remaining med value features

GWYDDION_FEATURE_GAP.md

@@ -27,18 +27,18 @@ Reference for future implementation. Grouped by value to typical SPM workflows.
 
 | # | Feature | Gwyddion Source | Description |
 |---|---------|---------------|-------------|
-| 15 | Correlation / Pattern Matching | crosscor.c, maskcor.c | Find repeated features or align images via cross-correlation. |
+| ~~15~~ | ~~Correlation / Pattern Matching~~ | ~~crosscor.c, maskcor.c~~ | ~~Find repeated features or align images via cross-correlation.~~ **DONE** |
 | ~~16~~ | ~~Slope Distribution~~ | ~~slope_dist.c~~ | ~~Angular histogram of surface slopes. Characterizes surface texture directionality.~~ **DONE** |
 | ~~17~~ | ~~Grain Filtering~~ | ~~grain_filter.c~~ | ~~Remove grains by size, height, or border contact. Refine grain masks post-detection.~~ **DONE** |
 | ~~18~~ | ~~Field Arithmetic~~ | ~~arithmetic.c~~ | ~~Add/subtract/multiply/divide two DATA_FIELDs. Useful for difference maps, normalization.~~ **DONE** |
-| 19 | Spot Removal | spotremove.c | Interpolate over selected point defects (dust, spikes). |
+| ~~19~~ | ~~Spot Removal~~ | ~~spotremove.c~~ | ~~Interpolate over selected point defects (dust, spikes).~~ **DONE** |
 | ~~20~~ | ~~Tip Modeling / Deconvolution~~ | ~~tip_blind.c, tip_model.c~~ | ~~Estimate tip shape from image, deconvolve to recover true surface.~~ **DONE** |
 | ~~21~~ | ~~Radial Profile~~ | ~~rprofile tool~~ | ~~Azimuthally averaged profile from a center point. Good for circular features.~~ **DONE** |
-| 22 | Wavelet Transform | dwt.c, cwt.c | Discrete/continuous wavelet analysis. Multi-scale roughness decomposition. |
+| ~~22~~ | ~~Wavelet Transform~~ | ~~dwt.c, cwt.c~~ | ~~Discrete/continuous wavelet analysis. Multi-scale roughness decomposition.~~ **DONE** |
 | ~~23~~ | ~~Scale / Resample~~ | ~~scale.c, resample.c~~ | ~~Resize fields with interpolation.~~ **DONE** |
 | ~~24~~ | ~~Gradient~~ | ~~gradient.c~~ | ~~Compute x/y gradient magnitude maps.~~ **DONE** |
-| 25 | Custom Convolution | convolution_filter.c | User-defined kernel convolution. |
+| ~~25~~ | ~~Custom Convolution~~ | ~~convolution_filter.c~~ | ~~User-defined kernel convolution.~~ **DONE** |
-| 26 | Local Contrast Enhancement | local_contrast.c | Enhance visibility of local features in images. |
+| ~~26~~ | ~~Local Contrast Enhancement~~ | ~~local_contrast.c~~ | ~~Enhance visibility of local features in images.~~ **DONE** |
 
 ## Lower Priority
 
@@ -53,11 +53,11 @@ Reference for future implementation. Grouped by value to typical SPM workflows.
 | 33 | Facet Analysis | facet_analysis.c | Orientation distribution of surface facets (stereographic projection). |
 | 34 | Shape Fitting | fit-shape.c | Fit geometric primitives: sphere, paraboloid, cylinder, etc. |
 | 35 | Synthetic Surface Generation | *_synth.c (~20 modules) | Generate test surfaces: FBM, noise, lattice, waves, particles, fibers, etc. |
-| 36 | Entropy | entropy.c | Information entropy of height distribution. |
+| ~~36~~ | ~~Entropy~~ | ~~entropy.c~~ | ~~Information entropy of height distribution.~~ **DONE** |
 | 37 | Indentation Analysis | indent_analyze.c, hertz.c | Nanoindentation curve fitting (Hertz model). |
 | 38 | Deconvolution | deconvolve.c | Blind/regularized deconvolution for image restoration. |
 | 39 | Canny / Harris Detection | filters.c | Corner and edge feature detection beyond basic Sobel/Prewitt. |
-| 40 | Kuwahara Filter | filters.c | Edge-preserving smoothing filter. |
+| ~~40~~ | ~~Kuwahara Filter~~ | ~~filters.c~~ | ~~Edge-preserving smoothing filter.~~ **DONE** |
 
 ---
 

backend/nodes/__init__.py

@@ -69,4 +69,13 @@ from backend.nodes import (
     tip_model,
     tip_deconvolution,
     tip_blind_estimate,
+    # New: remaining Gwyddion feature-gap nodes
+    filter_kuwahara,
+    entropy,
+    local_contrast,
+    filter_custom,
+    spot_removal,
+    wavelet_denoise,
+    cross_correlate,
+    template_match,
 )

backend/nodes/cross_correlate.py

@@ -0,0 +1,68 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.data_types import DataField
+from backend.node_registry import register_node
+
+
+@register_node(display_name="Cross-Correlate")
+class CrossCorrelate:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field_a": ("DATA_FIELD",),
+                "field_b": ("DATA_FIELD",),
+                "mode": (["full", "same", "valid"], {"default": "same"}),
+                "normalize": ("BOOLEAN", {"default": True}),
+            }
+        }
+
+    OUTPUTS = (
+        ('DATA_FIELD', 'correlation'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Compute 2D cross-correlation between two fields. The correlation peak indicates "
+        "the offset where the two fields best match. Useful for drift measurement and feature "
+        "alignment. Equivalent to Gwyddion crosscor.c."
+    )
+
+    def process(
+        self,
+        field_a: DataField,
+        field_b: DataField,
+        mode: str,
+        normalize: bool,
+    ) -> tuple:
+        from scipy.signal import fftconvolve
+
+        a = field_a.data - field_a.data.mean()
+        b = field_b.data - field_b.data.mean()
+
+        # Cross-correlation via FFT: correlate(a,b) = ifft(fft(a) * conj(fft(b)))
+        # Achieved by convolving a with the flipped b
+        corr = fftconvolve(a, b[::-1, ::-1], mode=mode)
+
+        if normalize:
+            denom = np.sqrt((a ** 2).sum() * (b ** 2).sum())
+            if denom > 0:
+                corr = corr / denom
+
+        if mode == "same":
+            # Output is the same shape as field_a — reuse its physical dimensions
+            return (field_a.replace(data=corr),)
+
+        # For "full" mode: output shape is (Na+Nb-1, Ma+Mb-1)
+        # Scale physical dimensions proportionally
+        na, ma = field_a.data.shape
+        nb, mb = field_b.data.shape
+        out_y, out_x = corr.shape
+
+        # Physical size per pixel stays the same as field_a; total physical size scales
+        new_xreal = field_a.xreal * out_x / ma if ma > 0 else field_a.xreal
+        new_yreal = field_a.yreal * out_y / na if na > 0 else field_a.yreal
+
+        return (field_a.replace(data=corr, xreal=new_xreal, yreal=new_yreal),)

