allow nearblack mask on single band images
|Reported by:||maphew||Owned by:||warmerdam|
When nearblack is used on a single band image with -setmask it stops with an error:
nearblack -setmask -of gtiff -o decollared.tif gray.tif ERROR 1: Number of bands of file = 1. Expected 3 or 4.
Without setmask it works fine. It would be nice to be able to use masks on grayscale images without incurring the overhead of converting to RGB.