feat: add "auto" language for TesseractOcr (#759)
* Add "auto" language for TesseractOcr Signed-off-by: Pavel Denisov <pavel.denisov@iais.fraunhofer.de> * Add tesseract-ocr-script-latn installation for the "auto" language Signed-off-by: Pavel Denisov <pavel.denisov@iais.fraunhofer.de> * Modify "auto" language in TesseractOcr to initialize the script readers lazily Signed-off-by: Pavel Denisov <pavel.denisov@iais.fraunhofer.de> * Finalize script readers Signed-off-by: Pavel Denisov <pavel.denisov@iais.fraunhofer.de> * Fix script models prefix for Linux Signed-off-by: Pavel Denisov <pavel.denisov@iais.fraunhofer.de> --------- Signed-off-by: Pavel Denisov <pavel.denisov@iais.fraunhofer.de>
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Pavel Denisov
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.github/workflows/checks.yml
vendored
2
.github/workflows/checks.yml
vendored
@ -10,7 +10,7 @@ jobs:
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steps:
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- uses: actions/checkout@v4
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- name: Install tesseract
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run: sudo apt-get update && sudo apt-get install -y tesseract-ocr tesseract-ocr-eng tesseract-ocr-fra tesseract-ocr-deu tesseract-ocr-spa libleptonica-dev libtesseract-dev pkg-config
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run: sudo apt-get update && sudo apt-get install -y tesseract-ocr tesseract-ocr-eng tesseract-ocr-fra tesseract-ocr-deu tesseract-ocr-spa tesseract-ocr-script-latn libleptonica-dev libtesseract-dev pkg-config
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- name: Set TESSDATA_PREFIX
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run: |
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echo "TESSDATA_PREFIX=$(dpkg -L tesseract-ocr-eng | grep tessdata$)" >> "$GITHUB_ENV"
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@ -54,43 +54,56 @@ class TesseractOcrModel(BaseOcrModel):
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# Initialize the tesseractAPI
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_log.debug("Initializing TesserOCR: %s", tesseract_version)
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lang = "+".join(self.options.lang)
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self.script_readers: dict[str, tesserocr.PyTessBaseAPI] = {}
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if any([l.startswith("script/") for l in tesserocr_languages]):
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self.script_prefix = "script/"
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else:
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self.script_prefix = ""
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tesserocr_kwargs = {
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"psm": tesserocr.PSM.AUTO,
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"init": True,
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"oem": tesserocr.OEM.DEFAULT,
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}
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if self.options.path is not None:
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tesserocr_kwargs["path"] = self.options.path
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if lang == "auto":
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self.reader = tesserocr.PyTessBaseAPI(
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path=self.options.path,
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lang=lang,
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psm=tesserocr.PSM.AUTO,
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init=True,
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oem=tesserocr.OEM.DEFAULT,
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**{"lang": "osd", "psm": tesserocr.PSM.OSD_ONLY} | tesserocr_kwargs
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)
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else:
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self.reader = tesserocr.PyTessBaseAPI(
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lang=lang,
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psm=tesserocr.PSM.AUTO,
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init=True,
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oem=tesserocr.OEM.DEFAULT,
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**{"lang": lang} | tesserocr_kwargs,
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)
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self.reader_RIL = tesserocr.RIL
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def __del__(self):
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if self.reader is not None:
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# Finalize the tesseractAPI
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self.reader.End()
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for script in self.script_readers:
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self.script_readers[script].End()
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def __call__(
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self, conv_res: ConversionResult, page_batch: Iterable[Page]
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) -> Iterable[Page]:
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if not self.enabled:
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yield from page_batch
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return
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import tesserocr
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for page in page_batch:
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assert page._backend is not None
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if not page._backend.is_valid():
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yield page
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else:
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with TimeRecorder(conv_res, "ocr"):
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assert self.reader is not None
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ocr_rects = self.get_ocr_rects(page)
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@ -106,20 +119,55 @@ class TesseractOcrModel(BaseOcrModel):
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# Retrieve text snippets with their bounding boxes
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self.reader.SetImage(high_res_image)
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boxes = self.reader.GetComponentImages(
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if self.options.lang == ["auto"]:
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osd = self.reader.DetectOrientationScript()
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# No text, probably
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if osd is None:
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continue
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script = osd["script_name"]
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if script == "Katakana" or script == "Hiragana":
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script = "Japanese"
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elif script == "Han":
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script = "HanS"
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elif script == "Korean":
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script = "Hangul"
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_log.debug(
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f'Using model for the detected script "{script}"'
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)
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if script not in self.script_readers:
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self.script_readers[script] = tesserocr.PyTessBaseAPI(
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path=self.reader.GetDatapath(),
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lang=f"{self.script_prefix}{script}",
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psm=tesserocr.PSM.AUTO,
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init=True,
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oem=tesserocr.OEM.DEFAULT,
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)
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local_reader = self.script_readers[script]
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local_reader.SetImage(high_res_image)
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else:
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local_reader = self.reader
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boxes = local_reader.GetComponentImages(
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self.reader_RIL.TEXTLINE, True
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)
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cells = []
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for ix, (im, box, _, _) in enumerate(boxes):
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# Set the area of interest. Tesseract uses Bottom-Left for the origin
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self.reader.SetRectangle(
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local_reader.SetRectangle(
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box["x"], box["y"], box["w"], box["h"]
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)
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# Extract text within the bounding box
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text = self.reader.GetUTF8Text().strip()
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confidence = self.reader.MeanTextConf()
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text = local_reader.GetUTF8Text().strip()
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confidence = local_reader.MeanTextConf()
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left = box["x"] / self.scale
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bottom = box["y"] / self.scale
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right = (box["x"] + box["w"]) / self.scale
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@ -60,6 +60,7 @@ def test_e2e_conversions():
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RapidOcrOptions(),
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EasyOcrOptions(force_full_page_ocr=True),
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TesseractOcrOptions(force_full_page_ocr=True),
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TesseractOcrOptions(force_full_page_ocr=True, lang=["auto"]),
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TesseractCliOcrOptions(force_full_page_ocr=True),
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RapidOcrOptions(force_full_page_ocr=True),
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]
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@ -70,7 +71,9 @@ def test_e2e_conversions():
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engines.append(OcrMacOptions(force_full_page_ocr=True))
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for ocr_options in engines:
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print(f"Converting with ocr_engine: {ocr_options.kind}")
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print(
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f"Converting with ocr_engine: {ocr_options.kind}, language: {ocr_options.lang}"
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)
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converter = get_converter(ocr_options=ocr_options)
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for pdf_path in pdf_paths:
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print(f"converting {pdf_path}")
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