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; } } } |