Converting multiple BLPs (or PNGs) into a single BLP (or PNG)

[Ketho]

In the WoW artwork files, it seems common to see a bunch of BLP files, that actually form a single art file when glued together

• Are there any scripts, or specific tools available to convert them to a single BLP? So we don't have to use Photoshop/Gimp/etc?
• If an executable/script is required, is it possible to do this with Lua, or is this better done in "real" programming languages?
• It would also be great if instead of BLP files, it could work with PNG files instead, since most people would want to convert it to PNG anyway
  
  
• I found this post from Xinhuan, but the reference only exists in the Google Cache now, but it was focusing more about the MPQ's Minimap files in particular
  
  
• WorldMapFrame_Update and CreditsFrame_SetArtTextures seem to have the Lua logic for it, but I don't quite understand it, and it's only for making them appear pasted together ..
• I'm also wondering how Wowhead and MMO-Champion manage to do this

Here is an example:

http://imgur.com/a/e7K3d Interface\WorldMap\Pandaria\Pandaria1.blp Interface\WorldMap\Pandaria\Pandaria2.blp Interface\WorldMap\Pandaria\Pandaria3.blp Interface\WorldMap\Pandaria\Pandaria4.blp Interface\WorldMap\Pandaria\Pandaria5.blp Interface\WorldMap\Pandaria\Pandaria6.blp Interface\WorldMap\Pandaria\Pandaria7.blp Interface\WorldMap\Pandaria\Pandaria8.blp Interface\WorldMap\Pandaria\Pandaria9.blp Interface\WorldMap\Pandaria\Pandaria10.blp Interface\WorldMap\Pandaria\Pandaria11.blp Interface\WorldMap\Pandaria\Pandaria12.blp (10 images per post restriction)

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