Pixel purging
The next morning, I conducted a brute-force attempt to purge any retained pixels. This required loading an all-white screen capture in the gallery interface with on-screen UI disabled for 15 minutes. After that, I noticed reduced noise, but some fixed graininess remained on the screen. Again, the graininess was most noticeable with a full gray menu screen, not within games themselves. As I talked about my process with Ars colleagues, however, I became more convinced that the issue wasn't OLED image retention. It was the OLED display itself.
We'll learn more as teardowns emerge once the console goes live, and we're particularly interested in learning who supplied the first round of OLED panels for this Switch revision. We've seen certain suppliers earn a reputation for uneven, grainy OLED panels, most noticeable in all-gray images. (My colleague Ron Amadeo talks about this at length in his 2017 review of the Pixel 2 line of smartphones.) So I tested a Switch game that might emphasize such an issue: Hollow Knight, a modern 2D classic that involves giant swaths of gray and blue. I was delighted to see that this Switch OLED panel's potential graininess was hardly perceptible, even in its dark scenes full of solid chunks of dark coloring. Plus, as a dark and moody game, Hollow Knight benefited enormously from the OLED panel's infinite contrast ratio.