Details Ticket 789


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Serial Number 789
Subject i.grey.scale and FP maps
Area bug
Queue grass
Requestors neteler@itc.it
Owner none
Status resolved
Last User Contact Tue Jan 8 11:55:14 2002 (7 yr ago)
Current Priority 30
Final Priority 70
Due No date assigned
Last Action Tue Jan 8 11:55:50 2002 (7 yr ago)
Created Mon Aug 20 09:42:29 2001 (7 yr ago)

Transaction History Ticket 789


Mon, Aug 20 2001 09:42:29    Request created by guest  
Subject: i.grey.scale and FP maps

Platform: Linux/Intel
Linux distro: SuSe
grass downloaded at: CVS Server, Germany
grass sources source: yes, I am using the latest GRASS from CVS

Using i.grey.scale on FP maps leads to a stripy image:

Try
r.mapcalc test="row()*1.2"

i.grey.scale test
d.rast test

The algorithm should be similar to 
r.colors map cols=grey.eq

(or not?) r.colors doesn't allow to run cols="grey.eq" on FP maps.
This looks a bit confusing.

 Markus


Fri, Nov 16 2001 17:09:07    Mail sent by mneteler  
I suggest to remove i.grey.scale completely to reduce the
number of modules.
We have r.colors!

Markus
Fri, Jan 4 2002 17:16:56    Mail sent by alange  
I am able to reproduce the i.grey.scale bug (stripes).
It seems to be related to floating point IMHO:
The following works:
r.mapcalc test="int(row()*1.2))"
i.grey.scale test
(no stripes!)

But:
r.mapcalc test="row()*1.2"
r.colors map=test col=grey.eq 
does not work with floating point rasters, only with int rasters.

So perhaps i.grey.scale should simply check that the raster is not floating 
point?

Still confused & clueless,

Andreas
Fri, Jan 4 2002 17:21:32    Mail sent by neteler@itc.it  
Return-Path <neteler@itc.it>
Delivered-To grass-bugs@lists.intevation.de
Date Fri, 4 Jan 2002 17:21:28 +0100
From Markus Neteler <neteler@itc.it>
To Andreas Lange via RT <grass-bugs@intevation.de>
Cc grass5 developers list <grass5@grass.itc.it>
Subject Re: [bug #789] (grass) i.grey.scale and FP maps
Message-ID <20020104172128.U3608@itc.it>
Mail-Followup-To Andreas Lange via RT <grass-bugs@intevation.de>, grass5 developers list <grass5@grass.itc.it>
References <20020104161656.A299D13A12@lists.intevation.de>
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In-Reply-To <20020104161656.A299D13A12@lists.intevation.de>; from grass-bugs@intevation.de on Fri, Jan 04, 2002 at 05:16:56PM +0100
X-Spam-Status No, hits=0 required=5 tests=
On Fri, Jan 04, 2002 at 05:16:56PM +0100, Andreas Lange via RT wrote:
> 
> I am able to reproduce the i.grey.scale bug (stripes).
> It seems to be related to floating point IMHO:
> The following works:
> r.mapcalc test="int(row()*1.2))"
> i.grey.scale test
> (no stripes!)
> 
> But:
> r.mapcalc test="row()*1.2"
> r.colors map=test col=grey.eq 
> does not work with floating point rasters, only with int rasters.
> 
> So perhaps i.grey.scale should simply check that the raster is not floating
> point?
> 
> Still confused & clueless,
> 

Hi Andreas,

thanks for testing. However, my suggestion is to remove the 
i.grey.scale
completely from GRASS as r.colors provides identical functionality
(including the FP test). One less module to maintain.

Any objections to remove i.grey.scale? If not,
I'll do it.

Markus


Tue, Jan 8 2002 11:55:14    Mail sent by guest  
Well, no objections.
I have removed the i.grey.scale.

Markus
Tue, Jan 8 2002 11:55:50    Status changed to resolved by mneteler  
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