Re: [Freeciv-Dev] Tiles graphics format (xpm)

[Greg Wooledge <wooledge@xxxxxxxxxxx>]

Martin Willemoes Hansen (martin_w_hansen@xxxxxxxxxxxxxxx) wrote:

> Ralf engels suggested that we use the gif or png 
> format. I dont exactly know the difference between 
> these format. All I know is that the gif is widely used
> and I have heard that the png have a better license
> or something than gif has. Somebody enlighten me!

GIFs are compressed using LZW compression, which is covered by a patent
in the United States.  It is therefore illegal (in the USA) to write
software which creates GIF images, unless a license is obtained from
the patent holder (Unisys, I think).  I don't know what the situation
is in other countries.

As far as I know, it is OK to write software which *reads* GIFs, to
convert or display them -- but not to write them.

PNG (portable network graphics, right?) is supposed to become a GIF
replacement.  It's a lossless image format (unlike jpeg, which is a
great format, but lossy), and not subject to the patent problems of GIF.
Unfortunately, it hasn't caught on.

GIFs also offer no significant advantage over XPMs, except for file size.
GIFs are limited to 256 colors, and unlike XPMs, they can't easily be
treated like source code (readable patches generated).  Remember, XPMs
are ASCII text files, so diff/patch work great with them.

I'd vote to stay with XPM.

-- 
Greg Wooledge                    | Distributed.NET http://www.distributed.net/
wooledge@xxxxxxxxxxx             | because a CPU is a terrible thing to waste.
http://www.kellnet.com/wooledge/ |