Answer: Pixel Puzzle #216

The hidden picture is a robot!

The picture as Python

Here is the same picture stored as numbers in a Python list. The program reads each number and prints a symbol for it, so you can see the picture appear in the Python shell.

picture = [
    "0000110000",
    "0000220000",
    "0333333330",
    "0343333430",
    "0333333330",
    "0055555500",
    "0055555500",
    "0055555500",
    "0055555500",
    "0006006000",
]
symbols = " #@*o+="

for row in picture:
    line = ""
    for number in row:
        line = line + symbols[int(number)]
    print(line)

When you run it, it prints:

    ##
    @@
 ********
 *o****o*
 ********
  ++++++
  ++++++
  ++++++
  ++++++
   =  =

Squashing the picture smaller

Computers often save space with a trick called run-length encoding. Instead of storing every pixel, they count how many of the same colour are in a row. Here’s this picture written that way:

Show the run-length code

• Row 1: 4 × white, 2 × red, 4 × white
• Row 2: 4 × white, 2 × grey, 4 × white
• Row 3: 1 × white, 8 × orange, 1 × white
• Row 4: 1 × white, 1 × orange, 1 × yellow, 4 × orange, 1 × yellow, 1 × orange, 1 × white
• Row 5: 1 × white, 8 × orange, 1 × white
• Row 6: 2 × white, 6 × blue, 2 × white
• Row 7: 2 × white, 6 × blue, 2 × white
• Row 8: 2 × white, 6 × blue, 2 × white
• Row 9: 2 × white, 6 × blue, 2 × white
• Row 10: 3 × white, 1 × navy, 2 × white, 1 × navy, 3 × white