Definitions

ASCII (American Standard Code for Information Interchange)

• 7 bit character encoding
• Code 32 - 127 are printable characters
• Originally developed for use with teletypes
• Extended version with 8 bits also exists

Unicode (The Unicode Standard)

• Text encoding standard
• Capable of encoding more than 1.1 million characters
• Unicode has many encoding types, (UTF-8, UTF-16)
• UTF-8 backwards compatible with ASCII
• Includes Japanese characters, emojis etc

Shell

• Program that allows you to interact with the OS usually through CLI
• Bash, Zsh for example

Terminal

• The program where you type to execute commands
• Used to be a physical device with a keyboard
• Now commonly also known as teminal emulators
• The terminal is the environment which allows you to interact with the shell
• Modern terminals typically utilise Unicode
• Gnome Terminal for example

ANSI Escape Code

• Sequence of characters used to control the properties of text in a terminal
• Change text colour, background colour, text attributes etc

# Print Hello World in red in the terminal
printf "\033[31mHello World\033[m\n"

Demo

Image to ASCII

• Possible to convert image to ASCII based on intensity
• Greyscale/intensity to ASCII ramp

$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/|()1{}[]?-_+~<>i!lI;:,”^`’.

• ASCII characters on the left have larger density to appear more intense
• This depends on the typeset
• Width and height of character cell is usually not 1:1
• Need to double width to get a somewhat reasonable aspect ratio

• Below ASCII art was generated with the script in the Appendix
• Had to manually convert the coloured Tux using ansi2html command to display them nicely on the web

ASCII of Tux
                @@@@@@@@                
              @@@@@@@@hX*@              
              @@@@@@@@B@@@@             
             @@@@W@@@j[%@@@@            
             @x@w @@ @h @@@@            
             @@8@?+(>@@ @@@@            
              @\}?+i><<[@@@@            
              @v}?+<u((t@Bnh@           
             @@i-uYz}+:..@@@@@          
            @@  ^i>,.     @@@@@         
          @@@    .       ^'@@@@@@       
         @@@L:   ^     .:>!`@dB@@@      
        @h@.               ^.%h*B@@     
        M@]     '            @@@O@@@    
       @B@      ^             @@0@@@    
      @&ou      ^             @@M@@@$   
      |}8_      ^            YaB%aU@    
     |?-?)@m    '          r]}@@@@B-{   
 1???-----[@@@           `>x]}tLX(?_]   
 )---------?@@@          'iu[-?[]-___-{ 
 (?---------]n           @@u[________-]|
r}?----------}z@v    J@@@@@x]___-?{/xcM 
 purf/(1[?--](z@@@@@@@@@@@MY/)1(tvC     
         CzucQa            bmQLQZ     



ASCII of Tux with ANSI colour

                @@@@@@@@                
              @@@@@@@@hX*@              
              @@@@@@@@B@@@@             
             @@@@W@@@j[%@@@@            
             @x@w @@ @h @@@@            
             @@8@?+(>@@ @@@@            
              @\}?+i><<[@@@@            
              @v}?+<u((t@Bnh@           
             @@i-uYz}+:..@@@@@          
            @@  ^i>,.     @@@@@         
          @@@    .       ^'@@@@@@       
         @@@L:   ^     .:>!`@dB@@@      
        @h@.               ^.%h*B@@     
        M@]     '            @@@O@@@    
       @B@      ^             @@0@@@    
      @&ou      ^             @@M@@@$   
      |}8_      ^            YaB%aU@    
     |?-?)@m    '          r]}@@@@B-{   
 1???-----[@@@           `>x]}tLX(?_]   
 )---------?@@@          'iu[-?[]-___-{ 
 (?---------]n           @@u[________-]|
r}?----------}z@v    J@@@@@x]___-?{/xcM 
 purf/(1[?--](z@@@@@@@@@@@MY/)1(tvC     
         CzucQa            bmQLQZ       


ASCII of Tux with ANSI background colour


                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        

Appendix

# Print out art to your terminal
import math
from enum import Enum
import cv2
import numpy as np

ASCII_RAMP = "$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\|()1{}[]?-_+~<>i!lI;:,\"^`'. "
RAMP_LEN = len(ASCII_RAMP)

class Render(Enum):
    ASCII          = 1
    RGB_ASCII      = 2
    RGB_BACKGROUND = 3

# Changes text colour
def ansi_rgb(r, g, b, c):
    return "\x1b[38;2;"+str(r)+";"+str(g)+";"+str(b)+"m"+c+"\x1b[0m"

# Changes background colour
def ansi_rgb_bg(r, g, b):
    return "\x1b[48;2;"+str(r)+";"+str(g)+";"+str(b)+"m \x1b[0m"

img = cv2.imread("tux.png", cv2.IMREAD_UNCHANGED)
img = cv2.resize(img, (0,0), fx=0.1, fy=0.05)

height, width, depth = img.shape

art = ""

render = Render.RGB_ASCII

for i in range(height):
    for j in range(width):
        r = img[i,j,2]
        g = img[i,j,1]
        b = img[i,j,0]
        a = img[i,j,3] if depth == 4 else 255
        if a == 0:
            r = g = b = 255
        grey = 0.299 * r + 0.587 * g + 0.114 * b 
        c = ASCII_RAMP[math.ceil((RAMP_LEN - 1) * grey / 255)] 
        if render == Render.ASCII:
            art += c
        elif render == Render.RGB_ASCII:
            art += ansi_rgb(r, g, b, c)
        elif render == Render.RGB_BACKGROUND:
            art += ansi_rgb_bg(r, g, b)

    art += "\n"

print(art)