Microsoft has started rolling out a new Windows Phone update to its range of Lumia devices. Dubbed Lumia Denim, the latest update brings some significant camera improvements to the Lumia 830, Lumia 930, Lumia Icon, and Lumia 1520. The first noticeable change is a new Lumia Camera app that launches faster and takes photos more quickly. Microsoft’s Lumia 1520 has a more than capable camera, but the slowness of capturing photos often lets it down, and this update is designed to address that.

Hey Cortana command also part of Lumia Denim

The new Lumia Camera update also includes support for recording 4K-quality videos, improved capture for auto HDR, and Dynamic Flash. While the camera improvements are rolling out Microsoft’s high-end Lumias, they don’t appear to be arriving on the Lumia 1020, with no mention of additional support for the 41-megapixel shooter. Other improvements include a new “Hey Cortana” command that will activate Microsoft’s digital assistant on a Lumia 930 or Lumia 1520.

Microsoft is rolling out Lumia Denim to some Lumia handsets today in various countries, but it warns that “a wider rollout of Lumia Denim to all Lumia smartphones running Windows Phone 8.1 is expected to begin in early January, following partner testing and approvals.” Lumia 520, 530, 625, and Lumia 1320 are starting to receive the update broadly, and some Lumia 930 and Lumia 1520 owners are also seeing the new changes. Given that Verizon customers are still waiting on the previous Lumia Cyan update to roll out, it could be some time before all Lumia Windows Phones receive Denim. If you want to check on availability for your own Lumia Microsoft has a support site listing the roll out for each country and device.