arguments to force 16 or 8 bit color
This commit is contained in:
Nathan
167
compress_pngs.py
167
compress_pngs.py
@@ -6,14 +6,21 @@ Compresses all PNG files in subdirectories with maximum parallelism.
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import os
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import sys
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import argparse
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from pathlib import Path
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from concurrent.futures import ProcessPoolExecutor, as_completed
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from PIL import Image
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import multiprocessing
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import time
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def compress_png(input_path, output_path):
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"""Compress a single PNG file."""
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def compress_png(input_path, output_path, force_bitdepth=None):
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"""Compress a single PNG file.
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Args:
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input_path: Path to input image
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output_path: Path to output image
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force_bitdepth: None (auto-detect), '8' (force 8-bit), or '16' (force 16-bit)
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"""
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try:
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input_path = Path(input_path)
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output_path = Path(output_path)
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@@ -32,56 +39,90 @@ def compress_png(input_path, output_path):
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original_size = os.path.getsize(input_path)
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img = Image.open(input_path)
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# Check if image is 16-bit
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# PIL represents 16-bit grayscale as 'I' mode (32-bit integer)
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# For color images, check pixel values to determine bit depth
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is_16bit = False
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original_mode = img.mode
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if img.mode == 'I':
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# 'I' mode typically represents 16-bit grayscale
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# Determine target bit depth
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if force_bitdepth == '8':
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is_16bit = False
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elif force_bitdepth == '16':
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is_16bit = True
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elif img.mode in ('RGB', 'RGBA', 'LA'):
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# Check if max pixel value exceeds 8-bit range
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try:
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# Get a sample of pixels to check
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pixels = list(img.getdata())
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if pixels:
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# Flatten if needed (for multi-channel modes)
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if isinstance(pixels[0], (tuple, list)):
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max_val = max(max(p) for p in pixels[:1000]) # Sample first 1000 pixels
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else:
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max_val = max(pixels[:1000])
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if max_val > 255:
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is_16bit = True
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except:
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# If we can't determine, assume 8-bit to be safe
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pass
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# Preserve 16-bit depth if present, otherwise convert as needed
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if is_16bit:
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# For 16-bit images, preserve the mode
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# PIL will save 16-bit when mode is 'I' (grayscale) or when using specific modes
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else:
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# Auto-detect bit depth
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is_16bit = False
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original_mode = img.mode
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if img.mode == 'I':
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# Keep 16-bit grayscale
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pass
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elif img.mode in ('RGB', 'RGBA'):
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# Keep color mode - PIL may preserve 16-bit depending on how it was loaded
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# Note: PIL's PNG save may convert 16-bit RGB to 8-bit, but we preserve the mode
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pass
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else:
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# Convert other modes while trying to preserve bit depth
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if 'A' in img.mode:
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# 'I' mode typically represents 16-bit grayscale
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is_16bit = True
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elif img.mode in ('RGB', 'RGBA', 'LA'):
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# Check if max pixel value exceeds 8-bit range
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try:
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# Get a sample of pixels to check
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pixels = list(img.getdata())
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if pixels:
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# Flatten if needed (for multi-channel modes)
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if isinstance(pixels[0], (tuple, list)):
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max_val = max(max(p) for p in pixels[:1000]) # Sample first 1000 pixels
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else:
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max_val = max(pixels[:1000])
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if max_val > 255:
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is_16bit = True
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except:
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# If we can't determine, assume 8-bit to be safe
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pass
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# Handle bit depth conversion based on target
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if is_16bit:
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# Force or preserve 16-bit
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if force_bitdepth == '16':
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# Force 16-bit: convert to appropriate 16-bit mode
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if img.mode == 'I':
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# Already 16-bit grayscale
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pass
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elif 'A' in img.mode or img.mode == 'LA':
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# Convert to 16-bit RGBA (PIL limitation: may not fully preserve 16-bit color)
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img = img.convert('RGBA')
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else:
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# Convert to 16-bit RGB
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img = img.convert('RGB')
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else:
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# Preserve existing 16-bit
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if img.mode == 'I':
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# Keep 16-bit grayscale
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pass
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elif img.mode in ('RGB', 'RGBA'):
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# Keep color mode - PIL may preserve 16-bit depending on how it was loaded
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pass
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else:
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# Convert other modes while trying to preserve bit depth
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if 'A' in img.mode:
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img = img.convert('RGBA')
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else:
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img = img.convert('RGB')
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else:
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# 8-bit images: convert as needed
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if img.mode == 'RGBA':
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# Keep RGBA for transparency support
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img = img.convert('RGBA')
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elif img.mode != 'RGB':
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img = img.convert('RGB')
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# Force or use 8-bit
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if force_bitdepth == '8':
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# Force 8-bit: ensure we're in 8-bit mode
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if img.mode == 'I':
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# Convert 16-bit grayscale to 8-bit
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img = img.convert('L')
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elif img.mode == 'RGBA':
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# Keep RGBA for transparency support (8-bit)
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img = img.convert('RGBA')
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elif img.mode == 'RGB':
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# Already 8-bit RGB
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pass
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else:
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# Convert to 8-bit RGB
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if 'A' in img.mode:
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img = img.convert('RGBA')
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else:
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img = img.convert('RGB')
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else:
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# 8-bit images: convert as needed
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if img.mode == 'RGBA':
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# Keep RGBA for transparency support
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img = img.convert('RGBA')
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elif img.mode != 'RGB':
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img = img.convert('RGB')
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# Save with maximum compression
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# PIL will preserve 16-bit for 'I' mode automatically
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@@ -139,6 +180,38 @@ def format_time(seconds):
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return f"{hours:02d}:{minutes:02d}:{secs:02d}:{centiseconds:02d}"
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def main():
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# Parse command-line arguments
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parser = argparse.ArgumentParser(
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description='Multithreaded PNG compression script with maximum parallelism.'
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)
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parser.add_argument(
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'--8bit', '-8',
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action='store_true',
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dest='force_8bit',
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help='Force 8-bit color depth for all images'
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)
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parser.add_argument(
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'--16bit', '-16',
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action='store_true',
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dest='force_16bit',
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help='Force 16-bit color depth for all images'
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)
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args = parser.parse_args()
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# Determine bit depth setting
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if args.force_8bit and args.force_16bit:
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print("Error: Cannot specify both --8bit and --16bit. Choose one.")
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return
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elif args.force_8bit:
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force_bitdepth = '8'
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print("Mode: Forcing 8-bit color depth")
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elif args.force_16bit:
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force_bitdepth = '16'
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print("Mode: Forcing 16-bit color depth")
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else:
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force_bitdepth = None
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print("Mode: Auto-detect bit depth (preserve 16-bit if present)")
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input_dir = Path('input')
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output_dir = Path('output')
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@@ -181,7 +254,7 @@ def main():
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with ProcessPoolExecutor(max_workers=max_workers) as executor:
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# Submit all tasks
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future_to_file = {
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executor.submit(compress_png, str(f), str(get_output_path(f, input_dir, output_dir))): f
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executor.submit(compress_png, str(f), str(get_output_path(f, input_dir, output_dir)), force_bitdepth): f
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for f in png_files
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}
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