prewitt算子等等，也可以使用原图-高斯模糊效果图来实现，这样可以保留更加完整的边缘轮廓信息。

以上是对漫画算法的分析，在这里，使用的算法如下：

第一，使用上一篇水彩画滤镜算法，获得单一颜色的图像P，这里设置油画算法阈值为10，使P具有10种颜色描述。

第二，使用Sobel算子进行边缘检测，这里选用这个算法，主要是为了兼顾速度和边缘效果。

第三，设置边缘强度控制变量edgeIntensity(edgeIntensity>=0)，来控制边缘强度调节，公式如下：

Pedge(x,y) = Min(255, Pedge(x,y)+edgeIntensity);

第四，边缘融合，将第一和第三步骤中得到的结果图进行融合，来获得最终的漫画效果，公式如下：

Result(x,y) = Pedge(x,y)*P(x,y)/255;

以上就是算法的整个过程，这里放上核心代码如下：

private Bitmap SobelEdgeDetect(Bitmap src,int edgeIntensity)

{

int w = src.Width;

int h = src.Height;

Bitmap a = new Bitmap(w, h, System.Drawing.Imaging.PixelFormat.Format32bppArgb);

BitmapData srcData = src.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);

BitmapData dstData = a.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);

byte* pIn = (byte*)srcData.Scan0.ToPointer();

byte* pOut = (byte*)dstData.Scan0.ToPointer();

byte* p;

int offset = srcData.Stride - w * 4;

int r0, r1, r2, r3, r4, r5, r6, r7, r8;

int g1, g2, g3, g4, g5, g6, g7, g8, g0;

int b1, b2, b3, b4, b5, b6, b7, b8, b0;

double vR, vG, vB;

int stride = srcData.Stride;

int []lightMap={0, 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 39, 40, 41, 42, 43, 44, 45, 47, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 101, 102, 103, 104, 105, 107, 108, 109, 110, 111, 112, 113, 115, 116, 117, 118, 119, 120, 121, 123, 124, 125, 126, 127, 128, 129, 130, 132, 133, 134, 135, 136, 137, 138, 140, 141, 142, 143, 144, 145, 146, 147, 149, 150, 151, 152, 153, 154, 155, 156, 158, 159, 160, 161, 162, 163, 164, 165, 166, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 212, 213, 214, 215, 216, 217, 218, 219, 220, 220, 221, 222, 223, 224, 225, 225, 226, 227, 228, 229, 229, 230, 231, 232, 233, 233, 234, 235, 235, 236, 237, 238, 238, 239, 240, 240, 241, 242, 242, 243, 243, 244, 245, 245, 246, 246, 247, 248, 248, 249, 249, 250, 250, 251, 251, 252, 252, 253, 253, 253, 254, 254, 255, 255};

int gray = 0;

for (int j = 0; j < h; j++)

{

for (int i = 0; i < w; i++)

{

if (i == 0 || i == w - 1 || j == 0 || j == h - 1)

{

pOut[0] = (byte)0;

pOut[1] = (byte)0;

pOut[2] = (byte)0;

pOut[3] = (byte)255;

}

else

{

//左上

p = pIn - stride - 4;

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 + 4;

r3 = p[2];

g3 = p[1];

b3 = p[0];

//左

p = pIn - 4;

r4 = p[2];

g4 = p[1];

b4 = p[0];

//右

p = pIn + 4;

r5 = p[2];

g5 = p[1];

b5 = p[0];

//左下

p = pIn + stride - 4;

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 + 4;

r8 = p[2];

g8 = p[1];

b8 = p[0];

//中心点

p = pIn;

r0 = p[2];

g0 = p[1];

b0 = p[0];

