ARM has announced a brand new display processor built on a new architecture, the ARM Mali-Cetus display processor. Despite being not as popular as the CPU and GPU, a display processor is an important component of the display pipeline of smartphones and other ARM Mali GPU powered devices. The display processor serves to offload some of the computational workload and tasks like multi-layer composition and image post-processing, which improves the quality of the display output and also improves the efficiency of the SoC through the reduction of the overall power consumption. The Mali-Cetus allows ARM to be competitive in the graphics arena wherein HDR, Virtual Reality, and 4K features now start to appear in smartphones, with the more modern architecture of the ARM Mali-Cetus incorporating the support for these features natively.
The ARM Mali-Cetus display processor is composed of 5 different units, which are the ARM FrameBuffer Compression unit, the Global Control Unit, Layer Processing Unit, Composition Unit, and the Display Output Unit. Of all the 5 units, the improvements in the composition unit, which include the increase in the composition layers to 8 from 7 in previous display processors, are the most practically relevant for Android smartphone users, especially for the owners of smartphones with Android 7.0 Nougat. Each of the windows in the Android Nougat's multi-window mode occupies one layer, so the increase of composition layers are important to handle the other components of Android's UI. Another important improvement is the display processor's ability to split one massive 4K layer into smaller multiple layers, which improve the power efficiency of the SoC through distributing the workload to other, possibly idle, hardware. Also, there is now a tone-mapping unit in the display processor, which ARM calls the Assertive Display block. This block allows for native support of HDR displays along with the mapping of HDR images into SDR displays.
The ARM Mali-Cetus is an important product for ARM as it allows the company to keep pace with the recent trends in the smartphone industry like HDR displays and VR support. At this point, the latest flagship smartphones of Samsung and LG already support HDR content, with the technology expected to trickle down to more mid-range smartphones sometime in the future. In addition, smartphones are now adding virtual reality to their feature set with Google Daydream, in addition to Samsung's own Gear VR. So these display processors provide smartphone manufacturers the option to stay in ARM's graphics ecosystem, which includes, among other products, the ARM Mali GPUs.