Xv is also a common abbreviation for the X video extension

X video extension

The X video extension, often abbreviated as XVideo or Xv, is a video output mechanism for the X Window System. The protocol was designed by David Carver; the specification for version 2 of the protocol was written in July 1991. Its main use today is to rescale video playback in the video controller...

.

xv is a shareware

Shareware

The term shareware is a proprietary software that is provided to users without payment on a trial basis and is often limited by any combination of functionality, availability, or convenience. Shareware is often offered as a download from an Internet website or as a compact disc included with a...

 program written by John Bradley to display and modify digital images under the X Window System

X Window System

The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...

.

While popular in the early 1990s ('XV is widely considered to be the preeminent image viewer for the X Window System' ), no official releases have been made since December 1994. Bradley was unable to negotiate the LZW

LZW

Lempel–Ziv–Welch is a universal lossless data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. It was published by Welch in 1984 as an improved implementation of the LZ78 algorithm published by Lempel and Ziv in 1978...

 patent licence necessary for encoding the then-popular GIF format. The patent has now expired, so this legal constraint is no longer relevant.

Until at least 2000, Bradley collected third-party updates to xv, for example support for the PNG image format.
These were published as source code patches

Patch (Unix)

patch is a Unix program that updates text files according to instructions contained in a separate file, called a patch file. The patch file is a text file that consists of a list of differences and is produced by running the related diff program with the original and updated file as arguments...

 only.
Additional patches are still created and maintained by volunteers.

xv can be run from either the command line or through a graphical interface.
It distinguishes itself from many other bitmap viewing and editing programs with a very efficient interface in which the user edits just the parameters of a fixed pipeline of processing steps, rather than modifying the bitmap directly in each operation. As a result, the user can easily undo operations (such as cropping, color modifications, filtering) out of order, rather than only being able to undo the respective last operation. While this concept limits what xv can do compared to some alternatives, the functionality it provides can be applied very conveniently and efficiently.

xv is still present in recent Slackware

Slackware

Slackware is a free and open source Linux-based operating system. It was one of the earliest operating systems to be built on top of the Linux kernel and is the oldest currently being maintained. Slackware was created by Patrick Volkerding of Slackware Linux, Inc. in 1993...

 and openSUSE

OpenSUSE

openSUSE is a general purpose operating system built on top of the Linux kernel, developed by the community-supported openSUSE Project and sponsored by SUSE...

 releases, but it is no longer bundled with most Linux distribution

Linux distribution

A Linux distribution is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications...

s.

External links

• http://www.trilon.com/xv/ Official Website
• http://sonic.net/~roelofs/greg_xv.html Greg's Jumbo Patches for John Bradley's XV
• http://software.schmorp.de/pkg/CV.html A fast image viewer loosely modeled after XV and optimised for big directories