Script to detect page bounding boxes in facsimile images

utils/README.md

@@ -16,3 +16,7 @@ Currently requires pandas and python3. Run with `--help` for help.
 Hack to add the gsa 'Idents' to the metadata.
 
 Cf. faustedition/faust-gen-html#36.
+
+## detect_pages.py
+
+Tries to find the bounding box of the page in the facsimile images and writes them to a json file. Requires scikit-image, use `--help`.

utils/detect_pages.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python3
+
+from skimage.io import imread
+from skimage.filters import gaussian, threshold_otsu
+from skimage.segmentation import clear_border
+from skimage.measure import label, regionprops
+from pathlib import Path
+from os import fspath
+import argparse
+from joblib import Parallel, delayed
+import sys
+import json
+from tqdm import tqdm
+
+
+def find_page_in(imfile):
+    image = imread(fspath(imfile), as_gray=True)
+    image = gaussian(image, sigma=10)
+    thresh = 0.2 #threshold_otsu(image)
+    bw = image > thresh
+    labels = label(bw)
+    regions = regionprops(labels)
+    largest = max(regions, key=lambda rp: rp.bbox_area)
+    y, x, yy, xx = largest.bbox
+    return x, y, xx, yy
+
+
+def process_dir(path, glob='*_0.jpg', verbose=1):
+    files = list(path.glob(glob))
+    results = parallel(delayed(find_page_in)(file) for file in tqdm(files,
+                                                                    unit='image',
+                                                                    desc=f'Analyzing images in {path.stem}',
+                                                                    colour='blue',
+                                                                    leave=False))
+    return dict(zip(files, results))
+
+
+
+def _main():
+    p = argparse.ArgumentParser(#summary='Extract the largest region in each image.',
+                                description="""
+        The script analyzes all image files in the given directorie(s) and tries to automatically find
+        the page region, i.e. the non-dark region with the largest bounding box. It will then generate
+        a json file mapping the 'cleaned' version of each image file name to a bounding box.
+    """)
+    p.add_argument('folder', nargs='+', type=Path, help='image folder')
+    p.add_argument('-r', '--recursive', action='store_true', help='recursively search all directories')
+    p.add_argument('-f', '--force', action='store_true', help='overwrite existing files')
+    p.add_argument('-g', '--glob', default='*_0.jpg', help='glob pattern to search through each folder')
+    p.add_argument('-o', '--output', default='{folder}/zoom.json', help="""
+        Pattern for the output file names. Available expansions: {folder} - full path to folder, more TODO
+    """)
+    p.add_argument('-p', '--parallel', nargs='?', const=-1, type=int, metavar='JOBS', help='Run multiple jobs in parallel.')
+    p.add_argument('-v', '--verbose', action='count', default=0)
+    options = p.parse_args()
+
+    global parallel
+    parallel = Parallel(options.parallel, verbose=5*options.verbose)
+
+    if options.recursive:
+        folders = []
+        for folder in options.folder:
+            folders.extend(folder.glob('**/'))
+    else:
+        folders = options.folder
+
+    # noinspection PyBroadException
+    try:
+        suffix = options.glob[options.glob.rindex('*')+1:]
+        suffix_length = len(suffix)
+        def clean_path(path: Path):
+            if path.name[-suffix_length:] == suffix:
+                return path.name[:-suffix_length]
+            else:
+                return path.stem
+    except:
+        def clean_path(path: Path):
+            return path.stem
+
+    for folder in tqdm(folders, unit='folder', desc='Processing folders'):
+        outpath = Path(options.output.format_map(dict(folder=folder, dirname=folder.name)))
+        if options.force or not outpath.exists():
+            bboxes = process_dir(folder, options.glob, options.verbose)
+            if bboxes:
+                final = {clean_path(path): bboxes for path, bboxes in bboxes.items()}
+                outpath.parent.mkdir(parents=True, exist_ok=True)
+                with outpath.open('wt') as f:
+                    json.dump(dict(sorted(final.items())), f, separators=(',', ':'))
+
+
+
+if __name__ == '__main__':
+    _main()