Avoid direct changes on the input image in viz

Author: lolipopshock

setup.py

@@ -26,7 +26,7 @@
         "pyyaml>=5.1",
         "torch",
         "torchvision",
-        "pycocotools",
+        "pycocotools==2.0.1",
         "fvcore",
       ],
       extras_require={

src/layoutparser/visualization.py

@@ -104,6 +104,7 @@ def wrap(canvas, layout, *args, **kwargs):
         if isinstance(canvas, Image.Image):
             if canvas.mode != 'RGB':
                 canvas = canvas.convert('RGB')
+            canvas = canvas.copy()
         elif isinstance(canvas, np.ndarray):
             canvas = Image.fromarray(canvas)
         out = func(canvas, layout, *args, **kwargs)