OnePlus partnered with Hasselblad five years ago, starting with the OnePlus 9 series, and it has continued till the OnePlus 13. Well, OnePlus CEO Pete Lau has confirmed that the partnership has come to an end and OnePlus will debut its own colour science.
Pete Lau confirmed via a community post that the firm's new DetailMax Engine will be replacing Hasselblad in upcoming OnePlus flagships. The OnePlus 15 will presumably be the first to boast the new imaging engine.

He highlights that DetailMax Engine has been built from the ground up, while mentioning that the Hasselblad partnership has immensely helped and taught the brand.
Designed from the ground up to deliver the clearest and most real photos on a smartphone, it harnesses the full potential of computational imaging to present scenes as they truly are, without over-beautification or distortion.
— Pete Lau – CEO, OnePlus
The post prominently mentions "better zoom", which makes us believe that DetailMax could focus (pun intended) on delivering crisp zoom shots using computational processing, without much loss in quality.
OnePlus' parent firm Oppo is sticking to Hasselblad for its upcoming Find X9 series, and it should be interesting to see if it continues to do so. For those unaware, Oppo also launched one of its own imaging engines called Lumo, and it debuted with the Find X8s and Find X8 Ultra.
Considering both the brand's history of sharing features and, to some extent, operating systems, it's plausible that OnePlus' DetailMax Engine is at least using some aspects of the Lumo engine for better colours. However, Lumo had no association with the "better zoom photos" that Lau talked about in the post, so some features may have actually been built from the ground up.
Given that the OnePlus 15 is rumoured to launch in China in October or November 2025, we don't have to wait for long to see what the new engine brings to the table.
The OnePlus 15 is also expected to arrive with Snapdragon 8 Elite Gen 5, and leaks hint at a 165 Hz 1.5K OLED display. The phone could boast a 7,000mAh battery that could charge at 120W and 50W wirelessly. Stay tuned as we will cover more about OnePlus' new imaging engine and the OnePlus 15 as more details surface.