Asprise-OCR下载地址：
http://asprise.com/product/ocr/download.php?lang=csharp
其中需要使用的3个dll是AspriseOCR.dll、DevIL.dll、ILU.dll。
需要注意的是这几个.dll是vc写的引用要在程序中用DllImport引用，关键代码：
[DllImport("AspriseOCR.dll", EntryPoint = "OCR", CallingConvention = CallingConvention.Cdecl)]
public static extern IntPtr OCR(string file, int type);
[DllImport("AspriseOCR.dll", EntryPoint = "OCRpart", CallingConvention = CallingConvention.Cdecl)]
static extern IntPtr OCRpart(string file, int type, int startX, int startY, int width, int height);
[DllImport("AspriseOCR.dll", EntryPoint = "OCRBarCodes", CallingConvention = CallingConvention.Cdecl)]
static extern IntPtr OCRBarCodes(string file, int type);
[DllImport("AspriseOCR.dll", EntryPoint = "OCRpartBarCodes", CallingConvention = CallingConvention.Cdecl)]
static extern IntPtr OCRpartBarCodes(string file, int type, int startX, int startY, int width, int height);
调用代码很简单只有一句：
MessageBox.Show(Marshal.PtrToStringAnsi(OCRpart(img_path, -1, startX, startY, width, height)));
其中img_path：为图片路径，startX、startY坐标均为0即可，width、height图片的宽和高。
原文：http://www.cnblogs.com/wonder315/p/4343794.html