Answer: Pixel Puzzle #328

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 = [
    "0000000110000000",
    "0000000220000000",
    "0003333333330000",
    "0003333333330000",
    "0003433333430000",
    "0003333333330000",
    "0003355555330000",
    "0003333333330000",
    "0000666666600000",
    "0000666666600000",
    "0000666666600000",
    "0000666666600000",
    "0000666666600000",
    "0000666666600000",
    "0000666666600000",
    "0000050050000000",
]
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: 7 × white, 2 × red, 7 × white
• Row 2: 7 × white, 2 × grey, 7 × white
• Row 3: 3 × white, 9 × purple, 4 × white
• Row 4: 3 × white, 9 × purple, 4 × white
• Row 5: 3 × white, 1 × purple, 1 × yellow, 5 × purple, 1 × yellow, 1 × purple, 4 × white
• Row 6: 3 × white, 9 × purple, 4 × white
• Row 7: 3 × white, 2 × purple, 5 × navy, 2 × purple, 4 × white
• Row 8: 3 × white, 9 × purple, 4 × white
• Row 9: 4 × white, 7 × green, 5 × white
• Row 10: 4 × white, 7 × green, 5 × white
• Row 11: 4 × white, 7 × green, 5 × white
• Row 12: 4 × white, 7 × green, 5 × white
• Row 13: 4 × white, 7 × green, 5 × white
• Row 14: 4 × white, 7 × green, 5 × white
• Row 15: 4 × white, 7 × green, 5 × white
• Row 16: 5 × white, 1 × navy, 2 × white, 1 × navy, 7 × white