do DPI calculation as part of caching images

qurator/eynollah/eynollah.py

@@ -102,6 +102,8 @@ class Eynollah:
             self._imgs = self._cache_images(image_pil=image_pil)
         else:
             self._imgs = self._cache_images(image_filename=image_filename)
+        if override_dpi:
+            self.dpi = override_dpi
         self.image_filename = image_filename
         self.dir_out = dir_out
         self.allow_enhancement = allow_enhancement
@@ -109,7 +111,6 @@ class Eynollah:
         self.full_layout = full_layout
         self.allow_scaling = allow_scaling
         self.headers_off = headers_off
-        self.override_dpi = override_dpi
         self.plotter = None if not enable_plotting else EynollahPlotter(
             dir_of_all=dir_of_all,
             dir_of_deskewed=dir_of_deskewed,
@@ -138,8 +139,10 @@ class Eynollah:
         ret = {}
         if image_filename:
             ret['img'] = cv2.imread(image_filename)
+            self.dpi = check_dpi(image_filename)
         else:
             ret['img'] = pil2cv(image_pil)
+            self.dpi = check_dpi(image_pil)
         ret['img_grayscale'] = cv2.cvtColor(ret['img'], cv2.COLOR_BGR2GRAY)
         for prefix in ('',  '_grayscale'):
             ret[f'img{prefix}_uint8'] = ret[f'img{prefix}'].astype(np.uint8)
@@ -354,7 +357,7 @@ class Eynollah:
 
     def resize_and_enhance_image_with_column_classifier(self):
         self.logger.debug("enter resize_and_enhance_image_with_column_classifier")
-        dpi = self.override_dpi if self.override_dpi else check_dpi(self.imread())
+        dpi = self.dpi
         self.logger.info("Detected %s DPI", dpi)
         img = self.imread()
 

qurator/eynollah/processor.py

@@ -42,12 +42,6 @@ class EynollahProcessor(Processor):
             # XXX loses DPI information
             # page_image, _, _ = self.workspace.image_from_page(page, page_id, feature_filter='binarized')
             self.workspace.download_file(next(self.workspace.mets.find_files(url=page.imageFilename)))
-            if self.parameter['dpi'] <= 0:
-                exif = exif_from_filename(page.imageFilename)
-                dpi = exif.resolution
-                if exif.resolutionUnit == 'cm':
-                    dpi /= 2.54
-                self.parameter['dpi'] = dpi if dpi != 1 else 230
             eynollah_kwargs = {
                 'dir_models': self.resolve_resource(self.parameter['models']),
                 'allow_enhancement': self.parameter['allow_enhancement'],

qurator/eynollah/utils/pil_cv2.py

@@ -15,8 +15,14 @@ def pil2cv(img):
     return cvtColor(pil_as_np_array, color_conversion)
 
 def check_dpi(img):
+    if isinstance(img, Image.__class__):
+        pil_image = img
+    elif isinstance(img, str):
+        pil_image = Image.open(img)
+    else:
+        pil_image = cv2pil(img)
     try:
-        exif = OcrdExif(cv2pil(img))
+        exif = OcrdExif(pil_image)
         resolution = exif.resolution
         if resolution == 1:
             raise Exception()