[GRASS5] Bug? In d.his

[Glynn Clements]

Michael Barton wrote:

> I¹ve just discovered that when the ­n flag is set in d.his, it seems to
> treat 0¹s as NULL, regardless of whether or not they have been defined as
> NULL (i.e., using r.nulls). I¹m guessing that this is a holdover from much
> earlier versions of GRASS that lacked NULL support. If this is the case, it
> should probably be changed so that d.his actually respects true NULL values
> and treats 0¹s as real values.

If it does, that's a bug, not an oversight. Both d.his and the D_*
functions it uses go to some lengths to handle null values correctly.

Can you provide a recipe to reproduce this?

Note that:

1. d.his doesn't care about the actual cell values for non-null cells,
only their associated colours (for the intensity and saturation maps,
only the red level is used; it's assumed that these maps will have
grey-scale colour tables).

2. A cell should be transparent if that cell is null in any of the
input maps.

-- 
Glynn Clements <glynn at gclements.plus.com>