diff --git a/scripts/demo/streamlit_helpers.py b/scripts/demo/streamlit_helpers.py
index a5f1b03..a0f3848 100644
--- a/scripts/demo/streamlit_helpers.py
+++ b/scripts/demo/streamlit_helpers.py
@@ -132,7 +132,9 @@ def show_samples(samples, outputs):
 
 def get_guider(params: SamplingParams, key=1) -> SamplingParams:
     params.guider = Guider(
-        st.sidebar.selectbox(f"Discretization #{key}", [member.value for member in Guider])
+        st.sidebar.selectbox(
+            f"Discretization #{key}", [member.value for member in Guider]
+        )
     )
 
     if params.guider == Guider.VANILLA:
@@ -161,10 +163,14 @@ def init_sampling(
 ) -> Tuple[SamplingParams, int, int]:
     num_rows, num_cols = 1, 1
     if specify_num_samples:
-        num_cols = st.number_input(f"num cols #{key}", value=2, min_value=1, max_value=10)
+        num_cols = st.number_input(
+            f"num cols #{key}", value=2, min_value=1, max_value=10
+        )
 
     params.steps = int(
-        st.sidebar.number_input(f"steps #{key}", value=params.steps, min_value=1, max_value=1000)
+        st.sidebar.number_input(
+            f"steps #{key}", value=params.steps, min_value=1, max_value=1000
+        )
     )
 
     params.sampler = Sampler(
@@ -212,11 +218,15 @@ def get_sampler(params: SamplingParams, key=1) -> SamplingParams:
         )
 
     elif params.sampler in (Sampler.EULER_ANCESTRAL, Sampler.DPMPP2S_ANCESTRAL):
-        params.s_noise = st.sidebar.number_input("s_noise", value=params.s_noise, min_value=0.0)
+        params.s_noise = st.sidebar.number_input(
+            "s_noise", value=params.s_noise, min_value=0.0
+        )
         params.eta = st.sidebar.number_input("eta", value=params.eta, min_value=0.0)
 
     elif params.sampler == Sampler.LINEAR_MULTISTEP:
-        params.order = int(st.sidebar.number_input("order", value=params.order, min_value=1))
+        params.order = int(
+            st.sidebar.number_input("order", value=params.order, min_value=1)
+        )
     return params
 
 
diff --git a/sgm/inference/api.py b/sgm/inference/api.py
index d863f5e..87592dc 100644
--- a/sgm/inference/api.py
+++ b/sgm/inference/api.py
@@ -61,9 +61,9 @@ class SamplingParams:
     Parameters for sampling.
     """
 
-    width: int
-    height: int
-    steps: int
+    width: Optional[int] = None
+    height: Optional[int] = None
+    steps: Optional[int] = None
     sampler: Sampler = Sampler.EULER_EDM
     discretization: Discretization = Discretization.LEGACY_DDPM
     guider: Guider = Guider.VANILLA
@@ -286,6 +286,15 @@ class SamplingPipeline:
     ):
         if params is None:
             params = self.specs.default_params
+        else:
+            # Set defaults if optional params are not specified
+            if params.width is None:
+                params.width = self.specs.default_params.width
+            if params.height is None:
+                params.height = self.specs.default_params.height
+            if params.steps is None:
+                params.steps = self.specs.default_params.steps
+
         sampler = get_sampler_config(params)
 
         sampler.discretization = wrap_discretization(