Optimize images in a directory to reasonable quality without killing space

optimizeImages.py

#!python3
"""
Opens all .jpg files in a folder and
downsamples them to maximum 1280 pixels wide
and quality level 75
"""

import glob
import os
from skimage.io import imread, imsave
from skimage.transform import rescale
import numpy as np

IGNORE_OPTIMIZE_LIST = frozenset([
    "logo.png",
])

def _getImage(filePath):
    """
    Tidy file return
    """
    try:
        if os.path.basename(filePath) in IGNORE_OPTIMIZE_LIST:
            return None
        return imread(filePath).astype(np.uint8)
    except Exception: #pylint: disable= broad-except
        return None

def downscaleJPGs(relativeDir:str= "./", maxResolution:int= 1280):
    """
    Opens all .jpg files in a folder and downscale them to
    maxResolution
    """
    for jpgFile in glob.glob(os.path.join(relativeDir, '*.jpg')):
        img = _getImage(jpgFile)
        if img is None:
            continue
        scale = maxResolution / max(img.shape[0], img.shape[1])
        if scale >= 1:
            print(f"{jpgFile} OK size")
            continue
        print(f"Checking {jpgFile}")
        img = rescale(img, scale, anti_aliasing= True, preserve_range= True, multichannel= True).astype(np.uint8)
        try:
            imsave(jpgFile, img)
        except Exception as e: #pylint: disable= broad-except
            print(f">> Failed to convert {jpgFile} of shape {img.shape}: {e}")


def optimizePNGs(relativeDir:str= "./", maxResolution:int= 1280):
    """
    Call this function to optimize all .png files in a folder
    """
    validPNG = set()
    for pngFile in glob.glob(os.path.join(relativeDir, '*.png')):
        img = _getImage(pngFile)
        if img is None:
            continue
        scale = maxResolution / max(img.shape[0], img.shape[1])
        if scale >= 1:
            print(f"{pngFile} OK size")
            validPNG.update([pngFile])
            continue
        print(f"Resizing {pngFile}")
        img = rescale(img, scale, anti_aliasing= True, preserve_range= True, multichannel= True).astype(np.uint8)
        try:
            imsave(pngFile, img)
            validPNG.update([pngFile])
        except Exception as e: #pylint: disable= broad-except
            print(f">> Failed to convert {pngFile} of shape {img.shape}: {e}")
    # Now call optiPNG locally to optimize the rescaled images
    for pngFile in validPNG:
        print(f"Optimizing {pngFile}")
        cmd = f"optipng -o5 -v {pngFile}"
        os.system(cmd)

if __name__ == "__main__":
    downscaleJPGs()
    optimizePNGs()