World's smallest Sudoku!

Let's blow up that image so we can get a better look at the colors:

This doesn't look much like a sudoku yet. But...

the steganography tag is there...what if we look at the RGB values of each color?

It turns out that…

each color's R, G, and B don't share any digits other than zero. For example, the top left box is #60EA47 in hex, which is (96, 234, 71) in RGB. And in fact, if we were to lay them out in a grid, with red on the top, green in the middle, and blue on the bottom:



we can see that no digit (other than 0) repeats in a box, row, or column. In other words, now we've got a sudoku!

Solving the sudoku

is pretty trivial ... for the most part. It turns out that there are two 2x2 squares that don't resolve:



But hey, wait a minute ... that middle box now looks like it could be a different color if we reverse the process we did before!

Let's try that:

(82, 69, 100) is this color:



Unfortunately, it doesn't seem to have a common name, nor does it resolve to a common three-letter color name. Maybe we need to try something different ... what about hex? This color's hex code is #524564, and we'll probably want to separate that out into 52, 45, 64.

Now what could that mean?

I quickly thought of the ASCII table, and it turns out that all three of those letters resolve to letters when converted to ASCII characters. Namely, hex(52) is R, hex(45) is E, and hex(64) is d.

Therefore, the middle box secretly contains the color

REd!