diff --git a/modules/globals.py b/modules/globals.py
index 3d88931..2fbec38 100644
--- a/modules/globals.py
+++ b/modules/globals.py
@@ -6,10 +6,13 @@ from typing import List, Dict, Any
 ROOT_DIR = os.path.dirname(os.path.abspath(__file__))
 WORKFLOW_DIR = os.path.join(ROOT_DIR, "workflow")
 
-file_types = [
-    ("Image", ("*.png", "*.jpg", "*.jpeg", "*.gif", "*.bmp")),
-    ("Video", ("*.mp4", "*.mkv")),
-]
+# Canonical media extensions, defined once so the file dialogs and
+# has_image_extension never drift. GIF is intentionally excluded: OpenCV's
+# cv2.imread/imwrite (the only image I/O this app uses) cannot decode or
+# encode GIF on 4.10 or 4.11, so offering it would silently fail. WEBP works
+# via the libwebp bundled with opencv-python.
+IMAGE_EXTENSIONS = (".png", ".jpg", ".jpeg", ".bmp", ".webp")
+VIDEO_EXTENSIONS = (".mp4", ".mkv")
 
 # Face Mapping Data
 source_target_map: List[Dict[str, Any]] = [] # Stores detailed map for image/video processing
diff --git a/modules/ui.py b/modules/ui.py
index 4c89e3e..223e968 100644
--- a/modules/ui.py
+++ b/modules/ui.py
@@ -237,6 +237,18 @@ _RECENT_SOURCE_DIR: Optional[str] = None
 _RECENT_TARGET_DIR: Optional[str] = None
 _RECENT_OUTPUT_DIR: Optional[str] = None
 
+# QFileDialog filter strings, built from the canonical extension sets in
+# globals so every dialog stays in sync (no hand-copied lists to drift).
+_IMAGE_FILE_FILTER = "Images (" + " ".join(
+    f"*{ext}" for ext in modules.globals.IMAGE_EXTENSIONS
+) + ")"
+_MEDIA_FILE_FILTER = "Media (" + " ".join(
+    f"*{ext}" for ext in (*modules.globals.IMAGE_EXTENSIONS, *modules.globals.VIDEO_EXTENSIONS)
+) + ")"
+_VIDEO_FILE_FILTER = "Videos (" + " ".join(
+    f"*{ext}" for ext in modules.globals.VIDEO_EXTENSIONS
+) + ")"
+
 
 # ─── image utilities ─────────────────────────────────────────────────────
 
@@ -734,7 +746,7 @@ class MainWindow(QMainWindow):
         path, _filter = QFileDialog.getOpenFileName(
             self, _("select an source image"),
             _RECENT_SOURCE_DIR or "",
-            "Images (*.png *.jpg *.jpeg *.gif *.bmp)",
+            _IMAGE_FILE_FILTER,
         )
         if path and is_image(path):
             modules.globals.source_path = path
@@ -755,7 +767,7 @@ class MainWindow(QMainWindow):
         path, _filter = QFileDialog.getOpenFileName(
             self, _("select an target image or video"),
             _RECENT_TARGET_DIR or "",
-            "Media (*.png *.jpg *.jpeg *.gif *.bmp *.mp4 *.mkv)",
+            _MEDIA_FILE_FILTER,
         )
         if not path:
             return
@@ -886,13 +898,13 @@ class MainWindow(QMainWindow):
             path, _f = QFileDialog.getSaveFileName(
                 self, _("save image output file"),
                 os.path.join(_RECENT_OUTPUT_DIR or "", "output.png"),
-                "Images (*.png *.jpg *.jpeg *.bmp)",
+                _IMAGE_FILE_FILTER,
             )
         elif is_video(modules.globals.target_path):
             path, _f = QFileDialog.getSaveFileName(
                 self, _("save video output file"),
                 os.path.join(_RECENT_OUTPUT_DIR or "", "output.mp4"),
-                "Videos (*.mp4 *.mkv)",
+                _VIDEO_FILE_FILTER,
             )
         else:
             return
@@ -1334,7 +1346,7 @@ class MapperDialog(QDialog):
         path, _f = QFileDialog.getOpenFileName(
             self, _("select an source image"),
             _RECENT_SOURCE_DIR or "",
-            "Images (*.png *.jpg *.jpeg *.gif *.bmp)",
+            _IMAGE_FILE_FILTER,
         )
         if not path:
             return
@@ -1439,7 +1451,7 @@ class LiveMapperDialog(QDialog):
         path, _f = QFileDialog.getOpenFileName(
             self, _("select an source image"),
             _RECENT_SOURCE_DIR or "",
-            "Images (*.png *.jpg *.jpeg *.gif *.bmp)",
+            _IMAGE_FILE_FILTER,
         )
         if not path:
             return
diff --git a/modules/utilities.py b/modules/utilities.py
index 953ef3c..799fd99 100644
--- a/modules/utilities.py
+++ b/modules/utilities.py
@@ -262,11 +262,16 @@ def clean_temp(target_path: str) -> None:
 
 
 def has_image_extension(image_path: str) -> bool:
-    return image_path.lower().endswith(("png", "jpg", "jpeg"))
+    # splitext so only the real extension counts (e.g. "photo.png.bak" is not
+    # an image); the set is centralized in globals to stay in sync with dialogs.
+    return os.path.splitext(image_path)[1].lower() in modules.globals.IMAGE_EXTENSIONS
 
 
 def is_image(image_path: str) -> bool:
     if image_path and os.path.isfile(image_path):
+        # Extension check first — Windows mimetypes doesn't always register webp
+        if has_image_extension(image_path):
+            return True
         mimetype, _ = mimetypes.guess_type(image_path)
         return bool(mimetype and mimetype.startswith("image/"))
     return False