Band or tie point grids of a data product determine by two means whether or not a pixel at a certain position
a no-data value and/or
a valid pixel expression is set.
These properties can be adjusted using the Property Editor. If valid pixel
enabled, invalid pixels are excluded from range, histogram and other statistical computations.
In order to visualise the invalid pixel positions, the No-Data Overlay is used.
The no-data property of a band is also set by the Band Maths
and Reprojection tools.