Reading numbers from image PyTesseract

Question

So I'm trying to read the text in an image, and I'm experiencing some issues with it.

The image:

My code:

import cv2
import pytesseract


def read_img():
    pytesseract.pytesseract.tesseract_cmd = 'C:\\Program Files (x86)\\Tesseract-OCR\\tesseract.exe'
    return cv2.imread('Images/Image2.png')


def process_text(img):
    names = []
    data = pytesseract.image_to_data(img)
    for x, d in enumerate(data.splitlines()):
        if x != 0:
            d = d.split()
            if len(d) == 12:
                names.append(d[11])

    return names


img = read_img()
print(process_text(img))

Result:

['-', '©', '-', 'AceeZ.Rogue', 'a', '5540', 't', '3', '8', '&', '©', 'LeonGids.Rogue', 'a', 'seas', '8', '3', '8', 'e', 'ﬂ', 'karzheka.Rogue', 'a', '5151', '8', '2', '7', '48', '7', 'Q', 'ripz.Rogue', 'a', '5105', '8', '[', '5s', '27', 'm', 'korey.Rogue', 'a', '5105', '7', '2', '6', '36', '-', '[ZH]', 'Shaiiko.BDS', 'C', '3520', 'a', 'B', 's', '22', 'Cps', 'a', '2012', '8', 'i', '8', '21', 'ypc', 'Chee', 'e', '8', '-_', '22', '3', '(2)', 'Flemzje.BDS', 'a', '2420', 'a', '3', '10', '26', '(SF)', 'Renshiro.BDS', 'C', '2410', '6', '1', '8', 'Fo']

As you can see this is not the result I was hoping for. Here's what I've tried;

Splitting the image up

I've split the image up into two to have it more centered on the actual text:

The result of img1 is actually perfect:

['AceeZ.Rogue', 'LeonGids.Rogue', 'karzheka.Rogue', 'ripz.Rogue', 'korey.Rogue', 'Shaiiko.BDS', 'BriD.BDS', 'RaFaLe.BDS', 'Elemzje.BDS', 'Renshiro.BDS']

But with img2 issues arise again:

['5540', '5343', '5151', '5105', '5105', '3520', '29012', '2695', '2420', '2410', '11', '10']

It looks like tesseract is having issues reading numbers, because img1 with just text went fine? I've tried increasing the quality of the text (letsenhance.io) and also increasing contrast:

Neither of these methods worked.

Using config options

I've tried using config options like '--psm 6' and 'outbase digits' which didn't fix the problem either.

I saw on this page that training with the specified font is a possibility (https://stackoverflow.com/a/53763425/10503012) but I sadly don't know the font and https://www.myfonts.com/WhatTheFont/ didn't give me the exact font so I'm assuming that's not an option either.

So my question is; is it even possible to extract the text/numbers from this image or is this a lost case? What more can I do to improve the result tesseract gives me? I have the idea that the image with high contrast should work but it clearly doesn't.

Thanks for any help.

If you can reduce the space between the single digits, Tesseract should be able to detect them. I had tried this approach earlier in my project and it had improved efficiency of detection. Space can be reduced by first doing any kind of threshold(I'd prefer Otsu), and then iterate over the image and discard the pixel values which are surrounded by black pixels.(You can take the appropriate range) — jainmilnd
– jainmilnd, Commented Jul 8, 2020 at 17:31
@Beginner Thanks for your answer. I've tried some stuff with cv2 and I'm able to access the individual pixels. My question is; how are you able to 'discard' the pixels? I can currently change the value of them, but I've yet to find a way to actually remove/discard them from the image. — Stef
– Stef, Commented Jul 9, 2020 at 12:29
Images are stored in the form of NumPy arrays. You can make a new array with all pixel values to be 0(basically a black image), the dimensions will be equal to that of the original image. After that, you can run a loop on the original image(after threshold) array and for each pixel, you check if there is a white pixel around it in a certain range(let's keep the range to be 25pixels). If there is no white pixel around it in that range you can simply discard it. For all other cases, you'd just copy the original pixel value(will be 0 or 255) to your black image. — jainmilnd
– jainmilnd, Commented Jul 10, 2020 at 8:48
Discarding it means simply not copying it. For ex-consider an array [1, 2, 3, 2, 4, 2, 5] and I want to discard values which are equal to 2, Now we'll create a new blank array, temp = [0, 0, 0, 0, 0, 0, 0]. A variable count is initialized to -1. So each time we encounter a value !=2, we'll do temp[++count] = value. else we will simply not copy it or in other words discard it. The final temp array will be temp = [1,3, 4, 5, 0, 0] with variable count = 3. In this way, we have the required size = 4(count+1)so we can chop off the array to get the desired array[1,3, 4, 5]. Hope you understood. — jainmilnd
– jainmilnd, Commented Jul 10, 2020 at 9:03

bfris · Accepted Answer · 2020-07-20 15:23:37Z

Usually Tesseract likes black text on white background. So you should invert your input image. You should also consider thresholding the image to make it black and white. Finally, Tesseract can be sensitive to the size of each character. I found that the user names were recognized OK at the provided scale, but I had to scale the image by 1.25 to get the numbers to come out.

import cv2
import pytesseract

img = cv2.imread('acerogue.png', cv2.IMREAD_GRAYSCALE)  

thresh = cv2.threshold(img, 100, 255, cv2.THRESH_BINARY_INV+cv2.THRESH_OTSU)[1]
thresh = cv2.resize(thresh, (0,0), fx=1.25, fy=1.25)  # scale image 1.25X

detected_text = pytesseract.image_to_string(thresh, config = '--psm 6')
print(detected_text)

which gives

| ® AceeZ.Rogue 8 5540 11 2 8 -
© LeonGids.Rogue 8 5343 8 3 8 -

Ww karzheka.Rogue a 5151 8 2 7 48

7 tipz.Rogue a 5105 8 0 5 27
& korey.Rogue a 5105 7 2 6 36

| #4 Shaiiko.BDS B 3520 9 3 8 22
BriD.BDS mH 2912 8 1 8 21

S RaFaLe.BDS BH  —_2605 a 2 8 2

3 BS Elemzje.Bos H 2420 3 3 10 26
Se) Renshiro.BDS m 2410 6 1 8 45

Probably, you should precrop image to get rid of icons.

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