CV2-5181-Calculate-and-return-image_text_percentage-to-Check-API-as-part-of-the-OCR

app/main/controller/image_ocr_controller.py

@@ -18,6 +18,32 @@ def _after_log(retry_state):
 CLIENT = get_credentialed_google_client(vision.ImageAnnotatorClient)
 @api.route('/')
 class ImageOcrResource(Resource):
+    @staticmethod
+    def polygon_area(vertices):
+        area = 0
+        for i in range(len(vertices)):
+            x1, y1 = vertices[i]
+            x2, y2 = vertices[(i + 1) % len(vertices)]
+            area += (x1 * y2 - x2 * y1)
+        return abs(area) / 2
+
+    @staticmethod
+    def calculate_text_percentage(response):
+        bounds = []
+        for page in response.full_text_annotation.pages:
+            for block in page.blocks:
+                    bounds.append(block.bounding_box)
+        total_text_area = 0
+        for annotation in bounds:
+            vertices = [(v.x, v.y) for v in annotation.vertices]
+            area = ImageOcrResource.polygon_area(vertices)
+            total_text_area += area
+        # response object contains the whole image width and height in response.full_text_annotation.pages[0]
+        # as we are sending images, response.full_text_annotation.pages is always 1 page only
+        image_area = response.full_text_annotation.pages[0].width * response.full_text_annotation.pages[0].height
+        text_percentage = (total_text_area / image_area) * 100
+        return text_percentage
+
     @api.response(200, 'text successfully extracted.')
     @api.doc('Perform text extraction from an image')
     @api.doc(params={'url': 'url of image to extract text from'})
@@ -37,8 +63,13 @@ def post(self):
         if not texts:
             return
 
-        app.logger.info(
-            f"[Alegre OCR] [image_uri {image.source.image_uri}] Image OCR response package looks like {convert_text_annotation_to_json(texts[0])}")
+        #### calculate bounding boxes areas.
+        try:
+            text_percentage = ImageOcrResource.calculate_text_percentage(response)
+            app.logger.info(
+                f"[Alegre OCR] [image_uri {image.source.image_uri}] [percentage of image area covered by text {text_percentage}%] Image OCR response package looks like {convert_text_annotation_to_json(texts[0])}")
+        except Exception as caught_exception:
+            app.logger.error(f"[image_uri {image.source.image_uri}] Error calculating percentage of image area covered by text. Error was {caught_exception}. Image OCR response package looks like {convert_text_annotation_to_json(texts[0])}")
 
         return {
             'text': texts[0].description