backend/nodes/entropy.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.node_registry import register_node
+from backend.data_types import DataField, RecordTable
+from backend.execution_context import emit_table
+
+
+@register_node(display_name="Entropy")
+class Entropy:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+                "mode": (["height values", "slope magnitude"], {"default": "height values"}),
+                "n_bins": ("INT", {"default": 256, "min": 16, "max": 1024}),
+            }
+        }
+
+    OUTPUTS = (
+        ('FLOAT', 'entropy'),
+        ('FLOAT', 'normalised_entropy'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Shannon entropy of the height or slope distribution. "
+        "H = -\u03a3 p\u00b7ln(p). Equivalent to Gwyddion entropy.c."
+    )
+
+    def process(self, field: DataField, mode: str, n_bins: int) -> tuple:
+        n_bins = max(16, int(n_bins))
+        data = np.asarray(field.data, dtype=np.float64)
+
+        if mode == "slope magnitude":
+            # Compute slope magnitude from Sobel-like finite differences.
+            # Central differences along x and y (axis=1 and axis=0).
+            # np.gradient uses central differences, same spirit as Sobel.
+            dy, dx = np.gradient(data)
+            values = np.hypot(dx, dy).ravel()
+        else:
+            values = data.ravel()
+
+        # Remove non-finite values before binning.
+        values = values[np.isfinite(values)]
+
+        if values.size == 0:
+            h = 0.0
+            h_norm = 0.0
+        else:
+            counts, _ = np.histogram(values, bins=n_bins)
+            total = counts.sum()
+            if total == 0:
+                h = 0.0
+                h_norm = 0.0
+            else:
+                # Probability distribution; skip zero bins.
+                p = counts[counts > 0].astype(np.float64) / float(total)
+                h = float(-np.sum(p * np.log(p)))
+                # Maximum possible entropy for n_bins equally occupied bins is ln(n_bins).
+                h_max = float(np.log(n_bins))
+                h_norm = h / h_max if h_max > 0.0 else 0.0
+
+        table = RecordTable([
+            {"quantity": "entropy",            "value": h,      "unit": "nat"},
+            {"quantity": "normalised entropy", "value": h_norm, "unit": ""},
+            {"quantity": "mode",               "value": mode,   "unit": ""},
+            {"quantity": "n_bins",             "value": n_bins, "unit": ""},
+        ])
+        emit_table(table)
+
+        return (h, h_norm)

backend/nodes/filter_custom.py

@@ -0,0 +1,127 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.node_registry import register_node
+from backend.data_types import DataField
+from backend.execution_context import emit_warning
+
+_DEFAULT_KERNEL = "0 -1 0\n-1 5 -1\n0 -1 0"
+_MAX_KERNEL_DIM = 51
+
+
+def _parse_kernel(kernel_str: str) -> np.ndarray | None:
+    """Parse a multi-line kernel string into a 2-D float64 array.
+
+    Returns *None* and issues a warning via emit_warning if the string is
+    invalid.  The returned array is always at least 1×1 and at most
+    _MAX_KERNEL_DIM × _MAX_KERNEL_DIM.
+    """
+    lines = [ln for ln in kernel_str.splitlines() if ln.strip()]
+    if not lines:
+        emit_warning("Custom Convolution: kernel string is empty. Using identity.")
+        return None
+
+    rows = []
+    for ln in lines:
+        try:
+            row = [float(v) for v in ln.split()]
+        except ValueError:
+            emit_warning(
+                f"Custom Convolution: could not parse kernel row {ln!r}. "
+                "Input returned unchanged."
+            )
+            return None
+        if not row:
+            continue
+        rows.append(row)
+
+    if not rows:
+        emit_warning("Custom Convolution: kernel has no valid rows. Input returned unchanged.")
+        return None
+
+    # All rows must have the same length.
+    ncols = len(rows[0])
+    for i, row in enumerate(rows):
+        if len(row) != ncols:
+            emit_warning(
+                f"Custom Convolution: row {i} has {len(row)} values but row 0 has {ncols}. "
+                "All rows must be the same length. Input returned unchanged."
+            )
+            return None
+
+    arr = np.array(rows, dtype=np.float64)
+
+    if arr.ndim != 2 or arr.size == 0:
+        emit_warning("Custom Convolution: kernel is empty after parsing. Input returned unchanged.")
+        return None
+
+    nrows, ncols = arr.shape
+    if nrows > _MAX_KERNEL_DIM or ncols > _MAX_KERNEL_DIM:
+        emit_warning(
+            f"Custom Convolution: kernel size {nrows}×{ncols} exceeds maximum "
+            f"{_MAX_KERNEL_DIM}×{_MAX_KERNEL_DIM}. Input returned unchanged."
+        )
+        return None
+
+    if not np.all(np.isfinite(arr)):
+        emit_warning("Custom Convolution: kernel contains non-finite values. Input returned unchanged.")
+        return None
+
+    return arr
+
+
+@register_node(display_name="Custom Convolution")
+class CustomConvolution:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+                "kernel": ("STRING", {
+                    "multiline": True,
+                    "default": _DEFAULT_KERNEL,
+                    "placeholder": "kernel rows, space-separated",
+                }),
+                "normalize": ("BOOLEAN", {"default": True}),
+                "boundary": (["reflect", "nearest", "wrap"], {"default": "reflect"}),
+            }
+        }
+
+    OUTPUTS = (
+        ('DATA_FIELD', 'result'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Apply a user-defined convolution kernel. "
+        "Enter rows of space-separated numbers. "
+        "Example sharpen: '0 -1 0 / -1 5 -1 / 0 -1 0' (use newlines, not slashes). "
+        "Equivalent to Gwyddion convolution_filter.c."
+    )
+
+    def process(
+        self,
+        field: DataField,
+        kernel: str,
+        normalize: bool,
+        boundary: str,
+    ) -> tuple:
+        from scipy.ndimage import convolve
+
+        kernel_arr = _parse_kernel(kernel)
+        if kernel_arr is None:
+            # Fallback: return input unchanged.
+            return (field.replace(data=field.data.copy()),)
+
+        data = np.asarray(field.data, dtype=np.float64)
+
+        # scipy.ndimage.convolve boundary mode names match our choices directly.
+        result = convolve(data, kernel_arr, mode=boundary)
+
+        if normalize:
+            abs_sum = float(np.sum(np.abs(kernel_arr)))
+            if abs_sum > 0.0:
+                result = result / abs_sum
+
+        return (field.replace(data=result),)

