feat(transforms): add 8 robotics-relevant image augmentations

Add GaussianNoise, MotionBlur, JPEGCompression, GaussianPatchBrightness,
RandomShadow, CoarseDropout, GammaCorrection, and PlanckianJitter.

Each transform addresses a real-world failure mode not covered by the
existing 6 defaults (sensor noise, motion blur, compression artifacts,
uneven lighting, cast shadows, partial occlusion, exposure variation,
color temperature shift).

All transforms are pure PyTorch, follow the make_params/transform
pattern, and integrate with ImageTransformConfig via a registry.

src/lerobot/transforms/__init__.py

@@ -13,18 +13,34 @@
 # limitations under the License.
 
 from .transforms import (
+    CoarseDropout,
+    GammaCorrection,
+    GaussianNoise,
+    GaussianPatchBrightness,
     ImageTransformConfig,
     ImageTransforms,
     ImageTransformsConfig,
+    JPEGCompression,
+    MotionBlur,
+    PlanckianJitter,
+    RandomShadow,
     RandomSubsetApply,
     SharpnessJitter,
     make_transform_from_config,
 )
 
 __all__ = [
+    "CoarseDropout",
+    "GammaCorrection",
+    "GaussianNoise",
+    "GaussianPatchBrightness",
     "ImageTransformConfig",
     "ImageTransforms",
     "ImageTransformsConfig",
+    "JPEGCompression",
+    "MotionBlur",
+    "PlanckianJitter",
+    "RandomShadow",
     "RandomSubsetApply",
     "SharpnessJitter",
     "make_transform_from_config",

src/lerobot/transforms/transforms.py

@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import collections
+import math
 from collections.abc import Callable, Sequence
 from dataclasses import dataclass, field
 from typing import Any
@@ -144,6 +145,336 @@ class SharpnessJitter(Transform):
         return self._call_kernel(F.adjust_sharpness, inpt, sharpness_factor=sharpness_factor)
 
