enigmatic puzzle - What is Lukas Rotter's secret?

The former user Lukas Rotter has had¹ an intriguing profile picture:

This looks like it's some kind of encrypted message! And just to confirm my suspicions, on his profile he says:

By the way, my profile picture is also a little puzzle. You'll get +0 reputation if you solve it!

Now I'm a generous soul, so I'm going to award you at least +25 reputation if you solve it, and I'm sure you'll get more +10's from others too! How's that for a deal?

What is the solution of the puzzle in Lukas Rotter's profile picture?

_{Note 1: That user has now deleted their account; however, this puzzle is still self-contained and valid.}

_{Note 2: I do not know the solution myself. Obviously Lukas does, so you'll have to ask him for any hints or clues.}

_{Note 3: this isn't the first puzzle I've done like this, by the way ;-)}

Answer

It's

Hexadeximal encoded ASCII (translated onto RGB color space) for LukasRotter

Because

The colors are, from left to right #4C756B, #617352, #6F7474 and we add 65 and 72 as per the text, giving the full text:

4C 75 6B 61 73 52 6F 74 74 65 72 = LukasRotter

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To elaborate, ASCII is a standardized representation of text which assigns a numeric value to 128 different characters.

The RGB color space is an additive color model where we mix red, green, and blue in different proportions (in this case, as fractions of 255) to make any color we desire. These mixtures are commonly written in the form #RRGGBB where RR is the base-16 quantity of red, GG green, and BB blue. I used a color picker browser extension on the image to extract the hexadecimal representations of the colors.