  Off-chip memory traffic is a major source of power and energy consumption on
mobile platforms. A large amount of this off-chip traffic is used to manipulate
graphics framebuffer surfaces. To cut down the cost of accessing off-chip
memory, framebuffer surfaces are compressed to reduce the bandwidth consumed on
surface manipulation when rendering or displaying.
  In this work, we study the compression properties of framebuffer surfaces and
highlight the fact that surfaces from different applications have different
compression characteristics. We use the results of our analysis to propose a
scheme, Dynamic Color Palettes (DCP), which achieves higher compression rates
with UI and 2D surfaces.
  DCP is a hardware mechanism for exploiting inter-frame coherence in lossless
surface compression; it implements a scheme that dynamically constructs color
palettes, which are then used to efficiently compress framebuffer surfaces. To
evaluate DCP, we created an extensive set of OpenGL workload traces from 124
Android applications. We found that DCP improves compression rates by 91% for
UI and 20% for 2D applications compared to previous proposals. We also evaluate
a hybrid scheme that combines DCP with a generic compression scheme. We found
that compression rates improve over previous proposals by 161%, 124% and 83%
for UI, 2D and 3D applications, respectively.
