do not noise for the last step in ddim

lucidrains · Jul 10, 2022 · a598820 · a598820
1 parent 4878762
commit a598820
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Showing 2 changed files with 5 additions and 4 deletions.
diff --git a/dalle2_pytorch/dalle2_pytorch.py b/dalle2_pytorch/dalle2_pytorch.py
@@ -1059,10 +1059,10 @@ def p_sample_loop_ddim(self, shape, text_cond, *, timesteps, eta = 1., cond_scal
 
             c1 = eta * ((1 - alpha / alpha_next) * (1 - alpha_next) / (1 - alpha)).sqrt()
             c2 = ((1 - alpha_next) - torch.square(c1)).sqrt()
-            new_noise = torch.randn_like(image_embed)
+            noise = torch.randn_like(image_embed) if time_next > 0 else 0.
 
             img = x_start * alpha_next.sqrt() + \
-                  c1 * new_noise + \
+                  c1 * noise + \
                   c2 * pred_noise
 
         return image_embed
@@ -2275,9 +2275,10 @@ def p_sample_loop_ddim(self, unet, shape, image_embed, noise_scheduler, timestep
 
             c1 = eta * ((1 - alpha / alpha_next) * (1 - alpha_next) / (1 - alpha)).sqrt()
             c2 = ((1 - alpha_next) - torch.square(c1)).sqrt()
+            noise = torch.randn_like(img) if time_next > 0 else 0.
 
             img = x_start * alpha_next.sqrt() + \
-                  c1 * torch.randn_like(img) + \
+                  c1 * noise + \
                   c2 * pred_noise
 
         img = self.unnormalize_img(img)

diff --git a/dalle2_pytorch/version.py b/dalle2_pytorch/version.py
@@ -1 +1 @@
-__version__ = '0.19.3'
+__version__ = '0.19.4'