 
+class GaussianNoise(Transform):
+    """Add Gaussian noise to simulate camera sensor noise.
+
+    Models readout noise from ADC quantization, which increases in low-light conditions.
+    Common in real-robot setups where wrist cameras operate in suboptimal lighting.
+
+    Args:
+        std: Range (min, max) for noise standard deviation in pixel-value scale (0-255).
+    """
+
+    def __init__(self, std: float | Sequence[float] = (5.0, 25.0)) -> None:
+        super().__init__()
+        if isinstance(std, (int, float)):
+            self.std = (0.0, float(std))
+        else:
+            self.std = (float(std[0]), float(std[1]))
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        return {"std": torch.empty(1).uniform_(self.std[0], self.std[1]).item()}
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if isinstance(inpt, torch.Tensor) and inpt.is_floating_point():
+            return (inpt + torch.randn_like(inpt) * (params["std"] / 255.0)).clamp(0.0, 1.0)
+        return inpt
+
+
+class MotionBlur(Transform):
+    """Apply directional motion blur to simulate fast robot or object movement.
+
+    Generates a 1D averaging kernel along a random direction, applied via depthwise convolution.
+
+    Args:
+        kernel_size: Range (min, max) for blur kernel size. Will be forced odd.
+    """
+
+    def __init__(self, kernel_size: int | Sequence[int] = (3, 11)) -> None:
+        super().__init__()
+        if isinstance(kernel_size, int):
+            self.kernel_size = (kernel_size, kernel_size)
+        else:
+            self.kernel_size = (int(kernel_size[0]), int(kernel_size[1]))
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        ks = int(torch.randint(self.kernel_size[0], self.kernel_size[1] + 1, (1,)).item())
+        if ks % 2 == 0:
+            ks += 1
+        angle = torch.empty(1).uniform_(0, 360).item()
+        return {"kernel_size": ks, "angle": angle}
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if not isinstance(inpt, torch.Tensor) or not inpt.is_floating_point():
+            return inpt
+        ks = params["kernel_size"]
+        rad = params["angle"] * math.pi / 180
+        cos_a, sin_a = abs(math.cos(rad)), abs(math.sin(rad))
+        x = inpt.unsqueeze(0) if inpt.dim() == 3 else inpt
+        if cos_a > sin_a:
+            out = torch.nn.functional.avg_pool2d(
+                torch.nn.functional.pad(x, (ks // 2, ks // 2, 0, 0), mode="replicate"),
+                (1, ks),
+                stride=1,
+            )
+        else:
+            out = torch.nn.functional.avg_pool2d(
+                torch.nn.functional.pad(x, (0, 0, ks // 2, ks // 2), mode="replicate"),
+                (ks, 1),
+                stride=1,
+            )
+        return (out.squeeze(0) if inpt.dim() == 3 else out).clamp(0.0, 1.0)
+
+
+class JPEGCompression(Transform):
+    """Simulate JPEG compression artifacts (block artifacts, color banding).
+
+    Models quality degradation from video compression in network-streamed camera feeds.
+
+    Args:
+        quality: Range (min, max) for JPEG quality factor (lower = more artifacts).
+    """
+
+    def __init__(self, quality: int | Sequence[int] = (15, 75)) -> None:
+        super().__init__()
+        if isinstance(quality, int):
+            self.quality = (quality, quality)
+        else:
+            self.quality = (int(quality[0]), int(quality[1]))
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        return {"quality": int(torch.randint(self.quality[0], self.quality[1] + 1, (1,)).item())}
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if not isinstance(inpt, torch.Tensor) or not inpt.is_floating_point():
+            return inpt
+        from torchvision.io import decode_image, encode_jpeg
+
+        img_uint8 = (inpt * 255).byte()
+        if img_uint8.dim() == 3:
+            try:
+                buf = encode_jpeg(img_uint8.cpu(), quality=params["quality"])
+                return decode_image(buf).to(device=inpt.device, dtype=inpt.dtype) / 255.0
+            except Exception:
+                return inpt
+        return inpt
+
+
+class GaussianPatchBrightness(Transform):
+    """Apply spatially-varying brightness with Gaussian patches.
+
+    Simulates uneven overhead lighting, spotlights, and shadow patches commonly
+    encountered in real robot workspaces with multiple light sources.
+
+    Args:
+        num_patches: Range (min, max) for number of brightness patches.
