[gdal-dev] Re: Proposal: gdal_muladd.py

[Jukka Rahkonen]

Greg Coats <gregcoats <at> mac.com> writes:

> 
> I would prefer to obtain in one step the absolute value of the difference
between two pixels, in part because
> I do not see the meaning of a negative pixel value. In my example, I do not
see meaning to a signed byte value
> for a pixel channel being red=-51. Greg

Hi,

If somebody is doing for example change detection by comparing satellite images
from different dates, it is not at all the same if the result is 
 99-150=-51  or 150-99=51.

-Jukka Rahkonen-