Rectify a portion of an image using OpenCV

rectify.py

import cv2
import numpy as np
import argparse


def warp_quadrilateral(
    input_path: str,
    src_points: list[tuple[int, int]],
    output_path: str,
    output_size: tuple[int, int],
):
    """
    Warps a quadrilateral from an input image to a rectangular output image.

    :param input_path: Path to the input image.
    :param src_points: Four coordinates specifying vertices of the quadrilateral in the input image.
                   Format: [(x1, y1), (x2, y2), (x3, y3), (x4, y4)]
    :param output_path: Path where the output image will be saved.
    :param output_size: Size of the output image (width, height).
    """
    image = cv2.imread(input_path)

    src = np.array(src_points, dtype="float32")

    dst = np.array(
        [
            [0, 0],
            [output_size[0] - 1, 0],
            [output_size[0] - 1, output_size[1] - 1],
            [0, output_size[1] - 1],
        ],
        dtype="float32",
    )

    transform_matrix = cv2.getPerspectiveTransform(src, dst)
    warped = cv2.warpPerspective(image, transform_matrix, output_size)

    cv2.imwrite(output_path, warped)


def parse_coordinates(coordinate_string: str) -> list[tuple[int, int]]:
    """
    Parses a coordinate string formatted as "x0,y0;x1,y1;x2,y2;x3,y3" into a list of tuples.
    """
    return [tuple(map(int, point.split(","))) for point in coordinate_string.split(";")]


def main():
    parser = argparse.ArgumentParser(
        description="Warp a quadrilateral from an input image to a rectangular output image."
    )
    parser.add_argument("input_path", type=str, help="Path to the input image.")
    parser.add_argument(
        "output_path", type=str, help="Path where the output image will be saved."
    )
    parser.add_argument(
        "coordinates",
        type=str,
        help="List of coordinates for the quadrilateral formatted as x0,y0;x1,y1;x2,y2;x3,y3.",
    )
    parser.add_argument(
        "output_size", type=str, help="Output size as a (width,height) tuple"
    )

    args = parser.parse_args()

    src_points = parse_coordinates(args.coordinates)
    output_size = tuple(map(int, args.output_size.split(",")))
    warp_quadrilateral(args.input_path, src_points, args.output_path, output_size)


if __name__ == "__main__":
    main()