Use of "Lenna" image in computer image processing research stretches back to the 1970s.
The original post: /r/programming by /u/proboscisjoe on 2024-03-30 05:28:42.

I remember feeling 100% not at all like a creep using the Lenna image in my C (programming III) course in college.

Students were required to rotate an image pixel-wise, and I’d known about Lena from my personal study of/interest in computer vision algorithms.

Dear Lenna, you will be missed! (But I do get it.)