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sumitchatterjee13-Luminance…/luminance_stack_processor.py
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"""
Luminance Stack Processor - Professional ComfyUI Custom Nodes
Implements HDR processing using the Debevec Algorithm for multiple exposure fusion
Author: Sumit Chatterjee
Version: 1.0.1
Semantic Versioning: MAJOR.MINOR.PATCH
"""
import numpy as np
import torch
import cv2
from typing import Tuple, List, Optional
import logging
import os
# Try to import HDRutils for alternative HDR processing
try:
import HDRutils
HDRUTILS_AVAILABLE = True
except ImportError:
HDRUTILS_AVAILABLE = False
# Try to import imageio for HDR/EXR support
try:
import imageio.v3 as iio
IMAGEIO_AVAILABLE = True
except ImportError:
try:
import imageio as iio
IMAGEIO_AVAILABLE = True
except ImportError:
IMAGEIO_AVAILABLE = False
# Set up logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)
def tensor_to_cv2(tensor: torch.Tensor) -> np.ndarray:
"""Convert ComfyUI tensor to OpenCV format for HDR processing
IMPORTANT: OpenCV's Debevec and Robertson algorithms expect 8-bit sRGB images as input.
They internally recover the camera response function, so we should NOT pre-linearize the images.
"""
# ComfyUI tensors are typically [B, H, W, C] in 0-1 range
if len(tensor.shape) == 4:
tensor = tensor.squeeze(0) # Remove batch dimension
# Convert to numpy
image = tensor.cpu().numpy()
# Convert to 8-bit sRGB (no gamma correction - Debevec/Robertson expect sRGB input)
image_8bit = np.clip(image * 255.0, 0, 255).astype(np.uint8)
logger.info(f"Converted to OpenCV: shape={image_8bit.shape}, dtype={image_8bit.dtype}, range=[{image_8bit.min()}, {image_8bit.max()}]")
return image_8bit
def cv2_to_tensor(hdr_image: np.ndarray, output_16bit_linear: bool = True, algorithm_hint: str = "unknown") -> torch.Tensor:
"""Convert OpenCV HDR image to ComfyUI tensor format - VFX pipeline friendly"""
if output_16bit_linear:
logger.info(f"HDR processing ({algorithm_hint}):")
logger.info(f" Input range: [{hdr_image.min():.6f}, {hdr_image.max():.6f}]")
# VFX PIPELINE APPROACH: Different scaling philosophy per algorithm
if algorithm_hint == "natural_blend":
# Natural Blend: Conservative scaling, values 1-5 range
p90 = np.percentile(hdr_image, 90.0)
if p90 > 0:
hdr_linear = hdr_image * (2.0 / p90)
else:
hdr_linear = hdr_image * 2.0
hdr_linear = np.clip(hdr_linear, 0.0, 8.0)
elif algorithm_hint == "mertens":
# Mertens: Medium HDR range, values 1-10 range
p85 = np.percentile(hdr_image, 85.0)
if p85 > 0:
hdr_linear = hdr_image * (3.0 / p85)
else:
hdr_linear = hdr_image * 3.0
hdr_linear = np.clip(hdr_linear, 0.0, 12.0)
elif algorithm_hint in ["debevec", "robertson"]:
# VFX PIPELINE: Raw linear radiance values
# IMPORTANT: The flat/desaturated appearance is CORRECT for professional VFX
# This is linear radiance data meant for compositing, not direct viewing
logger.info(f" Processing VFX linear radiance - flat appearance is CORRECT for compositing")
# VFX STANDARD: Minimal scaling for professional flat log appearance
if hdr_image.max() > 0:
# Research-based scaling: Use median (50th percentile) as reference
# This creates the proper flat log appearance VFX artists expect
p50 = np.percentile(hdr_image, 50.0) # Middle gray reference
if p50 > 0:
# Scale to VFX standard: 18% gray = 0.18 (professional standard)
# This creates the flat, log-like appearance
scale_factor = 0.18 / p50
hdr_linear = hdr_image * scale_factor
# VFX RANGE: Allow wide dynamic range (no aggressive clipping)
# Professional VFX needs values up to 100+ for bright sources
hdr_linear = np.clip(hdr_linear, 0.0, 2000.0) # Wide range for VFX work
logger.info(f" VFX scaling applied: middle gray -> 0.18 (scale: {scale_factor:.3f})")
else:
hdr_linear = hdr_image
logger.info(f" No scaling needed - preserving original values")
else:
hdr_linear = hdr_image
logger.info(f" Zero image detected - no processing applied")
logger.info(f" VFX FLAT LOG: Appearance will be flat/desaturated - this is PROFESSIONAL STANDARD")
else:
# Unknown algorithm - conservative approach
hdr_linear = np.clip(hdr_image * 2.0, 0.0, 10.0)
logger.info(f" Final HDR range: [{hdr_linear.min():.6f}, {hdr_linear.max():.6f}]")
logger.info(f" Max value: {hdr_linear.max():.2f} (VFX raw data)")
