Adding a new script to the Python Script series. In this article we will see how to convert the colored image to ASCII art.

Dependecies:

You will need to install pillow python package. It is recommended that you create a virtual environment using python3 if not created already. 

Once virtual environment is activated use command pip install pillow to install the package.

Steps:

We are performing below actions to generate the ascii art from image.

- Get an image path as command line argument.
- Open the image from provided path.
- Calculate the aspect ratio.
- Resize the image. Here we are taking new width as 120 pixels. Adjusting the new height as per aspect ratio.
- Convert the image into greyscale format.
- Get all the pixels of image. Replace pixles with intentsity in a defined range with a character from list.
- Print image and save to text file.

Code:

import sys
from PIL import Image


# pass the image as command line argument
image_path = sys.argv[1]
img = Image.open(image_path)

# resize the image
width, height = img.size
aspect_ratio = height/width
new_width = 120
new_height = aspect_ratio * new_width * 0.55
img = img.resize((new_width, int(new_height)))
# new size of image
# print(img.size)

# convert image to greyscale format
img = img.convert('L')

pixels = img.getdata()

# replace each pixel with a character from array
chars = ["B","S","#","&","@","$","%","*","!",":","."]
new_pixels = [chars[pixel//25] for pixel in pixels]
new_pixels = ''.join(new_pixels)

# split string of chars into multiple strings of length equal to new width and create a list
new_pixels_count = len(new_pixels)
ascii_image = [new_pixels[index:index + new_width] for index in range(0, new_pixels_count, new_width)]
ascii_image = "\n".join(ascii_image)
print(ascii_image)

# write to a text file.
with open("ascii_image.txt", "w") as f:
    f.write(ascii_image)

If you are getting an elongated image in terminal, you can adjust the height accordingly. I am generating new_height using formula new_height = aspect_ratio * new_width * 0.55.

Statement list(img.getdata()) returns the list intensity of all pixels. Value of intensity will be between 0 to 255. Lower the value, darker the color. That is why we have characters in char list arranged from higher intensity to lower intensity. 

Value of pixel//25 , where 25 is the intensity range for one character, can be between 0 to 11 i.e why there are 11 characters in chars list. You may keep more characters in list, lets say 16 characters and then keep the range size as 17. 

How to use script:

python3 script_name path_to_image

python3 image_to_ascii.py /home/Downloads/image.png