#Overall interpretation
The top left corner is a small recreation of the whole image. It tells you what each part of the image is for.
It calls itself a "key", suggesting that it's necessary for the rest of the image. The four other black and white parts are binary numbers: 001, 010, 011, 100.
#Step 1
The tiny rectangle at the bottom has 26 pixels. So we can write the English alphabet inside it, and three letters are highlighted in different colors:
This gives a nice interpretation of the patterns above - as Roman numerals!
#Step 2
Now that we have step 1 done...
the colors across the left and top make sense: they're numbers, and the "across" and "down" sections form a nonogram puzzle!
The solution there is:
#Step 3
Okay, so what next?
There are a lot of repeating patterns in the nonogram solution. They look to form 6x6 "cells":
So, we should apply this step's instruction picture:
And then we get...
These form nautical flags! The flags are (by row):
AQHMJA / BQUXHJ / USPFSQ / BXJPMF.
#Step 4
Finally:
These are the seven colors of the rainbow -- they've even been helpfully labelled that way in the transcription. If we interpret these seven colors as numbers from 1 to 7, then Caesar-shift the flags forward by that amount, we get the message: DROPPED RADIO, BUT IT SEEMS OKAY.
