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Comment by byuu | Hacker News Reader

Phosphor glow is one of my favorite effects. One of these days I'd really love to have a software-mode C++ filter for that.

It can be done through filtering, but it's really hard to make it look good. A person named Psiga made this mock-up for Secret of Mana in Photoshop that has always astounded me: https://sites.google.com/site/psigamp3/PhosphorSimTest1.jpg

Unfortunately, no one's been able to figure out exactly how it was made to replicate it in software. But something like it would really add a lot.

There are however really good CRT simulation pixel shaders, such as CRT-Royale: http://emulation.gametechwiki.com/index.php/CRT-Royale

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Psiga seems to be a person named Patrick Murphy (based on the recent change history: https://sites.google.com/site/psigamp3/system/app/pages/rece...) and they've uploaded at least one other phosphor test such as this one from 2011: https://sites.google.com/site/psigamp3/phosphorsim-gettingcl...

They also uploaded something as recently as 2017 so it might be possible to reach out to them and get a response?

Not sure if that helps find / reach out to them but I can hope.

We have pinged them in the past about it, actually ^^;; It's been a mini-obsession of mine since I found it, hahah. They regrettably don't remember how it was made.

Ah bummer. I would have thought they'd have kept the PSD lying around somewhere like I do and it would've shed some light. Maybe someday someone will figure out something that looks right!

The Mana looks like two filters, a scan line plus a blur one. Lmk if you’d like me to give it a go to replicate in Photoshop

I would like that, thank you! A few people have tried over the years, and we even contacted the person who made the original image, but he didn't remember how he did it ^-^;

That phosphor image looks great! I wonder if it could be used to train a style transfer neural network to create a filter to replicate it?

Since the physics are known it's probably going to be easier to simulate from first principles.

You could probably use machine learning for fine-tuning the parameters of whatever fast approximation comes out of that though.

(having a plausible first-principles model and then automatically tuning the knobs until the error with a ground truth is minimised is a form of machine learning, right?)

Pretty sure a cross correlation of the source and resulting image will reveal most of the transformation's recipe, aside from a few details like the fine grid lines added in. If I have time tomorrow I might take a crack at it.

> Unfortunately, no one's been able to figure out exactly how it was made to replicate it in software.

Could that be due to something like the phosphor glow having non-linear properties or something?

Look at CRT draw in slow motion. You have an ultra bright flash, then an alarmingly quick phosphor glow falloff.

You'd need, basically, a high hz HDR monitor with an actual sub-ms response time... so you can superbright blink the character, essentially black framing it.

The rest of the actual softness of the glow can be emulated conventionally with shaders (there are some super swanky terminals and emulators that have that part already done).

> there are some super swanky terminals and emulators that have that part already done Like 'cool-retro-term': https://github.com/Swordfish90/cool-retro-term

Although this flicker would indeed be necessary for a 100% accurate reproduction, I'm not sure that is really the thing that current CRT shaders are missing for feeling "just right". After all, the linked example image feels very convincing and yet is static.

That's Seiken Densetsu 3 (unreleased in US but fan translated by Neill Corlett)

It was actually officially released internationally a few months ago as Trials of Mana!

It's not out yet, the release date is April 24, 2020.

You're thinking of the remake; the 16-bit original was recently released as part of a trilogy bundle.

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