Graphic artists usually meet on the artwork development forum. This is a great place to discuss new and current Wesnoth art and graphics, and to see what other people are contributing.
Unit and terrain art is stored in the portable network graphics (PNG) format. Each frame of a unit animation, and each variation of a terrain is stored as a separate .png file in the "images" subdirectory of wesnoth, and generally these files will be 72 x 72 pixels (the size of Wesnoth's basic hexagonal tile) with an alpha channel (a part of the file that indicates how transparent each pixel is). When creating your own images, you can test them without overwriting any game data by putting them in your userdata directory (see EditingWesnoth for details on Wesnoth's directory structure). The game also supports JPEG images, though these are better suited for story art.
To edit these graphics, you'll need some program capable of creating PNGs - some of the programs in the following list are free, open-source software, and will do the job nicely: Art Programs
If you need some inspiration, we have a Graphics Library which collects art posted on the forum. You can use this for ideas, and as a scrap heap for different parts of unit images (a technique described here). One of the best examples of the library's content came from the project artist "Neoriceisgood," which can be seen in the following forum thread.
A series of art tutorials are being worked on, which may be of help. These will describe both how to make art fit into wesnoth's style, as well as giving some considerable tips on drawing in general. Especially useful is the External Tutorials page which lists some very good art tutorials available on the web. If you're new to sprite art, or just want to play around, the Give Your Hero A Personality tutorial is a good place to start.
The following is information specific to drawing terrain for Wesnoth. Read Frame's "Tiles Tutorial" for a good overview of how terrain graphics work.
- Tiles Tutorial - Frame's tutorial describing the process of making terrain tiles in wesnoth, and how they interact with adjacent tiles.
- How To Make Seamless Tiles - Eleazar's tutorial on making your terrain tiles seamless. The tutorial is aimed at Photoshop users, but the technique is similar with The GIMP.
- Castle Tutorial - A description of how Wesnoth's castle tiles work (needs updating, but useful nonetheless)
- Multi-Hex Tiling Tutorial - A description of how multi-hex tiles work.
- Editing Castles - Instructions for how to make/edit castles (and other corner-based terrains) using yobbo's GIMP script.
To check what's being done and what needs doing, go here:
- Tiles Status - a roadmap/plan of sorts for future work
These describe the system used to specify how terrains behave in game:
- TerrainLettersWML - A list of the letters used to represent terrain types.
- TerrainGraphicsWML - If you really need to get technical, start here.
- Ayin's Terrain Graphics document - If you really, really need to get technical, this describes the terrain graphics WML system in depth.
The following are different tutorials about sprite work compiled by various wesnoth sprite artists. These will give you the most specific-to-wesnoth information about making sprites, and are well worth a read.
- Creating Unit Art - a list of specifications you will need to match.
- Give Your Hero A Personality - tricks for editing existing images, including some clip art.
- Basic Animation Tutorial - or "How to Animate Sprites for Dummies," covering the basic theory, and all of the mistakes to avoid.
- Team Color Shifting - how to use our new team color system (only for wesnoth 1.1 or greater).
- Creating Shadows Under Units - how we create the shadows for the units in-game
The following page contains dozens of links to tutorials covering all manner of artwork, including sprite art. These were not made by wesnoth artists, but should prove very useful for general instruction.