Files
BGfilter/bgfilter/despill.py
T
lhk229 7555321cfc Simplify to single-segmenter pipelines; add screen_color prior; drop rescue + recolor
Strategic pivot: the dropout-fill rescue, the anime-seg fill backend, the
BiRefNet+anime-seg intersection, and the recolor pass all existed to repair
source images whose hair was already green-contaminated or broken at generation
time. Fixing the source instead (clean pastel-background generation) makes the
matte high-contrast, so that whole compensation layer is unnecessary. Remove it.

- Two pipelines via segmentation.enabled:
    false -> chroma-only (Chroma + ViTMatte)
    true  -> single segmenter (default anime-seg, switchable birefnet) -> trimap
  then ViTMatte refines, pymatting estimates foreground, despill cleans spill.

- Generalise the green-hardcoded colour logic to a screen_color prior (hex, e.g.
  "#CFEFFF"; default null = green auto-detect, byte-identical). chroma keys off
  Lab/RGB distance to the colour; despill removes chroma along its Lab direction.
  Added --screen-color CLI flag.

- Removed dead code: fill_seg_dropouts + seg_fill*/intersection params,
  SegmentationSettings.fill_backend/fill_model_name/sharpen, unsharp_mask,
  recolor.py + RecolorSettings.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-07-01 15:33:58 +08:00

127 lines
5.0 KiB
Python

from __future__ import annotations
import numpy as np
from .chroma import BackgroundModel
from .settings import DespillSettings
def despill_green(
rgb: np.ndarray,
alpha: np.ndarray,
model: BackgroundModel,
settings: DespillSettings,
screen_color: tuple[float, float, float] | None = None,
) -> tuple[np.ndarray, np.ndarray]:
rgb_f = rgb.astype(np.float32) / 255.0
if not settings.enabled:
return rgb.copy(), np.zeros(alpha.shape, dtype=np.float32)
if screen_color is not None:
# Arbitrary background colour: despill along its Lab chroma direction.
return _despill_color(rgb, alpha, model, settings)
# (1) Despill across the whole foreground, not only the soft edge band.
# Green frequently bleeds into pixels ViTMatte marks as solid foreground
# (alpha ~ 1); the old upper bound left those uncorrected. Neutral pixels
# stay untouched because the green-excess term below is zero for them.
foreground = alpha > settings.edge_low
if settings.edge_expand_radius > 0:
from .deps import require_cv2
cv2 = require_cv2()
radius = settings.edge_expand_radius
kernel = cv2.getStructuringElement(
cv2.MORPH_ELLIPSE, (radius * 2 + 1, radius * 2 + 1)
)
foreground = cv2.dilate(foreground.astype(np.uint8), kernel).astype(bool)
r = rgb_f[..., 0]
g = rgb_f[..., 1]
b = rgb_f[..., 2]
neutral_green = np.maximum(r, b) + settings.green_excess_margin
excess = np.maximum(g - neutral_green, 0.0)
# (2) Keep full strength across the whole opaque range (alpha >= 0.5) and
# ease off only where the pixel is mostly transparent. The previous tent
# peaked at alpha 0.5 and starved exactly the solid hair that needs despill.
alpha_weight = np.maximum(
np.clip(alpha * 2.0, 0.0, 1.0), settings.alpha_weight_floor
)
# (3) Localise purely by green excess. bg_confidence is intentionally not a
# gate: it is low on the character edge where the spill lives, so using it
# suppressed the very correction we want.
green_weight = np.clip(excess / max(settings.green_excess_margin * 8.0, 1e-6), 0.0, 1.0)
mask = foreground.astype(np.float32) * alpha_weight * green_weight
out = rgb_f.copy()
target_green = np.minimum(g, neutral_green)
out[..., 1] = g * (1.0 - mask * settings.strength) + target_green * (
mask * settings.strength
)
# Light foreground color approximation: green spill usually removed too much
# luminance from thin hair edges, so redistribute part of the removed green
# into red/blue without changing fully opaque pixels.
bg_green = float(model.rgb_center[1])
compensation = excess * mask * settings.strength * min(0.25, bg_green * 0.15)
out[..., 0] = np.clip(out[..., 0] + compensation * 0.5, 0.0, 1.0)
out[..., 2] = np.clip(out[..., 2] + compensation * 0.5, 0.0, 1.0)
return np.clip(out * 255.0, 0, 255).astype(np.uint8), mask.astype(np.float32)
def _despill_color(
rgb: np.ndarray,
alpha: np.ndarray,
model: BackgroundModel,
settings: DespillSettings,
) -> tuple[np.ndarray, np.ndarray]:
"""Despill toward an arbitrary background colour.
Generalises the green channel algebra: the background's Lab a*/b* vector gives
a chroma direction; foreground chroma projecting along it beyond a margin is
treated as spill and pulled back, keeping luminance so texture survives. Reduces
to a green-style suppression when the background is a saturated primary, but also
handles low-chroma pastels where no single RGB channel dominates.
"""
from .deps import require_cv2
cv2 = require_cv2()
rgb_f = rgb.astype(np.float32) / 255.0
bg_lab = np.asarray(model.lab_center, dtype=np.float32)
va, vb = float(bg_lab[1]), float(bg_lab[2])
mag = float(np.hypot(va, vb))
if mag < 1e-3:
return rgb.copy(), np.zeros(alpha.shape, dtype=np.float32)
da, db = va / mag, vb / mag
foreground = alpha > settings.edge_low
if settings.edge_expand_radius > 0:
radius = settings.edge_expand_radius
kernel = cv2.getStructuringElement(
cv2.MORPH_ELLIPSE, (radius * 2 + 1, radius * 2 + 1)
)
foreground = cv2.dilate(foreground.astype(np.uint8), kernel).astype(bool)
lab = cv2.cvtColor(rgb_f, cv2.COLOR_RGB2LAB)
A, B = lab[..., 1], lab[..., 2]
proj = A * da + B * db # chroma toward the background hue
excess = np.maximum(proj - settings.color_margin_lab, 0.0)
alpha_weight = np.maximum(
np.clip(alpha * 2.0, 0.0, 1.0), settings.alpha_weight_floor
)
color_weight = np.clip(
excess / max(settings.color_margin_lab * 8.0, 1e-6), 0.0, 1.0
)
mask = foreground.astype(np.float32) * alpha_weight * color_weight
reduce = excess * mask * settings.strength # pull chroma back along the bg axis
lab_out = lab.copy()
lab_out[..., 1] = A - reduce * da
lab_out[..., 2] = B - reduce * db
out = cv2.cvtColor(lab_out, cv2.COLOR_LAB2RGB)
return np.clip(out * 255.0, 0, 255).astype(np.uint8), mask.astype(np.float32)