The RAW file format contains untouched raw pixel information that comes straight from sensors of a digital camera. In digital photography it is the equivalent of a negative from traditional film-based photography. Digital Cameras process the RAW file by changing it to a full colour JPEG or TIFF image file that is stored on a memory card for a camera, but it is usually possible to retain the original RAW file too. Generally as the RAW file comes straight from the sensor this gives photographers more control over how the final JPEG or TIFF image is displayed.
There is no single RAW format. Digital camera manufacturers have each developed their own proprietary (often undocumented) formats, often changing the format from one camera model to the next. Several major manufacturers, including Canon, Sony and Nikon encrypt elements of the file to prevent 3rd party tools from accessing them.
RAW files are made up of 12 or sometimes 14 bits compared to JPEG which is only made up of 8 bits. This provides for better image quality since any calculations used to generate the pixel values (often described as RGB) can be performed on the base data. This does however mean that RAW file sizes are often between two and six times large than standard JPEG images.
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PDF is a file format developed by Adobe Systems for representing documents in a manner that is separate from the original operating system, application or hardware from where it was originally created. A PDF file can be any length, contain any number of fonts and images and is designed to enable the creation and transfer of printer-ready output.
Each PDF file encapsulates a complete description of a 2D document (and, with the advent of Acrobat 3D, embedded 3D documents) that includes the text, fonts, images and 2D vector graphics that compose the document. They do not encode information that is specific to the application software, hardware, or operating system used to create or view the document.