Use larger border when estimating black/white, and check result.
Use larger border when estimating black/white, and check result.

darktable-org/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,mgehre/rawspeed,anarsoul/rawspeed,klauspost/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,anarsoul/rawspeed,mgehre/rawspeed,anarsoul/rawspeed,klauspost/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed