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title: "CRT emulation on LCDs can be hard. For example it's often easy to generate a pat" author: "NOTimothyLottes" handle: "@NOTimothyLottes" post_url: "https://x.com/NOTimothyLottes/status/1688491417109196800" post_id: "1688491417109196800" timestamp: "2023-08-07 10:04:59" post_count: 6 reply_count: 2 repost_count: 18 like_count: 98 view_count: 12960
@NOTimothyLottes — CRT emulation on LCDs can be hard. For example it's often easy to generate a pat
Post 1 (2023-08-07 10:04:59)
CRT emulation on LCDs can be hard. For example it's often easy to generate a pattern that causes a LCD hardware bug. NOT joking. Here is an example on the Steam Deck. The pattern in the window affects the scan (Deck scan is rotated) outside the window.
Post 2 (2023-08-07 10:08:14) — reply to Post 1
The actual pattern is this (it's a 2x1 pixel checker of {G,RB}).
Post 3 (2023-08-07 10:14:00) — reply to Post 2
The theory: Deck's 90deg scan results in {(bottom)R, G, B (top)} sub-pixel components. So could alternate {G,RB} only per pixel in a checker pattern to generate a new sub-pixel pattern at a different resolution. In this case trying for 640x400 virtual resolution.
Post 4 (2023-08-07 10:18:28) — reply to Post 3
For virtual pixel, shift energy into masked virtual phosphor. So 50% brightness red, would be {100%, 0%} for {in, out} of phosphor pixels. Over 50% one starts to increase non-phosphor pixels until some maximum so mask is still visible, but brightness isn't too compromised.
Post 5 (2023-08-07 10:23:35) — reply to Post 4
Of course this is done in linear, so it's energy conserving in theory. But when the panel fails, it breaks down and doesn't work. I see this problem on a bunch of different devices. My personal AMD laptop has the exact same fail case (but rotated differently).
Post 6 (2023-08-10 03:29:30) — reply to Post 1
@NOTimothyLottes Very interesting "crosstalk from voltage inversion" artifact. Some repeating patterns or flicker patterns can trigger crosstalk artifacts too. Behavior varies a lot between TN, IPS, and VA, but all of them have to alternate voltage polarity spatially and temporally.
