Monitor colors

[Jonathan L Deenik]

Hi Martijn,

Itried the exact procedure you suggest in your message to Morris, but 
there is no change.  The histogram continues to show that in TM band 4, 
for example, only 31 levels are present.

Jonathan

On Fri, 5 Aug 1994 martijn at scanner.frw.uva.nl wrote:

> Hi Morris,
> this is a feature of Grass that has caused reams of email already. You 
> can find a summary of the discussions on this list in my Grass Beginners' 
> Manual, available by anon ftp from scanner.frw.uva.nl:pub. Briefly, with 
> Grass in default condition, you will see only 6 different greys in an 
> image that has 256 grey values - I've never checked how many of 256 
> colors are actually visible. The d.colormode float command will release 
> additional colors for display, but only AFTER you d.erase and redisplay 
> your image. Hope this helps and that Grass developers will find a way to 
> emulate the display capabilities of Xv...
> 
> P. Martijn van Leusen
> Institute of Prehistory, University of Amsterdam   martijn at scanner.frw.uva.nl
> 
> 
> On Fri, 5 Aug 1994, Morris Trimmer wrote:
> 
> > GRASSers,
> >   I am not getting all the colors displaying on the GRASS display 
> > monitor.  Colormode float only seems to enhance the colors but not 
> > provide any more colors than does fixed mode. 
> >   The images I am displaying are scanned photographs that we are 
> > using v.digit to map on top of.  The colr file in the database shows 
> > 256 categories each with its own unique rgb mix, and yet when I run 
> > d.colortable many of the 256 colors are the same.
> >   When the image is displayed similar colors seem to be blended into 
> > one and this washes out some of the detail needed for mapping.
> >   Is this a problem with the display monitor (d.mon)?  Is it realy this 
> > limited in its color display capabilities?  Or am I just missing 
> > something here?
> >   The photographs are scanned, saved as tiff, converted to 
> > sunraster using xv (24 to 8 bit), and imported into GRASS using 
> > r.in.sunrast.  Both the tiff and sunraster files show all the colors 
> > when displayed using xv.
> >    Thanks!
> > Morris Trimmer
> > University Computing
> > Washington & Lee University
> > Lexington, VA. 24450
> > trimmer at wlu.edu
> > (703) 463-8846
> > 
>