better defaults

examples/train_ddpm.py

@@ -12,7 +12,7 @@ from torchvision.transforms import (
     Compose,
     InterpolationMode,
     Lambda,
-    RandomCrop,
+    CenterCrop,
     RandomHorizontalFlip,
     Resize,
     ToTensor,
@@ -39,7 +39,7 @@ def main(args):
     augmentations = Compose(
         [
             Resize(args.resolution, interpolation=InterpolationMode.BILINEAR),
-            RandomCrop(args.resolution),
+            CenterCrop(args.resolution),
             RandomHorizontalFlip(),
             ToTensor(),
             Lambda(lambda x: x * 2 - 1),
@@ -136,7 +136,7 @@ if __name__ == "__main__":
     parser.add_argument("--output_path", type=str, default="ddpm-model")
     parser.add_argument("--batch_size", type=int, default=16)
     parser.add_argument("--num_epochs", type=int, default=100)
-    parser.add_argument("--gradient_accumulation_steps", type=int, default=2)
+    parser.add_argument("--gradient_accumulation_steps", type=int, default=1)
     parser.add_argument("--lr", type=float, default=1e-4)
     parser.add_argument("--warmup_steps", type=int, default=500)
     parser.add_argument(