Removed offset noise from training, added init offset to pipeline

1 files changed, 39 insertions, 56 deletions

diff --git a/pipelines/stable_diffusion/vlpn_stable_diffusion.py b/pipelines/stable_diffusion/vlpn_stable_diffusion.py
index cb09fe1..c4f7401 100644
--- a/pipelines/stable_diffusion/vlpn_stable_diffusion.py
+++ b/pipelines/stable_diffusion/vlpn_stable_diffusion.py
@@ -293,53 +293,39 @@ class VlpnStableDiffusion(DiffusionPipeline):
 
         return prompt_embeds
 
-    def get_timesteps(self, latents_are_image, num_inference_steps, strength, device):
-        if latents_are_image:
-            # get the original timestep using init_timestep
-            offset = self.scheduler.config.get("steps_offset", 0)
-            init_timestep = int(num_inference_steps * strength) + offset
-            init_timestep = min(init_timestep, num_inference_steps)
-
-            t_start = max(num_inference_steps - init_timestep + offset, 0)
-            timesteps = self.scheduler.timesteps[t_start:]
-        else:
-            timesteps = self.scheduler.timesteps
+    def get_timesteps(self, num_inference_steps, strength, device):
+        # get the original timestep using init_timestep
+        offset = self.scheduler.config.get("steps_offset", 0)
+        init_timestep = int(num_inference_steps * strength) + offset
+        init_timestep = min(init_timestep, num_inference_steps)
+
+        t_start = max(num_inference_steps - init_timestep + offset, 0)
+        timesteps = self.scheduler.timesteps[t_start:]
 
         timesteps = timesteps.to(device)
 
         return timesteps
 
-    def prepare_latents(self, batch_size, num_channels_latents, height, width, dtype, device, generator, latents=None):
-        shape = (batch_size, num_channels_latents, height // self.vae_scale_factor, width // self.vae_scale_factor)
-
-        if isinstance(generator, list) and len(generator) != batch_size:
-            raise ValueError(
-                f"You have passed a list of generators of length {len(generator)}, but requested an effective batch"
-                f" size of {batch_size}. Make sure the batch size matches the length of the generators."
-            )
+    def prepare_image(self, batch_size, width, height, dtype, device, generator=None):
+        return torch.randn(
+            (batch_size, 1, 1, 1),
+            dtype=dtype,
+            device=device,
+            generator=generator
+        ).expand(batch_size, 3, width, height)
 
-        if latents is None:
-            latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
-        else:
-            latents = latents.to(device=device, dtype=dtype)
-
-        # scale the initial noise by the standard deviation required by the scheduler
-        latents = latents * self.scheduler.init_noise_sigma
-
-        return latents
-
-    def prepare_latents_from_image(self, init_image, timestep, batch_size, dtype, device, generator=None):
+    def prepare_latents(self, init_image, timestep, batch_size, dtype, device, generator=None):
         init_image = init_image.to(device=device, dtype=dtype)
-        init_latent_dist = self.vae.encode(init_image).latent_dist
-        init_latents = init_latent_dist.sample(generator=generator)
-        init_latents = 0.18215 * init_latents
+        init_latents = self.vae.encode(init_image).latent_dist.sample(generator=generator)
+        init_latents = self.vae.config.scaling_factor * init_latents
 
-        if batch_size > init_latents.shape[0]:
+        if batch_size % init_latents.shape[0] != 0:
             raise ValueError(
                 f"Cannot duplicate `init_image` of batch size {init_latents.shape[0]} to {batch_size} text prompts."
             )
         else:
-            init_latents = torch.cat([init_latents] * batch_size, dim=0)
+            batch_multiplier = batch_size // init_latents.shape[0]
+            init_latents = torch.cat([init_latents] * batch_multiplier, dim=0)
 
         # add noise to latents using the timesteps
         noise = torch.randn(init_latents.shape, generator=generator, device=device, dtype=dtype)
@@ -368,7 +354,7 @@ class VlpnStableDiffusion(DiffusionPipeline):
         return extra_step_kwargs
 
     def decode_latents(self, latents):
-        latents = 1 / 0.18215 * latents
+        latents = 1 / self.vae.config.scaling_factor * latents
         image = self.vae.decode(latents).sample
         image = (image / 2 + 0.5).clamp(0, 1)
         # we always cast to float32 as this does not cause significant overhead and is compatible with bfloa16
@@ -381,7 +367,7 @@ class VlpnStableDiffusion(DiffusionPipeline):
         prompt: Union[str, List[str], List[int], List[List[int]]],
         negative_prompt: Optional[Union[str, List[str], List[int], List[List[int]]]] = None,
         num_images_per_prompt: int = 1,
-        strength: float = 0.8,
+        strength: float = 1.0,
         height: Optional[int] = None,
         width: Optional[int] = None,
         num_inference_steps: int = 50,
@@ -461,7 +447,6 @@ class VlpnStableDiffusion(DiffusionPipeline):
         device = self.execution_device
         do_classifier_free_guidance = guidance_scale > 1.0
         do_self_attention_guidance = sag_scale > 0.0
-        latents_are_image = isinstance(image, PIL.Image.Image)
 
         # 3. Encode input prompt
         prompt_embeds = self.encode_prompt(
@@ -474,33 +459,31 @@ class VlpnStableDiffusion(DiffusionPipeline):
 
         # 4. Prepare timesteps
         self.scheduler.set_timesteps(num_inference_steps, device=device)
-        timesteps = self.get_timesteps(latents_are_image, num_inference_steps, strength, device)
+        timesteps = self.get_timesteps(num_inference_steps, strength, device)
 
         # 5. Prepare latent variables
-        num_channels_latents = self.unet.in_channels
-        if latents_are_image:
+        if isinstance(image, PIL.Image.Image):
             image = preprocess(image)
-            latent_timestep = timesteps[:1].repeat(batch_size * num_images_per_prompt)
-            latents = self.prepare_latents_from_image(
-                image,
-                latent_timestep,
+        elif image is None:
+            image = self.prepare_image(
                 batch_size * num_images_per_prompt,
-                prompt_embeds.dtype,
-                device,
-                generator
-            )
-        else:
-            latents = self.prepare_latents(
-                batch_size * num_images_per_prompt,
-                num_channels_latents,
-                height,
                 width,
+                height,
                 prompt_embeds.dtype,
                 device,
-                generator,
-                image,
+                generator
             )
 
+        latent_timestep = timesteps[:1].repeat(batch_size * num_images_per_prompt)
+        latents = self.prepare_latents(
+            image,
+            latent_timestep,
+            batch_size * num_images_per_prompt,
+            prompt_embeds.dtype,
+            device,
+            generator
+        )
+
         # 6. Prepare extra step kwargs. TODO: Logic should ideally just be moved out of the pipeline
         extra_step_kwargs = self.prepare_extra_step_kwargs(generator, eta)