Generate ASCII art from bitmaps in python

convert.py

from PIL import Image

"""Credit: https://www.hackerearth.com/notes/beautiful-python-a-simple-ascii-art-generator-from-images/
One change: the scaled images width is doubled to create better ASCII art.
"""

ASCII_CHARS = [ '#', '?', '%', '.', 'S', '+', '.', '*', ':', ',', '@']

def scale_image(image, new_width):
    """Resizes an image preserving the aspect ratio.
    """
    (original_width, original_height) = image.size
    aspect_ratio = original_height/float(original_width)
    new_height = int(aspect_ratio * new_width)

    # This scales it wider than tall, since characters are biased
    new_image = image.resize((new_width*2, new_height))
    return new_image

def convert_to_grayscale(image):
    return image.convert('L')

def map_pixels_to_ascii_chars(image, range_width=25):
    """Maps each pixel to an ascii char based on the range
    in which it lies.

    0-255 is divided into 11 ranges of 25 pixels each.
    """

    pixels_in_image = list(image.getdata())
    pixels_to_chars = [ASCII_CHARS[int(pixel_value/range_width)] for pixel_value in
            pixels_in_image]

    return "".join(pixels_to_chars)

def convert_image_to_ascii(image, new_width):
    image = scale_image(image,new_width)
    image = convert_to_grayscale(image)

    pixels_to_chars = map_pixels_to_ascii_chars(image)
    len_pixels_to_chars = len(pixels_to_chars)

    image_ascii = [pixels_to_chars[index: index + new_width*2] for index in
            range(0, len_pixels_to_chars, new_width*2)]

    return "\n".join(image_ascii)

def handle_image_conversion(image_filepath,new_width=100):
    image = None
    try:
        image = Image.open(image_filepath)
    except Exception as e:
        print("Unable to open image file {image_filepath}.".format(image_filepath=image_filepath))
        print(e)
        return

    image_ascii = convert_image_to_ascii(image,new_width)
    print(image_ascii)
    return image_ascii

if __name__=='__main__':
    import sys

    image_file_path = sys.argv[1]
    handle_image_conversion(image_file_path)