Simple commandline sctipt to convert SVG to grayscale (without svg filters use)

gray_svg.py

import argparse
import xml.etree.ElementTree as ET
import os
import re

def rgb_to_grayscale(r, g, b):
    """Convert RGB to grayscale using the luminance formula."""
    return round(0.299 * r + 0.587 * g + 0.114 * b)

def hex_to_rgb(hex_color):
    """Convert hex color to RGB tuple."""
    hex_color = hex_color.lstrip('#')
    return tuple(int(hex_color[i:i + 2], 16) for i in (0, 2, 4))

def rgb_to_hex(r, g, b):
    """Convert RGB tuple to hex color."""
    return f'#{r:02x}{g:02x}{b:02x}'

def color_to_grayscale(color):
    """Convert hex color to grayscale hex color."""
    if not color.startswith('#') or len(color) not in (4, 7):
        return color
    if len(color) == 4:
        color = '#' + ''.join([c*2 for c in color[1:]])
    r, g, b = hex_to_rgb(color)
    gray = rgb_to_grayscale(r, g, b)
    return rgb_to_hex(gray, gray, gray)

def convert_svg_colors_to_grayscale(input_file, output_file):
    ET.register_namespace('', 'http://www.w3.org/2000/svg')

    tree = ET.parse(input_file)
    root = tree.getroot()

    # Function to traverse and convert colors in attributes
    def traverse_and_convert(element):
        style_found = 'style' in element.attrib
        if style_found:
            styles = element.attrib['style'].split(';')
            new_styles = []
            for style in styles:
                if ':' in style:
                    prop, value = style.split(':')
                    if value.strip().startswith('#'):
                        value = color_to_grayscale(value.strip())
                    new_styles.append(f'{prop}:{value}')
            element.attrib['style'] = ';'.join(new_styles)

        # Modify fill and stroke colors directly if they exist
        for color_attr in ['fill', 'stroke']:
            if color_attr in element.attrib:
                element.attrib[color_attr] = color_to_grayscale(element.attrib[color_attr])

        for child in element:
            traverse_and_convert(child)

    # Traverse and convert colors starting from root
    traverse_and_convert(root)

    # Write the tree back to the new file (with XML declaration and namespace)
    tree.write(output_file, encoding='utf-8', xml_declaration=True)

def main():
    parser = argparse.ArgumentParser(description='Convert all colors in an SVG file to grayscale.')
    parser.add_argument('input_file', help='The SVG file to process')
    args = parser.parse_args()

    input_file = args.input_file
    if not os.path.isfile(input_file):
        print(f"The file {input_file} does not exist.")
        return

    output_file = os.path.join(os.path.dirname(input_file), "out_" + os.path.basename(input_file))

    convert_svg_colors_to_grayscale(input_file, output_file)
    print(f"Converted SVG saved to {output_file}")

if __name__ == '__main__':
    main()