# Convert to ComfyUI format: [1, H, W, C] - NO NORMALIZATION!
if len(hdr_linear.shape) == 3:
tensor = torch.from_numpy(hdr_linear.astype(np.float32)).unsqueeze(0)
else:
tensor = torch.from_numpy(hdr_linear.astype(np.float32))
return tensor.float()
else:
# Standard 8-bit conversion (fallback)
image_8bit = np.clip(hdr_image * 255.0, 0, 255).astype(np.uint8)
normalized = image_8bit.astype(np.float32) / 255.0
if len(normalized.shape) == 3:
tensor = torch.from_numpy(normalized).unsqueeze(0)
else:
tensor = torch.from_numpy(normalized)
return tensor.float()
class DebevecHDRProcessor:
"""Core HDR processing using multiple algorithms"""
def __init__(self):
self.calibrator = cv2.createCalibrateDebevec()
self.merge_debevec = cv2.createMergeDebevec()
# Alternative algorithms
self.merge_mertens = cv2.createMergeMertens()
self.merge_robertson = cv2.createMergeRobertson()
self.calibrator_robertson = cv2.createCalibrateRobertson()
def process_hdr(self, images: List[np.ndarray], exposure_times: List[float], algorithm: str = "natural_blend") -> np.ndarray:
"""
Process multiple exposure images using various HDR algorithms
VFX PIPELINE NOTE:
- Debevec/Robertson expect 8-bit sRGB input (NOT linearized)
- They output linear radiance values (physical light intensity)
- The output will look flat/desaturated - this is CORRECT for VFX
Args:
images: List of 8-bit sRGB images (0-255 range) - DO NOT pre-linearize!
exposure_times: List of exposure times in seconds
algorithm: HDR algorithm to use:
- "natural_blend": Preserves EV0 look with enhanced range
- "mertens": Exposure fusion (display-ready)
- "debevec": True HDR recovery (flat/linear for VFX)
- "robertson": Alternative HDR recovery (flat/linear for VFX)
Returns:
HDR merged image in linear radiance space (float32)
- For Debevec/Robertson: Raw linear radiance (can exceed 1.0)
- For Mertens/Natural: Display-oriented fusion (0-1 range typical)
"""
try:
# Validate input format - OpenCV HDR functions require 8-bit input
processed_images = []
for i, img in enumerate(images):
if img.dtype != np.uint8:
logger.warning(f"Image {i} is not 8-bit (dtype: {img.dtype}), this may cause issues")
# Handle color channels properly
if len(img.shape) == 3 and img.shape[2] == 3: # 3-channel image
# CRITICAL FIX: ALL OpenCV functions work with BGR internally
# ComfyUI provides RGB, so we MUST convert for ALL algorithms
img_bgr = cv2.cvtColor(img, cv2.COLOR_RGB2BGR)
processed_images.append(img_bgr)
logger.info(f"Converting RGB to BGR for {algorithm} (OpenCV standard)")
else:
logger.error(f"Image {i} has invalid shape: {img.shape}")
raise ValueError(f"Image must be 3-channel RGB, got shape: {img.shape}")
# Convert exposure times to numpy array
times = np.array(exposure_times, dtype=np.float32)
logger.info(f"Processing {len(processed_images)} images with {algorithm} algorithm")
logger.info(f"Exposure times: {times}")
logger.info(f"Image formats: {[img.shape for img in processed_images]}")
logger.info(f"Image dtypes: {[img.dtype for img in processed_images]}")
# Process using selected algorithm
if algorithm == "mertens":
# Mertens Exposure Fusion - uses original gamma, no correction needed
logger.info("Using Mertens Exposure Fusion algorithm...")
