Utility functions to resize, make square, and optimize (pngquant) images using Python

image_utils.py

from io import BytesIO
from subprocess import PIPE, Popen
from typing import Optional

from PIL import Image, ImageFile, UnidentifiedImageError
from PIL.Image import DecompressionBombError

SUPPORTED_IMAGE_FORMATS = ["PNG", "JPEG", "JPEG2000"]


def resize_png(image_data: bytes = None, size: int = None) -> Optional[bytes]:
    if not image_data:
        return None
    if not size:
        return None

    ImageFile.LOAD_TRUNCATED_IMAGES = True

    with BytesIO(image_data) as fh:
        try:
            image = Image.open(fh, formats=SUPPORTED_IMAGE_FORMATS)
        except (UnidentifiedImageError, DecompressionBombError):
            return None
        if image.mode != "RGB":
            image = image.convert("RGB")
        with BytesIO() as out:
            image.resize((size, size)).save(out, format="png")
            return out.getvalue()


def convert_image_to_png(image_data: bytes = None) -> Optional[bytes]:
    if not image_data:
        return None

    ImageFile.LOAD_TRUNCATED_IMAGES = True

    with BytesIO(image_data) as fh:
        try:
            image = Image.open(fh, formats=SUPPORTED_IMAGE_FORMATS)
        except (UnidentifiedImageError, DecompressionBombError):
            return None
        if image.mode != "RGB":
            image = image.convert("RGB")
        with BytesIO() as out:
            try:
                image.save(out, format="png")
            except OSError:
                return None
            return out.getvalue()


def make_image_square(image_data: bytes = None) -> Optional[bytes]:
    if not image_data:
        return None

    ImageFile.LOAD_TRUNCATED_IMAGES = True

    with BytesIO(image_data) as fh:
        try:
            image = Image.open(fh, formats=SUPPORTED_IMAGE_FORMATS)
        except (UnidentifiedImageError, DecompressionBombError):
            return None

        width, height = image.size
        if width == height:
            return image_data

        left, upper, right, lower = 0, 0, width, height

        diff = abs(width - height)
        if width < height:
            upper += int(diff / 2)
            lower -= int(diff / 2)
            if diff % 2 != 0:
                lower -= 1
        else:
            left += int(diff / 2)
            right -= int(diff / 2)
            if diff % 2 != 0:
                right -= 1

        with BytesIO() as out:
            image.crop((left, upper, right, lower)).save(out, format="png")
            return out.getvalue()


def optimize_png(image_data: bytes = None) -> Optional[bytes]:
    if not image_data:
        return None
    try:
        proc = Popen(["pngquant", "--strip", "-"], stdin=PIPE, stdout=PIPE, stderr=PIPE)
        (stdout, stderr) = proc.communicate(input=image_data)
        return stdout
    except:
        return image_data