When using graphicx's \includegraphics you can specify the file extension or not. For generic use and perhaps portability, extensions are commonly dropped. The types of "approved" inclusions and their order of precedence depends on the driver/compiler being used. What are these driver-defaults?
Related: Which graphics formats can be included in documents processed by latex or pdflatex?
pdftex.defVersion 2011/05/28 v0.06e
The list depends on
pdftex.def,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.defVersion: 1999/02/16 v3.01i
.eps,.ps,.eps.gz,.ps.gz,.eps.Z
Other supported extensions:
.pcx,.bmp,.msp,.pict,.pntg
dvipdfm.defVersion: 1999/9/6 vx.x (Bug: should be 1999/09/06)
.jpg,.jpeg,.pdf,.png
Also supported are EPS files.
dvipdfmx.defVersion: 1999/02/16 v3.0i
.pdf,.jpg,.jpeg,.png,.bmp,.ps,.eps,.pz,.eps.Z,.ps.Z,.ps.gz,.eps.gz
xetex.defVersion: 2009/11/22 v0.94
.pdf,.eps,.ps,.png,.jpg,.bmp,.pict,.tif,.psd,.mac,.sga,.tga,.gif
vtex.defVersion 2001/10/02 v7.45
.gif,.png,.jpg,.tif,.bmp,.tga,.pcx,.eps,.ps,.mps,.emf,.wmf
(also .tiff, .targa, .jpeg)
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)
I recommend package grfext for manipulating the list of graphics extensions.
\AppendGraphicsExtensions, \PrependGraphicsExtensions.\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.
.png has precedence over .pdf in pdflatex. I mean, if you have a vector and a bitmap version of the same image, the bitmap version should be preferred? Does anybody have a clue about the rationale behind this?
pdftex.def.
Commented
Sep 18, 2012 at 8:02
If someone came here because he/she tried to take e.g. .pngs instead of .pdfs for the draft, put this in your preamble:
\DeclareGraphicsExtensions{.png,.pdf}
Feel free to adapt this to your needs.
As of ~2021 (MiKTeX 21.7), it seems the order has been updated. (install directory e.g. MiKTeX)\tex\latex\graphics-def\pdftex.def, line 586:
\def\Gin@extensions{%
.pdf,.png,.jpg,.mps,.jpeg,.jbig2,.jb2,%
.PDF,.PNG,.JPG,.JPEG,.JBIG2,.JB2%
}
