385 lines
12 KiB
Python
Executable File
385 lines
12 KiB
Python
Executable File
#%%
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import numpy as np
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import cv2
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# Flat pattern scale before warping to a dome: 1 mm == 100 pixels.
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PX_PER_MM = 100.0
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def mm_to_px(mm, scale_px_per_mm=PX_PER_MM):
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"""Convert millimetres to pixels (default 1 mm = 100 px)."""
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return mm * scale_px_per_mm
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def px_to_mm(px, scale_px_per_mm=PX_PER_MM):
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"""Convert pixels to millimetres (default 1 mm = 100 px)."""
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return px / scale_px_per_mm
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def merge_intervals(intervals):
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# Merge overlapping intervals.
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if not intervals:
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return []
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intervals.sort(key=lambda x: x[0])
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merged = [intervals[0]]
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for current in intervals[1:]:
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last = merged[-1]
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if current[0] <= last[1]:
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merged[-1] = (last[0], max(last[1], current[1]))
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else:
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merged.append(current)
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return merged
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def get_allowed_intervals(neighbor_values, delta):
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# Compute forbidden intervals for this channel from neighbor values.
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forbidden = []
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for c in neighbor_values:
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low = max(0, c - delta)
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high = min(1, c + delta)
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forbidden.append((low, high))
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# Merge overlapping forbidden intervals.
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merged = merge_intervals(forbidden)
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allowed = []
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# Allowed region before the first forbidden interval.
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if merged:
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if merged[0][0] > 0:
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allowed.append((0, merged[0][0]))
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# Allowed regions between forbidden intervals.
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for i in range(1, len(merged)):
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allowed.append((merged[i-1][1], merged[i][0]))
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# Allowed region after the last forbidden interval.
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if merged[-1][1] < 1:
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allowed.append((merged[-1][1], 1))
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else:
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allowed.append((0, 1))
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return allowed
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def sample_from_allowed(allowed):
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# Choose a random value from the allowed intervals with probability proportional to interval length.
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lengths = [end - start for start, end in allowed]
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total_length = sum(lengths)
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if total_length <= 0:
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return None
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point = np.random.rand() * total_length
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cumulative = 0
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for (start, end), length in zip(allowed, lengths):
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cumulative += length
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if point <= cumulative:
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return np.random.uniform(start, end)
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return allowed[-1][0]
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def sample_channel(neighbor_values, delta):
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# Compute allowed intervals and sample a value.
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allowed = get_allowed_intervals(neighbor_values, delta)
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if not allowed:
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return None
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return sample_from_allowed(allowed)
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def generate_valid_color(neighbors, r):
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"""
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Generate a random color that satisfies, for each neighbor,
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|R - R_neighbor| >= sqrt(r), and similarly for G and B.
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neighbors: list of neighbor colors (each is an array of shape (3,))
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r: threshold for squared difference.
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"""
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delta = np.sqrt(r)
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color = np.zeros(3)
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for channel in range(3):
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neighbor_channel = [n[channel] for n in neighbors]
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sampled = sample_channel(neighbor_channel, delta)
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# If the allowed intervals are empty, use a fallback.
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if sampled is None:
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sampled = np.random.rand()
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color[channel] = sampled
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return color
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def _easing_progress(t, easing, gamma):
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"""
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Map normalized position t in [0, 1] along an axis to a progress u in [0, 1]
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for patch-size interpolation: size = start + (end - start) * u.
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"""
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t = float(np.clip(t, 0.0, 1.0))
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e = (easing or "linear").lower()
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if e == "linear":
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return t
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if e == "power":
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g = float(gamma)
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return t**g
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if e == "cosine":
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return 0.5 * (1.0 - np.cos(np.pi * t))
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if e in ("dome", "dome_sin2"):
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# Shallow rise from left (t=0) to right (t=1); slows change near the left
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# (useful when the left is farther on a dome and needs larger flat patches).
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return np.sin(0.5 * np.pi * t) ** 2
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raise ValueError(
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f"Unknown easing {e!r}; use 'linear', 'power', 'cosine', or 'dome'"
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)
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def patch_sizes_nonlinear_along_length(
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total_len_px,
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patch_px_start,
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patch_px_end,
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*,
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easing="power",
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gamma=2.0,
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):
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"""
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Integer segment lengths along an axis of length ``total_len_px``, with **nonlinear**
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nominal patch size from ``patch_px_start`` (at the beginning of the axis, e.g. left)
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to ``patch_px_end`` (at the end, e.g. right).
