The UK's Digital Imaging and Scanning Specialists


The Image Cloud Blog

Up to date news and advice on digitisation, digital preservation and document management.


Common File Formats Explained

There are many many many file formats each have their own place within the digital format hierarchy, some are better for web, some are better for graphic design and printing whilst other formats have been made specifically for digital preservation. Here is a short list of formats we use on a day-to-day basis.



Portable Document Format each PDF file encapsulates a complete layout of raster and vector images. PDF was a proprietary software controlled by adobe but was released as an open standard in 2008.

Extensions to this file format include:

PDF/A is a standardised version of PDF, used in archiving and long term preservation of electronic documents, PDF/A differs from PDF by prohibiting features unsuitable for long term archiving.

PDF/X is used to facilitate graphics exchange, and it therefore has a series of printing related requirements which do not apply to standard PDF files. Mainly used when the image or graphics saved is for printing.


Joint Photographic Experts Group, JPEG, named after the group that created the format, is the standard for compressed digital images. A degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality.


Tagged Image File Format, created by the Aldus corporation in 1992 and subsequently updated by Adobe Systems after they purchased Aldus in 1994. A popular uncompressed method of storing raster graphics, popular with photographers and graphic designers.


Portable Network Graphics, used mainly for any image that has a transparent background(Usually shown by a checkerboard background on image editors) and is used mainly for compressed images on the internet.

RAW image file formats

Sometimes called digital negatives, as they fulfil the same purpose, RAW files are not directly usable, but carry all the information of the image. To be able to edit a RAW image file it needs to be developed using a RAW image editor software. This would then be saved as TIFF or JPEG.

There is no single RAW format as manufacturers use their own proprietary formats occasionally encrypting part of the file so as to prevent third party tools from accessing them. Some formats include: 3FR (Hasselblad), CRW CR2 CR3 (Canon), NEF (Nikon), ORF (Olympus), PEF (Pentax), RW2 (Panasonic) and ARW, SRF, SR2 (Sony) and DCR, K25, KDC (Kodak).