[GRASSLIST:2285] Re: Poor quality PNG file driver output

[Jason Horn]

Glynn, Hamish

Thanks for all the information - it helps tremendously to have the 
benefit of your familiarity and experience with GRASS.  I never would 
have known, for example that 5.3 doesn't need the gd library anymore 
unless you'd told me.

Glynn, I can't use manual screen capture because I'm writing a script 
to automate the building and output of hundreds of images that will be 
used in an animation sequence (each is a NEXRAD RADAR image overlaid on 
a shaded landscape and that has labels identifying point features)  
Looks like the xwd will work fine until I re-compile 5.3.

To Everyone,
Sorry for the attachments.  I'm new to the list - won't make that 
mistake again. :)

Cheers,

Jason


Jason Horn
Boston University Department of Biology
5 Cumington Street  Boston, MA 02891

jhorn at bu.edu
617 353 6975

On Jan 19, 2004, at 2:12 AM, Glynn Clements wrote:

>
> Jason Horn wrote:
>
>> As for re-compiling grass, I'm not sure if I could do it.  I am using
>> 5.0.2 off of the OpenOSX CD because I'm not an expert with UNIX.  It
>> was a two-day ordeal for me to get the gd library compiled and running
>> on my system.  However, I would try to compile it (and all the other
>> libraries that go with it) if I thought it would help.  So, for 
>> Hamish,
>> or anyone else who can help...
>>
>> 1) Why do you think re-compiling would help?  I wouldn't want to waste
>> days on that endeavor if it wouldn't work.
>
> If the PNG driver was built using GD 1.x, it will use GD 1.x at
> run-time (or fail to run if GD 1.x can't be found). There isn't any
> way to make it use GD 2.x without re-compiling it.
>
> The quote from Markus' book:
>
> 	"If the Gd2.x library is installed the driver supports true
> 	color output"
>
> isn't entirely accurate. The determining factor is whether the driver
> was built with GD 2.x, not whether GD 2.x happens to be present on the
> system.
>
> The official recommendation was to use GD 1.x, because more systems
> have it installed, and GD 2.x was considered "beta" until recently.
>
>> 2) If I do, which version should I compile?
>
> Hard to say. 5.0.3 has some fixes; however, OpenOSX made some
> Mac-specific changes to improve integration (e.g. allowing tcltkgrass
> to use the Aqua version of Tcl/Tk) which aren't in the stock source
> releases.
>
> If you build 5.0.2 from the OpenOSX source code, you could just
> replace the PNG driver ($GISBASE/driver/PNG) and continue using the
> other OpenOSX binaries. That way, it wouldn't matter if you had
> problems building any of the other components, so long as you could
> build the PNG driver successfully.
>
> FWIW, the current CVS version (5.3) no longer uses the GD library, and
> will always support 24-bpp images.
>
>> 3) Why do you think I'm getting the kind of poor quality from the PNG
>> driver?  Am I correct in assuming that it's because I don't have the
>> TRUECOLOR support from the gd library (even though it's now 
>> installed)?
>
> Yes. GD 1.x only supports 256-colour images, and you can't make the
> PNG driver use GD 2.x without re-compiling it.
>
> -- 
> Glynn Clements <glynn.clements at virgin.net>
>