====== BandMath ======
BandMath compares the bands at each pixel of a multiband image. The "output" can be a **single band** or a **multiband** image.

===== Single-band output =====
This is suited to multispectral images, with tens of bands. Choose the "operation":

^ Operation ^ Output at each pixel ^
| min | the smallest band value |
| max | the largest band value |
| mod | the modulation, (max − min) ÷ (max + min) |
| median | the median of the band values |

The output is the same type as the input.

===== Multiband output =====
This is designed for hyperspectral or XRF images, with thousands of bands. Choose how to "merge" the bands over a "width", a number of bands:
  * **reduce** averages each group of "width" bands into one band, so the output has (input bands ÷ width) bands.
  * **blend** keeps the same number of bands, but each output band is the average of the "width" neighboring bands around it.

The width must be positive, and no larger than the number of bands. The output is floating point.