mIRC - NicheInterests/mistfunk GitHub Wiki
A venerable [IRC] client going back to the Trumpet Winsock days under Windows 3.x, started in 1994 and first shared publicly in 1995. Operating under a GUI gave users the ability to visually compartmentalise their public and private conversations as well as locally control the user experience with sounds, colours and interface buttons. Like most Windows apps of the era, it defaults to notepad-style text display of black characters against a white background.
Like many IRC clients, it will allow the display of [low-ASCII] text and punctuation characters and you can even approximate the display of ANSI art using proprietary colour codes (this is called [mIRCart]), but textmode images shared in this way will not necessarily be intelligible to non-MIRC-using IRC users, and in any case, posting text art to IRC channels is an excellent way to trigger flood protections and be kicked from the channel.
(Contrast with [BitchX], a popular underground IRC client for *nix users, that runs in terminal mode, presumably with a black background.)