Why will tesseract not detect this letter? - python

I am trying to detect this letter but it doesn't seem to recognize it.
import cv2
import pytesseract as tess
img = cv2.imread("letter.jpg")
imggray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
print(tess.image_to_string(imggray))
this is the image in question:

Preprocessing of the image (e.g. inverting it) should help, and also you could take advantage of pytesseract image_to_string config options.
For instance, something along these lines:
import pytesseract
import cv2 as cv
import requests
import numpy as np
import io
# I read this directly from imgur
response = requests.get('https://i.stack.imgur.com/LGFAu.jpg')
nparr = np.frombuffer(response.content, np.uint8)
img = cv.imdecode(nparr, cv.IMREAD_GRAYSCALE)
# simple inversion as preprocessing
neg_img = cv.bitwise_not(img)
# invoke tesseract with options
text = pytesseract.image_to_string(neg_img, config='--psm 7')
print(text)
should parse the letter correctly.
Have a look at related questions for some additional info about preprocessing and tesseract options:
Why does pytesseract fail to recognise digits from image with darker background?
Why does pytesseract fail to recognize digits in this simple image?
Why does tesseract fail to read text off this simple image?

#Davide Fiocco 's answer is definitely correct.
I just want to show another way of doing it with adaptive-thresholding
When you apply adaptive-thesholding result will be:
Now when you read it:
txt = pytesseract.image_to_string(thr, config="--psm 7")
print(txt)
Result:
B
Code:
import cv2
import pytesseract
img = cv2.imread("LGFAu.jpg")
gry = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
thr = cv2.adaptiveThreshold(gry, 252, cv2.ADAPTIVE_THRESH_MEAN_C,
cv2.THRESH_BINARY_INV, 11, 2)
txt = pytesseract.image_to_string(thr, config="--psm 7")
print(txt)

Related

Can pytesseract read and print exponents?

Using this code
'''
import cv2
import numpy as np
import pytesseract
from PIL import Image
pytesseract.pytesseract.tesseract_cmd = r'C:\Program Files\New folder\tesseract.exe'
# Grayscale image
img = Image.open(r"C:\Users\gusta\Downloads\PyQuad-master\test.png").convert('L')
ret,img = cv2.threshold(np.array(img), 180, 500, cv2.THRESH_BINARY)
# Older versions of pytesseract need a pillow image
# Convert back if needed
img = Image.fromarray(img.astype(np.uint8))
print(pytesseract.image_to_string(img))
text = pytesseract.image_to_string(img)
with open('file.txt', mode ='w') as f:
f.write(text)
'''
I get a text file:
Find the y-intercept of the parabola with the followin
y = —6x? — 10x — 2
Which was converted from:
Is there a way I could get it to read the ^2 exponent and also print it as ^2?

Recognize numbers from an image python

I am trying to extract numbers from in game screenshots.
I'm trying to extract:
98
3430
5/10
from PIL import Image
import pytesseract
image="D:/img/New folder (2)/1.png"
pytesseract.pytesseract.tesseract_cmd = 'C:/Program Files/Tesseract-OCR/tesseract.exe'
text = pytesseract.image_to_string(Image.open(image),lang='eng',config='--psm 5')
print(text)
output is gibberish
‘t hl) keteeeees
ek pSlaerenen
JU) pgrenmnreserenny
Rates B
d dali eas. 5
cle aM (Sores
|, S| pgranmrerererecons
a cee 3
pea 3
oS :
(geo eenee
ey
=
es A
okay, so I tried changing it into grayscale, reverse contrast or use different treshold, but it all seems to be fairly inaccurate.
The issue seems to be the tilted and smaller numbers. You do not happen to have any hiher res image?
Most accurate I could get was the following code.
import cv2
import pytesseract
import imutils
pytesseract.pytesseract.tesseract_cmd = r"C:\Program Files\Tesseract-OCR\tesseract.exe"
img = cv2.imread('D:/img/New folder (2)/1.png') #test.png is your original image
img = imutils.resize(img, width=1400)
crop = img[340:530, 100:400]
data = pytesseract.image_to_string(crop,config=' --psm 1 --oem 3 -c tessedit_char_whitelist=0123456789/')
print(data)
cv2.imshow('crop', crop)
cv2.waitKey()
Otherwise I recommend one of these methods as described in the similar question
or in this one.
if the text is surrounded with the designs, tesseract suffers a lot
insted of tesseract try using findcontours in opencv (after little blurring, dilating)
you will get bounding boxes, then it might cover that text also

Tesseract OCR on binary image

I have a binary image like this,
I want to extract the numbers in the image using tesseract ocr in Python. I used pytesseract like this on the image,
txt = pytesseract.image_to_string(img)
But I am not getting any good results.
What can I do in pre-processing or augmentation that can help tesseract do better.?
I tried to localize the text from the image using East Text Detector but it was not able to recognize the text.
How to proceed with this in python.?
I think the page-segmentation-mode is an important factor here.
Since we are trying to read column values, we could use --psm 4 (source)
import cv2
import pytesseract
img = cv2.imread("k7bqx.jpg")
gry = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
txt = pytesseract.image_to_string(gry, config="--psm 4")
We want to get the text starts with #
txt = sorted([t[:2] for t in txt if "#" in t])
Result:
['#3', '#7', '#9', '#€']
But we miss 4, 5, we could apply adaptive-thresholding:
Result:
['#3', '#4', '#5', '#7', '#9', '#€']
Unfortunately, #2 and #6 are not recognized.
Code:
import cv2
import pytesseract
img = cv2.imread("k7bqx.jpg")
gry = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
thr = cv2.adaptiveThreshold(gry, 252, cv2.ADAPTIVE_THRESH_MEAN_C,
cv2.THRESH_BINARY_INV, blockSize=131, C=100)
bnt = cv2.bitwise_not(thr)
txt = pytesseract.image_to_string(bnt, config="--psm 4")
txt = txt.strip().split("\n")
txt = sorted([t[:2] for t in txt if "#" in t])
print(txt)

