@zdenop: the code I posted in the @OP doesn't have do the rescaled image and removed borders but I've already tried with no luck. I excuse myself if I called you ignorant, but doesn't your sentence "It does not matter how many times you post this (SO, issue tracker)..." feel a little bit aggressive for no reason against me...? Even if I try to improve quality, it doesn't mean it has to work at all. :-) I acknowledge that you may have contributed to the Tesseract project, but could we please keep a non arrogant tone? I'm not familiar with Tesseract. It's the first time I'm using it, maybe I'm doing something wrong. Did you actually find the solution to my problem (does it work for you by rescaling/removing borders)? If yes, I'd ask if you can post the code you used, because it didn't work for me.
Thanks. Il giorno sabato 9 aprile 2022 alle 09:40:21 UTC+2 zdenop ha scritto: > Well https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md > > > *Rescaling *-> Optimal resolution suggests that the size of input letters > should be 30-33 points. YOU IGNORED it - your has 240 points!!! > "for 4.x version use dark text on light background" -> YOU IGNORED IT. > *Border *-> you did not remove them > > Conclusion: you are ignoring documentation. Good luck with asking for > support while blaming others for ignorance. > > Zdenko > > > pi 8. 4. 2022 o 0:56 javalover <[email protected]> napísal(a): > >> @zdenop: it doesn't matter how much arrogant/ignorant you can be, you >> wouldn't have never understood that the reason I'm posting here is just >> because of this >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#still-having-problems> >> . >> Thus, if you had actually read the page you linked me (Still having >> problems? paragraph), you would have come to the conclusion that all >> proposed solutions don't work: >> >> If you've tried the above and are still getting low accuracy results, ask >> on the forum >> <https://groups.google.com/forum/?fromgroups#!forum/tesseract-ocr> for >> help, ideally posting an example image. >> that page suggested to ask here for further problems. And as you've >> already said, somebody has already suggested me to work on these image >> processing procedures before feeding it to Tesseract: >> >> - Rescaling >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#rescaling> >> - Binarisation >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#binarisation> >> - Noise Removal >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#noise-removal> >> - Dilation / Erosion >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#dilation-and-erosion> >> - Rotation / Deskewing >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#rotation--deskewing> >> - Borders >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#Borders> >> - Transparency / Alpha channel >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#transparency--alpha-channel> >> - Tools / Libraries >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#tools--libraries> >> - Examples >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#examples> >> - Tables recognitions >> >> <https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md#tables-recognitions> >> >> So, I think you're smart enough to understand why I'm still here. Thanks. >> >> Il giorno giovedì 7 aprile 2022 alle 15:14:45 UTC+2 zdenop ha scritto: >> >>> It does not matter how many times you post this (SO, issue tracker) - >>> answer will be same: read and follow instruction in >>> https://github.com/tesseract-ocr/tessdoc/blob/main/ImproveQuality.md >>> >>> Zdenko >>> >>> >>> št 7. 4. 