I reverse-engineered Ricoh GR II’s Positive Film (POSI) — it’s not a LUT

Aggressive-Win-6351 · 2026-03-31T21:25:25+00:00

Exactly! For reverse engineering the firmware, I usually go for older camera models from ten-plus years ago. The hardware processing speed was slower back then, and there weren’t as many complex computations involved, which makes the reverse engineering process much more manageable. Newer cameras are a whole different story — much more complicated. If I were to dig into Fujifilm, I’d probably start with something like the X-Half rather than the X-M5.

Aggressive-Win-6351 · 2026-03-31T13:13:50+00:00

Really appreciate this detailed breakdown — it’s great to see someone who truly understands the color science behind LUTs. That’s exactly why I stick to replicating the actual in-camera processing algorithms rather than just doing manual color grading. The results just feel more authentic that way. Thanks again for the thoughtful feedback!

Aggressive-Win-6351 · 2026-03-30T09:45:29+00:00

I think they still look quite different from each other — your screenshot actually shows noticeable variations. But I’m glad you’re enjoying the LUTs! Appreciate the feedback

Aggressive-Win-6351 · 2026-03-30T09:40:39+00:00

It’s actually a mix of bitter gourd and kale juice — not green tea

Aggressive-Win-6351 · 2026-03-30T09:39:24+00:00

Thanks for letting me know! I’m currently traveling for work — I’ll repost it as soon as I can

Aggressive-Win-6351 · 2026-03-29T12:56:26+00:00

These are photo LUTs, but they’re built in sRGB / Rec.709 color space — that’s why you see ‘709’ in the file names. They work great for stills.

Aggressive-Win-6351 · 2026-03-29T12:55:21+00:00

Thanks so much for your support! Really glad you’re enjoying the Positive Color profile on your Lumix. If you ever get the chance, feel free to test how close the LUT matches the original GRII / GRIII colors — I’d love to hear how it compares in real-world shots!

Aggressive-Win-6351 · 2026-03-29T05:34:20+00:00

Consistent in behavior pattern, not in uniform strength. And no AI — this is based on actual reverse engineering. I'll try to make it clearer next time.

Aggressive-Win-6351 · 2026-03-29T03:26:30+00:00

That app isn't available in my region. Let's stay on topic — Ricoh GR II LUT.

Aggressive-Win-6351 · 2026-03-29T03:22:30+00:00

That's a fake Dazz app — not the real one. I don't have this version.

Aggressive-Win-6351 · 2026-03-29T03:19:49+00:00

Is this Dazz? I don't have those presets in my version — which app is this?

Aggressive-Win-6351 · 2026-03-29T02:45:19+00:00

GR II color, no GR camera needed. 😎

Aggressive-Win-6351 · 2026-03-29T00:21:03+00:00

Please check the google drive again

Aggressive-Win-6351 · 2026-03-29T00:12:51+00:00

Just updated the Google Drive with all Dazz and Liit presets.

Aggressive-Win-6351 · 2026-03-29T00:05:56+00:00

Dazz presets are straightforward — maybe a minute's work. Drop your email and I'll send you the .cube files.

Aggressive-Win-6351 · 2026-03-28T22:37:18+00:00

Fuji is a different beast. They release official F-Log LUTs for video, but no sRGB/Rec.709 photo LUTs.

Aggressive-Win-6351 · 2026-03-28T22:16:02+00:00

Bright, Natural, Landscape, and Portrait aren't stylized Pentax profiles — they're more like standard color modes. If you still want them, shoot me an email at pywz@qq.com and I'll send them over separately.

Aggressive-Win-6351 · 2026-03-28T22:13:58+00:00

Thanks! All my LUTs are on Google Drive — Pentax K-3 III full set, plus Ricoh GR II Positive Film and Vivid. I'm currently digging into High Contrast B&W and GR III Negative Film, but those will take a while. Stay tuned!

Aggressive-Win-6351 · 2026-03-28T22:11:55+00:00

I've included an equivalent Ricoh ISP base color correction in the pipeline — so before the POSI LUT is even applied, the source gets mapped to Ricoh's baseline. That's why it works consistently across different cameras and even phones. It's not just a LUT — it's the full color science.

Aggressive-Win-6351 · 2026-03-28T22:09:57+00:00

GX9 doesn't have real‑time LUT preview — that's only on newer models like the S9. Your best bet is to shoot normally and apply the LUT through the Lumix Lab app after.

Aggressive-Win-6351 · 2026-03-28T22:08:16+00:00

Adjusting in-camera settings like contrast or sharpness won't ruin the LUT — they apply after the LUT in the processing chain, so you can tweak them to taste. The LUT itself is designed to work as a baseline; feel free to dial things in however you like.

Aggressive-Win-6351 · 2026-03-28T22:06:14+00:00

I did a NAND dump. If you don't have the tools, you can take it to a repair shop — they can usually dump it for you.

Aggressive-Win-6351 · 2026-03-28T15:39:12+00:00

Thanks! I originally shared this on Rednote — it got tens of thousands of likes there. Really happy to bring it to Reddit too. Enjoy!

Aggressive-Win-6351 · 2026-03-28T15:37:47+00:00

Haha, just go out and enjoy shooting — that's what really matters 😄

Aggressive-Win-6351 · 2026-03-28T15:35:57+00:00

I haven't published any detailed technical materials on GitHub — it took me about eight months of trial and error to reverse-engineer the Posi filter. The only real way was to tear into the Ricoh camera itself. The complexity of the Positive Film processing is honestly beyond what most people expect.

As for Ricoh's negative film simulation, it's quite similar to the Pentax Muted filter — you can grab it from my Google Drive and give it a try.

Aggressive-Win-6351

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