Subtly changing my profile picture until anyone notices

I have had the same profile picture forever on Discord - I think I’ve had the same one for 5 years at least. The picture is the cropped face of some poor stock photo model posed as a stereotypical French man, with baret, baguette and all.

One evening, I decided to perform a little experiment on my friends. How long would it take for them to notice that the brightly coloured red hat worn in my profile picture had changed color? I decided to only change the color subtly to not alert their attention.

I cut the hat out of the picture and placed it in a separate file and used ImageMagick to change the hue 1%. In particular, I used the -modulate transformation in ImageMagick which allows me to alter the HSL color values of every pixel. Using ImageMagick, I then composited this on top of the old image.

I scripted the entire thing in Powershell (I hated it) and the script can be seen below:

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$start_date = "04-07-2023"

$datestr = Get-Date -Format "yyyyMMdd"
$date = Get-Date -Format "MM-dd-yyyy"
$day = (New-TimeSpan -Start $start_date -End $date).Days

magick french_hat.png -modulate 100,100,(100+$day) french_hat_hue.png
magick composite french_hat_hue.png french.jpg french_hue.png
$outpath = ("hues/" + $datestr + ".jpg")
Copy-Item french_hue.png $outpath
Set-Clipboard (Resolve-Path french_hue.png)
Echo "Path copied to clipboard. Set as Discord avatar"
Pause

The script runs every time I start my desktop computer where I then manually set the Discord avatar.

I am writing this now, because I have been discovered. After 15 days, someone remarked on my profile picture, asking if I had changed it or they were going colourblind. My friends were a lot more observant than expected - I was expecting to hit yellow before someone noticed. The experiment is concluded with this very Andy Warhol-like montage: