AGTH is a tool for capturing text from running programs. Main purpose - extracting text from japanese games for translation.
AGTH works by intercepting program calls of system text functions. So when game tries to print some text on the screen - it's not just printed but also captured as text. AGTH doesn't scan for text any files or program memory, doesn't try to OCR any screen area - it just logs text interaction of program and system. So if game uses text already printed on images - nothing useful can be captured from it.
Besides fixed set of system functions, AGTH can be configured to capture text from arbitrary program address making it possible to directly capture text from internal processing program functions.
There are some other tools for capturing/translating text from games. AGTH's main difference from them is that it specializes on reliable text capturing with as little interference to original process workflow as possible. No built-in translation, no custom text filtering - use other programs side-by-side with AGTH for that.
AGTH requires Windows 2000 or newer NT-based system, x64 and server variants are also supported. Recommended operation system - Windows 2003 and newer (yes, some features won't work on XP). With Vista/Win7 you would likely want to run AGTH with elevated rights or disable UAC.
Current version: 2011.5.9
SHA1 checksums of files: agth.exe AA0573835F083F175F9A9DDF2F22D2CAF073B45A agth.dll 3C38C1AE1779EFA7FC891259241CCDC8C9B749CF
Previous stable version: 2011.4.21
SHA1 checksums of files: agth.exe 635439EF33372D9428CC00B47B80167E158DF0F8 agth.dll A7F4F7E945634F7EA8F692ECD7851213A4AD0D62
If these checksums match and your antivirus finds a virus/trojan in AGTH - ask its creators to reanalyze the files.