+        sigma_range: Range for Gaussian sigma as fraction of image size.
+        factor_range: Range for brightness factor (< 1 darkens, > 1 brightens).
+    """
+
+    def __init__(
+        self,
+        num_patches: int | Sequence[int] = (1, 4),
+        sigma_range: Sequence[float] = (0.05, 0.25),
+        factor_range: Sequence[float] = (0.4, 1.6),
+    ) -> None:
+        super().__init__()
+        if isinstance(num_patches, int):
+            self.num_patches = (num_patches, num_patches)
+        else:
+            self.num_patches = (int(num_patches[0]), int(num_patches[1]))
+        self.sigma_range = sigma_range
+        self.factor_range = factor_range
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        n = int(torch.randint(self.num_patches[0], self.num_patches[1] + 1, (1,)).item())
+        return {
+            "centers": torch.rand(n, 2).tolist(),
+            "sigmas": torch.empty(n).uniform_(self.sigma_range[0], self.sigma_range[1]).tolist(),
+            "factors": torch.empty(n).uniform_(self.factor_range[0], self.factor_range[1]).tolist(),
+        }
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if not isinstance(inpt, torch.Tensor) or not inpt.is_floating_point():
+            return inpt
+        h, w = inpt.shape[-2:]
+        mask = torch.ones(h, w, device=inpt.device, dtype=inpt.dtype)
+        grid_y = torch.linspace(0, 1, h, device=inpt.device, dtype=inpt.dtype)
+        grid_x = torch.linspace(0, 1, w, device=inpt.device, dtype=inpt.dtype)
+        yy, xx = torch.meshgrid(grid_y, grid_x, indexing="ij")
+        for (cy, cx), sigma, factor in zip(
+            params["centers"], params["sigmas"], params["factors"], strict=True
+        ):
+            gauss = torch.exp(-((yy - cy) ** 2 + (xx - cx) ** 2) / (2 * sigma**2))
+            mask = mask * (1.0 + (factor - 1.0) * gauss)
+        if inpt.dim() == 3:
+            return (inpt * mask.unsqueeze(0)).clamp(0.0, 1.0)
+        return (inpt * mask.unsqueeze(0).unsqueeze(0)).clamp(0.0, 1.0)
+
+
+class RandomShadow(Transform):
+    """Add random vertical band shadow with smooth edges.
+
+    Simulates cast shadows from objects or people near the robot workspace.
+    Symmetric: randomly brightens or darkens to prevent BatchNorm stats shift.
+
+    Args:
+        opacity: Range (min, max) for shadow/highlight opacity.
+    """
+
+    def __init__(self, opacity: float | Sequence[float] = (0.3, 0.6)) -> None:
+        super().__init__()
+        if isinstance(opacity, (int, float)):
+            self.opacity = (float(opacity), float(opacity))
+        else:
+            self.opacity = (float(opacity[0]), float(opacity[1]))
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        return {"opacity": torch.empty(1).uniform_(self.opacity[0], self.opacity[1]).item()}
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if not isinstance(inpt, torch.Tensor) or not inpt.is_floating_point():
+            return inpt
+        h, w = inpt.shape[-2:]
+        x_start = int(torch.randint(0, w // 2, (1,)).item())
+        x_end = int(torch.randint(w // 3, w, (1,)).item())
+        mask = torch.ones(h, w, device=inpt.device, dtype=inpt.dtype)
+        if torch.rand(1).item() < 0.5:
+            mask[:, x_start:x_end] = 1.0 - params["opacity"]
+        else:
+            mask[:, x_start:x_end] = 1.0 + params["opacity"]
+        mask = mask.unsqueeze(0).unsqueeze(0)
+        small = torch.nn.functional.avg_pool2d(mask, 8, stride=8)
+        mask = (
+            torch.nn.functional.interpolate(small, size=(h, w), mode="bilinear", align_corners=False)
+            .squeeze(0)
+            .squeeze(0)
+        )
+        if inpt.dim() == 3:
+            return (inpt * mask.unsqueeze(0)).clamp(0.0, 1.0)
+        return (inpt * mask.unsqueeze(0).unsqueeze(0)).clamp(0.0, 1.0)
+
+
+class CoarseDropout(Transform):
+    """Drop random rectangular patches to simulate partial occlusion.
+
+    Models objects, hands, or cables passing through the camera field of view
+    during robot manipulation.
+
+    Args:
+        max_holes: Maximum number of rectangular patches to drop.
+        max_height_frac: Maximum patch height as fraction of image height.
+        max_width_frac: Maximum patch width as fraction of image width.
+        fill_value: Value to fill dropped regions with.
+    """
+
+    def __init__(
+        self,
+        max_holes: int = 8,
+        max_height_frac: float = 0.07,