backend/nodes/filter_kuwahara.py

@@ -0,0 +1,86 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.node_registry import register_node
+from backend.data_types import DataField
+
+
+def _kuwahara_pass(data: np.ndarray) -> np.ndarray:
+    """Single pass of the 5x5 Kuwahara filter.
+
+    Divides a 5x5 neighbourhood around each pixel into four overlapping 3x3
+    quadrants (TL, TR, BL, BR), computes the mean and variance of each quadrant,
+    and replaces the centre pixel with the mean of the quadrant that has the
+    smallest variance. Boundary pixels are handled by reflecting the image.
+    """
+    # Pad with reflect so every pixel has a full 5x5 neighbourhood.
+    padded = np.pad(data, pad_width=2, mode="reflect")
+
+    rows, cols = data.shape
+
+    # For each of the four 3x3 quadrant offsets we need the per-pixel mean and
+    # variance.  The quadrant window positions (relative to the padded array)
+    # for a centre pixel at (r+2, c+2) are:
+    #   TL : rows r..r+2,  cols c..c+2    →  offset (0,0) in padded
+    #   TR : rows r..r+2,  cols c+2..c+4  →  offset (0,2)
+    #   BL : rows r+2..r+4, cols c..c+2   →  offset (2,0)
+    #   BR : rows r+2..r+4, cols c+2..c+4 →  offset (2,2)
+    # Each window is 3×3 = 9 pixels.
+
+    quadrant_offsets = [(0, 0), (0, 2), (2, 0), (2, 2)]
+    n = 9  # 3×3 quadrant
+
+    # Accumulate sum and sum-of-squares for each quadrant using a simple nested
+    # index loop over the 3×3 window positions.
+    quad_sum = np.zeros((4, rows, cols), dtype=np.float64)
+    quad_sum2 = np.zeros((4, rows, cols), dtype=np.float64)
+
+    for qi, (dr0, dc0) in enumerate(quadrant_offsets):
+        for drow in range(3):
+            for dcol in range(3):
+                patch = padded[dr0 + drow: dr0 + drow + rows,
+                               dc0 + dcol: dc0 + dcol + cols]
+                quad_sum[qi] += patch
+                quad_sum2[qi] += patch * patch
+
+    quad_mean = quad_sum / n
+    # var = E[x^2] - (E[x])^2, clamped to 0 to avoid floating-point negatives.
+    quad_var = np.maximum(quad_sum2 / n - quad_mean * quad_mean, 0.0)
+
+    # Select the quadrant index with minimum variance for each pixel.
+    best_qi = np.argmin(quad_var, axis=0)  # shape (rows, cols)
+
+    # Gather the mean from the winning quadrant.
+    result = np.choose(best_qi, quad_mean)
+    return result.astype(np.float64)
+
+
+@register_node(display_name="Kuwahara Filter")
+class KuwaharaFilter:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+                "iterations": ("INT", {"default": 1, "min": 1, "max": 20}),
+            }
+        }
+
+    OUTPUTS = (
+        ('DATA_FIELD', 'filtered'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Edge-preserving smoothing using Kuwahara's minimum-variance quadrant method. "
+        "Unlike Gaussian blur, sharp boundaries are preserved. "
+        "Equivalent to Gwyddion's Kuwahara filter."
+    )
+
+    def process(self, field: DataField, iterations: int) -> tuple:
+        data = np.asarray(field.data, dtype=np.float64)
+        iterations = max(1, int(iterations))
+        for _ in range(iterations):
+            data = _kuwahara_pass(data)
+        return (field.replace(data=data),)

backend/nodes/local_contrast.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.node_registry import register_node
+from backend.data_types import DataField
+
+
+@register_node(display_name="Local Contrast")
+class LocalContrast:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+                "kernel_size": ("INT", {"default": 10, "min": 2, "max": 100}),
+                "weight": ("FLOAT", {"default": 0.5, "min": 0.0, "max": 1.0, "step": 0.05}),
+            }
+        }
+
+    OUTPUTS = (
+        ('DATA_FIELD', 'result'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Expand the local dynamic range at each pixel. "
+        "Reveals fine surface features that are hidden by global contrast range. "
+        "Equivalent to Gwyddion local_contrast.c."
+    )
+
+    def process(self, field: DataField, kernel_size: int, weight: float) -> tuple:
+        from scipy.ndimage import minimum_filter, maximum_filter
+
+        data = np.asarray(field.data, dtype=np.float64)
+        kernel_size = max(2, int(kernel_size))
+        weight = float(np.clip(weight, 0.0, 1.0))
+
+        local_min = minimum_filter(data, size=kernel_size, mode="reflect")
+        local_max = maximum_filter(data, size=kernel_size, mode="reflect")
+
+        global_min = float(data.min())
+        global_max = float(data.max())
+
+        local_range = local_max - local_min
+        eps = np.finfo(np.float64).eps * max(abs(global_max), abs(global_min), 1.0)
+
+        # Remap each pixel from its local range to the global range.
+        # Where local_range is near zero, the pixel is already flat: leave it
+        # unchanged (enhancement factor = 1).
+        safe_range = np.where(local_range > eps, local_range, 1.0)
+        global_span = global_max - global_min
+        if global_span <= eps:
+            # Uniform field – nothing to enhance.
+            return (field.replace(data=data.copy()),)
+
+        enhancement_factor = global_span / safe_range
+        # Locally enhanced value: remap v from [local_min, local_max] → [global_min, global_max]
+        v_enhanced = global_min + enhancement_factor * (data - local_min)
+
+        # Blend between original and enhanced.
+        result = (1.0 - weight) * data + weight * v_enhanced
+
+        return (field.replace(data=result),)

