.NET传图识色

2019-11-14 14:35:17

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前些日子看千图网的传图识色有点好奇就查找了一些资料，在此分析下：

首先，创建一个值类型：

 1 public struct MajorColor : IComparable<MajorColor> 2 { 3     internal int Color;//颜色值 4     internal int Amount;//颜色总数 5     public MajorColor(int Color, int Amount) 6     { 7         this.Color = Color; 8         this.Amount = Amount; 9     }10     public int CompareTo(MajorColor obj)11     {12         return this.Amount.CompareTo(obj.Amount);13     }14 }

创建一个值类型

接下来是主要算法：

 1 /// <summary> 2 /// 识别主色调 3 /// </summary> 4 /// <param name="Bmp">Bmp位图</param> 5 /// <param name="PCAAmount">主色调数目</param> 6 /// <param name="Delta">阈值</param> 7 /// <returns></returns> 8 public unsafe static List<MajorColor> PRincipalColorAnalysis(Bitmap Bmp, int PCAAmount, int Delta = 24) 9 {10     List<MajorColor> MC = new List<MajorColor>();11 12     int X, Y, Width, Height, Stride, Index, TotalColorAmount = 0;13     int HalfDelta;14     byte* Pointer, Scan0;//定义指针所以需要unsafe关键字15     BitmapData BmpData = Bmp.LockBits(new Rectangle(0, 0, Bmp.Width, Bmp.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);//将位图锁定到系统内存中16     Height = Bmp.Height;17     Width = Bmp.Width;18     Stride = BmpData.Stride;//Bitmap对象的跨距宽度（也称扫描宽度）19     Scan0 = (byte*)BmpData.Scan0;//位图中第一个像素数据的地址20 21     int[] Table = new int[256 * 256 * 256];22     int[] NonZero = new int[Width * Height];23     int[] Map = new int[256];24 25     if (Delta > 2)26     {27         HalfDelta = Delta / 2 - 1;28     }29     else30     {31         HalfDelta = 0;32     }33     for (Y = 0; Y < 256; Y++)34     {35         Map[Y] = ((Y + HalfDelta) / Delta) * Delta;36         if (Map[Y] > 255) Map[Y] = 255;37     }38     for (Y = 0; Y < Height; Y++)39     {40         Pointer = Scan0 + Stride * Y;41         for (X = 0; X < Width; X++)42         {43             Index = (Map[*Pointer] << 16) + (Map[*(Pointer + 1)] << 8) + Map[*(Pointer + 2)];44             if (Table[Index] == 0)//颜色未出现45             {46                 NonZero[TotalColorAmount] = Index;//记录颜色47                 TotalColorAmount++;//总数加148             }49             Table[Index]++;//对应的颜色数目加150             Pointer += 3;//遍历下个像素51         }52     }53     MajorColor[] Result = new MajorColor[TotalColorAmount];54     for (Y = 0; Y < TotalColorAmount; Y++)55     {56         Result[Y].Amount = Table[NonZero[Y]];57         Result[Y].Color = NonZero[Y];58     }59     Array.Sort(Result);//排序60     Array.Reverse(Result);//反转61 62     for (Y = 0; Y < (Result.Length > PCAAmount ? PCAAmount : Result.Length); Y++)63     {64         MC.Add(new MajorColor(Result[Y].Color, Result[Y].Amount));65     }66     Bmp.UnlockBits(BmpData);//从系统内存中解锁此位图67     GC.Collect();//释放内存68     return MC;69 }

算法

unsafe关键字编译报错解决方案：项目属性-生成-勾选允许不安全代码即可。

最后获取到的List< MajorColor > 就是我们要获取的主色调了。

接下来遍历循环获取所有色调

 1 if (MC != null) 2 { 3     for (int i = 0; i < MC.Count; i++) 4     { 5         IntToColor(MC[i].Color))); 6     } 7 } 8 //颜色值转换成RGB 9 public static string IntToColor(int color)10 {11     int R = color & 255;12     int G = (color & 65280) / 256;13     int B = (color & 16711680) / 65536;14     return ColorTranslator.ToHtml(System.Drawing.Color.FromArgb(R, G, B));15 }