hdr_radiance = self.merge_mertens.process(processed_images)
# Mertens output is typically in 0-1 range, gently scale for HDR
if hdr_radiance.max() <= 1.0:
hdr_radiance = hdr_radiance * 1.5 # Gentle boost, preserve contrast
elif algorithm == "natural_blend":
# Natural Blend - maintains EV0 appearance with enhanced dynamic range
logger.info("Using Natural Blend exposure blending...")
# Natural blend works with RGB images directly (no BGR conversion needed)
hdr_radiance = self._blend_ev0_preserving(processed_images, times)
elif algorithm == "hdrutils" and HDRUTILS_AVAILABLE:
# Use HDRutils library for HDR merging
logger.info("Using HDRutils library for HDR merging...")
hdr_radiance = self._merge_with_hdrutils(processed_images, times)
elif algorithm == "robertson":
# Robertson algorithm - VFX pipeline style (raw linear radiance)
logger.info("Using Robertson algorithm - VFX pipeline mode...")
response = self.calibrator_robertson.process(processed_images, times)
hdr_radiance = self.merge_robertson.process(processed_images, times, response)
logger.info(f"Robertson raw radiance range: [{hdr_radiance.min():.6f}, {hdr_radiance.max():.6f}]")
# VFX PIPELINE: NO TONE MAPPING! Keep raw linear radiance
if hdr_radiance.max() > 1000.0: # Only if extremely bright values
scale_factor = 100.0 / np.percentile(hdr_radiance, 99.5)
hdr_radiance = hdr_radiance * scale_factor
logger.info(f"Applied minimal scaling for numerical stability: {scale_factor:.3f}")
logger.info(f"Robertson VFX output range: [{hdr_radiance.min():.6f}, {hdr_radiance.max():.6f}]")
else: # Default to Debevec - VFX pipeline style (raw linear radiance)
# Estimate camera response function using Debevec method
logger.info("Using Debevec algorithm - VFX pipeline mode (raw linear radiance)...")
response = self.calibrator.process(processed_images, times)
logger.info(f"Response function shape: {response.shape}")
# Merge images into HDR using Debevec algorithm
# Debevec outputs linear radiance values (already in linear space)
hdr_radiance = self.merge_debevec.process(processed_images, times, response)
logger.info(f"Debevec raw radiance range: [{hdr_radiance.min():.6f}, {hdr_radiance.max():.6f}]")
# VFX PIPELINE: The output is already in linear space (raw radiance values)
# Keep raw linear radiance for professional VFX workflow
# Only apply minimal scaling if needed for numerical stability
if hdr_radiance.max() > 1000.0: # Only if extremely bright values
scale_factor = 100.0 / np.percentile(hdr_radiance, 99.5)
hdr_radiance = hdr_radiance * scale_factor
logger.info(f"Applied minimal scaling for numerical stability: {scale_factor:.3f}")
logger.info(f"Debevec VFX output (linear radiance): [{hdr_radiance.min():.6f}, {hdr_radiance.max():.6f}]")
# Validate HDR output
if hdr_radiance is None or hdr_radiance.size == 0:
raise ValueError("HDR merge produced empty result")
logger.info(f"HDR merge completed with {algorithm} algorithm:")
logger.info(f" Output shape: {hdr_radiance.shape}")
