Small image showing fix

src/gui/widgets/annotation_canvas_widget.py

@@ -246,10 +246,10 @@ class AnnotationCanvasWidget(QWidget):
             return
 
         try:
-            # Get RGB image data
-            if self.current_image.channels == 3:
+            # Get image data in a format compatible with Qt
+            if self.current_image.channels in (3, 4):
                 image_data = self.current_image.get_rgb()
-                height, width, channels = image_data.shape
+                height, width = image_data.shape[:2]
             else:
                 image_data = self.current_image.get_grayscale()
                 height, width = image_data.shape