diff --git a/cryoet_data_portal_neuroglancer/models/json_generator.py b/cryoet_data_portal_neuroglancer/models/json_generator.py
index 154cf71..96cb9a8 100644
--- a/cryoet_data_portal_neuroglancer/models/json_generator.py
+++ b/cryoet_data_portal_neuroglancer/models/json_generator.py
@@ -116,13 +116,16 @@ class ImageJSONGenerator(RenderingJSONGenerator):
     volume_rendering_is_visible: bool = False
     volume_rendering_gain: float = 0.0
     can_hide_high_values_in_neuroglancer: bool = False
+    blend: str = "additive"
+    opacity: float = 1.0
 
     def __post_init__(self):
         self._type = RenderingTypes.IMAGE
 
     def _compute_contrast_limits(self) -> tuple[float, float]:
         if self.mean is None or self.rms is None:
-            return self.contrast_limits
+            # return self.contrast_limits
+            return (0.0, 1.0)
         width = 3 * self.rms
         return (self.mean - width, self.mean + width)
 
@@ -140,7 +143,7 @@ def _create_shader_and_controls(self) -> dict[str, Any]:
         else:
             shader_builder = ImageShaderBuilder(
                 contrast_limits=self.contrast_limits,
-                can_hide_high_values_in_neuroglancer=self.can_hide_high_values_in_neuroglancer,
+                # can_hide_high_values_in_neuroglancer=self.can_hide_high_values_in_neuroglancer,
             )
         return shader_builder.build()
 
@@ -159,7 +162,8 @@ def generate_json(self) -> dict:
             "type": self.layer_type,
             "name": self.name,
             "source": create_source(f"zarr://{self.source}", self.scale, self.scale),
-            "opacity": 0.51,
+            "opacity": self.opacity,
+            "blend": self.blend,
             "tab": "rendering",
             "visible": self.is_visible,
             "volumeRendering": "on" if self.volume_rendering_is_visible else "off",
@@ -268,6 +272,8 @@ class ImageVolumeJSONGenerator(RenderingJSONGenerator):
 
     color: str
     rendering_depth: int
+    blend: str = "additive"
+    opacity: float = 1.0
 
     def __post_init__(self):
         self._type = RenderingTypes.IMAGE
@@ -291,7 +297,8 @@ def generate_json(self) -> dict:
             "name": f"{self.name}",
             "source": create_source(f"zarr://{self.source}", self.scale, self.scale),
             "tab": "rendering",
-            "blend": "additive",
+            "blend": self.blend,
+            "opacity": self.opacity,
             "volumeRendering": "on",
             "volumeRenderingDepthSamples": self.rendering_depth,
             "visible": self.is_visible,
diff --git a/cryoet_data_portal_neuroglancer/state_generator.py b/cryoet_data_portal_neuroglancer/state_generator.py
index e1f9e42..3ffbb5b 100644
--- a/cryoet_data_portal_neuroglancer/state_generator.py
+++ b/cryoet_data_portal_neuroglancer/state_generator.py
@@ -185,6 +185,8 @@ def generate_image_layer(
     volume_rendering_is_visible: bool = False,
     volume_rendering_gain: float = -7.8,
     can_hide_high_values_in_neuroglancer: bool | None = None,
+    blend: str = "additive",
+    opacity: float = 1.0,
 ) -> dict[str, Any]:
     """Generates JSON for an image layer with optional contrast limits.
 
@@ -211,6 +213,8 @@ def generate_image_layer(
         volume_rendering_is_visible=volume_rendering_is_visible,
         volume_rendering_gain=volume_rendering_gain,
         can_hide_high_values_in_neuroglancer=can_hide_high_values_in_neuroglancer,
+        blend=blend,
+        opacity=opacity,
     ).to_json()
 
 
@@ -222,6 +226,8 @@ def generate_image_volume_layer(
     scale: tuple[float, float, float] | list[float] | float = (1.0, 1.0, 1.0),
     is_visible: bool = True,
     rendering_depth: int = 1024,
+    blend: str = "additive",
+    opacity: float = 1.0,
 ) -> dict[str, Any]:
     source, name, url, _, scale = _setup_creation(source, name, url, scale=scale)
     _validate_color(color)
@@ -232,6 +238,8 @@ def generate_image_volume_layer(
         scale=scale,
         is_visible=is_visible,
         rendering_depth=rendering_depth,
+        blend=blend,
+        opacity=opacity,
     ).to_json()
 
 
diff --git a/tests/test_state_generators.py b/tests/test_state_generators.py
new file mode 100644
index 0000000..0d8e00e
--- /dev/null
+++ b/tests/test_state_generators.py
@@ -0,0 +1,9 @@
+from cryoet_data_portal_neuroglancer.state_generator import generate_image_layer
+
+
+def test__generate_image_layer_default_values():
+    state = generate_image_layer(source="mysource", scale=1.5, size={"a": 2.0})
+
+    assert "blend" in state
+    assert state["blend"] == "additive"
+    assert state["opacity"] == 1.0