[GRASSLIST:2271] Re: Poor quality PNG file driver output

[Hamish]

> I'm having trouble outputting images from the PNG file driver - the 
> quality of the resulting .png images is very poor.  I put together the 
> maps that I want to output using:
> 
> d.mon start=PNG
> d.mon select=PNG
> d.rast dem.relshade
> d.mon stop=PNG
> 
> This does NOT give me what I'd see in the grass monitor if I'd used 
> d.mon start=x0 instead of the PNG driver.  The colors in the image are 
> interpolated, not enough shades of grey, for instance, as if the color 
> palette was very small.  Lots of blotchy colors, and no smooth 
> transitions and  gradients.
> 
> Markus, in your book you make the following reference on p. 187 in the 
> section 8.1.3 on "Monitor output to PNG and HTML files"
> 
> "If the Gd2.x library is installed the driver supports true color 
> output"
> 
> Because my images look like they don't have enough colors, I assumed 
> this was the problem.  So, I installed the gd  2.0.9 library and tested 
> it to make sure it was working.  I get the same poor quality images.  I 
> AM setting the GRASS_TRUECOLOR=TRUE environment variable.
> 
> What's going on here?  Why is the output from PNG file driver so 
> different from the output from the GRASS monitor?


Did you recompile GRASS after installing GD 2.0?


maybe one of the following two scripts will be helpful.


Hamish

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