lhk229
c56e58affe
Backports master's non-flat matting (chroma.enabled: false + the hue-free cross-check gate) into server-edition, and exposes it over HTTP without surfacing the internal "chroma" wording: /remove-background gains a background_mode form field (flat, default | complex). complex maps to chroma disabled -- no colour key, segmentation alone drives the trimap and every colour-keyed stage (auto-detect, hue split, chroma suppression, despill) is bypassed. The cross-check veto still works in complex mode via its second-opinion-confidence gate (cross_check.second_lo/hi) but defaults OFF there (it costs the HR-matting forward); an explicit cross_check=on re-enables it. No new model weights: complex mode reuses the already-provisioned BiRefNet seg + ViTMatte (+ optional HR-matting cross-check). Flat mode is unchanged (bit-identical), and server-edition's own extras (cross_check.lock, foreground.use_gpu CuPy path) are preserved -- the port is surgical, not a copy of master's files. - settings: ChromaSettings.enabled, CrossCheckSettings.second_lo/hi - config: override_settings chroma passthrough - despill/foreground: model=None safe guards (foreground keeps GPU path) - alpha_post: cross_check_alpha hue-free gate when proj is None - pipeline: _process_rgb complex branch (seg-only trimap, skip colour stages) - service/app: process(chroma=), background_mode field, complex-defaults-off cross-check, X-BGFilter-Background-Mode header - cli: --chroma/--no-chroma - configs/docs: gpu.yaml + default.yaml + README/README_ZH Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
62 lines
2.7 KiB
Python
62 lines
2.7 KiB
Python
from __future__ import annotations
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import numpy as np
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from .chroma import BackgroundModel
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from .deps import require_cv2
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from .settings import DespillSettings
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def despill(
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rgb: np.ndarray,
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alpha: np.ndarray,
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model: BackgroundModel | None,
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settings: DespillSettings,
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) -> tuple[np.ndarray, np.ndarray]:
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"""Remove background-colour spill from the foreground.
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The background's Lab a*/b* vector gives a chroma direction; foreground chroma
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projecting along it beyond a margin is treated as spill and pulled back toward
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neutral, keeping luminance so hair texture and shading survive. This works for
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any flat background: a saturated primary (green/blue screen) reduces to classic
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channel suppression, while low-chroma pastels -- where no single RGB channel
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dominates -- are handled by the same projection.
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Returns the corrected RGB (uint8) and the per-pixel despill weight (float32).
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"""
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# model is None with chroma disabled: no key colour means no spill direction.
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if not settings.enabled or model is None:
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return rgb.copy(), np.zeros(alpha.shape, dtype=np.float32)
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bg_lab = np.asarray(model.lab_center, dtype=np.float32)
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va, vb = float(bg_lab[1]), float(bg_lab[2])
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mag = float(np.hypot(va, vb))
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if mag < 1e-3: # near-neutral background: no chroma direction, nothing to despill
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return rgb.copy(), np.zeros(alpha.shape, dtype=np.float32)
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da, db = va / mag, vb / mag
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cv2 = require_cv2()
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rgb_f = rgb.astype(np.float32) / 255.0
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foreground = alpha > settings.edge_low
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if settings.edge_expand_radius > 0:
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radius = settings.edge_expand_radius
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kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (radius * 2 + 1, radius * 2 + 1))
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foreground = cv2.dilate(foreground.astype(np.uint8), kernel).astype(bool)
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lab = cv2.cvtColor(rgb_f, cv2.COLOR_RGB2LAB)
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A, B = lab[..., 1], lab[..., 2]
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proj = A * da + B * db # chroma toward the background hue
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excess = np.maximum(proj - settings.color_margin_lab, 0.0)
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# Full strength across the opaque range; ease off only where mostly transparent.
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alpha_weight = np.maximum(np.clip(alpha * 2.0, 0.0, 1.0), settings.alpha_weight_floor)
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color_weight = np.clip(excess / max(settings.color_margin_lab * 8.0, 1e-6), 0.0, 1.0)
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mask = foreground.astype(np.float32) * alpha_weight * color_weight
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reduce = excess * mask * settings.strength # pull chroma back along the bg axis
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lab_out = lab.copy()
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lab_out[..., 1] = A - reduce * da
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lab_out[..., 2] = B - reduce * db
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out = cv2.cvtColor(lab_out, cv2.COLOR_LAB2RGB)
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return np.clip(out * 255.0, 0, 255).astype(np.uint8), mask.astype(np.float32)
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