//使用模板

vR = (double)(Math.Abs(r1 + 2 * r4 + r6 - r3 - 2 * r5 - r8) + Math.Abs(r1 + 2 * r2 + r3 - r6 - 2 * r7 - r8));

vG = (double)(Math.Abs(g1 + 2 * g4 + g6 - g3 - 2 * g5 - g8) + Math.Abs(g1 + 2 * g2 + g3 - g6 - 2 * g7 - g8));

vB = (double)(Math.Abs(b1 + 2 * b4 + b6 - b3 - 2 * b5 - b8) + Math.Abs(b1 + 2 * b2 + b3 - b6 - 2 * b7 - b8));

vB = Math.Min(255, Math.Max(0, vB));

vG = Math.Min(255, Math.Max(0, vG));

vR = Math.Min(255, Math.Max(0, vR));

gray = lightMap[255 - (int)(vB + vG + vR) / 3];

gray = Math.Min(255, gray + edgeIntensity);

pOut[0] = (byte)gray;

pOut[1] = (byte)gray;

pOut[2] = (byte)gray;

pOut[3] = (byte)255;

}

pIn += 4;

pOut += 4;

}

pIn += offset;

pOut += offset;

}

a.UnlockBits(dstData);

src.UnlockBits(srcData);

return a;

}

private Bitmap OilpaintFilterProcess(Bitmap srcBitmap, int radius, int smooth)

{

if (radius == 0)

return srcBitmap;

smooth = smooth < 1 ? 1 : smooth;

smooth = Math.Max(1, smooth);

Bitmap a = new Bitmap(srcBitmap);

int w = srcBitmap.Width;

int h = srcBitmap.Height;

if (radius > Math.Min(w, h) / 2)

radius = (int)(Math.Min(w, h) / 2 - 0.5);

System.Drawing.Imaging.BitmapData srcData = a.LockBits(new Rectangle(0, 0, w, h), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb);

IntPtr ptr = srcData.Scan0;

int bytes = h * srcData.Stride;

byte[] srcValues = new byte[bytes];

System.Runtime.InteropServices.Marshal.Copy(ptr, srcValues, 0, bytes);

byte[] tempValues = (byte[])srcValues.Clone();

int stride = srcData.Stride;

int i, j, k;

int unit = 4;

int[] gray_bt = new int[smooth];

int[] r_bt = new int[smooth];

int[] g_bt = new int[smooth];

int[] b_bt = new int[smooth];

int[] gray_bt_src = new int[smooth];

int[] r_bt_src = new int[smooth];

int[] g_bt_src = new int[smooth];

int[] b_bt_src = new int[smooth];

int r, g, b;

int gray = 0, bt_index = 0, max = 0, maxindex = 0;

i = 0;

bool frist = true;

int pos = 0;

for (j = 0; j < h; j++)

{

if (frist)

{

for (int m = -radius; m <= radius; m++)

{

for (int n = -radius; n <= radius; n++)

{

pos = Math.Abs(n) * unit + Math.Abs(m) * stride;

b = srcValues[pos++];

g = srcValues[pos++];

r = srcValues[pos];

gray = (b + g + r) / 3;

bt_index = gray * smooth >> 8;

gray_bt_src[bt_index]++;

b_bt_src[bt_index] += b;

g_bt_src[bt_index] += g;

r_bt_src[bt_index] += r;

}

Array.Copy(gray_bt_src, gray_bt, smooth);

Array.Copy(b_bt_src, b_bt, smooth);

Array.Copy(g_bt_src, g_bt, smooth);

Array.Copy(r_bt_src, r_bt, smooth);

max = 0;

maxindex = 0;

for (k = 0; k < smooth; k++)

{

if (max < gray_bt[k])

{

max = gray_bt[k];

maxindex = k;

}

pos = j * stride;

tempValues[pos++] = (byte)(b_bt[maxindex] / max);

tempValues[pos++] = (byte)(g_bt[maxindex] / max);

tempValues[pos] = (byte)(r_bt[maxindex] / max);

frist = false;

}

else

{

for (int m = -radius; m <= radius; m++)

