Examples:

This is the main function signature: main(image_path: str, block_size=20, color=True, fast=True, height_reduction_factor=0.6)

Here are some examples:

main('image.jpg')

main('image.jpg', block_size=8)

main('image.jpg', color=False)

Fast version requires scipy. Howerver it won't raise an error if you try to run main with fast=True without scipy. You will just get a warning and it will run as if fast was set to False.
It is recommended not to change too much (0.4 - 0.6) the hight_reduction_factor parameter, otherwise the result will be distorted.
Honestly, this is just a small school project not worth your time. It is very limited and the results are often inaccurate. Even if programs allowing to convert a picture into structure based ASCI are rare, this one is incomplete as it only uses straight symbols. Consider using a CNN or a KNN algorithm if you want better results.