Microsoft announced Lumia Denim at IFA 2014 in Berlin, Germany. Lumia Denim is the latest firmware for Lumia handsets and brings a handful of new features like passive-listening Cortana, 4K video, Rich Capture and more. It coincides with the Windows Phone 8.1 Update 1 OS refresh.

During development, Lumia Denim was codenamed 'Debian Red.' Lumia Denim follows the naming convention used by Microsoft for their firmware in Lumia handsets. The firmware names go in alphabetical order, starting with A for Lumia Amber, B for Lumia Black, C for Lumia Cyan and now D for Lumia Denim.

Lumia Denim is most notable for bringing a handful of new features to the Lumia Camera application on Lumia handsets. Camera speed is by far the area with the biggest improvement brought on by Lumia Denim, with between-shot times of milliseconds. Here's the full list of camera changes coming with Lumia Denim (to supported handsets)

  • Speed: Never miss a moment with Lumia Camera and its fast camera start-up and capture speeds. Take numerous photos with just milliseconds beyond shots.
  • High definition: Using Moment Capture, a long press of the camera button within the app automatically starts 4K-quality video recording at 24 frames per second. Each frame is of high image quality at 8.3 megapixels, allowing every single video frame to be selected and saved as a still picture.
  • Intuitiveness: Get the best shot every time with Rich Capture, which simplifies picture-taking with auto HDR and Dynamic Flash. With Rich Capture, people can avoid the hassle adjusting camera settings; they can shoot first and edit and select the perfect shot later.
  • Quality: Capture high-quality smartphone images in low light with the latest-generation imaging algorithms.

Lumia Denim will be available with the Lumia 730, Lumia 735 and Lumia 830 and come to other Lumia handsets during Q4 2014.