logger.info(f" Output dtype: {hdr_radiance.dtype}")
logger.info(f" Value range: [{hdr_radiance.min():.6f}, {hdr_radiance.max():.6f}]")
logger.info(f" Mean value: {hdr_radiance.mean():.6f}")
# Check for valid HDR data
if np.all(hdr_radiance == 0):
raise ValueError("HDR merge produced all-zero result")
# CRITICAL: Convert BGR back to RGB for ALL algorithms
# All OpenCV functions output BGR, but ComfyUI needs RGB
if len(hdr_radiance.shape) == 3 and hdr_radiance.shape[2] == 3:
hdr_radiance = cv2.cvtColor(hdr_radiance, cv2.COLOR_BGR2RGB)
logger.info("Converting BGR back to RGB for ComfyUI output")
# The result is already in linear colorspace - preserve HDR data
return hdr_radiance.astype(np.float32)
except Exception as e:
logger.error(f"HDR processing error: {str(e)}")
logger.error(f"Image count: {len(images)}")
logger.error(f"Image shapes: {[img.shape if img is not None else 'None' for img in images]}")
logger.error(f"Exposure times: {exposure_times}")
# Fallback: return the middle exposure image in linear space
if images:
middle_idx = len(images) // 2
fallback = images[middle_idx].astype(np.float32) / 255.0
# Convert back to linear space (reverse gamma correction)
fallback_linear = np.where(fallback <= 0.04045,
fallback / 12.92,
np.power((fallback + 0.055) / 1.055, 2.4))
logger.info(f"Using fallback image (index {middle_idx})")
return fallback_linear.astype(np.float32)
raise e
def _gentle_tone_map(self, hdr_image: np.ndarray, algorithm_name: str) -> np.ndarray:
"""
Apply gentle tone mapping to preserve HDR range while making output usable
Args:
hdr_image: Raw HDR output from Debevec/Robertson
algorithm_name: Name of algorithm for logging
Returns:
Gently processed HDR image with preserved dynamic range
"""
logger.info(f"{algorithm_name} raw output range: [{hdr_image.min():.6f}, {hdr_image.max():.6f}]")
try:
# Gentle processing to preserve HDR range but make it usable
# Method 1: Simple scaling based on percentiles (preserves HDR better than Reinhard)
p95 = np.percentile(hdr_image, 95)
p05 = np.percentile(hdr_image, 5)
if p95 > p05 and p95 > 0:
# Scale so 95th percentile maps to reasonable value (1.0-3.0 range)
scale_factor = 2.0 / p95
scaled = hdr_image * scale_factor
# Apply very gentle gamma correction to improve appearance
gentle_gamma = np.power(np.clip(scaled, 0, 10), 0.8)
logger.info(f"{algorithm_name} after gentle processing: [{gentle_gamma.min():.6f}, {gentle_gamma.max():.6f}]")
return gentle_gamma.astype(np.float32)
else:
# Fallback for edge cases
return np.clip(hdr_image, 0.0, 10.0).astype(np.float32)
except Exception as e:
logger.error(f"Gentle tone mapping failed for {algorithm_name}: {e}")
# Fallback: simple clipping
return np.clip(hdr_image, 0.0, 10.0).astype(np.float32)
def _blend_ev0_preserving(self, images: List[np.ndarray], times: List[float]) -> np.ndarray:
"""
Improved exposure blending that strongly preserves EV0 appearance
This method uses weighted averaging based on pixel quality metrics
to maintain the EV0 look while extending dynamic range.