{

pos = Math.Abs(m) * unit + Math.Abs(j - radius - 1) * stride;

b = srcValues[pos++];

g = srcValues[pos++];

r = srcValues[pos];

gray = (b + g + r) / 3;

bt_index = gray * smooth >> 8;

gray_bt_src[bt_index]--;

b_bt_src[bt_index] -= b;

g_bt_src[bt_index] -= g;

r_bt_src[bt_index] -= r;

pos = Math.Abs(m) * unit + Math.Abs(j + radius) % h * stride;

b = srcValues[pos++];

g = srcValues[pos++];

r = srcValues[pos];

gray = (b + g + r) / 3;

bt_index = gray * smooth >> 8;

gray_bt_src[bt_index]++;

b_bt_src[bt_index] += b;

g_bt_src[bt_index] += g;

r_bt_src[bt_index] += r;

}

Array.Copy(gray_bt_src, gray_bt, smooth);

Array.Copy(b_bt_src, b_bt, smooth);

Array.Copy(g_bt_src, g_bt, smooth);

Array.Copy(r_bt_src, r_bt, smooth);

}

for (i = 1; i < w; i++)

{

for (int m = -radius; m <= radius; m++)

{

pos = Math.Abs(i - radius - 1) * unit + Math.Abs(j + m) % h * stride;

b = srcValues[pos++];

g = srcValues[pos++];

r = srcValues[pos];

gray = (b + g + r) / 3;

bt_index = gray * smooth >> 8;

gray_bt[bt_index]--;

b_bt[bt_index] -= b;

g_bt[bt_index] -= g;

r_bt[bt_index] -= r;

pos = Math.Abs(i + radius) % w * unit + Math.Abs(j + m) % h * stride;

b = srcValues[pos++];

g = srcValues[pos++];

r = srcValues[pos];

gray = (b + g + r) / 3;

bt_index = gray * smooth >> 8;

gray_bt[bt_index]++;

b_bt[bt_index] += b;

g_bt[bt_index] += g;

r_bt[bt_index] += r;

}

max = 0;

maxindex = 0;

for (k = 0; k < smooth; k++)

{

if (max < gray_bt[k])

{

max = gray_bt[k];

maxindex = k;

}

pos = i * unit + j * stride;

tempValues[pos++] = (byte)(b_bt[maxindex] / max);

tempValues[pos++] = (byte)(g_bt[maxindex] / max);

tempValues[pos] = (byte)(r_bt[maxindex] / max);

}

srcValues = (byte[])tempValues.Clone();

System.Runtime.InteropServices.Marshal.Copy(srcValues, 0, ptr, bytes);

a.UnlockBits(srcData);

return a;

}

private Bitmap CartoonFilterProcess(Bitmap src, int edgeIntensity)

{

Bitmap edgeBitmap = SobelEdgeDetect(src, edgeIntensity);

Bitmap dst = OilpaintFilterProcess(new Bitmap(src),12,10);;

int w = dst.Width;

int h = dst.Height;

BitmapData dstData = dst.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);

BitmapData edgeData = edgeBitmap.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);

byte* pEdge = (byte*)edgeData.Scan0;

byte* pDst = (byte*)dstData.Scan0;

int offset = dstData.Stride - w * 4;

for (int j = 0; j < h; j++)

{

for (int i = 0; i < w; i++)

{

pDst[0] = (byte)(pDst[0] * pEdge[0] / 255);

pDst[1] = (byte)(pDst[1] * pEdge[1] / 255);

pDst[2] = (byte)(pDst[2] * pEdge[2] / 255);

pDst[3] = (byte)255;

pEdge += 4;

pDst += 4;

}

pEdge += offset;

pDst += offset;

}

dst.UnlockBits(dstData);

edgeBitmap.UnlockBits(edgeData);

return dst;

}

来源：oschina

链接：https://my.oschina.net/u/4203900/blog/4332072

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