[GRASSLIST:3375] Re: PNG driver 24 bit

[Glynn Clements]

Ulrich Leopold wrote:

> I do not manage to get true color support. I installed the png driver
> with 24 bit.
> 
> But when I 'export GRASS_TRUECOLOR=TRUE' for the PNG monitor the map
> legend appears with steps in the color change. In the X-monitors it is
> shown correctly with a smooth change in colours.
> I guess this is because of non-true colours?
> 
> gd-2 and libpng-1.2.5 are installed.
> 
> Any ideas how I can achieve the true color support and a smooth gradient
> in the legend for the PNG monitor?

Does "d.mon start=PNG" print the message:

	PNG: GRASS_TRUECOLOR status: TRUE

If it doesn't, then either the PNG driver was built without
true-colour support, or the GRASS_TRUECOLOR environment variable
hasn't been set correctly.

You can check whether the PNG driver was built with true-colour
support by running "strings" on it and checking for the existence of
the string GRASS_TRUECOLOR in the output, e.g.:

	$ strings /usr/local/grass5/driver/PNG | fgrep GRASS_TRUECOLOR
	GRASS_TRUECOLOR
	PNG: GRASS_TRUECOLOR status: TRUE

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