The icoutils are a set of command-line programs for extracting and converting
images in Microsoft Windows(R) icon and cursor files. These files usually have
the extension .ico or .cur, but they can also be embedded in executables and
libraries (.dll-files).

The icotool program converts icon and cursor files into a set of PNG images.
(Each icon/cursor file may contain multiple images, usually of different sizes
and with different number of colors.) Icotool can also create icon/cursor files
from PNG images.

The wrestool program can extract both icons and cursors from 32-bit ("PE") and
16-bit ("NE") executables and libraries. It writes .ico and .cur files that can
be used on Windows(R) operating systems as well. Other types of embedded
resourced can be extracted, however only in raw form - icons and cursors require
additional conversion before they can be saved as icon and cursor files.

The extresso script automates the tasks of extracting and converting icons. This
is done with the help of of special resource scripts. The purpose of these
scripts are to give names to the icons in the executables and libraries.

WWW: https://www.nongnu.org/icoutils/