Following the release of the GTA VI launch trailer, its HDR processing has come under scrutiny. Analysts believe that the trailer's HDR highlights did not present more detail than the SDR source material, leading to suspicions that the HDR footage may have been derived from SDR via inverse mapping.
After analyzing the trailer frame by frame, HDR and tone mapping expert Filippo Tarpini pointed out that the bright blues in the pool scene appeared purplish, and the gradients around the pool lights showed breaks. Adjusting the image levels made these edges even more pronounced.
Tarpini believes these phenomena may be related to per-channel tone mapping, leading him to speculate that the trailer might have used the AgX scheme. However, this judgment is based solely on the characteristics of the final video, not on information released by the developers. Another analyst, MusaRenoDX, examined the HDR footage and proposed the possibility of SDR inverse mapping, and Tarpini also acknowledged his observations regarding highlight details.
The trailer also went through recording, editing, encoding, and platform playback stages, so the final version of the game cannot be judged based solely on existing materials. The actual HDR implementation, display device adaptation, and final calibration effects of GTA VI during gameplay still need to be confirmed through in-game footage.
Foreign media report:
Yesterday's GTA VI launch trailer confirmed that this open-world game will indeed be released in just over a month. Like previous GTA trailers, this video has also been analyzed frame by frame by players.
Generally, fans look for specific cars, NPCs, or weapons in trailers. Filippo Tarpini, an expert in HDR and tone mapping, focuses on visual presentation. He posted a lengthy thread on X, analyzing various tone mapping issues appearing in the GTA VI launch trailer item by item.
He pointed out that the issue of bright blues turning purple appeared again in the trailer. This problem is obvious in the scene where characters jump into the pool. According to him, this is a common phenomenon when performing tone mapping on a per-color-channel basis. Unreal Engine and ACES have a "blue correction" feature that can handle this issue, but it may also introduce new problems like banding, where originally smooth color gradients show distinct boundaries.
Therefore, he believes the most reasonable speculation is that GTA VI used AgX. AgX also processes each color channel individually, so it is usually difficult to avoid the issue of blues turning purple. Since it lacks gamut mapping, this phenomenon might even be more severe. AgX generates some colors that cannot be displayed in sRGB and then simply clips the excess, which can result in hue shifts such as blues turning purple.
He also cited the broken color gradients around the pool lights as evidence. By adjusting the image's levels, the edges of these gradients, known as banding, become clearly visible.
As for why AgX was speculated, Tarpini explained that many studios follow industry trends when choosing tone mapping schemes, adopting those considered superior and widely discussed at the time. Grand Theft Auto V and Red Dead Redemption 2 used Hable, a scheme also adopted by Naughty Dog.exe. During the PS4 generation, Hable and ACES were the two mainstream solutions. Now, neither of these schemes is truly satisfactory, and with almost no other alternatives available on the market, everyone is turning to AgX.
However, AgX has one issue: it lacks an official HDR implementation. Tarpini believes that no one in the industry seems to have adapted its mathematical principles for HDR, though he stated that he could do it.
He also showed the original footage alongside a quickly readjusted version. After adjustment, the reds appeared closer to orange and less pinkish. He reminded everyone not to worry about hue shifts in other colors. With careful adjustment, these changes can be avoided, and they can certainly be achieved within the game code.
@MusaRenoDX analyzed the trailer's HDR footage. He believes that GTA VI may have used inverse tone mapping, which converts SDR footage to HDR, as the highlight areas did not show additional details. If this assessment is correct, it is not a good sign. He feels it is regrettable that GTA VI, as the world's largest game, would adopt the lower-cost method of converting SDR to HDR. However, when it comes to HDR, people seem accustomed to assuming the worst-case scenario.
Unfortunately, the author believes his assessment is correct. As discussed in an exclusive interview last December, the overall state of HDR gaming is currently poor, especially on PC. Tarpini is trying to improve this situation, but he is only one person.
As for what HDR scheme GTA VI actually employs, it will need to be evaluated once the game is officially released. Even if issues are found at that time, there will be no way to fix them before the PC version launches. Rumor has it that the GTA VI PC version is scheduled for release in the first quarter of 2027.