This program reads images from a folder named "images" and produces a long image by stacking those images together.

img-stack.py

# /// script
# requires-python = ">=3.4"
# dependencies = [
#     "opencv-python",
# ]
# ///

from pathlib import Path
import cv2
import numpy as np


def fit_resize(img: np.ndarray, new_width: int) -> np.ndarray:
    """Resize the image to the new width, keeping the aspect ratio.

    Args:
        img (np.ndarray): input image
        new_width (int): new width of the output image

    Returns:
        np.ndarray: resized image
    """
    height, width = img.shape[:2]
    new_height = height**2 // width
    return cv2.resize(img, (new_width, new_height))


def main(img_dir: Path) -> None:
    """Main function to resize images and stack them horizontally.

    Args:
        img_dir (Path): Path to the directory containing images.
    """

    # A container for all the images
    img_list: list[np.ndarray] = list()

    # Match ".jpg" and ".jpeg"
    for f in img_dir.glob("*.jp*g"):
        img = cv2.imread(str(f))
        img_list.append(img)

    # Get the minimum width of all the images
    min_width = min(img.shape[1] for img in img_list)

    # Resize all oversized images to the minimum width, and stack them horizontally
    output = cv2.vconcat(
        tuple(
            fit_resize(img, min_width) for img in img_list if img.shape[1] > min_width
        )
    )
    cv2.imwrite("output.jpg", output)


if __name__ == "__main__":
    # Run the main function with the "images" directory
    main(Path("images"))