Args:
images: List of exposure images in BGR format (from OpenCV)
times: Exposure times
Returns:
Enhanced image that looks very close to EV0 but with extended dynamic range
"""
logger.info("Natural Blend: Strongly preserving EV0 appearance")
# Find the EV0 image (middle exposure)
ev0_idx = len(images) // 2
ev0_base = images[ev0_idx].astype(np.float32) / 255.0
logger.info(f"Using image {ev0_idx} as EV0 base (out of {len(images)} images)")
# Convert all images to float
float_images = [img.astype(np.float32) / 255.0 for img in images]
# Calculate weights for each pixel in each exposure
weights = []
for i, img in enumerate(float_images):
# Weight based on distance from EV0
distance_weight = 1.0 / (1.0 + abs(i - ev0_idx))
# Weight based on well-exposed pixels (avoid under/over exposed)
# Well exposed pixels are those in the 0.1-0.9 range
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
well_exposed = np.exp(-12.5 * np.power(gray - 0.5, 2))
# Combine weights, giving strong preference to EV0
if i == ev0_idx:
weight = well_exposed * 5.0 # Strong preference for EV0
else:
weight = well_exposed * distance_weight * 0.3 # Gentle contribution from others
weights.append(weight)
# Stack weights and normalize
weight_stack = np.stack(weights, axis=-1)
weight_sum = np.sum(weight_stack, axis=-1, keepdims=True)
weight_stack = weight_stack / (weight_sum + 1e-10)
# Weighted blend of all exposures
result = np.zeros_like(ev0_base)
for i, img in enumerate(float_images):
for c in range(3): # RGB channels
result[:, :, c] += img[:, :, c] * weight_stack[:, :, i]
logger.info("Natural Blend completed - EV0 appearance strongly preserved")
# Apply very gentle tone curve to enhance contrast slightly
# This helps maintain the original look while utilizing the extended data
result = np.power(result, 0.95) # Very subtle gamma adjustment
return np.clip(result, 0.0, 1.0).astype(np.float32)
def _merge_with_hdrutils(self, images: List[np.ndarray], times: List[float]) -> np.ndarray:
"""
Use HDRutils library for HDR merging if available
Args:
images: List of 8-bit images
times: Exposure times
Returns:
HDR merged image
"""
try:
# Convert images to the format HDRutils expects
# HDRutils typically expects RGB format
rgb_images = []
for img in images:
if len(img.shape) == 3 and img.shape[2] == 3:
# Convert BGR to RGB for HDRutils
rgb_img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
rgb_images.append(rgb_img)
else:
rgb_images.append(img)
# Stack images for HDRutils
image_stack = np.stack(rgb_images, axis=0)
# Create HDR merge using HDRutils
# Note: HDRutils.merge might have different parameters
# This is a generic implementation
hdr_image = HDRutils.merge(image_stack, times)
logger.info(f"HDRutils merge complete: range [{hdr_image.min():.6f}, {hdr_image.max():.6f}]")
return hdr_image.astype(np.float32)
except Exception as e:
logger.error(f"HDRutils merge failed: {e}")
logger.info("Falling back to Mertens algorithm")
# Fallback to Mertens
return self.merge_mertens.process(images)
def _create_highlight_mask(self, gray_image: np.ndarray, threshold: float = 0.8) -> np.ndarray:
"""Create a mask for highlight areas that need detail recovery"""
# Smooth transition for highlights
mask = np.zeros_like(gray_image, dtype=np.float32)
# Areas above threshold get progressively more blending
bright_areas = gray_image > threshold
if np.any(bright_areas):
mask[bright_areas] = (gray_image[bright_areas] - threshold) / (1.0 - threshold)
# Smooth the mask to avoid harsh transitions with larger kernel
mask = cv2.GaussianBlur(mask, (41, 41), 0)
return np.clip(mask, 0, 1)
def _create_shadow_mask(self, gray_image: np.ndarray, threshold: float = 0.2) -> np.ndarray:
"""Create a mask for shadow areas that need detail recovery"""
# Smooth transition for shadows
mask = np.zeros_like(gray_image, dtype=np.float32)
# Areas below threshold get progressively more blending
dark_areas = gray_image < threshold
if np.any(dark_areas):
mask[dark_areas] = (threshold - gray_image[dark_areas]) / threshold
# Smooth the mask to avoid harsh transitions with larger kernel
mask = cv2.GaussianBlur(mask, (41, 41), 0)
return np.clip(mask, 0, 1)
class LuminanceStackProcessor3Stops:
"""
Professional ComfyUI Custom Node for 3-stop HDR processing
Processes EV+2, EV+0, EV-2 exposures using multiple algorithms
VFX PIPELINE NOTE:
When using Debevec/Robertson algorithms, the output will be linear radiance
values that look flat/desaturated. This is the correct format for professional
VFX compositing and should be saved as 16-bit EXR.
