1 files changed, 36 insertions, 35 deletions

diff --git a/pipelines/stable_diffusion/vlpn_stable_diffusion.py b/pipelines/stable_diffusion/vlpn_stable_diffusion.py
index a8ecedf..b4c85e9 100644
--- a/pipelines/stable_diffusion/vlpn_stable_diffusion.py
+++ b/pipelines/stable_diffusion/vlpn_stable_diffusion.py
@@ -178,35 +178,6 @@ class VlpnStableDiffusion(DiffusionPipeline):
         # set timesteps
         self.scheduler.set_timesteps(num_inference_steps)
 
-        offset = self.scheduler.config.get("steps_offset", 0)
-
-        if latents is not None and isinstance(latents, PIL.Image.Image):
-            latents = preprocess(latents, width, height)
-            latent_dist = self.vae.encode(latents.to(self.device)).latent_dist
-            latents = latent_dist.sample(generator=generator)
-            latents = 0.18215 * latents
-
-            # expand init_latents for batch_size
-            latents = torch.cat([latents] * batch_size)
-
-            # get the original timestep using init_timestep
-            init_timestep = int(num_inference_steps * strength) + offset
-            init_timestep = min(init_timestep, num_inference_steps)
-
-            if isinstance(self.scheduler, LMSDiscreteScheduler):
-                timesteps = torch.tensor(
-                    [num_inference_steps - init_timestep] * batch_size, dtype=torch.long, device=self.device
-                )
-            else:
-                timesteps = self.scheduler.timesteps[-init_timestep]
-                timesteps = torch.tensor([timesteps] * batch_size, dtype=torch.long, device=self.device)
-
-            # add noise to latents using the timesteps
-            noise = torch.randn(latents.shape, generator=generator, device=self.device)
-            latents = self.scheduler.add_noise(latents, noise, timesteps)
-        else:
-            init_timestep = num_inference_steps + offset
-
         # get prompt text embeddings
         text_inputs = self.tokenizer(
             prompt,
@@ -243,6 +214,10 @@ class VlpnStableDiffusion(DiffusionPipeline):
             # to avoid doing two forward passes
             text_embeddings = torch.cat([uncond_embeddings, text_embeddings])
 
+        offset = self.scheduler.config.get("steps_offset", 0)
+        init_timestep = num_inference_steps + offset
+        ensure_sigma = not isinstance(latents, PIL.Image.Image)
+
         # get the initial random noise unless the user supplied it
 
         # Unlike in other pipelines, latents need to be generated in the target device
@@ -257,23 +232,48 @@ class VlpnStableDiffusion(DiffusionPipeline):
                 device=latents_device,
                 dtype=text_embeddings.dtype,
             )
+        elif isinstance(latents, PIL.Image.Image):
+            latents = preprocess(latents, width, height)
+            latent_dist = self.vae.encode(latents.to(self.device)).latent_dist
+            latents = latent_dist.sample(generator=generator)
+            latents = 0.18215 * latents
+
+            # expand init_latents for batch_size
+            latents = torch.cat([latents] * batch_size)
+
+            # get the original timestep using init_timestep
+            init_timestep = int(num_inference_steps * strength) + offset
+            init_timestep = min(init_timestep, num_inference_steps)
+
+            if isinstance(self.scheduler, LMSDiscreteScheduler):
+                timesteps = torch.tensor(
+                    [num_inference_steps - init_timestep] * batch_size, dtype=torch.long, device=self.device
+                )
+            else:
+                timesteps = self.scheduler.timesteps[-init_timestep]
+                timesteps = torch.tensor([timesteps] * batch_size, dtype=torch.long, device=self.device)
+
+            # add noise to latents using the timesteps
+            noise = torch.randn(latents.shape, generator=generator, device=self.device)
+            latents = self.scheduler.add_noise(latents, noise, timesteps)
         else:
             if latents.shape != latents_shape:
                 raise ValueError(f"Unexpected latents shape, got {latents.shape}, expected {latents_shape}")
             latents = latents.to(self.device)
 
+        # if we use LMSDiscreteScheduler, let's make sure latents are multiplied by sigmas
+        if ensure_sigma:
+            if isinstance(self.scheduler, LMSDiscreteScheduler):
+                latents = latents * self.scheduler.sigmas[0]
+            elif isinstance(self.scheduler, EulerAScheduler):
+                latents = latents * self.scheduler.sigmas[0]
+
         t_start = max(num_inference_steps - init_timestep + offset, 0)
 
         # Some schedulers like PNDM have timesteps as arrays
         # It's more optimzed to move all timesteps to correct device beforehand
         timesteps_tensor = torch.tensor(self.scheduler.timesteps[t_start:], device=self.device)
 
-        # if we use LMSDiscreteScheduler, let's make sure latents are multiplied by sigmas
-        if isinstance(self.scheduler, LMSDiscreteScheduler):
-            latents = latents * self.scheduler.sigmas[0]
-        elif isinstance(self.scheduler, EulerAScheduler):
-            latents = latents * self.scheduler.sigmas[0]
-
         # prepare extra kwargs for the scheduler step, since not all schedulers have the same signature
         # eta (η) is only used with the DDIMScheduler, it will be ignored for other schedulers.
         # eta corresponds to η in DDIM paper: https://arxiv.org/abs/2010.02502
@@ -292,6 +292,7 @@ class VlpnStableDiffusion(DiffusionPipeline):
 
             # expand the latents if we are doing classifier free guidance
             latent_model_input = torch.cat([latents] * 2) if do_classifier_free_guidance else latents
+
             if isinstance(self.scheduler, LMSDiscreteScheduler):
                 sigma = self.scheduler.sigmas[t_index]
                 # the model input needs to be scaled to match the continuous ODE formulation in K-LMS