feat: improve T2I num_inference_steps behavoir

This commit improves the implementation and defaults for the
num_inference_steps parameter.

runner/app/pipelines/text_to_image.py

@@ -5,14 +5,6 @@
 
 import PIL
 import torch
-from app.pipelines.base import Pipeline
-from app.pipelines.utils import (
-    SafetyChecker,
-    get_model_dir,
-    get_torch_device,
-    is_lightning_model,
-    is_turbo_model,
-)
 from diffusers import (
     AutoPipelineForText2Image,
     EulerDiscreteScheduler,
@@ -23,6 +15,15 @@
 from huggingface_hub import file_download, hf_hub_download
 from safetensors.torch import load_file
 
+from app.pipelines.base import Pipeline
+from app.pipelines.utils import (
+    SafetyChecker,
+    get_model_dir,
+    get_torch_device,
+    is_lightning_model,
+    is_turbo_model,
+)
+
 logger = logging.getLogger(__name__)
 
 
@@ -183,6 +184,7 @@ def __call__(
         self, prompt: str, **kwargs
     ) -> Tuple[List[PIL.Image], List[Optional[bool]]]:
         seed = kwargs.pop("seed", None)
+        num_inference_steps = kwargs.get("num_inference_steps", None)
         safety_check = kwargs.pop("safety_check", True)
 
         if seed is not None:
@@ -195,7 +197,7 @@ def __call__(
                     torch.Generator(get_torch_device()).manual_seed(s) for s in seed
                 ]
 
-        if "num_inference_steps" in kwargs and kwargs["num_inference_steps"] < 1:
+        if num_inference_steps is None or num_inference_steps < 1:
             del kwargs["num_inference_steps"]
 
         if (
@@ -217,8 +219,8 @@ def __call__(
             elif "8step" in self.model_id:
                 kwargs["num_inference_steps"] = 8
             else:
-                # Default to 2step
-                kwargs["num_inference_steps"] = 2
+                # Default to 8step
+                kwargs["num_inference_steps"] = 8
 
         output = self.ldm(prompt, **kwargs)
 

runner/app/routes/text_to_image.py

@@ -26,7 +26,7 @@ class TextToImageParams(BaseModel):
     negative_prompt: str = ""
     safety_check: bool = True
     seed: int = None
-    num_inference_steps: int = 50  # TODO: Make optional.
+    num_inference_steps: int = 50  # NOTE: Hardcoded due to varying pipeline values.
     num_images_per_prompt: int = 1