如何在Python中将OpenCV图像传递给Tesseract？

Question

鉴于Python代码调用Tesseract的C API并使用ctypes库,选项#1图像由Tesseract加载,它工作正常!问题出现在选项#2中,当我尝试传递OpenCV加载的图像时,T​​esseract返回垃圾:

from ctypes import *
import cv2

class API(Structure):
    _fields_ = []

lang = "eng"
ts = cdll.LoadLibrary("c:/Tesseract-OCR/libtesseract302.dll")
ts.TessBaseAPICreate.restype = POINTER(API)
api = ts.TessBaseAPICreate()
rc = ts.TessBaseAPIInit3(api, 'c:/Tesseract-OCR/', lang)

##### Option #1
out = ts.TessBaseAPIProcessPages(api, 'c:/Tesseract-OCR/doc/eurotext.tif', None, 0)
print 'Option #1 => ' + string_at(out)

##### Option #2
#TESS_API void  TESS_CALL TessBaseAPISetImage(TessBaseAPI* handle, const unsigned char* imagedata, int width, int height,
#                                             int bytes_per_pixel, int bytes_per_line);

im = cv2.imread('c:/Temp/Downloads/test-slim/eurotext.jpg', cv2.COLOR_BGR2GRAY)
c_ubyte_p = POINTER(c_ubyte)
##ts.TessBaseAPISetImage.argtypes = [POINTER(API), c_ubyte_p, c_int, c_int, c_int, c_int]
ts.TessBaseAPISetImage(api, im.ctypes.data_as(c_ubyte_p), 800, 1024, 3, 800 * 3)
out = ts.TessBaseAPIGetUTF8Text(api)
print 'Option #2 => ' + string_at(out)

输出如下:

选项#1 =>(快速)[棕色] {狐狸}跳!超过$ 43,456.78#90 dog&duck/goose,因为来自aspammer@website.com的12.5%的电子邮件是垃圾邮件.Der ,, schnelle'braune Fuchsspringtï¬ berdenfaulen Hund.Le renard brun«rapide»saute par-dessus le chien paresseux.La volpe marone rapida salta sopra il cane pigro.Elzorromarrénrépidosalta sobre el perro perezoso.一种raposa marrom rzipida salta sobreocï preguicoso.

选项#2 => 7？:5:*:> \' - 〜; 2 - ; i3E:？:; i3".i:ii ... 3;"f-i©%:::â€:::？:=’:: =£<:7“§5.<:“¡¡¡¡¡¡¡¡¡ “...... =:a,'; 2â€:3â€:3_3:l.':“:“:Â:“:-_:§ 3 ;;%§%AI5〜一«:é:: 3%的IAA»â,¬E:

备注:

• 我尝试了python-tesseract和tightocr库,这些库已经
  足够好了,但缺少文档
• 这里我使用opencv.imread,以便有可能在矩阵上应用数学算法

有任何想法如何将OpenCV图像(numpy.ndarray)传递给Tesseract？任何帮助都会有用.

Answer 1

我用python 3 :( bw_img是一个numpy.ndarray)

import numpy as np
import cv2
from PIL import Image
import pytesseract

...

(thresh, bw_img) = cv2.threshold(bw_img, 128, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)
...

img = Image.fromarray(bw_img)
txt = pytesseract.image_to_string(img)
print(txt)