(This entry was taken from Wikipedia and edited.)
Image file formats are a standardised means of organising and storing images. This entry is about digital image formats used to store photographic and other images.
There are two types of files – lossless and lossy
• Lossless & Lossless compression – are files that do not loose information when they are saved. Lossless compression algorithms reduce file size without losing image quality. When image quality is valued above file size, use this one. This is usually a TIFF format.
• Lossy compression – are files that loose information when they are saved. Lossy compression algorithms take advantage of the inherent limitations of the human eye and discard invisible information. There are varying quality levels that can be used, higher quality uses lower compression and therefore larger files size, or conversely lower quality uses higher compression and produces a smaller file size. At the highest compression levels, image deterioration becomes noticeable. A common format that uses lossy compression JPEG
Image file formats uses – These are all explained below
• Photographic & Print Media – Jpeg and Tiff are used for storing large photographic images.
• Web Based Media – PNG, JPEG, and GIF formats are most often used to display images on the Internet.
• Graphics file formats – EPS and PDF. These files formats are used by design professionals when producing brochures and other printed material.
File Format Explaination
JPEG (Joint Photographic Experts Group) files are (in most cases) a lossy format. Nearly every digital camera can save images in the JPEG format. When not too great, the compression does not noticeably detract from the image’s quality, but JPEG files suffer generational degradation when repeatedly edited and saved. Photographic images may be better stored in a lossless non-JPEG format if they will be re-edited repeatedly. The JPEG format also is used as the image compression algorithm in many Adobe PDF files.
The TIFF (Tagged Image File Format) is a flexible format. TIFFs are lossy and lossless, offering relatively good lossless compression, using the LZW compression algorithm. Later versions of the TIFF format use lossy compression in the form of JPEG & Zip compression algorithms. The TIFF image format is not widely supported by web browsers, but remains widely accepted as a photograph file standard in the printing business. The TIFF can handle device-specific colour spaces, such as the CMYK defined by a particular set of printing press inks.
The PNG (Portable Network Graphics) file format was created as the free, open-source successor to the GIF. The PNG file format supports 16 million colours while the GIF supports only 256 colours. The PNG file excels when the image has large, uniformly coloured areas. The lossless PNG format is best suited for editing pictures, and the lossy formats, like JPG, are best for the final distribution of photographic images, because JPG files are smaller than PNG files. All contemporary web browsers now support all common uses of the PNG format.
GIF (Graphics Interchange Format) is limited to 256 colors. This makes the GIF format suitable for storing graphics with relatively few colors such as simple diagrams, shapes, logos and cartoon style images. The GIF format supports animation and is still widely used to provide image animation effects. It also uses a lossless compression that is more effective when large areas have a single color, and ineffective for detailed images or dithered images.
The BMP file format (Windows bitmap) handles graphics files within the Microsoft Windows OS. Typically, BMP files are uncompressed, hence they are large; the advantage is their simplicity, wide acceptance, and use in Windows programs.
PDF (Portable Document Format)
The PDF is a file format created by Adobe Systems in 1993 for document exchange. PDF is used for representing two-dimensional documents in a manner independent of the application software, hardware, and operating system. Each PDF file encapsulates a complete description of a fixed-layout 2-D document (and, with Acrobat 3-D, embedded 3-D documents) that includes the text, fonts, images, and 2-D vector graphics which compose the documents.
EPS (Encapsulated PostScript)
EPS is a Vector file format that can contain images. files PostScript document with additional restrictions intended to make EPS files usable as a graphics file format. In other words, EPS files are more-or-less self-contained, reasonably predictable PostScript documents that describe an image or drawing, that can be placed within another PostScript document.