updates to transparency filtering, fixing mass tag edit autocomplete

app/utils/image_importer.py

@@ -105,26 +105,54 @@ def is_mostly_transparent(file_path: str, threshold: float = 0.9) -> bool:
     """
     Check if an image is mostly transparent (> threshold % of pixels are transparent).
     Returns False for images without alpha channel.
+
+    Args:
+        file_path: Path to the image file
+        threshold: Percentage of pixels that must be transparent (0.0-1.0, default 0.9 = 90%)
+
+    Returns:
+        True if the image has > threshold% transparent pixels
     """
     try:
         with Image.open(file_path) as img:
-            if img.mode not in ("RGBA", "LA", "P"):
+            original_mode = img.mode
+
+            # Handle different image modes that may have transparency
+            if original_mode == "RGBA":
+                # Already has alpha channel
+                pass
+            elif original_mode == "LA":
+                # Grayscale with alpha
+                img = img.convert("RGBA")
+            elif original_mode == "P":
+                # Palette mode - check for transparency
+                if "transparency" in img.info:
+                    img = img.convert("RGBA")
+                else:
+                    return False
+            elif original_mode == "PA":
+                # Palette with alpha
+                img = img.convert("RGBA")
+            else:
+                # RGB, L, etc. - no alpha channel
                 return False
 
-            # Convert palette images with transparency
-            if img.mode == "P" and "transparency" in img.info:
-                img = img.convert("RGBA")
-            elif img.mode == "LA":
-                img = img.convert("RGBA")
-            elif img.mode != "RGBA":
+            # Get alpha channel
+            bands = img.split()
+            if len(bands) < 4:
                 return False
 
-            # Get alpha channel and count transparent pixels
-            alpha = img.split()[-1]
+            alpha = bands[3]  # Alpha is the 4th channel (index 3)
+            alpha_data = alpha.getdata()
             total_pixels = alpha.size[0] * alpha.size[1]
+
+            if total_pixels == 0:
+                return False
+
             # Count pixels where alpha < 128 (more than 50% transparent)
-            transparent_count = sum(1 for p in alpha.getdata() if p < 128)
+            transparent_count = sum(1 for p in alpha_data if p < 128)
             transparency_ratio = transparent_count / total_pixels
+
             return transparency_ratio > threshold
     except Exception as e:
         print(f"[WARN] Failed to check transparency for {file_path}: {e}")