Compressing images using libvips

compress_img.py

import os
import sys
import pyvips

options = {
  'Q': 75,
  'quant_table': 3,
  'interlace': True,
  'strip': True,
  'optimize_coding': True,
  'optimize_scans': True,
  'trellis_quant': True,
}

def transform(filename: str):
    image = pyvips.Image.new_from_file(filename, access='sequential')

    print('Compressing {} ...'.format(filename))
    dir = os.path.join(os.path.dirname(filename), 'dist')
    name, ext = os.path.splitext(os.path.basename(filename))
    output_filename = os.path.join(dir, '{}.{}'.format(name, 'jpg'))

    if ext == '.png':
        image.autorot().write_to_file(output_filename, **options)
    else:
        image.autorot().resize(0.5).write_to_file(output_filename, **options)


def is_image(f: str) -> bool:
    return f.endswith('jpg') or f.endswith('JPG') or f.endswith('png')


def transform_dir(dir: str):
    output_dir = os.path.join(dir, 'dist')
    os.makedirs(output_dir, exist_ok=True)

    images = [os.path.join(dir, f) for f in os.listdir(dir) if is_image(f)]
    for f in images:
        transform(f)


# Usage: python compress_img.py /path/to/dir
if __name__ == "__main__":
    dirs = [d for d in sys.argv[1:] if os.path.isdir(d)]
    for d in dirs:
        transform_dir(d)