Re: [LIBART] Cool demo, graphics bug

[Raph Levien <raph levien com>]

On Tue, Sep 11, 2001 at 11:57:35AM +0200, k.wetzel wrote:
> > Here is the correct link:
> > 	
> > 	http://galatea.stetson.edu/~dholth/
> 
> (Yes, fortunately you've had the right spelling in your email address.)
> 
> > 	There are a couple of libart-drawn maps there now.
> 
> Cool.  What do the black lines represent ?  Does anybody know why
> PNG gives such a poor compression rate on this image (only
> about 1:4) ?  
> Are you developing some application or do you only do this to
> test libart ?

I've just got back from Chicago. Looks neat!

The "paint leaking to the right" bug is known and will, in fact, be
fixed soon (after over two years).

The compression ratio is poor because Libart does its antialiasing
analytically, so all gray values are represented. You can improve
PNG compression by doing quantization prior to compression:

$ ls -la orange1.png 
-rw-r--r--    1 raph     raph      1144356 Sep 11 09:18 orange1.png
$ pngtopnm orange1.png | pnmdepth 3 | pnmtopng | wc -c
 235035
$ pngtopnm orange1.png | pnmdepth 7 | pnmtopng | wc -c
 305838

Raph