  This paper presents a quarter Laplacian filter that can preserve corners and
edges during image smoothing. Its support region is $2\times2$, which is
smaller than the $3\times3$ support region of Laplacian filter. Thus, it is
more local. Moreover, this filter can be implemented via the classical box
filter, leading to high performance for real time applications. Finally, we
show its edge preserving property in several image processing tasks, including
image smoothing, texture enhancement, and low-light image enhancement. The
proposed filter can be adopted in a wide range of image processing
applications.
