You'll need three extra things first;
--
Dragon Unpacker (which includes the new CiV plugin) to access & open the
UITextures.fpk file found in the ..YourCivgame../Resource/DX9 folder.
-- Gimp! and its DDS plugin to read (or resave as PNG, BMP, JPG, etc as you'd wish) any of these resources.
-- Sterkhov's
Unpacker utility/tool; which specifically reassembles some of these DDS "masters" (IIRC correctly the Wonders are stand-alone though) with their corresponding
***-index.dds files.
Secondly, aaaallllll the way down in that archive -- the
wonderconcept****.dds files are the actual images used within the game. Extract where you want.
Then, double-clicking from MS-Explorer on any of the newly unpacked dds should open-up Gimp where you'll see them.
OR...... simply click below and
save image as from your browser.