graduated neutral density (GND) filter. This is because GND filters extend dynamic range while still maintaining local contrast. Scenes which are ideally suited for GND filters are those with simple lighting geometries, such as the linear blend from dark to light encountered commonly in landscape photography (corresponding to the relatively dark land transitioning into bright sky)... suggest to use “neutral density filters to control drastically varying light. If used properly, these do not induce halo artifacts while still maintaining local contrast. Further, these have been a standard by landscape photographers for nearly a century” -
hdr tutorial
