如何將 C++ tesseract-ocr 代碼轉換為 Python？ (how to convert C++ tesseract-ocr code to Python?)

問題描述

如何將 C++ tesseract‑ocr 代碼轉換為 Python？ (how to convert C++ tesseract‑ocr code to Python?)

我想在tesseract‑ocr doc中轉換C++版本Result iterator example到 Python。

  Pix *image = pixRead("/usr/src/tesseract/testing/phototest.tif");
  tesseract::TessBaseAPI *api = new tesseract::TessBaseAPI();
  api‑>Init(NULL, "eng");
  api‑>SetImage(image);
  api‑>Recognize(0);
  tesseract::ResultIterator* ri = api‑>GetIterator();
  tesseract::PageIteratorLevel level = tesseract::RIL_WORD;
  if (ri != 0) {
    do {
      const char* word = ri‑>GetUTF8Text(level);
      float conf = ri‑>Confidence(level);
      int x1, y1, x2, y2;
      ri‑>BoundingBox(level, &x1, &y1, &x2, &y2);
      printf("word: '%s';  \tconf: %.2f; BoundingBox: %d,%d,%d,%d;\n",
               word, conf, x1, y1, x2, y2);
      delete[] word;
    } while (ri‑>Next(level));
  }

到目前為止我能做的如下：

import ctypes
liblept = ctypes.cdll.LoadLibrary('liblept‑5.dll')
pix = liblept.pixRead('11.png'.encode()) 
print(pix)

tesseractLib = ctypes.cdll.LoadLibrary(r'C:\Program Files\tesseract‑OCR\libtesseract‑4.dll')

tesseractHandle = tesseractLib.TessBaseAPICreate()

tesseractLib.TessBaseAPIInit3(tesseractHandle, '.', 'eng')

tesseractLib.TessBaseAPISetImage2(tesseractHandle, pix)
#tesseractLib.TessBaseAPIRecognize(tesseractHandle, tesseractLib.TessMonitorCreate())

我無法轉換 C++ api‑>Recognize(0)到 Python（我嘗試過的是代碼的最後一行（註釋），但它是錯誤的），我對 C++ 沒有經驗，所以我不能再繼續了，任何人都可以幫助轉換嗎？API：

• 來自 tess4j：tesserocr 的項目可以讓我免於轉換，但問題在於項目是他們不提供最新的 Windows Python 輪子，這是我進行轉換的主要原因。

  ---

  參考解法

  方法 1:

  I think the problem is that api‑>Recognize() expects a pointer as first argument. They mistakenly put a 0 in their example but it should be nullptr. 0 and nullptr both have the same value but on 64bits systems they don't have the same size (usually ; I assume on some weird non‑x86 systems this may not be true either).

  Their example still works with a C++ compiler because the compiler is aware that the function expects a pointer (64bits) and fix it silently.

  In your example, it seems you haven't specified the exact prototype of TessBaseAPIRecognize() to ctypes. So ctypes can't know a pointer (64 bits) is expected by this function. Instead it assumes that this function expects an integer (32 bits) ‑‑> it crashes.

  My suggestions:

  1. Use ctypes.c_void_p(None) instead of 0
  2. If you intend to use that in production, specify to ctypes all the function prototypes
  3. Be careful with the examples you look at: Those examples use Tesseract base API (C++ API) whereas if you want to use libtesseract with Python + ctypes, you have to use Tesseract C API. Those 2 APIs are very similar but may not be identical.

  If you need further help, you can have a look at how things are done in PyOCR. If you decide to use PyOCR in your project, just beware that the license of PyOCR is GPLv3+, which implies some restrictions.

  (by iMath、Jerome Flesch)

  參考文件

  1. how to convert C++ tesseract‑ocr code to Python? (CC BY‑SA 2.5/3.0/4.0)