[GRASS5] Compression (?) of CELL maps (int)

[Glynn Clements]

Markus Neteler wrote:

> > > > FWIW, I intend to completely re-write the raster I/O code once I move
> > > > to 5.1. 
> > > 
> > > Wouldn't be better to wait for 5.3 for this then?
> > 
> > Why? The changes would be substantially less far-reaching than the
> > 5.1. vector re-write.
> 
> Would it comprise also a rewrite of the NULL handling?

When a separate NULL bitmap is present, the nulls would be embedded
prior to the rescaling.

There should at least be the option of storing NULLs in the main
raster file rather than a separate file.

Also, the scaling should probably be done arithmetically (Bressenham
or DDA) rather than using a lookup table. On modern CPUs, arithmetic
operations are faster than memory accesses.

-- 
Glynn Clements <glynn.clements at virgin.net>