LaTeX Error: Unknown graphics extension: .XXX

This error appears when you have used a graphics extension which LaTeX does not recognise. It can also appear when you have used a 'bad' file path which causes LaTeX to get confused.

The allowed image formats in LaTeX depend on the choice of compiler you are using. This is specified in the left hand menu as shown below.

Compiling with pdfLaTeX:

When compiling with pdfLaTeX, you have a wide choice of image formats to choose from. These are listed below

• JPG - This is the most common image format for basic use. It does not take up much space and is useful for inserting pictures in most instances.
• PNG - This is another very common format. This is better for images which require higher resolution as it is a lossless format. Diagrams should be included in PNG format
• EPS - To use EPS images when compiling with pdfLaTeX, you must use the epstopdf package.
• PDF - This is useful for including documents in your LaTeX projects. It supports vector images, as with EPS, and as such is very useful when you want high resolution images for large documents such as posters.

Compiling with LaTeX:

When compiling with LaTeX, the only image format you can use is Encapsulated PostScript or EPS. EPS files are vector based, which means that the images are invariant under scaling and is useful for if you want to create large documents such as posters, with high quality images. EPS files naturally declare the size of the image, so it is easier for LaTeX to structure the text and graphics in a nice way.

Common Causes

Using a image format which is not supported:

The most common cause of this error is when an image format which is not supported by a given compiler, such as .gif or .ps is used. The best way around this is to convert to a supported format wherever possible.

Using a bad file name:

Whenever LaTeX sees a full stop, it will interpret whatever follows to be the file extension. Therefore, if there is a full stop in the file name, such as image.logo.jpg, LaTeX will get confused as it will think that the file extension is .logo.jpg. For this reason, you must always name your images such that they do not have full stops in their titles.