backend/nodes/spot_removal.py

@@ -0,0 +1,122 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.data_types import DataField
+from backend.node_registry import register_node
+
+
+@register_node(display_name="Spot Removal")
+class SpotRemoval:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+                "method": (["laplace", "mean", "zero"], {"default": "laplace"}),
+                "max_iter": ("INT", {"default": 100, "min": 1, "max": 2000, "step": 1}),
+            },
+            "optional": {
+                "mask": ("IMAGE", {"label": "defects"}),
+            },
+        }
+
+    OUTPUTS = (
+        ('DATA_FIELD', 'result'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Fill defect pixels (hot pixels, dropouts, scan artifacts) by interpolation. "
+        "The mask defines defect locations. Laplace method solves the 2D Laplace equation "
+        "for smooth inpainting. Equivalent to Gwyddion spotremove.c."
+    )
+
+    def process(
+        self,
+        field: DataField,
+        method: str,
+        max_iter: int,
+        mask: np.ndarray | None = None,
+    ) -> tuple:
+        if mask is None:
+            return (field,)
+
+        mask_array = np.asarray(mask)
+        # Reshape mask to match field shape if it has extra dimensions (e.g. HxWx1)
+        if mask_array.ndim == 3:
+            mask_array = mask_array[:, :, 0]
+        if mask_array.shape != field.data.shape:
+            raise ValueError(
+                f"Mask shape {mask_array.shape} does not match field shape {field.data.shape}."
+            )
+
+        defect = mask_array > 0
+
+        if not np.any(defect):
+            return (field,)
+
+        data = np.asarray(field.data, dtype=np.float64)
+
+        if method == "zero":
+            result = data.copy()
+            result[defect] = 0.0
+            return (field.replace(data=result),)
+
+        if method == "mean":
+            result = _mean_fill(data, defect)
+            return (field.replace(data=result),)
+
+        # method == "laplace"
+        result = _laplace_fill(data, defect, int(max_iter))
+        return (field.replace(data=result),)
+
+
+def _mean_fill(data: np.ndarray, defect: np.ndarray) -> np.ndarray:
+    """Fill defect pixels with the mean of non-defect neighbours in a 3x3 window."""
+    result = data.copy()
+    yres, xres = data.shape
+
+    # Global fallback: mean of all non-defect pixels
+    non_defect_vals = data[~defect]
+    global_mean = float(non_defect_vals.mean()) if non_defect_vals.size > 0 else 0.0
+
+    defect_coords = np.argwhere(defect)
+    for y, x in defect_coords:
+        y0 = max(y - 1, 0)
+        y1 = min(y + 2, yres)
+        x0 = max(x - 1, 0)
+        x1 = min(x + 2, xres)
+
+        neighbourhood_data = data[y0:y1, x0:x1]
+        neighbourhood_defect = defect[y0:y1, x0:x1]
+        good = neighbourhood_data[~neighbourhood_defect]
+
+        if good.size > 0:
+            result[y, x] = float(good.mean())
+        else:
+            result[y, x] = global_mean
+
+    return result
+
+
+def _laplace_fill(data: np.ndarray, defect: np.ndarray, max_iter: int) -> np.ndarray:
+    """Iterative Laplace solver: set defect pixels to neighbour average each iteration."""
+    non_defect_vals = data[~defect]
+    init_val = float(non_defect_vals.mean()) if non_defect_vals.size > 0 else 0.0
+
+    result = data.copy()
+    result[defect] = init_val
+
+    for _ in range(max_iter):
+        # Compute neighbour averages via rolled arrays
+        neighbour_sum = (
+            np.roll(result, -1, axis=0)
+            + np.roll(result,  1, axis=0)
+            + np.roll(result, -1, axis=1)
+            + np.roll(result,  1, axis=1)
+        )
+        new_vals = neighbour_sum / 4.0
+        result[defect] = new_vals[defect]
+
+    return result

backend/nodes/template_match.py

@@ -0,0 +1,52 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.data_types import DataField
+from backend.node_registry import register_node
+
+
+@register_node(display_name="Template Match")
+class TemplateMatch:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "image": ("DATA_FIELD",),
+                "template": ("DATA_FIELD",),
+                "threshold": (
+                    "FLOAT",
+                    {"default": 0.8, "min": 0.0, "max": 1.0, "step": 0.05},
+                ),
+            }
+        }
+
+    OUTPUTS = (
+        ('DATA_FIELD', 'score'),
+        ('IMAGE', 'detections'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Find a template pattern within a larger data field using normalised cross-correlation. "
+        "The score output shows match quality (1 = perfect match). Detections mask marks positions "
+        "above the threshold. Equivalent to Gwyddion maskcor.c."
+    )
+
+    def process(
+        self,
+        image: DataField,
+        template: DataField,
+        threshold: float,
+    ) -> tuple:
+        from skimage.feature import match_template
+
+        score = match_template(image.data, template.data, pad_input=True)
+
+        # Clip to [0, 1] for display (match_template returns values in [-1, 1])
+        score_clipped = np.clip(score, 0.0, 1.0)
+
+        detections = (score_clipped >= float(threshold)).astype(np.uint8) * 255
+
+        score_field = image.replace(data=score_clipped)
+        return (score_field, detections)

backend/nodes/wavelet_denoise.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+import numpy as np
+
+from backend.data_types import DataField
+from backend.node_registry import register_node
+
+
+@register_node(display_name="Wavelet Denoise")
+class WaveletDenoise:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "field": ("DATA_FIELD",),
+                "wavelet": (
+                    ["db1", "db2", "db4", "db8", "sym4", "coif1", "bior1.3"],
+                    {"default": "db4"},
+                ),
+                "method": (["BayesShrink", "VisuShrink"], {"default": "BayesShrink"}),
+                "sigma": (
+                    "FLOAT",
+                    {"default": 0.0, "min": 0.0, "max": 1.0, "step": 0.01},
+                ),
+                "mode": (["soft", "hard"], {"default": "soft"}),
+            }
+        }
+
+    OUTPUTS = (
+        ('DATA_FIELD', 'denoised'),
+    )
+    FUNCTION = "process"
+
+    DESCRIPTION = (
+        "Denoise using wavelet coefficient thresholding. BayesShrink adapts the threshold "
+        "per sub-band; VisuShrink uses a global threshold. Equivalent to applying DWT from "
+        "Gwyddion dwt.c with coefficient thresholding."
+    )
+
+    def process(
+        self,
+        field: DataField,
+        wavelet: str,
+        method: str,
+        sigma: float,
+        mode: str,
+    ) -> tuple:
+        from skimage.restoration import denoise_wavelet
+
+        d = field.data
+        dmin = float(d.min())
+        drange = float(np.ptp(d))
+
+        if drange == 0:
+            return (field,)
+
+        norm = (d - dmin) / drange
+        sigma_val = float(sigma) if sigma > 0 else None
+
+        # `mode` is a Python builtin name; use threshold_mode locally to avoid shadowing
+        threshold_mode = mode
+
+        denoised_norm = denoise_wavelet(
+            norm,
+            wavelet=wavelet,
+            method=method,
+            mode=threshold_mode,
+            sigma=sigma_val,
+            rescale_sigma=True,
+            channel_axis=None,
+        )
+
+        result = denoised_norm * drange + dmin
+        return (field.replace(data=result),)

pyproject.toml

@@ -17,6 +17,7 @@ dependencies = [
     "nanonispy>=1.1",
     "numpy>=1.26,<3",
     "pillow>=10,<12",
+    "pywavelets>=1.8.0",
     "scikit-image>=0.22,<1",
     "scipy>=1.12,<2",
 ]