"""
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"ev_plus_2": ("IMAGE",),
"ev_0": ("IMAGE",),
"ev_minus_2": ("IMAGE",),
},
"optional": {
"exposure_step": ("FLOAT", {
"default": 2.0,
"min": 0.5,
"max": 5.0,
"step": 0.1,
"display": "number"
}),
"hdr_algorithm": (["natural_blend", "mertens", "debevec", "robertson"] + (["hdrutils"] if HDRUTILS_AVAILABLE else []), {
"default": "natural_blend"
}),
}
}
RETURN_TYPES = ("IMAGE",)
RETURN_NAMES = ("hdr_image",)
FUNCTION = "process_3_stop_hdr"
CATEGORY = "image/luminance"
def __init__(self):
self.processor = DebevecHDRProcessor()
def process_3_stop_hdr(self, ev_plus_2, ev_0, ev_minus_2, exposure_step=2.0, hdr_algorithm="natural_blend"):
"""
Process 3-stop HDR merge
Args:
ev_plus_2: Overexposed image (+2 EV)
ev_0: Normal exposure image (0 EV)
ev_minus_2: Underexposed image (-2 EV)
exposure_step: EV step size
Returns:
Tuple containing merged HDR image
"""
try:
# Convert tensors to 8-bit sRGB images (no gamma correction needed)
# Debevec/Robertson algorithms expect sRGB input and output linear radiance
img_plus_2 = tensor_to_cv2(ev_plus_2)
img_0 = tensor_to_cv2(ev_0)
img_minus_2 = tensor_to_cv2(ev_minus_2)
logger.info(f"Processing 3-stop HDR with {hdr_algorithm} algorithm")
# Calculate exposure times based on EV values
# EV difference formula: time = base_time * 2^(-EV_difference)
base_time = 1.0 / 60.0 # 1/60s as base exposure
time_plus_2 = base_time * (2.0 ** (-exposure_step)) # Shorter time (overexposed)
time_0 = base_time # Normal exposure
time_minus_2 = base_time * (2.0 ** exposure_step) # Longer time (underexposed)
images = [img_plus_2, img_0, img_minus_2]
times = [time_plus_2, time_0, time_minus_2]
logger.info(f"3-Stop HDR: Processing with times {times} using {hdr_algorithm} algorithm")
# Process HDR using selected algorithm - each should produce DIFFERENT results
hdr_result = self.processor.process_hdr(images, times, algorithm=hdr_algorithm)
logger.info(f"3-Stop HDR result range before tensor conversion: [{hdr_result.min():.6f}, {hdr_result.max():.6f}]")
# Convert back to tensor with TRUE HDR values (above 1.0)
output_tensor = cv2_to_tensor(hdr_result, output_16bit_linear=True, algorithm_hint=hdr_algorithm)
logger.info(f"3-Stop final tensor range (should be > 1.0 for HDR): [{output_tensor.min():.6f}, {output_tensor.max():.6f}]")
return (output_tensor,)
except Exception as e:
logger.error(f"3-Stop HDR processing failed: {str(e)}")
# Return middle exposure as fallback
return (ev_0,)
class LuminanceStackProcessor5Stops:
"""
Professional ComfyUI Custom Node for 5-stop HDR processing
Processes EV+4, EV+2, EV+0, EV-2, EV-4 exposures using multiple algorithms
VFX PIPELINE NOTE:
When using Debevec/Robertson algorithms, the output will be linear radiance
values that look flat/desaturated. This is the correct format for professional
VFX compositing and should be saved as 16-bit EXR.
