HDR expert suspects GTA 6 of cheap SDR conversion a month before release

Filippo Tarpini, a game industry veteran and HDR and color grading specialist at Gamma Studios, believes Rockstar Games might be using a cheaper SDR upgrade in Grand Theft Auto 6 instead of true high-quality HDR.

Tarpini shared his findings in a series of social media posts, breaking down several scenes from the launch trailer released this week.

The video itself is SDR, meaning standard dynamic range. According to Tarpini, even that format shows how the studio works with color. He liked the overall picture, but one problem stood out right away.

Filippo Tarpini said:

The launch trailer is SDR but still gives us insight into how they are working with colors. Overall, what I see looks nice. Nothing appears particularly broken with one big exception. Gradients are smooth. Skin tones are great. Hue paths/shifts are ok. There's a lot of clipping, but that's unavoidable in SDR. However… as often happens: bright blue turns purple!

As an example, Tarpini pointed to the swimming pool scene. Ideally, bright lights should turn the blue water a lighter shade of blue while keeping its hue. In the trailer, the brightest points show the water going purple instead.

Tarpini ties this effect to per-channel tonemapping. Tonemapping handles how the wide brightness range inside an engine gets compressed to fit what a display can show. With a per-channel approach, the red, green, and blue channels are processed separately, and at high brightness the ratio between them gets distorted, so the color drifts.

This is a typical trait of tonemapping per channel; Unreal/ACES have a "blue correction" feature to remedy this problem, which introduces issues like banding.

Banding happens when a smooth color transition breaks up into visible stripes. ACES, meanwhile, is a color management standard that came out of the film industry and is widely used in games.

Tarpini thinks Rockstar is using a per-channel solution called AgX. The system originally appeared in the open-source 3D suite Blender and is valued for its soft handling of bright areas.

It usually doesn't escape this problem, in fact, it can even make it worse given it has no gamut adaptation.

He then showed several more frames where colors display incorrectly because of the high brightness of specific elements.

Tarpini also explained why the studio might have picked AgX over other methods. His main complaint concerns the HDR version of the game. He noted that AgX has no official HDR implementation, and "nobody in the industry seems to be able to adapt its math to HDR." Citing analysis by modder MusaRenoDX, Tarpini believes Rockstar is producing its HDR image through inverse tonemapping.

The method takes a finished SDR image and artificially stretches it to a wider brightness range. No extra detail appears in the highlights, since that information is already lost at the SDR stage.

Filippo Tarpini added:

That does not bode well! The biggest game in the world using a cheap SDR-to-HDR upgrade method would be a real shame, but we have come to expect the worst when it comes to HDR. Hopefully I'll be positively surprised.

There was some praise too. In a separate post, Tarpini singled out the explosions in the trailer, which he said are "clearly tuned to look great in SDR too."

The launch trailer also revealed new story details. It shows glimpses of Jason's backstory and how he and Lucia get pulled into a life of crime.

The trailer also mentions that Jason left the Army "not on the best of terms." There's talk of an "easy score" that seemingly went wrong, leaving the two wondering whether they'll be "okay."

Grand Theft Auto 6 is set to launch on PS5 and Xbox Series on November 19, 2026. With a little over a month to go, Tarpini's conclusions can soon be tested against the final version.