feat: add options for choosing OCR engine

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

docling/datamodel/pipeline_options.py

@@ -1,6 +1,7 @@
 from enum import Enum, auto
+from typing import List, Literal, Union
 
-from pydantic import BaseModel
+from pydantic import BaseModel, Field
 
 
 class TableFormerMode(str, Enum):
@@ -18,8 +19,24 @@ class TableStructureOptions(BaseModel):
     mode: TableFormerMode = TableFormerMode.FAST
 
 
+class OcrOptions(BaseModel):
+    kind: str
+
+
+class EasyOcrOptions(OcrOptions):
+    kind: Literal["easyocr"] = "easyocr"
+    lang: List[str] = ["fr", "de", "es", "en"]
+
+
+class TesseractOcrOptions(OcrOptions):
+    kind: Literal["tesseract"] = "tesseract"
+
+
 class PipelineOptions(BaseModel):
     do_table_structure: bool = True  # True: perform table structure extraction
     do_ocr: bool = True  # True: perform OCR, replace programmatic PDF text
 
     table_structure_options: TableStructureOptions = TableStructureOptions()
+    ocr_options: Union[EasyOcrOptions, TesseractOcrOptions] = Field(
+        EasyOcrOptions(), discriminator="kind"
+    )

docling/models/base_ocr_model.py

@@ -3,21 +3,21 @@ import logging
 from abc import abstractmethod
 from typing import Iterable, List, Tuple
 
-import numpy
 import numpy as np
 from PIL import Image, ImageDraw
 from rtree import index
 from scipy.ndimage import find_objects, label
 
 from docling.datamodel.base_models import BoundingBox, CoordOrigin, OcrCell, Page
+from docling.datamodel.pipeline_options import OcrOptions
 
 _log = logging.getLogger(__name__)
 
 
 class BaseOcrModel:
-    def __init__(self, config):
-        self.config = config
-        self.enabled = config["enabled"]
+    def __init__(self, enabled: bool, options: OcrOptions):
+        self.enabled = enabled
+        self.options = options
 
     # Computes the optimum amount and coordinates of rectangles to OCR on a given page
     def get_ocr_rects(self, page: Page) -> Tuple[bool, List[BoundingBox]]:

docling/models/easyocr_model.py

@@ -4,21 +4,23 @@ from typing import Iterable
 import numpy
 
 from docling.datamodel.base_models import BoundingBox, CoordOrigin, OcrCell, Page
+from docling.datamodel.pipeline_options import EasyOcrOptions
 from docling.models.base_ocr_model import BaseOcrModel
 
 _log = logging.getLogger(__name__)
 
 
 class EasyOcrModel(BaseOcrModel):
-    def __init__(self, config):
-        super().__init__(config)
+    def __init__(self, enabled: bool, options: EasyOcrOptions):
+        super().__init__(enabled=enabled, options=options)
+        self.options: EasyOcrOptions
 
         self.scale = 3  # multiplier for 72 dpi == 216 dpi.
 
         if self.enabled:
             import easyocr
 
-            self.reader = easyocr.Reader(config["lang"])
+            self.reader = easyocr.Reader(lang_list=self.options.lang)
 
     def __call__(self, page_batch: Iterable[Page]) -> Iterable[Page]:
 

docling/pipeline/standard_model_pipeline.py

@@ -1,6 +1,11 @@
 from pathlib import Path
 
-from docling.datamodel.pipeline_options import PipelineOptions
+from docling.datamodel.pipeline_options import (
+    EasyOcrOptions,
+    PipelineOptions,
+    TesseractOcrOptions,
+)
+from docling.models.base_ocr_model import BaseOcrModel
 from docling.models.easyocr_model import EasyOcrModel
 from docling.models.layout_model import LayoutModel
 from docling.models.table_structure_model import TableStructureModel
@@ -14,19 +19,35 @@ class StandardModelPipeline(BaseModelPipeline):
     def __init__(self, artifacts_path: Path, pipeline_options: PipelineOptions):
         super().__init__(artifacts_path, pipeline_options)
 
+        ocr_model: BaseOcrModel
+        if isinstance(pipeline_options.ocr_options, EasyOcrOptions):
+            ocr_model = EasyOcrModel(
+                enabled=pipeline_options.do_ocr,
+                options=pipeline_options.ocr_options,
+            )
+        elif isinstance(pipeline_options.ocr_options, TesseractOcrOptions):
+            raise NotImplemented()
+            # TODO
+            # ocr_model = TesseractOcrModel(
+            #     enabled=pipeline_options.do_ocr,
+            #     options=pipeline_options.ocr_options,
+            # )
+        else:
+            raise RuntimeError(
+                f"The specified OCR kind is not supported: {pipeline_options.ocr_options.kind}."
+            )
+
         self.model_pipe = [
-            EasyOcrModel(
-                config={
-                    "lang": ["fr", "de", "es", "en"],
-                    "enabled": pipeline_options.do_ocr,
-                }
-            ),
+            # OCR
+            ocr_model,
+            # Layout
             LayoutModel(
                 config={
                     "artifacts_path": artifacts_path
                     / StandardModelPipeline._layout_model_path
                 }
             ),
+            # Table structure
             TableStructureModel(
                 config={
                     "artifacts_path": artifacts_path