tests/node_tests/cross_correlate.py

@@ -0,0 +1,89 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_cross_correlate_same_field_peak_at_center():
+    """Correlating a field with itself in 'same' mode peaks at the centre."""
+    from backend.nodes.cross_correlate import CrossCorrelate
+
+    rng = np.random.default_rng(0)
+    data = rng.standard_normal((32, 32))
+    field = make_field(data=data)
+    node = CrossCorrelate()
+    result, = node.process(field, field, mode="same", normalize=True)
+
+    peak_y, peak_x = np.unravel_index(np.argmax(result.data), result.data.shape)
+    cy, cx = result.data.shape[0] // 2, result.data.shape[1] // 2
+    # Peak should be within a few pixels of centre
+    assert abs(peak_y - cy) <= 2
+    assert abs(peak_x - cx) <= 2
+
+
+def test_cross_correlate_same_mode_shape_equals_a():
+    from backend.nodes.cross_correlate import CrossCorrelate
+
+    rng = np.random.default_rng(1)
+    a = make_field(data=rng.standard_normal((32, 48)))
+    b = make_field(data=rng.standard_normal((32, 48)))
+    node = CrossCorrelate()
+    result, = node.process(a, b, mode="same", normalize=True)
+    assert result.data.shape == a.data.shape
+
+
+def test_cross_correlate_full_mode_shape():
+    """Full mode output shape should be Na+Nb-1 × Ma+Mb-1."""
+    from backend.nodes.cross_correlate import CrossCorrelate
+
+    rng = np.random.default_rng(2)
+    a = make_field(data=rng.standard_normal((20, 30)))
+    b = make_field(data=rng.standard_normal((20, 30)))
+    node = CrossCorrelate()
+    result, = node.process(a, b, mode="full", normalize=True)
+    assert result.data.shape == (20 + 20 - 1, 30 + 30 - 1)
+
+
+def test_cross_correlate_normalized_peak_is_one():
+    """Self-correlation normalised should give peak = 1."""
+    from backend.nodes.cross_correlate import CrossCorrelate
+
+    rng = np.random.default_rng(3)
+    data = rng.standard_normal((32, 32))
+    field = make_field(data=data)
+    node = CrossCorrelate()
+    result, = node.process(field, field, mode="same", normalize=True)
+    assert result.data.max() == pytest.approx(1.0, abs=1e-6)
+
+
+def test_cross_correlate_unnormalized_runs():
+    from backend.nodes.cross_correlate import CrossCorrelate
+
+    rng = np.random.default_rng(4)
+    data = rng.standard_normal((16, 16))
+    field = make_field(data=data)
+    node = CrossCorrelate()
+    result, = node.process(field, field, mode="same", normalize=False)
+    assert result.data.shape == (16, 16)
+
+
+def test_cross_correlate_valid_mode():
+    from backend.nodes.cross_correlate import CrossCorrelate
+
+    rng = np.random.default_rng(5)
+    a = make_field(data=rng.standard_normal((16, 16)))
+    b = make_field(data=rng.standard_normal((8, 8)))
+    node = CrossCorrelate()
+    result, = node.process(a, b, mode="valid", normalize=True)
+    # Valid mode output: (16-8+1, 16-8+1) = (9, 9)
+    assert result.data.shape == (9, 9)
+
+
+def test_cross_correlate_preserves_metadata_same_mode():
+    from backend.nodes.cross_correlate import CrossCorrelate
+
+    rng = np.random.default_rng(6)
+    field = make_field(data=rng.standard_normal((16, 16)))
+    node = CrossCorrelate()
+    result, = node.process(field, field, mode="same", normalize=True)
+    assert result.xreal == field.xreal
+    assert result.yreal == field.yreal

tests/node_tests/entropy.py

@@ -0,0 +1,75 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_entropy_uniform_field_low():
+    """A field with a single unique value has zero entropy."""
+    from backend.nodes.entropy import Entropy
+
+    node = Entropy()
+    field = make_field(data=np.full((32, 32), 3.14))
+    h, h_norm = node.process(field, mode="height values", n_bins=256)
+    # All values fall in one bin → p=1 → H = 0
+    assert h == pytest.approx(0.0, abs=1e-10)
+    assert h_norm == pytest.approx(0.0, abs=1e-10)
+
+
+def test_entropy_random_field_positive():
+    """A random field should have positive entropy."""
+    from backend.nodes.entropy import Entropy
+
+    rng = np.random.default_rng(0)
+    field = make_field(data=rng.standard_normal((64, 64)))
+    node = Entropy()
+    h, h_norm = node.process(field, mode="height values", n_bins=256)
+    assert h > 0.0
+    assert 0.0 < h_norm <= 1.0
+
+
+def test_entropy_normalised_leq_one():
+    """Normalised entropy should never exceed 1."""
+    from backend.nodes.entropy import Entropy
+
+    rng = np.random.default_rng(2)
+    field = make_field(data=rng.uniform(0, 1, (64, 64)))
+    node = Entropy()
+    _, h_norm = node.process(field, mode="height values", n_bins=64)
+    assert h_norm <= 1.0 + 1e-12
+
+
+def test_entropy_slope_mode():
+    """Slope mode should work and return valid entropy values."""
+    from backend.nodes.entropy import Entropy
+
+    rng = np.random.default_rng(3)
+    field = make_field(data=rng.standard_normal((32, 32)))
+    node = Entropy()
+    h, h_norm = node.process(field, mode="slope magnitude", n_bins=128)
+    assert h > 0.0
+    assert 0.0 <= h_norm <= 1.0
+
+
+def test_entropy_more_uniform_is_higher():
+    """Uniformly distributed values have higher entropy than a spiked distribution."""
+    from backend.nodes.entropy import Entropy
+
+    rng = np.random.default_rng(4)
+    uniform = rng.uniform(0, 1, (64, 64))
+    spiked = np.zeros((64, 64))
+    spiked[0, 0] = 1.0
+
+    node = Entropy()
+    h_uniform, _ = node.process(make_field(data=uniform), mode="height values", n_bins=64)
+    h_spiked, _ = node.process(make_field(data=spiked), mode="height values", n_bins=64)
+    assert h_uniform > h_spiked
+
+
+def test_entropy_returns_floats():
+    from backend.nodes.entropy import Entropy
+
+    field = make_field()
+    node = Entropy()
+    h, h_norm = node.process(field, mode="height values", n_bins=256)
+    assert isinstance(h, float)
+    assert isinstance(h_norm, float)

