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Merge 3332e0949e into 1d1099bea0

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HK416-TYPED 2026-07-18 01:21:33 +08:00 committed by GitHub
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1 changed files with 33 additions and 3 deletions
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36
comfy_extras/nodes_images.py
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@ -902,6 +902,29 @@ def hlg_to_linear(t: torch.Tensor) -> torch.Tensor:
return torch.where(t <= 0.5, low, high)
# ARRI LogC4 constants (2022 specification).
_LOGC4_A = (2.0 ** 18 - 16.0) / 117.45
_LOGC4_B = (1023.0 - 95.0) / 1023.0
_LOGC4_C = 95.0 / 1023.0
_LOGC4_S = (7.0 * math.log(2.0) * 2.0 ** (7.0 - 14.0 * _LOGC4_C / _LOGC4_B)) / (_LOGC4_A * _LOGC4_B)
_LOGC4_T = (2.0 ** (14.0 * (-_LOGC4_C / _LOGC4_B) + 6.0) - 64.0) / _LOGC4_A
def logc4_to_linear(t: torch.Tensor) -> torch.Tensor:
"""Inverse ARRI LogC4 curve (2022 spec). Maps a LogC4-encoded signal in
[0, 1] to scene-linear light; highlights decode above 1.0. Piecewise: a
linear segment below the log cut, an exponential above.
Operates on RGB channels only; alpha is passed through unchanged."""
if t.shape[-1] == 4:
rgb, alpha = t[..., :3], t[..., 3:]
return torch.cat([logc4_to_linear(rgb), alpha], dim=-1)
high = (torch.exp2(14.0 * (t - _LOGC4_C) / _LOGC4_B + 6.0) - 64.0) / _LOGC4_A
low = t * _LOGC4_S + _LOGC4_T
return torch.where(t >= _LOGC4_C, high, low)
# ---------------------------------------------------------------------------
# Metadata injection
# ---------------------------------------------------------------------------
@ -1007,11 +1030,12 @@ def inject_exr_metadata(
new_blob += _exr_attribute(key, "string", json.dumps(value).encode("utf-8"))
if colorspace is not None:
# Map each colorspace option to the RGB primaries the linear pixels
# are now in. "sRGB" and "linear" both produce Rec. 709 linear; "HDR"
# (HLG-encoded Rec. 2020 input) produces Rec. 2020 linear.
# are now in. "sRGB", "LogC4" and "linear" all produce Rec. 709 linear;
# "HDR" (HLG-encoded Rec. 2020 input) produces Rec. 2020 linear.
primaries_name = {
"sRGB": "Rec.709",
"linear": "Rec.709",
"LogC4": "Rec.709",
"HDR": "Rec.2020",
}.get(colorspace, "Rec.709")
new_blob += _exr_attribute(
@ -1100,6 +1124,9 @@ def _encode_image(
"sRGB" → input is sRGB-encoded Rec. 709; apply inverse sRGB EOTF.
"HDR" → input is HLG-encoded Rec. 2020 (BT.2100); apply inverse HLG
OETF to get scene-linear, per BT.2100 Note 5a.
"LogC4" → input is ARRI LogC4-encoded Rec. 709; apply inverse LogC4 to
get scene-linear (highlights above 1.0). Use for HDR authored
or generated in LogC4 space.
"linear" → input is already scene-linear (Rec. 709 primaries); write
through unchanged. Use this for renderer/compositor output.
@ -1123,6 +1150,8 @@ def _encode_image(
img_tensor = srgb_to_linear(img_tensor)
elif colorspace == "HDR":
img_tensor = hlg_to_linear(img_tensor)
elif colorspace == "LogC4":
img_tensor = logc4_to_linear(img_tensor)
img_np = img_tensor.cpu().numpy().astype(np.float32)
else:
# PNG path: quantize to integer range.
@ -1180,13 +1209,14 @@ class SaveImageAdvanced(IO.ComfyNode):
IO.Combo.Input("bit_depth", options=["32-bit float"], default="32-bit float", advanced=True),
IO.Combo.Input(
"input_color_space",
options=["sRGB", "HDR", "linear"],
options=["sRGB", "HDR", "LogC4", "linear"],
default="sRGB",
advanced=True,
tooltip=(
"Colorspace of the input tensor. The EXR is always written as scene-linear in the matching gamut.\n"
"sRGB — input is sRGB-encoded Rec.709; the inverse sRGB EOTF is applied.\n"
"HDR — input is HLG-encoded Rec.2020 (BT.2100); the inverse HLG OETF is applied to get scene-linear light.\n"
"LogC4 — input is ARRI LogC4-encoded Rec.709; the inverse LogC4 curve is applied to get scene-linear light (highlights above 1.0). Use for HDR authored/generated in LogC4 space.\n"
"linear — input is already scene-linear (Rec.709 primaries); written through unchanged. Use this for renderer/compositor output."
),
),