About releasegroups:
Scene Art

Scene art are digitally produced images. Offcourse they are not just created by releasegroups. As a result of the artscene's early affiliations with hacker and software piracy organizations, the digital art is quite detached to the scene. There are two types of art types used for the scene. First here is ASCII art and second there is ANSI art.

ASCII art is an artistic medium that are graphics pieced together from the 95 printable characters defined by ASCII. ASCII art is used in the releasegroup's nfo file. The standard viewer for NFO files is Damn NFO Viewer, but you can also view them with notepad.

NFO files were first introduced by the releasegroup THG (The Humble Guys) with their release of the pc game "Bubble Bobble". This nfo file was a replacement of the more common "readme.txt" files. Nowadays the nfo file is like a signature of the group, so it's important to have a cool and good-looking nfo. A typical modern day NFO file is elaborate and highly decorated, with ussually a large logo at the top with all the release-related information below.

ANSI art
As computer technology developed, monitors were available that could display color. Eventually, text artists began incorporating this new level of flexibility to the existing medium of ascii art by adding color to their text-based art, or animating their art by manipulating the cursor control codes. Quite simply, this is what is commonly referred to today as ANSI art.

The majority of the early created ANSI art in the IBM PC artscene were distributed as coded executables called loaders or intros/cracktro's rather than raw bitmap images. A crack intro, also known as a cracktro, loader, or just intro, is a small introduction sequence added to cracked software, designed to inform the user which releasegroup or individual cracker was responsible for removing the software's copy prevention and distributing the crack.
Cracking groups would use the intros not just to gain credit for cracking, but to advertise their bulletin boards, greet friends, and to give themselves recognition.

For more info and examples i refer you to the website of ROY from SAC.