Webify a directory of images

webImages.py

#!python3
"""
When run as a script, opens all .jpg and .png
files in the folder and downsamples them to
maximum 1280 pixels wide and quality level 75

PNG optimization requires OptiPNG to be installed
in your PATH: http://optipng.sourceforge.net/
(GitHub mirror: https://github.com/countingpine/optipng )

@author Philip Kahn <https://github.com/tigerhawkvok/>
@license MIT
@url https://gist.github.com/tigerhawkvok/2d5ecd4a56235edc06ac8f96984fb5d6
"""

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

IGNORE_OPTIMIZE_LIST = frozenset([
    "logo.png",
    "fps_pfe_4x6.png",
])

def _getImage(filePath) -> Union[np.ndarray, None]:
    """
    Tidy file return.
    Renames the file if the extension doesn't match
    the filetype.
    """
    try:
        if os.path.basename(filePath) in IGNORE_OPTIMIZE_LIST:
            return None
        fileExtension = os.path.splitext(filePath)[1][1:]
        what = imghdr.what(filePath)
        filePathNew = None
        if what == "jpeg" and fileExtension.lower() not in ("jpg", "jpeg"):
            filePathNew = filePath.replace(f".{fileExtension}", ".jpg")
        elif what is not None and fileExtension.lower() != what:
            filePathNew = filePath.replace(f".{fileExtension}", f".{what}")
        if filePathNew is not None:
            # Rename the file with the corrected resolution
            os.rename(filePath, filePathNew)
            filePath = filePathNew
        return imread(filePath).astype(np.uint8)
    except Exception: #pylint: disable= broad-except
        return None

def downscaleJPGs(relativeDir:str= "./", maxResolution:int= 1280, quality:int= 75):
    """
    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, quality= quality)
        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__":
    TARGET_MAX_RESOLUTION_PX = 1280
    downscaleJPGs(maxResolution= TARGET_MAX_RESOLUTION_PX)
    optimizePNGs(maxResolution= TARGET_MAX_RESOLUTION_PX)