C#实现谷歌相似图片查询算法

using System; 
using System.IO; 
using System.Drawing; 
  
namespace SimilarPhoto 
{ 
    class SimilarPhoto 
    { 
        Image SourceImg; 
  
        public SimilarPhoto(string filePath) 
        { 
            SourceImg = Image.FromFile(filePath); 
        } 
  
        public SimilarPhoto(Stream stream) 
        { 
            SourceImg = Image.FromStream(stream); 
        } 
  
        public String GetHash() 
        { 
            Image image = ReduceSize(); 
            Byte[] grayValues = ReduceColor(image); 
            Byte average = CalcAverage(grayValues); 
            String reslut = ComputeBits(grayValues, average); 
            return reslut; 
        } 
  
        // Step 1 : Reduce size to 8*8 
        private Image ReduceSize(int width = 8, int height = 8) 
        { 
            Image image = SourceImg.GetThumbnailImage(width, height, () => { return false; }, IntPtr.Zero); 
            return image; 
        } 
  
        // Step 2 : Reduce Color 
        private Byte[] ReduceColor(Image image) 
        { 
            Bitmap bitMap = new Bitmap(image); 
            Byte[] grayValues = new Byte[image.Width * image.Height]; 
  
            for(int x = 0; x<image.Width; x++) 
                for (int y = 0; y < image.Height; y++) 
                { 
                    Color color = bitMap.GetPixel(x, y); 
                    byte grayValue = (byte)((color.R * 30 + color.G * 59 + color.B * 11) / 100); 
                    grayValues[x * image.Width + y] = grayValue; 
                } 
            return grayValues; 
        } 
  
        // Step 3 : Average the colors 
        private Byte CalcAverage(byte[] values) 
        { 
            int sum = 0; 
            for (int i = 0; i < values.Length; i++) 
                sum += (int)values[i]; 
            return Convert.ToByte(sum / values.Length); 
        } 
  
        // Step 4 : Compute the bits 
        private String ComputeBits(byte[] values, byte averageValue) 
        { 
            char[] result = new char[values.Length]; 
            for (int i = 0; i < values.Length; i++) 
            { 
                if (values[i] < averageValue) 
                    result[i] = '0'; 
                else
                    result[i] = '1'; 
            } 
            return new String(result); 
        } 
  
        // Compare hash 
        public static Int32 CalcSimilarDegree(string a, string b) 
        { 
            if (a.Length != b.Length) 
                throw new ArgumentException(); 
            int count = 0; 
            for (int i = 0; i < a.Length; i++) 
            { 
                if (a[i] != b[i]) 
                    count++; 
            } 
            return count; 
        } 
    } 
}