fix: apply flexible compression ratio

Refs: #152

web-app/django/VIM/apps/instruments/management/commands/download_imgs.py

@@ -46,13 +46,47 @@ def _save_image_as_png(self, img_content, url, save_path):
         except IOError as e:
             self.stderr.write(f"Failed to save image from {url}: {e}")
 
-    def create_thumbnail(self, image_path, thumbnail_path, compression_ratio=0.35):
+    def calculate_compression_ratio(self, original_width, original_height):
+        """
+        Calculate a flexible compression ratio based on the original dimensions of an image.
+
+        Parameters:
+        original_width (int): The width of the original image.
+        original_height (int): The height of the original image.
+
+        Returns:
+        float: The compression ratio.
+        """
+        # Determine the larger dimension to base compression on (could be width or height)
+        max_dimension = max(original_width, original_height)
+
+        # Set a target size for compression based on original dimensions
+        if max_dimension > 4000:
+            # Large images (e.g., 4K or higher): compress significantly
+            compression_ratio = 0.2  # 20% of the original size
+        elif max_dimension > 2000:
+            # Medium-large images: moderate compression
+            compression_ratio = 0.5  # 50% of the original size
+        elif max_dimension > 1000:
+            # Medium images: light compression
+            compression_ratio = 0.75  # 75% of the original size
+        else:
+            # Small images: minimal compression
+            compression_ratio = 0.9  # 90% of the original size
+
+        return compression_ratio
+
+    def create_thumbnail(self, image_path, thumbnail_path):
         """Create a thumbnail of an image."""
         try:
             with Image.open(image_path) as original_img:
+                original_width, original_height = original_img.size
+                compression_ratio = self.calculate_compression_ratio(
+                    original_width, original_height
+                )
                 new_size = (
-                    int(original_img.width * compression_ratio),
-                    int(original_img.height * compression_ratio),
+                    int(original_width * compression_ratio),
+                    int(original_height * compression_ratio),
                 )
                 original_img.thumbnail(new_size)
                 original_img.save(thumbnail_path, "PNG")