Development of the TGA file format began in the mid eighties. A TGA file is most commonly associated with a TARGA image file (Truevision Advanced Raster Graphics Adapter). TGA files are bitmapped images, they were originally developed for use with Truevision's (now Pinnacle Systems) high-end graphics cards which were designed for video editing. TGA files are often seen in the video and animation industry, as well as by computer game manufacturers who use the TGA format to store texture files.
TGA files can store images with a range of bits, these include 8-bit, 16-bit, 24-bit or 32-bit which is 24-bit colour with transparency. They use a palette to define all available colours in an image. TGA images have typically large file sizes as every pixel is represented by a certain number of bits (dependant on the colour depth). However, they can be compressed using simple lossless run-length encoding, which can result in greatly reduced file sizes.
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.