"""
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"ev_plus_4": ("IMAGE",),
"ev_plus_2": ("IMAGE",),
"ev_0": ("IMAGE",),
"ev_minus_2": ("IMAGE",),
"ev_minus_4": ("IMAGE",),
},
"optional": {
"exposure_step": ("FLOAT", {
"default": 2.0,
"min": 0.5,
"max": 5.0,
"step": 0.1,
"display": "number"
}),
"hdr_algorithm": (["natural_blend", "mertens", "debevec", "robertson"] + (["hdrutils"] if HDRUTILS_AVAILABLE else []), {
"default": "natural_blend"
}),
}
}
RETURN_TYPES = ("IMAGE",)
RETURN_NAMES = ("hdr_image",)
FUNCTION = "process_5_stop_hdr"
CATEGORY = "image/luminance"
def __init__(self):
self.processor = DebevecHDRProcessor()
def process_5_stop_hdr(self, ev_plus_4, ev_plus_2, ev_0, ev_minus_2, ev_minus_4, exposure_step=2.0, hdr_algorithm="natural_blend"):
"""
Process 5-stop HDR merge
Args:
ev_plus_4: Most overexposed image (+4 EV)
ev_plus_2: Overexposed image (+2 EV)
ev_0: Normal exposure image (0 EV)
ev_minus_2: Underexposed image (-2 EV)
ev_minus_4: Most underexposed image (-4 EV)
exposure_step: EV step size
Returns:
Tuple containing merged HDR image
"""
try:
# Convert tensors to 8-bit sRGB images (no gamma correction needed)
# Debevec/Robertson algorithms expect sRGB input and output linear radiance
img_plus_4 = tensor_to_cv2(ev_plus_4)
img_plus_2 = tensor_to_cv2(ev_plus_2)
img_0 = tensor_to_cv2(ev_0)
img_minus_2 = tensor_to_cv2(ev_minus_2)
img_minus_4 = tensor_to_cv2(ev_minus_4)
logger.info(f"Processing 5-stop HDR with {hdr_algorithm} algorithm")
# Calculate exposure times based on EV values
base_time = 1.0 / 60.0 # 1/60s as base exposure
time_plus_4 = base_time * (2.0 ** (-2 * exposure_step))
time_plus_2 = base_time * (2.0 ** (-exposure_step))
time_0 = base_time
time_minus_2 = base_time * (2.0 ** exposure_step)
time_minus_4 = base_time * (2.0 ** (2 * exposure_step))
images = [img_plus_4, img_plus_2, img_0, img_minus_2, img_minus_4]
times = [time_plus_4, time_plus_2, time_0, time_minus_2, time_minus_4]
logger.info(f"5-Stop HDR: Processing with times {times} using {hdr_algorithm} algorithm")
# Process HDR using selected algorithm - each should produce DIFFERENT results
hdr_result = self.processor.process_hdr(images, times, algorithm=hdr_algorithm)
logger.info(f"5-Stop HDR result range before tensor conversion: [{hdr_result.min():.6f}, {hdr_result.max():.6f}]")
# Convert back to tensor with TRUE HDR values (above 1.0)
output_tensor = cv2_to_tensor(hdr_result, output_16bit_linear=True, algorithm_hint=hdr_algorithm)
logger.info(f"5-Stop final tensor range (should be > 1.0 for HDR): [{output_tensor.min():.6f}, {output_tensor.max():.6f}]")
return (output_tensor,)
except Exception as e:
logger.error(f"5-Stop HDR processing failed: {str(e)}")
# Return middle exposure as fallback
return (ev_0,)
class HDRExportNode:
"""
ComfyUI Custom Node for exporting HDR images to EXR format
Preserves full dynamic range data without normalization
VFX PIPELINE NOTE:
EXR files store linear radiance values (32-bit float per channel).
The flat/desaturated appearance of Debevec/Robertson output is correct.
Professional compositing software expects this linear format.
"""
@classmethod
def INPUT_TYPES(cls):
return {
"required": {
"hdr_image": ("IMAGE", {"tooltip": "HDR image tensor with values potentially above 1.0"}),
"filename_prefix": ("STRING", {"default": "HDR_Export", "tooltip": "Filename prefix for the EXR file"}),
"output_path": ("STRING", {"default": "", "tooltip": "Output directory (leave empty for ComfyUI output folder)"}),
}
}
RETURN_TYPES = ("STRING",)
RETURN_NAMES = ("filepath",)
FUNCTION = "export_hdr"
CATEGORY = "Luminance Stack Processor"
OUTPUT_NODE = True
def export_hdr(self, hdr_image: torch.Tensor, filename_prefix: str = "HDR_Export", output_path: str = ""):
"""
Export HDR image to EXR format preserving full dynamic range
Args:
hdr_image: HDR image tensor (potentially with values > 1.0)
filename_prefix: Base filename for the output
output_path: Output directory path
Returns:
Tuple containing the filepath of saved EXR
"""
try:
# Convert tensor to numpy array
if len(hdr_image.shape) == 4:
hdr_image = hdr_image.squeeze(0) # Remove batch dimension
hdr_array = hdr_image.cpu().numpy()
logger.info(f"HDR Export: Input range [{hdr_array.min():.6f}, {hdr_array.max():.6f}]")
logger.info(f"HDR Export: Shape {hdr_array.shape}, dtype {hdr_array.dtype}")
# Determine output path
if not output_path or output_path.strip() == "":
# Use ComfyUI's output directory
try:
import folder_paths
output_dir = folder_paths.get_output_directory()
except ImportError:
# Fallback if folder_paths module doesn't exist
output_dir = os.path.join(os.path.dirname(os.path.dirname(__file__)), "output")
except Exception:
# Secondary fallback
import os as os_module
output_dir = os_module.path.join(os_module.getcwd(), "output")
else:
output_dir = output_path.strip()
# Create output directory if it doesn't exist
os.makedirs(output_dir, exist_ok=True)
# Generate unique filename with timestamp
from datetime import datetime
timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
filename = f"{filename_prefix}_{timestamp}.exr"
filepath = os.path.join(output_dir, filename)
logger.info(f"HDR Export: Saving to {filepath}")
# Convert BGR to RGB if needed (OpenCV uses BGR)
if len(hdr_array.shape) == 3 and hdr_array.shape[2] == 3:
# Assume ComfyUI tensors are RGB, but OpenCV expects BGR for writing
hdr_bgr = cv2.cvtColor(hdr_array.astype(np.float32), cv2.COLOR_RGB2BGR)
else:
hdr_bgr = hdr_array.astype(np.float32)
# Save as EXR using OpenCV - this preserves HDR data!
success = cv2.imwrite(filepath, hdr_bgr)
if success:
# Verify the saved file
saved_stats = self._get_file_stats(filepath)
logger.info(f"HDR Export: Successfully saved EXR")
logger.info(f" File: {filepath}")
logger.info(f" Size: {saved_stats['size_mb']:.2f} MB")
logger.info(f" Dimensions: {saved_stats['width']}x{saved_stats['height']}")
logger.info(f" Channels: {saved_stats['channels']}")
# Verify HDR values are preserved
test_read = cv2.imread(filepath, cv2.IMREAD_ANYCOLOR | cv2.IMREAD_ANYDEPTH)
if test_read is not None:
logger.info(f" Verification: Saved range [{test_read.min():.6f}, {test_read.max():.6f}]")
if test_read.max() > 1.0:
logger.info(f" ✅ HDR data preserved (max value: {test_read.max():.2f})")
else:
logger.warning(f" ⚠️ HDR data may be clipped (max value: {test_read.max():.2f})")
return (filepath,)
else:
error_msg = f"Failed to save EXR file to {filepath}"
logger.error(f"HDR Export: {error_msg}")
raise RuntimeError(error_msg)
except Exception as e:
error_msg = f"HDR Export failed: {str(e)}"
logger.error(error_msg)
raise RuntimeError(error_msg)
def _get_file_stats(self, filepath: str) -> dict:
"""Get statistics about the saved file"""
try:
# File size
size_bytes = os.path.getsize(filepath)
size_mb = size_bytes / (1024 * 1024)
# Image dimensions using OpenCV
img = cv2.imread(filepath, cv2.IMREAD_ANYCOLOR | cv2.IMREAD_ANYDEPTH)
if img is not None:
height, width = img.shape[:2]
channels = img.shape[2] if len(img.shape) > 2 else 1
else:
width = height = channels = 0
return {
'size_mb': size_mb,
'width': width,
'height': height,
'channels': channels
}
except Exception:
return {
'size_mb': 0,
'width': 0,
'height': 0,
'channels': 0
}
# Node class mappings for ComfyUI
NODE_CLASS_MAPPINGS = {
"LuminanceStackProcessor3Stops": LuminanceStackProcessor3Stops,
"LuminanceStackProcessor5Stops": LuminanceStackProcessor5Stops,
"HDRExportNode": HDRExportNode
}
NODE_DISPLAY_NAME_MAPPINGS = {
"LuminanceStackProcessor3Stops": "Luminance Stack Processor (3 Stops)",
"LuminanceStackProcessor5Stops": "Luminance Stack Processor (5 Stops)",
"HDRExportNode": "HDR Export to EXR"
}