2022 o 7:19 javalover <[email protected]> napísal(a): >>> >>>> I'm deskewing an image containing a number using Projection profile >>>> based skew estimation algorithm >>>> <http://www.cvc.uab.es/~bagdanov/pubs/ijdar98.pdf> and extracting it >>>> through OCR. >>>> >>>> In order to calculate the correct skew angle, we compare the maximum >>>> difference between peaks and using this skew angle, thus rotate the image >>>> using the correct angle to correct the skew. >>>> >>>> Each image (which has a single number) has prefixed background and >>>> foreground (number) color: >>>> >>>> - If the first pixel of the background is black, the foreground is >>>> dark gray. >>>> - If the first pixel of the background is white, the foreground is >>>> dark white. >>>> >>>> Here are some sample images: >>>> >>>> [image: 1.jpg] [image: 2.jpg] [image: 3.jpg] [image: 4.jpg] >>>> >>>> which all of them get successfully deskewed to these: >>>> >>>> [image: 1.png] [image: 2.png] [image: 3.png] [image: 4.png] >>>> >>>> After it's been deskewed, I've tried with no luck to improve image >>>> quality to let OCR (PyTesseract) recognize the numbers. >>>> >>>> >>>> import cv2 >>>> import numpy as np >>>> import scipy.ndimage >>>> import pytesseract >>>> from PIL import Image, ImageEnhance, ImageFilter >>>> >>>> >>>> from scipy.ndimage import interpolation as inter >>>> >>>> def correct_skew(image, delta=6, limit=150): >>>> def determine_score(arr, angle): >>>> data = inter.rotate(arr, angle, reshape=False, order=0) >>>> histogram = np.sum(data, axis=1) >>>> score = np.sum((histogram[1:] - histogram[:-1]) ** 2) >>>> return histogram, score >>>> >>>> gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) >>>> >>>> blur = cv2.medianBlur(gray, 21) >>>> >>>> thresh = cv2.threshold(blur, 0, 255, cv2.THRESH_BINARY | >>>> cv2.THRESH_OTSU)[1] >>>> >>>> >>>> scores = [] >>>> angles = np.arange(-limit, limit + delta, delta) >>>> for angle in angles: >>>> histogram, score = determine_score(thresh, angle) >>>> scores.append(score) >>>> >>>> best_angle = angles[scores.index(max(scores))] + 90 >>>> >>>> (h, w) = image.shape[:2] >>>> center = (w // 2, h // 2) >>>> M = cv2.getRotationMatrix2D(center, best_angle, 1.0) >>>> rotated = cv2.warpAffine(image, M, (w, h), flags=cv2.INTER_CUBIC) >>>> >>>> >>>> ## Image processing to improve OCR accuracy >>>> """ >>>> #rotated = cv2.medianBlur(rotated, 20) >>>> >>>> rotated = rotated.astype(np.float) / 255. >>>> >>>> # Calculate channel K: >>>> rotated = 1 - np.max(rotated, axis=2) >>>> >>>> # Convert back to uint 8: >>>> rotated = (255 * rotated).astype(np.uint8) >>>> >>>> binaryThresh = 190 >>>> _, binaryImage = cv2.threshold(rotated, binaryThresh, 255, >>>> cv2.THRESH_BINARY) >>>> >>>> binaryThresh = 190 >>>> _, binaryImage = cv2.threshold(rotated, binaryThresh, 255, >>>> cv2.THRESH_BINARY) >>>> >>>> # Use a little bit of morphology to clean the mask: >>>> # Set kernel (structuring element) size: >>>> kernelSize = 3 >>>> # Set morph operation iterations: >>>> opIterations = 2 >>>> # Get the structuring element: >>>> morphKernel = cv2.getStructuringElement(cv2.MORPH_RECT, >>>> (kernelSize, kernelSize)) >>>> # Perform closing: >>>> rotated = cv2.morphologyEx(binaryImage, cv2.MORPH_CLOSE, >>>> morphKernel, None, None, opIterations, cv2.BORDER_REFLECT101) >>>> """ >>>> >>>> return best_angle, rotated >>>> >>>> if __name__ == '__main__': >>>> image = cv2.imread('number.jpg') >>>> if image[0][0][0] > 128: image = cv2.bitwise_not(image) >>>> angle, rotated = correct_skew(image) >>>> print(angle) >>>> cv2.imshow('rotated', rotated) >>>> cv2.imwrite('rotated.png', rotated) >>>> pytesseract.pytesseract.tesseract_cmd = r'C:\\Program >>>> Files\\Tesseract-OCR\\tesseract.exe' >>>> >>>> text = pytesseract.image_to_string(rotated, config="-c >>>> tessedit_char_whitelist=0123456789") >>>> print("number:", text) >>>> cv2.waitKey() >>>> >>>> >>>> This code (PyTesseract) recognizes the first >>>> <https://i.stack.imgur.com/aPHQ3.png> and the second >>>> <https://i.stack.imgur.com/ih5ei.png> number, while not the others. >>>> Why? 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