feat: Add Tesseract PSM options support (#2411)

* feat: Add Tesseract PSM options support

Signed-off-by: Bruno Pio <913963+blap@users.noreply.github.com>

* apply formatting

Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>

* add tesseract_cli in checks

Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>

---------

Signed-off-by: Bruno Pio <913963+blap@users.noreply.github.com>
Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>
Co-authored-by: Michele Dolfi <dol@zurich.ibm.com>

docling/cli/main.py

@@ -57,6 +57,8 @@ from docling.datamodel.pipeline_options import (
     PipelineOptions,
     ProcessingPipeline,
     TableFormerMode,
+    TesseractCliOcrOptions,
+    TesseractOcrOptions,
     VlmPipelineOptions,
 )
 from docling.datamodel.settings import settings
@@ -380,6 +382,13 @@ def convert(  # noqa: C901
             help="Provide a comma-separated list of languages used by the OCR engine. Note that each OCR engine has different values for the language names.",
         ),
     ] = None,
+    psm: Annotated[
+        Optional[int],
+        typer.Option(
+            ...,
+            help="Page Segmentation Mode for the OCR engine (0-13).",
+        ),
+    ] = None,
     pdf_backend: Annotated[
         PdfBackend, typer.Option(..., help="The PDF backend to use.")
     ] = PdfBackend.DLPARSE_V2,
@@ -596,6 +605,10 @@ def convert(  # noqa: C901
         ocr_lang_list = _split_list(ocr_lang)
         if ocr_lang_list is not None:
             ocr_options.lang = ocr_lang_list
+        if psm is not None and isinstance(
+            ocr_options, (TesseractOcrOptions, TesseractCliOcrOptions)
+        ):
+            ocr_options.psm = psm
 
         accelerator_options = AcceleratorOptions(num_threads=num_threads, device=device)
         # pipeline_options: PaginatedPipelineOptions

docling/datamodel/pipeline_options.py

@@ -154,6 +154,9 @@ class TesseractCliOcrOptions(OcrOptions):
     lang: List[str] = ["fra", "deu", "spa", "eng"]
     tesseract_cmd: str = "tesseract"
     path: Optional[str] = None
+    psm: Optional[int] = (
+        None  # Page Segmentation Mode (0-13), defaults to tesseract's default
+    )
 
     model_config = ConfigDict(
         extra="forbid",
@@ -166,6 +169,9 @@ class TesseractOcrOptions(OcrOptions):
     kind: ClassVar[Literal["tesserocr"]] = "tesserocr"
     lang: List[str] = ["fra", "deu", "spa", "eng"]
     path: Optional[str] = None
+    psm: Optional[int] = (
+        None  # Page Segmentation Mode (0-13), defaults to tesseract's default
+    )
 
     model_config = ConfigDict(
         extra="forbid",

docling/models/tesseract_ocr_cli_model.py

@@ -117,6 +117,10 @@ class TesseractOcrCliModel(BaseOcrModel):
             cmd.append("--tessdata-dir")
             cmd.append(self.options.path)
 
+        # Add PSM option if specified in the configuration
+        if self.options.psm is not None:
+            cmd.extend(["--psm", str(self.options.psm)])
+
         cmd += [ifilename, "stdout", "tsv"]
         _log.info("command: {}".format(" ".join(cmd)))
 

docling/models/tesseract_ocr_model.py

@@ -86,7 +86,6 @@ class TesseractOcrModel(BaseOcrModel):
                 self.script_prefix = ""
 
             tesserocr_kwargs = {
-                "psm": tesserocr.PSM.AUTO,
                 "init": True,
                 "oem": tesserocr.OEM.DEFAULT,
             }
@@ -96,14 +95,23 @@ class TesseractOcrModel(BaseOcrModel):
             if self.options.path is not None:
                 tesserocr_kwargs["path"] = self.options.path
 
+            # Set main OCR reader with configurable PSM
+            main_psm = (
+                tesserocr.PSM(self.options.psm)
+                if self.options.psm is not None
+                else tesserocr.PSM.AUTO
+            )
             if lang == "auto":
-                self.reader = tesserocr.PyTessBaseAPI(**tesserocr_kwargs)
+                self.reader = tesserocr.PyTessBaseAPI(psm=main_psm, **tesserocr_kwargs)
             else:
                 self.reader = tesserocr.PyTessBaseAPI(
-                    **{"lang": lang} | tesserocr_kwargs,
+                    lang=lang,
+                    psm=main_psm,
+                    **tesserocr_kwargs,
                 )
+            # OSD reader must use PSM.OSD_ONLY for orientation detection
             self.osd_reader = tesserocr.PyTessBaseAPI(
-                **{"lang": "osd", "psm": tesserocr.PSM.OSD_ONLY} | tesserocr_kwargs
+                lang="osd", psm=tesserocr.PSM.OSD_ONLY, **tesserocr_kwargs
             )
             self.reader_RIL = tesserocr.RIL
 
@@ -187,7 +195,9 @@ class TesseractOcrModel(BaseOcrModel):
                                         tesserocr.PyTessBaseAPI(
                                             path=self.reader.GetDatapath(),
                                             lang=lang,
-                                            psm=tesserocr.PSM.AUTO,
+                                            psm=tesserocr.PSM(self.options.psm)
+                                            if self.options.psm is not None
+                                            else tesserocr.PSM.AUTO,
                                             init=True,
                                             oem=tesserocr.OEM.DEFAULT,
                                         )