layout/extract-images/processor: write AlternativeImage if binarized…

- layout/extract-images: when running with `input_binary`, then
  pass the binarized image of the full page to the writer
- writer: if there is a binarized image, then add an `AlternativeImage`
  to the top-level of the output PAGE (with the array instead of a
  file name)
- writer.write_xml (standalone CLIs): save the image in the same
  directory as the output file, but with `.bin.png` isntead of
  `.xml` as suffix
- processor: convert the binarized image array to PIL and pass over
  as OcrdPageResultImage for the final path name

src/eynollah/extract_images.py

@@ -252,6 +252,7 @@ class EynollahImageExtractor(Eynollah):
         images = [image for image in images if image.area]
         pcgts = writer.build_pagexml(
             page=page,
+            img_bin=self.imread(image, binary=True) if self.input_binary else None,
             num_col=num_col_classifier,
             images=images,
         )

src/eynollah/eynollah.py

@@ -2098,6 +2098,7 @@ class Eynollah:
 
             pcgts = writer.build_pagexml(
                 page=page,
+                img_bin=self.imread(image, binary=True) if self.input_binary else None,
                 num_col=num_col_classifier,
                 order_of_texts=[0],
                 textregions=textregions,
@@ -2170,6 +2171,7 @@ class Eynollah:
 
             pcgts = writer.build_pagexml(
                 page=page,
+                img_bin=self.imread(image, binary=True) if self.input_binary else None,
                 num_col=0,
             )
             if writer.pcgts is None:
@@ -2370,6 +2372,7 @@ class Eynollah:
         self.logger.info("Step 5/5: Output Generation")
         pcgts = writer.build_pagexml(
             page=page,
+            img_bin=self.imread(image, binary=True) if self.input_binary else None,
             num_col=num_col_classifier,
             order_of_texts=order_text,
             textregions=textregions,

src/eynollah/processor.py

@@ -1,5 +1,6 @@
 from functools import cached_property
 from typing import Optional
+from PIL import Image
 from ocrd_models import OcrdPage
 from ocrd import OcrdPageResultImage, Processor, OcrdPageResult
 
@@ -95,4 +96,9 @@ class EynollahProcessor(Processor):
                                  img_pil=page_image, pcgts=pcgts,
                                  # ocrd.Processor will handle OCRD_EXISTING_OUTPUT more flexibly
                                  overwrite=True)
+        if self.parameter['binarize'] and (img_alt := next(
+                (img for img in pcgts.Page.AlternativeImage
+                 if img.comments == "binarized"), None)):
+            result.images.append(OcrdPageResultImage(
+                Image.fromarray(img_alt.filename), '.IMG-BIN', img_alt))
         return result

src/eynollah/writer.py

@@ -4,12 +4,14 @@ from pathlib import Path
 import os.path
 import logging
 from typing import Optional, List, Tuple
+
 import numpy as np
 import cv2
 from shapely import affinity, clip_by_rect
 
 from ocrd_utils import points_from_polygon
 from ocrd_models.ocrd_page import (
+    AlternativeImageType,
     BorderType,
     CoordsType,
     TextLineType,
@@ -80,6 +82,13 @@ class EynollahXmlWriter:
 
     def write_pagexml(self, pcgts):
         self.logger.info("output filename: '%s'", self.output_filename)
+        if img_alt := next(
+                (img for img in pcgts.Page.AlternativeImage
+                 if img.comments == "binarized"
+                 and isinstance(img.filename, np.ndarray)), None):
+            img_alt_filename = self.output_filename[:-4] + '.bin.png'
+            cv2.imwrite(img_alt_filename, img_alt.filename)
+            img_alt.filename = os.path.basename(img_alt_filename)
         with open(self.output_filename, 'w') as f:
             f.write(to_xml(pcgts))
 
@@ -87,7 +96,8 @@ class EynollahXmlWriter:
         self,
         *,
         page: Region,
-        num_col=1,
+        img_bin: Optional[np.ndarray] = None,
+        num_col: int = 1,
         order_of_texts: List[int] = [],
         textregions: List[TextRegion] = [],
         textregions_h: List[TextRegion] = [],
@@ -104,6 +114,10 @@ class EynollahXmlWriter:
         pcgts = self.pcgts if self.pcgts else create_page_xml(
             self.image_filename, self.image_height, self.image_width)
         pcgts.Metadata.Comments = "num_col %d" % num_col
+        if img_bin is not None:
+            img_alt = AlternativeImageType(filename=img_bin, # will be replaced later
+                                           comments="binarized")
+            pcgts.Page.add_AlternativeImage(img_alt)
         pcgts.Page.set_custom('layout {num_col:%d;} ' % num_col)
         pcgts.Page.set_orientation(-page.skew)
         pcgts.Page.set_Border(BorderType(Coords=CoordsType(