= V =
vdiff /vee'dif/ v.,n.
Visual diff. The operation of
finding differences between two files by eyeball search. The
term `optical diff' has also been reported, and is sometimes more
specifically used for the act of superimposing two nearly identical
printouts on one another and holding them up to a light to spot
differences. Though this method is poor for detecting omissions in
the `rear' file, it can also be used with printouts of graphics, a
claim few if any diff programs can make. See diff.
An interesting variant of the vdiff technique usable by anyone who
has sufficient control over the parallax of their eyeballs
(e.g. those who can easily view random-dot stereograms), is to hold
up two paper printouts and go cross-eyed to superimpose them. This
invokes deep, fast, built-in image comparison wetware (the same
machinery responsible for depth perception) and differences stand
out almost immediately. This technique is good for finding edits
in graphical images, or for comparing an image with a compressed
version to spot artifacts.
--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.