[GRASS-dev] On i.histo.match (Re: On (Landsat) imagery naming patterns)

[Nikos Alexandris]

Nikos wrote:

> > Just FYI, results look nice!  I even convert back to 0-1.0 via
> > r.mapcalc --o "${HistoMatchedMap} = ${HistoMatchedMap} / 1000.0"
..
> > ps- I wonder if *10000 is *better* for higher precision?

Hamish wrote: 

> depending on the sensor's 8-bitnesss or not, you can probably calculate by
> hand now many significant digits are useful. A little bit extra probably
> doesn't hurt.
> 1 / 2^8 = 0.00390625

- Does this add up (practically a lot?) to the computational cost for "mortal" 
machines?

And  two more questions on <i.histo.match>:

- is there a reason, besides time, not to make <i.histo.match> understand 
floating points?

- the algorithm implemented in  <i.histo.match>  does take Average pixel 
values as reference(s) upon which all computations are based on for the histo-
matched values, right?

--%<--- lines 165 ~ 167 --- --- --- %<---
# calculate new value of pixel_frequency
        average = (tot/n_images)  
        cHist = cHist + int(average)
--->%-- --- --- --- --->%-- --- -- --- --->%---

thnx, Nikos
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