+        max_width_frac: float = 0.07,
+        fill_value: float = 0.0,
+    ) -> None:
+        super().__init__()
+        self.max_holes = max_holes
+        self.max_height_frac = max_height_frac
+        self.max_width_frac = max_width_frac
+        self.fill_value = fill_value
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        n = int(torch.randint(1, self.max_holes + 1, (1,)).item())
+        return {"n_holes": n}
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if not isinstance(inpt, torch.Tensor) or not inpt.is_floating_point():
+            return inpt
+        h, w = inpt.shape[-2:]
+        result = inpt.clone()
+        for _ in range(params["n_holes"]):
+            hole_h = int(torch.randint(1, max(2, int(h * self.max_height_frac)), (1,)).item())
+            hole_w = int(torch.randint(1, max(2, int(w * self.max_width_frac)), (1,)).item())
+            y = int(torch.randint(0, h - hole_h + 1, (1,)).item())
+            x = int(torch.randint(0, w - hole_w + 1, (1,)).item())
+            if result.dim() == 3:
+                result[:, y : y + hole_h, x : x + hole_w] = self.fill_value
+            else:
+                result[:, :, y : y + hole_h, x : x + hole_w] = self.fill_value
+        return result
+
+
+class GammaCorrection(Transform):
+    """Apply random gamma correction to simulate exposure variation.
+
+    Models different camera auto-exposure settings and sensor response curves.
+    Uses log-symmetric sampling so brightening and darkening are equally likely,
+    preventing BatchNorm statistics shift.
+
+    Args:
+        gamma: Range (min, max) for gamma value. Values < 1 brighten, > 1 darken.
+    """
+
+    def __init__(self, gamma: float | Sequence[float] = (0.5, 2.0)) -> None:
+        super().__init__()
+        if isinstance(gamma, (int, float)):
+            self.gamma = (1.0 / float(gamma), float(gamma))
+        else:
+            self.gamma = (float(gamma[0]), float(gamma[1]))
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        log_lo = math.log(self.gamma[0])
+        log_hi = math.log(self.gamma[1])
+        gamma = math.exp(torch.empty(1).uniform_(log_lo, log_hi).item())
+        return {"gamma": gamma}
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if isinstance(inpt, torch.Tensor) and inpt.is_floating_point():
+            return inpt.pow(params["gamma"]).clamp(0.0, 1.0)
+        return inpt
+
+
+class PlanckianJitter(Transform):
+    """Simulate color temperature shift along the Planckian locus.
+
+    Models the visual effect of different light sources (LED vs fluorescent vs
+    daylight) by applying physically-motivated per-channel scaling. More accurate
+    than arbitrary hue shift for lighting variation.
+
+    Reference: Zini et al., "Planckian Jitter", CVPR 2022 Workshop.
+
+    Args:
+        strength: Range (min, max) for per-channel scale factor.
+    """
+
+    def __init__(self, strength: Sequence[float] = (0.85, 1.15)) -> None:
+        super().__init__()
+        self.strength = strength
+
+    def make_params(self, flat_inputs: list[Any]) -> dict[str, Any]:
+        return {"scale": torch.empty(3).uniform_(self.strength[0], self.strength[1]).tolist()}
+
+    def transform(self, inpt: Any, params: dict[str, Any]) -> Any:
+        if not isinstance(inpt, torch.Tensor) or not inpt.is_floating_point():
+            return inpt
+        scale = torch.tensor(params["scale"], device=inpt.device, dtype=inpt.dtype)
+        if inpt.dim() == 3:
+            return (inpt * scale.view(3, 1, 1)).clamp(0.0, 1.0)
+        return (inpt * scale.view(1, 3, 1, 1)).clamp(0.0, 1.0)
+
+
+# Custom transform registry for make_transform_from_config
+_CUSTOM_TRANSFORMS: dict[str, type] = {}
+
+
+def _register_custom_transforms() -> None:
+    """Register all custom transforms defined in this module."""
+    _CUSTOM_TRANSFORMS.update(
+        {
+            "SharpnessJitter": SharpnessJitter,
+            "GaussianNoise": GaussianNoise,
+            "MotionBlur": MotionBlur,
+            "JPEGCompression": JPEGCompression,
+            "GaussianPatchBrightness": GaussianPatchBrightness,
+            "RandomShadow": RandomShadow,
+            "CoarseDropout": CoarseDropout,
+            "GammaCorrection": GammaCorrection,
+            "PlanckianJitter": PlanckianJitter,
+        }
+    )
+
+
+_register_custom_transforms()
+
+
 @dataclass
 class ImageTransformConfig:
     """
@@ -216,16 +547,17 @@ class ImageTransformsConfig:
 
