[C#]几种Bitmap比较方式
这里选取图片，规格如下：
大小：
关键代码：
using System; using System.Diagnostics; using System.Drawing; using System.Drawing.Imaging; using System.IO; using System.Runtime.InteropServices; namespace ConsoleApplication27 { class Program { static void Main(string[] args) { try { Stopwatch _watch = new Stopwatch(); _watch.Start(); bool _compareByMenCmpResult = Resource1.cat.CompareByMemCmp(Resource1.cat); _watch.Stop(); Console.WriteLine(string.Format("CompareByMemCmp: {0} {1}", _compareByMenCmpResult, _watch.ElapsedMilliseconds)); _watch.Reset(); _watch.Start(); bool _compareByPixel = Resource1.cat.CompareByPixel(Resource1.cat); _watch.Stop(); Console.WriteLine(string.Format("CompareByPixel: {0} {1}", _compareByPixel, _watch.ElapsedMilliseconds)); _watch.Reset(); _watch.Start(); bool _compareByBase64String = Resource1.cat.CompareByBase64String(Resource1.cat); _watch.Stop(); Console.WriteLine(string.Format("CompareByBase64String: {0} {1}", _compareByBase64String, _watch.ElapsedMilliseconds)); _watch.Reset(); _watch.Start(); bool _compareByArray = Resource1.cat.CompareByArray(Resource1.cat); _watch.Stop(); Console.WriteLine(string.Format("CompareByArray: {0} {1}", _compareByArray, _watch.ElapsedMilliseconds)); } catch (Exception ex) { Console.WriteLine(ex.Message); } finally { Console.ReadLine(); } } } public static class ImageTool { [DllImport("msvcrt.dll")] private static extern int memcmp(IntPtr b1, IntPtr b2, long count); /// <summary> /// Bitmap比较 /// </summary> /// <param name="b1">Bitmap1</param> /// <param name="b2">Bitmap2</param> /// <returns>比较结果</returns> public static bool CompareByMemCmp(this Bitmap b1, Bitmap b2) { /*说明 *参考链接： *http://stackoverflow.com/questions/2031217/what-is-the-fastest-way-i-can-compare-two-equal-size-bitmaps-to-determine-whethe */ if ((b1 == null) != (b2 == null)) return false; if (b1.Size != b2.Size) return false; BitmapData _bdata1 = b1.LockBits(new Rectangle(new Point(0, 0), b1.Size), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb); BitmapData _bdata2 = b2.LockBits(new Rectangle(new Point(0, 0), b2.Size), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb); try { IntPtr _bd1scan0 = _bdata1.Scan0; IntPtr _bd2scan0 = _bdata2.Scan0; int _stride = _bdata1.Stride; int _len = _stride * b1.Height; return memcmp(_bd1scan0, _bd2scan0, _len) == 0; } finally { b1.UnlockBits(_bdata1); b2.UnlockBits(_bdata2); } } /// <summary> /// 通过比较bitmap两者ToBase64String来判断是否相等 /// </summary> /// <param name="b1">Bitmap1</param> /// <param name="b2">Bitmap2</param> /// <returns>比较结果</returns> public static bool CompareByBase64String(this Bitmap b1, Bitmap b2) { /*说明 *参考链接： *http://blogs.msdn.com/b/domgreen/archive/2009/09/06/comparing-two-images-in-c.aspx */ string _b1Base64String, _b2Base64String; MemoryStream _ms = new MemoryStream(); try { b1.Save(_ms, ImageFormat.Png); _b1Base64String = Convert.ToBase64String(_ms.ToArray()); _ms.Position = 0; b2.Save(_ms, ImageFormat.Png); _b2Base64String = Convert.ToBase64String(_ms.ToArray()); } finally { _ms.Close(); } return _b1Base64String.Equals(_b2Base64String); } /// <summary> /// 通过比较bitmap两者像素颜色来判断两者是否相等 /// </summary> /// <param name="b1">Bitmap1</param> /// <param name="b2">Bitmap2</param> /// <returns>比较结果</returns> public static bool CompareByPixel(this Bitmap b1, Bitmap b2) { /*说明 *参考链接： *http://blogs.msdn.com/b/domgreen/archive/2009/09/06/comparing-two-images-in-c.aspx */ bool _flag = false; if (b1.Width == b2.Width && b1.Height == b2.Height) { _flag = true; Color _pixel1; Color _pixel2; for (int i = 0; i < b1.Width; i++) { for (int j = 0; j < b1.Height; j++) { _pixel1 = b1.GetPixel(i, j); _pixel2 = b2.GetPixel(i, j); if (_pixel1 != _pixel2) { _flag = false; break; } } } } return _flag; } /// <summary> /// memcmp API /// </summary> /// <param name="b1">字节数组1</param> /// <param name="b2">字节数组2</param> /// <returns>如果两个数组相同，返回0；如果数组1小于数组2，返回小于0的值；如果数组1大于数组2，返回大于0的值。</returns> [DllImport("msvcrt.dll")] private static extern IntPtr memcmp(byte[] b1, byte[] b2, IntPtr count); /// <summary> /// 通过比较bitmap两者byte[]来判断是否相等 /// </summary> /// <param name="b1">Bitmap1</param> /// <param name="b2">Bitmap2</param> /// <returns>比较结果</returns> public static bool CompareByArray(this Bitmap b1, Bitmap b2) { /*说明 *参考链接： *http://www.cnblogs.com/zgqys1980/archive/2009/07/13/1522546.html */ IntPtr _result = new IntPtr(-1); MemoryStream _ms = new MemoryStream(); try { b1.Save(_ms, ImageFormat.Png); byte[] _b1Array = _ms.ToArray(); _ms.Position = 0; b2.Save(_ms, ImageFormat.Png); byte[] _b2Array = _ms.ToArray(); _result = memcmp(_b1Array, _b2Array, new IntPtr(_b1Array.Length)); } finally { _ms.Close(); } return _result.ToInt32() == 0; } } }测试结果：
希望有所帮助！