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At cumulative pixel position ``pos`` (start of a segment), let ``t = pos / total_len_px``.
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Nominal size is::
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patch_px_start + (patch_px_end - patch_px_start) * easing(t)
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Segments are at least 1 pixel wide; the sum of segment lengths equals ``total_len_px``.
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Parameters
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----------
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total_len_px : int
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Full extent in pixels (e.g. image width after ``mm_to_px(length_mm)``).
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patch_px_start, patch_px_end : int
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Patch size in pixels at the start vs end of the axis.
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easing : str
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- ``'linear'``: same as uniform interpolation in ``t``
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- ``'power'``: ``t ** gamma`` (gamma > 1 keeps sizes nearer ``patch_px_start`` longer)
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- ``'cosine'``: smooth cosine half-period
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- ``'dome'``: ``sin(pi/2 * t) ** 2`` (gentle dome-style progression)
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gamma : float
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Exponent for ``easing='power'`` (ignored otherwise).
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See Also
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--------
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patch_sizes_from_mm : same logic with inputs in millimetres.
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"""
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if total_len_px <= 0:
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return []
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a = max(1, int(round(float(patch_px_start))))
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b = max(1, int(round(float(patch_px_end))))
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tl = float(total_len_px)
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sizes = []
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pos = 0
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while pos < total_len_px:
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t = pos / tl
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u = _easing_progress(t, easing, gamma)
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nominal = a + (b - a) * u
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seg = int(max(1, round(float(nominal))))
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seg = min(seg, total_len_px - pos)
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sizes.append(seg)
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pos += seg
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diff = total_len_px - sum(sizes)
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if diff != 0 and sizes:
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sizes[-1] += diff
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sizes[-1] = max(1, sizes[-1])
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return sizes
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def patch_sizes_from_mm(
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length_mm,
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patch_mm_start,
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patch_mm_end,
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*,
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px_per_mm=PX_PER_MM,
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**kwargs,
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):
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"""
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Same as ``patch_sizes_nonlinear_along_length`` but axis length and patch bounds
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are given in **millimetres**; converted with ``1 mm = px_per_mm`` pixels (default 100).
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"""
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L = int(round(float(length_mm) * float(px_per_mm)))
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a = max(1, int(round(float(patch_mm_start) * float(px_per_mm))))
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b = max(1, int(round(float(patch_mm_end) * float(px_per_mm))))
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return patch_sizes_nonlinear_along_length(L, a, b, **kwargs)
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def patch_sizes_along_length(total_len, size_at_start, size_at_end):
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"""
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Integer segment lengths along an axis of length `total_len`, varying **linearly**
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from `size_at_start` (at the beginning of the axis) to `size_at_end` (at the end).
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Equivalent to ``patch_sizes_nonlinear_along_length(..., easing='linear')``.
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"""
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return patch_sizes_nonlinear_along_length(
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total_len, size_at_start, size_at_end, easing="linear", gamma=1.0
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)
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def generate_color_pattern_varying_horizontal(
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h,
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w,
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patch_w_max_left,
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patch_w_min_right,
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r,
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*,
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easing="linear",
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gamma=2.0,
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):
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"""
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Like ``generate_color_pattern``, but patch **size** varies along x (largest on the
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left, smallest on the right). Each patch is **square**: side length equals that
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column's width, and the same step is used vertically within the column.
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Parameters
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----------
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h, w : int
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Output image size.
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patch_w_max_left : int
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Square side length at the left edge (maximum).
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patch_w_min_right : int
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Square side length toward the right edge (minimum).
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r : float
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Same neighbor color constraint as ``generate_color_pattern``.
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easing : str
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Passed to ``patch_sizes_nonlinear_along_length`` (e.g. ``'dome'`` for dome warp).
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gamma : float
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Exponent when ``easing='power'``.
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Note
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----
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If ``h`` is not a multiple of a column's side length ``s``, the last row in that
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column is shorter than ``s`` pixels tall while the width stays ``s`` (a thin strip).