tests/node_tests/filter_custom.py

@@ -0,0 +1,95 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_custom_convolution_identity_kernel():
+    """[[1]] with normalize=True (abs_sum=1) should return input unchanged."""
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    data = np.random.default_rng(0).standard_normal((32, 32))
+    field = make_field(data=data)
+    result, = node.process(field, kernel="1", normalize=False, boundary="reflect")
+    assert np.allclose(result.data, data)
+
+
+def test_custom_convolution_uniform_kernel_normalized():
+    """An all-ones kernel with normalize=True is a box filter (mean filter)."""
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    data = np.random.default_rng(1).standard_normal((32, 32))
+    field = make_field(data=data)
+    # 3x3 all-ones kernel, normalized → each pixel becomes mean of its neighbourhood
+    kernel = "1 1 1\n1 1 1\n1 1 1"
+    result, = node.process(field, kernel=kernel, normalize=True, boundary="reflect")
+    # Output std should be less than input std (smoothing)
+    assert result.data.std() < data.std()
+
+
+def test_custom_convolution_sharpen_increases_variation():
+    """A sharpening kernel should increase local variation on a smooth field."""
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    # Smooth ramp field — very low frequency content
+    data = np.outer(np.linspace(0, 1, 32), np.linspace(0, 1, 32))
+    field = make_field(data=data)
+    sharpen = "0 -1 0\n-1 5 -1\n0 -1 0"
+    result, = node.process(field, kernel=sharpen, normalize=False, boundary="reflect")
+    # Sharpening without normalisation keeps the ramp intact plus adds edges
+    # The std of the sharpened field should differ from input
+    assert result.data.std() != pytest.approx(data.std(), rel=0.0)
+
+
+def test_custom_convolution_shape_preserved():
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    field = make_field(shape=(48, 64))
+    result, = node.process(field, kernel="0 1 0\n1 1 1\n0 1 0", normalize=True, boundary="reflect")
+    assert result.data.shape == (48, 64)
+
+
+def test_custom_convolution_invalid_kernel_fallback():
+    """An invalid kernel string should return the input field unchanged."""
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    data = np.random.default_rng(2).standard_normal((16, 16))
+    field = make_field(data=data)
+    result, = node.process(field, kernel="", normalize=True, boundary="reflect")
+    assert np.allclose(result.data, data)
+
+
+def test_custom_convolution_ragged_kernel_fallback():
+    """A ragged (non-rectangular) kernel should be rejected gracefully."""
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    data = np.random.default_rng(3).standard_normal((16, 16))
+    field = make_field(data=data)
+    result, = node.process(field, kernel="1 2\n1 2 3", normalize=True, boundary="reflect")
+    assert np.allclose(result.data, data)
+
+
+def test_custom_convolution_boundary_modes():
+    """All boundary modes should produce valid output without error."""
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    field = make_field()
+    for mode in ("reflect", "nearest", "wrap"):
+        result, = node.process(field, kernel="1 1 1\n1 1 1\n1 1 1", normalize=True, boundary=mode)
+        assert result.data.shape == field.data.shape
+
+
+def test_custom_convolution_preserves_metadata():
+    from backend.nodes.filter_custom import CustomConvolution
+
+    node = CustomConvolution()
+    field = make_field()
+    result, = node.process(field, kernel="1", normalize=False, boundary="reflect")
+    assert result.xreal == field.xreal
+    assert result.si_unit_z == field.si_unit_z

tests/node_tests/filter_kuwahara.py

@@ -0,0 +1,75 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_kuwahara_shape_preserved():
+    from backend.nodes.filter_kuwahara import KuwaharaFilter
+
+    node = KuwaharaFilter()
+    field = make_field(shape=(48, 64))
+    result, = node.process(field, iterations=1)
+    assert result.data.shape == (48, 64)
+
+
+def test_kuwahara_flat_field_unchanged():
+    """A constant field should pass through the Kuwahara filter unchanged."""
+    from backend.nodes.filter_kuwahara import KuwaharaFilter
+
+    node = KuwaharaFilter()
+    field = make_field(data=np.full((32, 32), 7.5))
+    result, = node.process(field, iterations=1)
+    assert np.allclose(result.data, 7.5)
+
+
+def test_kuwahara_reduces_noise():
+    """Applying the filter to a noisy field should reduce standard deviation."""
+    from backend.nodes.filter_kuwahara import KuwaharaFilter
+
+    rng = np.random.default_rng(0)
+    noisy = rng.standard_normal((64, 64))
+    node = KuwaharaFilter()
+    field = make_field(data=noisy)
+    result, = node.process(field, iterations=1)
+    assert result.data.std() < noisy.std()
+
+
+def test_kuwahara_preserves_step_edge():
+    """The Kuwahara filter should preserve a sharp step edge better than a blur."""
+    from backend.nodes.filter_kuwahara import KuwaharaFilter
+
+    # Left half = 0, right half = 1
+    data = np.zeros((32, 64))
+    data[:, 32:] = 1.0
+    node = KuwaharaFilter()
+    field = make_field(data=data)
+    result, = node.process(field, iterations=1)
+
+    # The edge column should have a large jump (edge preserved)
+    col_before = result.data[:, 30].mean()
+    col_after = result.data[:, 34].mean()
+    assert col_after - col_before > 0.5
+
+
+def test_kuwahara_multiple_iterations():
+    """Running multiple iterations should further reduce noise."""
+    from backend.nodes.filter_kuwahara import KuwaharaFilter
+
+    rng = np.random.default_rng(1)
+    noisy = rng.standard_normal((32, 32))
+    node = KuwaharaFilter()
+    field = make_field(data=noisy)
+    result1, = node.process(field, iterations=1)
+    result3, = node.process(field, iterations=3)
+    assert result3.data.std() <= result1.data.std()
+
+
+def test_kuwahara_preserves_metadata():
+    from backend.nodes.filter_kuwahara import KuwaharaFilter
+
+    node = KuwaharaFilter()
+    field = make_field()
+    result, = node.process(field, iterations=1)
+    assert result.xreal == field.xreal
+    assert result.yreal == field.yreal
+    assert result.si_unit_z == field.si_unit_z

