Answer: Pixel Puzzle #227

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",
    "0033333000",
    "0034343000",
    "0033533000",
    "0033333000",
    "0006660000",
    "0006660000",
    "0006660000",
    "0000500000",
]
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: 2 × white, 5 × blue, 3 × white
• Row 4: 2 × white, 1 × blue, 1 × yellow, 1 × blue, 1 × yellow, 1 × blue, 3 × white
• Row 5: 2 × white, 2 × blue, 1 × navy, 2 × blue, 3 × white
• Row 6: 2 × white, 5 × blue, 3 × white
• Row 7: 3 × white, 3 × purple, 4 × white
• Row 8: 3 × white, 3 × purple, 4 × white
• Row 9: 3 × white, 3 × purple, 4 × white
• Row 10: 4 × white, 1 × navy, 5 × white