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;
}
}
}