tests/node_tests/local_contrast.py

@@ -0,0 +1,67 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_local_contrast_shape_preserved():
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field(shape=(48, 64))
+    result, = node.process(field, kernel_size=10, weight=0.5)
+    assert result.data.shape == (48, 64)
+
+
+def test_local_contrast_weight_zero_unchanged():
+    """weight=0 blends 100% original → result equals input."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    data = np.random.default_rng(0).standard_normal((32, 32))
+    field = make_field(data=data)
+    result, = node.process(field, kernel_size=5, weight=0.0)
+    assert np.allclose(result.data, data)
+
+
+def test_local_contrast_uniform_field_unchanged():
+    """A flat field has nothing to enhance; it should be returned as-is."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field(data=np.full((32, 32), 2.0))
+    result, = node.process(field, kernel_size=5, weight=1.0)
+    assert np.allclose(result.data, 2.0)
+
+
+def test_local_contrast_increases_dynamic_range():
+    """Weight=1 full enhancement should not compress global range beyond input."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    rng = np.random.default_rng(1)
+    data = rng.standard_normal((64, 64))
+    field = make_field(data=data)
+    node = LocalContrast()
+    result, = node.process(field, kernel_size=8, weight=1.0)
+    # Global min/max should be preserved (by construction of the algorithm)
+    assert np.isclose(result.data.min(), data.min(), atol=1e-6)
+    assert np.isclose(result.data.max(), data.max(), atol=1e-6)
+
+
+def test_local_contrast_preserves_metadata():
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field()
+    result, = node.process(field, kernel_size=10, weight=0.5)
+    assert result.xreal == field.xreal
+    assert result.si_unit_z == field.si_unit_z
+
+
+def test_local_contrast_weight_clipped():
+    """Values outside [0,1] should be clipped without error."""
+    from backend.nodes.local_contrast import LocalContrast
+
+    node = LocalContrast()
+    field = make_field()
+    result, = node.process(field, kernel_size=5, weight=2.0)
+    assert result.data.shape == field.data.shape

tests/node_tests/save.py

@@ -156,10 +156,16 @@ def test_save_generic():
         except ValueError:
             pass
 
+        # LINE as plot image (PNG / TIFF)
+        node.save(filename="line_plot_png", directory_path=tmpdir, format="PNG", value=line)
+        assert Path(tmpdir, "line_plot_png.png").exists()
+        node.save(filename="line_plot_tiff", directory_path=tmpdir, format="TIFF", value=line)
+        assert Path(tmpdir, "line_plot_tiff.tiff").exists()
+
         # Unsupported LINE format
         try:
-            node.save(filename="line_bad", directory_path=tmpdir, format="TIFF", value=line)
+            node.save(filename="line_bad", directory_path=tmpdir, format="OBJ", value=line)
-            assert False, "Expected ValueError for LINE + TIFF"
+            assert False, "Expected ValueError for LINE + OBJ"
         except ValueError:
             pass
 

tests/node_tests/spot_removal.py

@@ -0,0 +1,110 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def _make_mask(shape, defect_positions):
+    """Create a uint8 mask array with 255 at given (row, col) positions."""
+    mask = np.zeros(shape, dtype=np.uint8)
+    for r, c in defect_positions:
+        mask[r, c] = 255
+    return mask
+
+
+def test_spot_removal_no_mask_returns_field_unchanged():
+    """Without a mask input the field should be returned as-is."""
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    field = make_field()
+    result, = node.process(field, method="laplace", max_iter=50)
+    # Should be the identical object (short-circuit path)
+    assert result is field
+
+
+def test_spot_removal_zero_fill():
+    """method='zero' sets defect pixels to exactly 0."""
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    data = np.ones((16, 16)) * 5.0
+    field = make_field(data=data)
+    mask = _make_mask((16, 16), [(4, 4), (8, 8)])
+    result, = node.process(field, method="zero", max_iter=1, mask=mask)
+    assert result.data[4, 4] == pytest.approx(0.0)
+    assert result.data[8, 8] == pytest.approx(0.0)
+    # Non-defect pixels should stay 5.0
+    assert result.data[0, 0] == pytest.approx(5.0)
+
+
+def test_spot_removal_mean_fill_surrounded_by_constant():
+    """On a constant field, mean fill should give back the constant."""
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    data = np.full((16, 16), 3.0)
+    field = make_field(data=data)
+    mask = _make_mask((16, 16), [(7, 7)])
+    result, = node.process(field, method="mean", max_iter=1, mask=mask)
+    assert result.data[7, 7] == pytest.approx(3.0, abs=1e-10)
+
+
+def test_spot_removal_laplace_fill_surrounded_by_constant():
+    """Laplace fill on a constant field should recover the constant at the defect."""
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    data = np.full((16, 16), 2.5)
+    field = make_field(data=data)
+    mask = _make_mask((16, 16), [(8, 8)])
+    result, = node.process(field, method="laplace", max_iter=200, mask=mask)
+    assert result.data[8, 8] == pytest.approx(2.5, abs=1e-3)
+
+
+def test_spot_removal_laplace_smooth_interpolation():
+    """Laplace should interpolate between boundary values smoothly."""
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    # Left half = 0, right half = 10; single defect in the middle
+    data = np.zeros((16, 16))
+    data[:, 8:] = 10.0
+    field = make_field(data=data)
+    # Defect at the boundary column
+    mask = _make_mask((16, 16), [(8, 7)])
+    result, = node.process(field, method="laplace", max_iter=500, mask=mask)
+    # The filled value should be between 0 and 10
+    filled = result.data[8, 7]
+    assert 0.0 <= filled <= 10.0
+
+
+def test_spot_removal_shape_preserved():
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    field = make_field(shape=(48, 64))
+    mask = _make_mask((48, 64), [(10, 20)])
+    result, = node.process(field, method="mean", max_iter=10, mask=mask)
+    assert result.data.shape == (48, 64)
+
+
+def test_spot_removal_mask_shape_mismatch_raises():
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    field = make_field(shape=(16, 16))
+    bad_mask = np.ones((32, 32), dtype=np.uint8)
+    with pytest.raises(ValueError, match="Mask shape"):
+        node.process(field, method="zero", max_iter=1, mask=bad_mask)
+
+
+def test_spot_removal_empty_mask_unchanged():
+    """An all-zero mask means no defects — field returned unchanged."""
+    from backend.nodes.spot_removal import SpotRemoval
+
+    node = SpotRemoval()
+    data = np.random.default_rng(0).standard_normal((16, 16))
+    field = make_field(data=data)
+    mask = np.zeros((16, 16), dtype=np.uint8)
+    result, = node.process(field, method="laplace", max_iter=50, mask=mask)
+    assert result is field

