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#!/usr/bin/env python3
import numpy as np
import cv2
import argparse
import os
def compute_sdf(img, n_px, bit_depth=8):
# Convert to binary image if not already
_, binary = cv2.threshold(img, 127, 255, cv2.THRESH_BINARY)
# Compute distance transform for both foreground and background
dist_transform_fg = cv2.distanceTransform(binary, cv2.DIST_L2, 5)
dist_transform_bg = cv2.distanceTransform(255 - binary, cv2.DIST_L2, 5)
# Combine to get signed distance field (positive outside, negative inside)
sdf = dist_transform_fg - dist_transform_bg
# Clip to ±n_px range
sdf = np.clip(sdf, -n_px, n_px)
# Map from [-n_px, +n_px] to [0, 1]
sdf_normalized = (sdf + n_px) / (2 * n_px)
# Quantize to requested bit depth
if bit_depth == 8:
max_value = 255
dtype = np.uint8
elif bit_depth == 16:
max_value = 65535
dtype = np.uint16
else:
raise ValueError(f"Unsupported bit depth: {bit_depth}")
sdf_quantized = np.round(sdf_normalized * max_value).astype(dtype)
return sdf_quantized
def main():
parser = argparse.ArgumentParser(description='Generate SDF from black and white image with fixed range encoding')
parser.add_argument('input_images', nargs='+', help='Path to input image(s)')
parser.add_argument('--n_px', type=float, default=64.0,
help='Maximum distance to encode in pixels (default: 64)')
parser.add_argument('--bit_depth', type=int, default=8, choices=[8, 16],
help='Output bit depth (default: 8)')
args = parser.parse_args()
# Process each input image
for input_path in args.input_images:
# Get input and output paths
filename, ext = os.path.splitext(input_path)
output_path = f"{filename}-sdf{ext}"
# Read input image
img = cv2.imread(input_path, cv2.IMREAD_GRAYSCALE)
if img is None:
print(f"Error: Could not read image {input_path}")
continue
# Compute SDF with fixed range
sdf = compute_sdf(img, args.n_px, args.bit_depth)
# Save result
if args.bit_depth == 16:
# For 16-bit images, ensure proper saving
cv2.imwrite(output_path, sdf)
else:
cv2.imwrite(output_path, sdf)
print(f"SDF generated and saved to {output_path} (±{args.n_px}px range, {args.bit_depth}-bit)")
print(f" Decoding: 0.5 = contour, 0.0 = -{args.n_px}px (inside), 1.0 = +{args.n_px}px (outside)")
if __name__ == "__main__":
main()
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