Graphics file extensions and their order of inclusion when not specified

pdftex.def

Version 2011/05/28 v0.06e

The list depends on

• the version of pdftex.def,
• the version of pdfTeX (temporarily TIFF was available, latest addition is JBIG2),
• the version of the generated PDF (JBIG2 requires PDF 1.4).

For the current versions (2012) and PDF ≥ 1.4, the list is:

.png,.pdf,.jpg,.mps,.jpeg,.jbig2,.jb2,.PNG,.PDF,.JPG,.JPEG,.JBIG2,.JB2

The order of the list is not optimal, it is a victim of compatibility.

The list can be extended by package epstopdf that adds .eps to the list and provide means to support further image formats.

dvips.def

Version: 1999/02/16 v3.01i

.eps,.ps,.eps.gz,.ps.gz,.eps.Z

Other supported extensions:

.pcx,.bmp,.msp,.pict,.pntg

dvipdfm.def

Version: 1999/9/6 vx.x (Bug: should be 1999/09/06)

.jpg,.jpeg,.pdf,.png

Also supported are EPS files.

dvipdfmx.def

Version: 1999/02/16 v3.0i

.pdf,.jpg,.jpeg,.png,.bmp,.ps,.eps,.pz,.eps.Z,.ps.Z,.ps.gz,.eps.gz

xetex.def

Version: 2009/11/22 v0.94

.pdf,.eps,.ps,.png,.jpg,.bmp,.pict,.tif,.psd,.mac,.sga,.tga,.gif

vtex.def

Version 2001/10/02 v7.45

.gif,.png,.jpg,.tif,.bmp,.tga,.pcx,.eps,.ps,.mps,.emf,.wmf
(also .tiff, .targa, .jpeg)

Other drivers in the graphics bundle

Version: 1999/02/16 v3.0i

dvipdf.def:  .eps,.ps,.eps.gz,.ps.gz,.eps.Z
dvipson.def: .eps,.ps,.pcx,.bmp (also .tif)
dviwin.def:  .eps,.ps,.wmf,.tif
emtex.def:   .eps,.ps,.pcx,.bmp
pctex32.def: .eps,.ps,.wmf,.bmp
pctexhp.def: .pcl
pctexps.def: .eps.ps
pctexwin.def: .eps,.ps,.wmf,.bmp
tcidvi.def:   <empty> (also .ps,.eps,.PS,.EPS and BMP)
truetex.def:  .eps,.ps (also .tif,.bmp)

List manipulation

I recommend package grfext for manipulating the list of graphics extensions.

• Extensions can be added: \AppendGraphicsExtensions, \PrependGraphicsExtensions.
• Extensions can be removed: \RemoveGraphicsExtensions.

For example, prefer vector graphics over bitmap graphics, indenpendent of the driver:

\documentclass{article}
\usepackage{graphicx}
\usepackage{grfext}

\AtBeginDocument{%
  \PrependGraphicsExtensions*{
    .mps,.MPS,.pdf,.PDF,.eps,.EPS,.ps,.PS,
    .png,.PNG,.jpg,.jpeg,.JPG,.JPEG,
    .funny,.foobar
  }%
  \PrintGraphicsExtensions % see .log file
}

\begin{document}
\end{document}

Package grfext prints the list in the .log file (example for pdflatex/TL2011):

Package grfext Info: Graphics extension search list:
(grfext)             [.mps,.pdf,.PDF,.eps,.png,.PNG,.jpg,.jpeg,.JPG,.JPEG,.jbig2,.jb2,.JBIG2,.JB2]

The star form of \PrependGraphicsExtensions only adds the extensions that are supported by the graphics driver.

The defaults are defined in the driver files, not by graphicx itself. A simple way to see them is to use texdef, e.g. texdef -t pdflatex -p graphicx Gin@extensions.

For latex in DVI mode the default extension list is .eps,.ps,.eps.gz,.ps.gz,.eps.Z, for pdflatex and lualatex it is .png,.pdf,.jpg,.mps,.jpeg,.jbig2,.jb2,.PNG,.PDF,.JPG,.JPEG,.JBIG2,.JB2,.eps and for xelatex it is .pdf,.eps,.ps,.png,.jpg,.bmp,.pict,.tif,.psd,.mac,.sga,.tga,.gif.