File Formats

(A great research tool for future reference is ‘Prepressure’, for information on file formats and other computer-related topics)

PDF

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PDF stands for ‘Portable Document Format’ and was invented by Adobe Systems. It is regarded now as the standard electronic document exchange by the International Organisation for Standardization (ISO). Converting documents, forms, graphics and web pages to .PDF look as they would if they were to be printed, yet these files contain clickable links, buttons, video and audio. By using Adobe Reader the recipient of a shared .PDF file can read it. Examples of software which uses .PDF include the conversion of documents from programmes such as InDesign.

PSD

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The Photoshop Document is a layered image file used in Photoshop and is the default format which Photoshop uses. .PSD files can be opened with Photoshop, Photoshop Elements and Corel’s Paintshop Pro. This file type allows the user to work with the images seperate layers even after the file has been saved. Once an image is complete, it can be flattened and converted into numerous file types including; .JPG, .GIF and .TIF. However, once a PSD file has been compressed it cannot be converted back into a .PSD.

JPEG

 

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Taking its name from the committee which created it, the .JPEG (Joint Photographic Experts Group) and is the common file format for digital photos and graphics used on websites. The higher the file siz of the .JPEG, the better the quality of the image. A benefit of this file format is that there is room to reduce the file size without losing too much of the image quality. Image editing software such as Microsoft Paint and Photoshop commonly use this file format.

TIF

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Standing for ‘Tagged Image File’, it was created in 1986 as a file format for scanned images in an attempt to standardise file formats across multiple companies. Today it is used for high quality graphics which have a high colour depth. Now owned by Adobe, they can be compressed using LZW compression to reduce its file size. The file can also be converted to a number of different file formats using Image Converter Plus. .TIF’s are used exclusively for bitmap data and doesn’t contain text or vector data. It benefits from being a highly flexible and platform-independant format with numerous image processing applications supporting it.

PNG

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Although not entirely popular because of not supporting CMYK, .PNG (Portable Network Graphics) was designed to replace the .GIF. It is patent-free and offers enough features to make it an alternative to the .TIF file. .PNG is meant to store bitmap data and all major applications such as Photoshop and InDesign support it. PNG allows the image to be filtered before being compressed so as to improve the compressibility of the data.

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