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"""
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pattern = np.zeros((h, w, 3), dtype=np.float32)
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col_widths = patch_sizes_nonlinear_along_length(
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w, patch_w_max_left, patch_w_min_right, easing=easing, gamma=gamma
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)
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x_edges = np.concatenate([[0], np.cumsum(col_widths, dtype=np.int64)])
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num_cols = len(col_widths)
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for j in range(num_cols):
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s = int(col_widths[j])
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x0 = int(x_edges[j])
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x1 = int(x_edges[j + 1])
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y = 0
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while y < h:
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y1 = min(y + s, h)
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neighbors = []
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if y >= s:
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patch_above = pattern[y - s : y, x0:x1]
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if patch_above.size:
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neighbors.append(np.mean(patch_above, axis=(0, 1)))
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if j > 0:
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xl0 = int(x_edges[j - 1])
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patch_left = pattern[y:y1, xl0:x0]
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if patch_left.size:
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neighbors.append(np.mean(patch_left, axis=(0, 1)))
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if len(neighbors) == 0:
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new_color = np.random.rand(3)
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else:
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new_color = generate_valid_color(neighbors, r)
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pattern[y:y1, x0:x1] = new_color
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y = y1
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return pattern
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def generate_color_pattern(h, w, d, r):
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"""
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Generate a dense color pattern.
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h, w: height and width of the output image in pixels.
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d: patch size in pixels (each patch is d x d).
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r: randomness regulation factor. For each neighbor the condition is:
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(|channel_new - channel_neighbor|)^2 >= r.
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"""
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pattern = np.zeros((h, w, 3), dtype=np.float32)
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num_patches_x = h // d
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num_patches_y = w // d
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for i in range(num_patches_x):
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for j in range(num_patches_y):
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# Collect neighbor patch colors (using mean because patches have uniform color).
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neighbors = []
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if i > 0:
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patch_above = pattern[(i-1)*d:i*d, j*d:(j+1)*d]
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neighbors.append(np.mean(patch_above, axis=(0, 1)))
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if j > 0:
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patch_left = pattern[i*d:(i+1)*d, (j-1)*d:j*d]
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neighbors.append(np.mean(patch_left, axis=(0, 1)))
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if len(neighbors) == 0:
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# For the first patch use a random color.
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new_color = np.random.rand(3)
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else:
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new_color = generate_valid_color(neighbors, r)
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pattern[i*d:(i+1)*d, j*d:(j+1)*d] = new_color
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print('Patch ({}, {})'.format(i, j))
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return pattern
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def draw_center_cross_bgr(
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img,
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*,
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color=(0, 0, 0),
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arm_half_len=None,
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thickness=3,
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):
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"""
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Draw a black (+) cross centered on the image for print / camera alignment.
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`img` is modified in place (BGR uint8).
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"""
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h, w = img.shape[:2]
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cx, cy = w // 2, h // 2
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if arm_half_len is None:
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arm_half_len = max(8, min(h, w) // 40)
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half = int(arm_half_len)
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cv2.line(
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img,
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(cx - half, cy),
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(cx + half, cy),
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color,
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thickness,
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lineType=cv2.LINE_AA,
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)
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cv2.line(
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img,
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(cx, cy - half),
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(cx, cy + half),
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color,
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thickness,
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lineType=cv2.LINE_AA,
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)
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def main():
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# Parameters for the pattern.
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# For example, using 100x100 pixels image with patches of 3x3 pixels.
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# height = 2750
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# width = 1950
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height = 1502
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width = 1738
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patch_size = 12
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# Set r to a value that gives sufficient difference.
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# Note: r is the threshold for squared difference per channel, and the condition is
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# |c - c_neighbor| >= sqrt(r). Very high r may make it impossible to satisfy.
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r = 1000
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# 1 mm = 100 px: e.g. width_mm = px_to_mm(width); patch sizes in mm -> px with mm_to_px.
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# Column widths only (nonlinear for dome — left farther): patch_sizes_from_mm(
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# length_mm=px_to_mm(width), patch_mm_start=0.30, patch_mm_end=0.06, easing="dome"
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# )
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pattern = generate_color_pattern_varying_horizontal(
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height, width, patch_w_max_left=30, patch_w_min_right=6, r=r, easing="linear"
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)
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# pattern = generate_color_pattern(height, width, patch_size, r)
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# Scale to 0-255 for display and saving.
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pattern_display = (pattern * 255).astype(np.uint8)
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draw_center_cross_bgr(pattern_display)
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# Display the pattern with OpenCV.
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cv2.imshow('Pattern', pattern_display)
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cv2.waitKey(0)
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cv2.destroyAllWindows()
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# Save the pattern as an image file.
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cv2.imwrite('color_pattern.png', pattern_display)
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if __name__ == '__main__':
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main()
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