tests/node_tests/template_match.py

@@ -0,0 +1,93 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_template_match_exact_match_score_one():
+    """When template equals the image, the peak score should be 1."""
+    from backend.nodes.template_match import TemplateMatch
+
+    rng = np.random.default_rng(0)
+    data = rng.standard_normal((32, 32))
+    image_field = make_field(data=data)
+    # Template is the full image → perfect correlation everywhere → peak = 1
+    template_field = make_field(data=data)
+    node = TemplateMatch()
+    score_field, detections = node.process(image_field, template_field, threshold=0.9)
+    assert score_field.data.max() == pytest.approx(1.0, abs=1e-6)
+
+
+def test_template_match_output_shape_matches_image():
+    from backend.nodes.template_match import TemplateMatch
+
+    rng = np.random.default_rng(1)
+    image_field = make_field(data=rng.standard_normal((32, 32)))
+    template_field = make_field(data=rng.standard_normal((8, 8)))
+    node = TemplateMatch()
+    score_field, detections = node.process(image_field, template_field, threshold=0.5)
+    assert score_field.data.shape == image_field.data.shape
+    assert detections.shape == image_field.data.shape
+
+
+def test_template_match_score_in_range():
+    """Score values should be clipped to [0, 1]."""
+    from backend.nodes.template_match import TemplateMatch
+
+    rng = np.random.default_rng(2)
+    image_field = make_field(data=rng.standard_normal((32, 32)))
+    template_field = make_field(data=rng.standard_normal((6, 6)))
+    node = TemplateMatch()
+    score_field, _ = node.process(image_field, template_field, threshold=0.5)
+    assert score_field.data.min() >= 0.0 - 1e-10
+    assert score_field.data.max() <= 1.0 + 1e-10
+
+
+def test_template_match_detections_binary():
+    """Detection mask values should be 0 or 255 only."""
+    from backend.nodes.template_match import TemplateMatch
+
+    rng = np.random.default_rng(3)
+    image_field = make_field(data=rng.standard_normal((32, 32)))
+    template_field = make_field(data=rng.standard_normal((8, 8)))
+    node = TemplateMatch()
+    _, detections = node.process(image_field, template_field, threshold=0.5)
+    unique_values = set(np.unique(detections))
+    assert unique_values <= {0, 255}
+
+
+def test_template_match_threshold_zero_all_detected():
+    """threshold=0 should mark all pixels as detections (score always >= 0)."""
+    from backend.nodes.template_match import TemplateMatch
+
+    rng = np.random.default_rng(4)
+    image_field = make_field(data=rng.standard_normal((16, 16)))
+    template_field = make_field(data=rng.standard_normal((4, 4)))
+    node = TemplateMatch()
+    _, detections = node.process(image_field, template_field, threshold=0.0)
+    assert np.all(detections == 255)
+
+
+def test_template_match_threshold_one_sparse_detections():
+    """threshold=1.0 should detect very few (or no) positions."""
+    from backend.nodes.template_match import TemplateMatch
+
+    rng = np.random.default_rng(5)
+    image_field = make_field(data=rng.standard_normal((32, 32)))
+    template_field = make_field(data=rng.standard_normal((8, 8)))
+    node = TemplateMatch()
+    _, detections = node.process(image_field, template_field, threshold=1.0)
+    # At threshold=1.0, only perfect matches count (rare for random data)
+    detected_count = int((detections == 255).sum())
+    assert detected_count < 10  # very few or none
+
+
+def test_template_match_preserves_metadata():
+    from backend.nodes.template_match import TemplateMatch
+
+    rng = np.random.default_rng(6)
+    image_field = make_field(data=rng.standard_normal((32, 32)))
+    template_field = make_field(data=rng.standard_normal((8, 8)))
+    node = TemplateMatch()
+    score_field, _ = node.process(image_field, template_field, threshold=0.5)
+    assert score_field.xreal == image_field.xreal
+    assert score_field.yreal == image_field.yreal

tests/node_tests/wavelet_denoise.py

@@ -0,0 +1,85 @@
+import numpy as np
+import pytest
+from tests.node_tests._shared import make_field
+
+
+def test_wavelet_denoise_shape_preserved():
+    from backend.nodes.wavelet_denoise import WaveletDenoise
+
+    node = WaveletDenoise()
+    field = make_field(shape=(64, 64))
+    result, = node.process(field, wavelet="db4", method="BayesShrink", sigma=0.0, mode="soft")
+    assert result.data.shape == (64, 64)
+
+
+def test_wavelet_denoise_reduces_noise():
+    """Denoising noisy data should reduce standard deviation."""
+    from backend.nodes.wavelet_denoise import WaveletDenoise
+
+    rng = np.random.default_rng(0)
+    clean = np.outer(np.linspace(0, 1, 32), np.linspace(0, 1, 32))
+    noisy = clean + rng.normal(0, 0.1, clean.shape)
+    field = make_field(data=noisy)
+    node = WaveletDenoise()
+    result, = node.process(field, wavelet="db4", method="BayesShrink", sigma=0.0, mode="soft")
+    # Denoised should be closer to clean than the noisy input
+    denoised_err = np.std(result.data - clean)
+    noisy_err = np.std(noisy - clean)
+    assert denoised_err < noisy_err
+
+
+def test_wavelet_denoise_uniform_field_unchanged():
+    """A flat field (no variation) is returned as-is."""
+    from backend.nodes.wavelet_denoise import WaveletDenoise
+
+    node = WaveletDenoise()
+    field = make_field(data=np.full((32, 32), 5.0))
+    result, = node.process(field, wavelet="db1", method="VisuShrink", sigma=0.0, mode="hard")
+    # The short-circuit path returns the original field object
+    assert result is field
+
+
+def test_wavelet_denoise_preserves_range():
+    """Output values should stay within the input data range (approx)."""
+    from backend.nodes.wavelet_denoise import WaveletDenoise
+
+    rng = np.random.default_rng(1)
+    data = rng.standard_normal((32, 32))
+    field = make_field(data=data)
+    node = WaveletDenoise()
+    result, = node.process(field, wavelet="db4", method="BayesShrink", sigma=0.0, mode="soft")
+    # The normalisation ensures output is within [data.min(), data.max()]
+    assert result.data.min() >= data.min() - 1e-10
+    assert result.data.max() <= data.max() + 1e-10
+
+
+def test_wavelet_denoise_all_wavelets():
+    """All supported wavelets should run without error."""
+    from backend.nodes.wavelet_denoise import WaveletDenoise
+
+    rng = np.random.default_rng(2)
+    field = make_field(data=rng.standard_normal((32, 32)))
+    node = WaveletDenoise()
+    for wavelet in ("db1", "db2", "db4", "db8", "sym4", "coif1", "bior1.3"):
+        result, = node.process(field, wavelet=wavelet, method="BayesShrink", sigma=0.0, mode="soft")
+        assert result.data.shape == field.data.shape
+
+
+def test_wavelet_denoise_visu_shrink():
+    from backend.nodes.wavelet_denoise import WaveletDenoise
+
+    rng = np.random.default_rng(3)
+    field = make_field(data=rng.standard_normal((32, 32)))
+    node = WaveletDenoise()
+    result, = node.process(field, wavelet="db4", method="VisuShrink", sigma=0.0, mode="soft")
+    assert result.data.shape == field.data.shape
+
+
+def test_wavelet_denoise_preserves_metadata():
+    from backend.nodes.wavelet_denoise import WaveletDenoise
+
+    node = WaveletDenoise()
+    field = make_field()
+    result, = node.process(field, wavelet="db4", method="BayesShrink", sigma=0.0, mode="soft")
+    assert result.xreal == field.xreal
+    assert result.si_unit_z == field.si_unit_z