GSoC/GCI Archive
Google Code-in 2012 Copyleft Games Group

Wesnoth: Remove almost-transparent pixels

completed by: Samuel Kim

mentors: Alarantalara, mattsc, Nils Kneuper

Some of Wesnoth's core/images/terrain images contain mostly transparent pixels that do not contribute visually to the image and were not noticed by the artist prior to submission. As compositing such pixels into the final terrain has a relatively high cost for little effect, we want to identify images that have disconnected areas of mostly transparent pixels and remove those pixels from the image. Mostly is roughly defined as having an alpha values less than or equal to 10 out of 255.

[IMAGE*checkout*/wesnoth/trunk/data/core/images/terrain/walls/wall-stone-lit-A05-n-ne.png?revision=48839]This old version of a wall is an example of an image with such pixels. [IMAGE*checkout*/wesnoth/trunk/data/core/images/terrain/walls/wall-stone-lit-A05-n-ne.png?revision=55674]This is the same image after manual removal of the mostly transparent pixels. While some connected pixels are also removed here, it is not required to remove those pixels to complete this task.

Successful completion of this task is achieved by writing an automated method to find and remove such pixels along with instructions for use. The automated method must use open source software and tools that are equally available for Linux, OS X and Windows. Suggested tools include Python and/or Gimp as both are already used within the project.