[SD] Fix Stencil scribble crash by updating image resize (#1255)

-- This commit updates Stencil resize feature to cap the size of
   images within [128,768] as supported by the SD pipeline.
-- This solves the issue of scribble crashing on larger image.

Signed-off-by: Abhishek Varma <abhishek@nod-labs.com>
Co-authored-by: Abhishek Varma <abhishek@nod-labs.com>

apps/stable_diffusion/scripts/img2img.py

@@ -24,15 +24,15 @@ init_import_mlir = args.import_mlir
 
 # For stencil, the input image can be of any size but we need to ensure that
 # it conforms with our model contraints :-
-#   Both width and height should be > 384 and multiple of 8.
+#   Both width and height should be in the range of [128, 768] and multiple of 8.
 # This utility function performs the transformation on the input image while
 # also maintaining the aspect ratio before sending it to the stencil pipeline.
 def resize_stencil(image: Image.Image):
     width, height = image.size
     aspect_ratio = width / height
     min_size = min(width, height)
-    if min_size < 384:
-        n_size = 384
+    if min_size < 128:
+        n_size = 128
         if width == min_size:
             width = n_size
             height = n_size / aspect_ratio
@@ -45,6 +45,22 @@ def resize_stencil(image: Image.Image):
     n_height = height // 8
     n_width *= 8
     n_height *= 8
+
+    min_size = min(width, height)
+    if min_size > 768:
+        n_size = 768
+        if width == min_size:
+            height = n_size
+            width = n_size * aspect_ratio
+        else:
+            width = n_size
+            height = n_size / aspect_ratio
+    width = int(width)
+    height = int(height)
+    n_width = width // 8
+    n_height = height // 8
+    n_width *= 8
+    n_height *= 8
     new_image = image.resize((n_width, n_height))
     return new_image, n_width, n_height