Pytesseract reading receipt

I have tried to read text from image of receipt using pytesseract. But a result text have a lot weird characters and it really looks awful.
There is my code which i used to manipulate image:
import sys
from PIL import Image
import cv2 as cv
import numpy as np
import pytesseract
def manipulate_image(img):
img = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
kernel = np.ones((1,1), dtype = "uint8")
img = cv.erode(img, kernel, iterations = 1)
img = cv.threshold(img, 0, 255,
cv.THRESH_BINARY | cv.THRESH_OTSU)[1]
img = cv.medianBlur(img, 3)
return img
if len(sys.argv) > 2:
print("Please provide only name of image.")
elif len(sys.argv) == 2:
img = cv.imread(sys.argv[1])
img = manipulate_image(img)
cv.imwrite("test.png", img)
text = pytesseract.image_to_string(img)
print text.encode('utf8')
else:
print("Please provide name of image.")
there is my test receipt image:
https://imgur.com/a/RjeQ9dL
and there is output image after manupulate:
https://imgur.com/a/1tFZRdq
and there is text result:
""'9vco4v‘l7
0 .Vt3t00N 00t300N BUNUUS
SKLEP PUU POPUGOH|
UL. JHGIELLUNSKA 25, 70-364 SZCZ[C|N
TEL. 91 4841-20-58
N|P: 955—150-21-B2
dn.19r03.05 Uydr.8534
PARAGON FISKALNY
CIHSTKH 17 0,3 ¥ 16,30 = 4.89 B
Sp.0p.B 4,89 PTU B= 8,00% 0,35
Razem PTU 0,35
ZOP{HCUNU GUTUNKQ PLN
RESZTA PLN
0025/1373 H0103 0N|0 H.
15F H9HF[B9416} 13fl02D6k0[20D4334C
7?? BW 140
Any idea how to perform it in better way to get nicer results?
Applying simple thresholding will not be enough for pyTesseract to properly detect the characters. There is much more preprocessing that can be done to drastically improve your results, such as:
using Tesseract V4, where deep learning is implemented
segmenting characters
using only the part of the receipt where the text is through edge detection
perspective transform to straighten out the text
These are somewhat lengthy topics to write all in one answer, but you can check out some articles on pyImageSearch, where this is talked about in much more depth:
https://www.pyimagesearch.com/2014/09/01/build-kick-ass-mobile-document-scanner-just-5-minutes/
https://www.pyimagesearch.com/2018/09/17/opencv-ocr-and-text-recognition-with-tesseract/

extracting text information from a national id

I'm trying to do OCR arabic on the following ID but I get a very noisy picture, and can't extract information from it.
Here is my attempt
import tesserocr
from PIL import Image
import pytesseract
import matplotlib as plt
import cv2
import imutils
import numpy as np
image = cv2.imread(r'c:\ahmed\ahmed.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gray = cv2.bilateralFilter(gray,11,18,18)
gray = cv2.GaussianBlur(gray,(5,5), 0)
kernel = np.ones((2,2), np.uint8)
gray = cv2.adaptiveThreshold(gray,255,cv2.ADAPTIVE_THRESH_GAUSSIAN_C,
cv2.THRESH_BINARY,11,2)
#img_dilation = cv2.erode(gray, kernel, iterations=1)
#cv2.imshow("dilation", img_dilation)
cv2.imshow("gray", gray)
text = pytesseract.image_to_string(gray, lang='ara')
print(text)
with open(r"c:\ahmed\file.txt", "w", encoding="utf-8") as myfile:
myfile.write(text)
cv2.waitKey(0)
result
sample
The text for your id is in black color which makes the extraction process easy. All you need to do is threshold the dark pixels and you should be able to get the text out.
Here is a snip of the code
import cv2
import numpy as np
# load image in grayscale
image = cv2.imread('AVXjv.jpg',0)
# remove noise
dst = cv2.blur(image,(3,3))
# extract dark regions which corresponds to text
val, dst = cv2.threshold(dst,80,255,cv2.THRESH_BINARY_INV)
# morphological close to connect seperated blobs
dst = cv2.dilate(dst,None)
dst = cv2.erode(dst,None)
cv2.imshow("dst",dst)
cv2.waitKey(0)
And here is the result:
This is my output using ImageMagick TextCleaner script:
Script: textcleaner -g -e stretch -f 50 -o 30 -s 1 C:/Users/PC/Desktop/id.jpg C:/Users/PC/Desktop/out.png
Take a look here if you want to install and use TextCleaner script on Windows... It's a tutorial I made as simple as possible after few researches I made when I was in your same situation.
Now it should be very easy to detect the text and (not sure how simple) recognize it.

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