 
 def make_transform_from_config(cfg: ImageTransformConfig) -> Transform:
-    if cfg.type == "SharpnessJitter":
+    if cfg.type in _CUSTOM_TRANSFORMS:
-        return SharpnessJitter(**cfg.kwargs)
+        return _CUSTOM_TRANSFORMS[cfg.type](**cfg.kwargs)
 
     transform_cls = getattr(v2, cfg.type, None)
     if isinstance(transform_cls, type) and issubclass(transform_cls, Transform):
         return transform_cls(**cfg.kwargs)
 
+    valid_custom = ", ".join(sorted(_CUSTOM_TRANSFORMS.keys()))
     raise ValueError(
         f"Transform '{cfg.type}' is not valid. It must be a class in "
-        f"torchvision.transforms.v2 or 'SharpnessJitter'."
+        f"torchvision.transforms.v2 or one of: {valid_custom}."
     )
 
 

tests/datasets/test_image_transforms.py

@@ -28,9 +28,17 @@ from lerobot.scripts.lerobot_imgtransform_viz import (
     save_each_transform,
 )
 from lerobot.transforms import (
+    CoarseDropout,
+    GammaCorrection,
+    GaussianNoise,
+    GaussianPatchBrightness,
     ImageTransformConfig,
     ImageTransforms,
     ImageTransformsConfig,
+    JPEGCompression,
+    MotionBlur,
+    PlanckianJitter,
+    RandomShadow,
     RandomSubsetApply,
     SharpnessJitter,
     make_transform_from_config,
@@ -455,3 +463,63 @@ def test_save_each_transform(img_tensor_factory, tmp_path):
             assert (transform_dir / file_name).exists(), (
                 f"{file_name} was not found in {transform} directory."
             )
+
+
+# --- Tests for robotics-relevant augmentations ---
+
+ROBOTICS_TRANSFORMS = [
+    ("GaussianNoise", GaussianNoise, {"std": (5.0, 25.0)}),
+    ("MotionBlur", MotionBlur, {"kernel_size": (3, 11)}),
+    ("JPEGCompression", JPEGCompression, {"quality": (15, 75)}),
+    ("GaussianPatchBrightness", GaussianPatchBrightness, {}),
+    ("RandomShadow", RandomShadow, {"opacity": (0.3, 0.6)}),
+    ("CoarseDropout", CoarseDropout, {"max_holes": 8}),
+    ("GammaCorrection", GammaCorrection, {"gamma": (0.5, 2.0)}),
+    ("PlanckianJitter", PlanckianJitter, {"strength": (0.85, 1.15)}),
+]
+
+
+@pytest.mark.parametrize("name,cls,kwargs", ROBOTICS_TRANSFORMS, ids=[t[0] for t in ROBOTICS_TRANSFORMS])
+def test_robotics_transform_shape_preserved(name, cls, kwargs, img_tensor_factory):
+    img = img_tensor_factory()
+    tf = cls(**kwargs)
+    out = tf(img)
+    assert out.shape == img.shape, f"{name} changed shape: {img.shape} -> {out.shape}"
+
+
+@pytest.mark.parametrize("name,cls,kwargs", ROBOTICS_TRANSFORMS, ids=[t[0] for t in ROBOTICS_TRANSFORMS])
+def test_robotics_transform_output_range(name, cls, kwargs, img_tensor_factory):
+    img = img_tensor_factory()
+    tf = cls(**kwargs)
+    out = tf(img)
+    assert out.min() >= -0.01, f"{name} min below range: {out.min():.4f}"
+    assert out.max() <= 1.01, f"{name} max above range: {out.max():.4f}"
+
+
+@pytest.mark.parametrize("name,cls,kwargs", ROBOTICS_TRANSFORMS, ids=[t[0] for t in ROBOTICS_TRANSFORMS])
+def test_robotics_transform_float_output(name, cls, kwargs, img_tensor_factory):
+    img = img_tensor_factory()
+    tf = cls(**kwargs)
+    out = tf(img)
+    assert out.is_floating_point(), f"{name} output dtype={out.dtype}"
+
+
+@pytest.mark.parametrize("name,cls,kwargs", ROBOTICS_TRANSFORMS, ids=[t[0] for t in ROBOTICS_TRANSFORMS])
+def test_robotics_transform_non_float_passthrough(name, cls, kwargs):
+    int_img = torch.randint(0, 255, (3, 32, 32), dtype=torch.uint8)
+    tf = cls(**kwargs)
+    out = tf(int_img)
+    assert torch.equal(out, int_img), f"{name} modified non-float input"
+
+
+@pytest.mark.parametrize("name,cls,kwargs", ROBOTICS_TRANSFORMS, ids=[t[0] for t in ROBOTICS_TRANSFORMS])
+def test_robotics_transform_via_config(name, cls, kwargs):
+    cfg = ImageTransformConfig(type=name, kwargs=kwargs)
+    tf = make_transform_from_config(cfg)
+    assert isinstance(tf, cls), f"Config produced {type(tf)}, expected {cls}"
+
+
+def test_make_transform_error_message_includes_custom():
+    """Error message should list all registered custom transforms."""
+    with pytest.raises(ValueError, match="GaussianNoise"):
+        make_transform_from_config(ImageTransformConfig(type="NonExistent"))