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		What file types are you talking about? Where do these file types come from? What is postscript? What does encapsulated postscript mean? Is postscript a computer language? What is a RIP? Who says what file formats will become standard? What do you mean by vector? What do you mean by raster or bitmapped? What is a native file? When do I use TIFF files? What is TIFF/IT? What is DCS? What does JPEG mean? When do I use a PICT file? What is a PDF? What are postscript files?
	TO TOP	What file types are you talking about?
		The software applications commonly used in the graphics arts industry fall into two groups: 1 Graphics programs (drawing, painting and image-editing).    These programs are either vector or raster. 2 Page-layout programs (combine graphics and text).    These are prepared in native formats. Most software programs now allow the operator to save a file in different formats. Over the years, some file formats have become more popular than others. Each option has its strengths and weaknesses. A welcome trend in the Graphic Arts industry is the shrinking list of file format options.
	TO TOP	Where do these file types come from?
		When electronic publishing began in the early 1980s, software developers worked within closed, proprietary systems called colour electronic prepress systems (CEPS). There were no common hardware platforms. No-one was thinking about sharing digital files, so transportability was not an issue. The evolution of desktop publishing in the mid 1980s completely changed this paradigm. The modular, open systems of this revolutionary system meant that a variety of software packages and peripheral devices had to be compatible with work stations. The new techology demanded that users work with electronic files that can be reliably moved from one hardware and software environment to another. The key to this new world is that the computers and peripherals operate using the same page description language. Postscript has become the de facto standard for electronic publishing.
	TO TOP	What is postscript?
		Postcript was the revolutionary technology that enabled electronic publishing to move from closed proprietary systems to the current environment of open systems. The graphics arts industry has spent nearly a decade developing tools and procedures to make postscript work in the electronic prepress workflow. Postscript is a DEVICE-INDEPENDENT PAGE DESCRIPTION LANGUAGE. This definition implies that an operator should be able to send a Postscript file to any device that can interpret Postscript. However, Postscript is not a file format for digital file delivery, it is a computer language. Once an application file has been converted to Postscript, it is embedded with certain characteristics of the target device and there is a good chance that the file will not output on any other device other than the one intended.
	TO TOP	What does encapsulated postscript mean?
		EPS is is a common variant of Postscript. It is a limited implementation of Postscript that allows users to exchange individual graphics and individual pages while maintaining the integrity of the file's contents.
	TO TOP	Is postscript a computer language?
		If you use three different applications to generate Postcript such as Pagemaker, QuarkXpress and Publisher, they each use a slightly different version of Postscript. These digital differences are accomodated in the same way as humans using different dialects of the same language. And, just like differet dialects, there are no exact rules as to what constitutes a correct Postscript file. When these three Postscript files of different dialects are sent to the same RIP (Raster Image Processor), each file may or may not output as expected. Also, if you send these three different files to three RIPs from three diffferent manufacturers, you may get nine slightly different results, including Postscript error messages. The output glitches are due in part to that part of the RIP called the interpreter.
	TO TOP	What is a RIP?
		A RIP is the driver for laser printers, imagesetters and platesetters. It has three distinct parts: an interpreter, a rasterizing engine and a screening engine. The language that the applications use is Postscript, but the different dialects cause output problems and unfortunate Postscrip errors. The interpreter of the RIP may not understand each file immediately because of the different dialects and vocabularies
	TO TOP	Who says what file formats will become standard?
		Standards are being developed as electronic colour publishing evolves. A standard is usually developed by a group of companies and users. To achieve accreditation, a standard is submitted several times to national and international bodies for balloting. Because of the committee-based nature of accreditation standards, they typically take time to progress from concept to being released as a standard. Two years of development is a reasonable period for a standard to reach accreditation. A standard is entirely in the public domain and is owned by no one company. De facto standards, established by general consent, tend to be developed by one or two companies to address specific needs. They are market driven and the gestation period for de facto standards is less than for accredited standards. The most useful standards are those that are implemented industry-wide. By exercising their purchasing power, users of electronic publishing software and hardware can influence vendors' conformance to industry standards.
	TO TOP	What do you mean by vector?
		Vector files are a collection of geometric shapes / lines, vectors, and colour information / illustrations. Graphics created using most drawing software packages are vector based (object orientated) - Illustrator, Corel Draw, Freehand, to name the most common. Vector files are modified very easily, have very small file sizes, and the resolution is determined by the output device - the image is drawn via algorithmic instruction. However, vector images do not handle photographic detail very well.
	TO TOP	What do you mean by raster or bitmapped?
		Raster or bitmapped files are used to depict continuous tone, photographic and grey-scale images - images captured by a scanner, manipulated by image-editing software programs or created by a paint program. Raster images are described pixel by pixel and contain value information (in bits) for individual pixels. The numbers of bytes per pixel is called bit depth. The number of different colours that a pixel can have depends on bit depth. Raster images are not easily edited and require a lot of computer memory. They cannot be scaled in size without affecting the output resolution. High res raster scans should not be scaled up more than 10% or down more than 30% without affecting final output quality. Raster file formats have many advantages: they maintain the fidelity of photographic originals very well, they require less processing time, they can be easily exchanged or converted to different raster file formats. A vector image can be converted to a raster image. Converting a raster image to a vector image is nearly impossible.
	TO TOP	What is a native file?
		Application files are the native format of the application that created them. The majority of files delivered to Repros are native files. Native files are easily edited using the same software that created the file. This ease of editing, however may lead to inadvertant errors as the file moves through the production process. Reprographics must have the same version of software as the originator. Also if an application file is opened on a workstation without the same combination of fonts, plug-ins or additions used to create the file, problems are sure to arise.
	TO TOP	When do I use TIFF files?
		The tagged image file format (TIFF) is the most common format for the exchange of graphic raster files. TIFF files consist of two primary components: graphic data and tag information. The graphic data can consist of graphics in one of several possible fromats. It is the tag information that describes the make-up of the graphic data to your software and makes TIFF such an excellent choice for file exchange.
	TO TOP	What is TIFF/ IT?
		Because the TIFF format allows for such a great degree of flexibility, it is not necessarily an ideal format for graphic arts applications. A variant of TIFF called the tag image file format for image technology (TIFF/ IT) allows for the exchange of proprietary, high-end graphic arts workstation (CEPS) file formats. The TIFF/ IT standard limits variability and its allowable graphic data formats are not easily editable. This format is very suitable for the exchange of final files and delivery to printers but only a few desktop applications support TIFF/ IT.
	TO TOP	What is DCS?
		Desktop colour separation (DCS) files are used for four-colour pre-separated images and include five image components: cyan, magenta, yellow and black and a low-resolution composite placement image.
	TO TOP	What does JPEG mean?
		The Joint Photographic Experts Group (JPEG) bitmap compression format is often used when files are sent via modem over a telephone line or when removable media storage capacity is limited. JPEG provides several compression options: Lossless compression results in zero data loss or modification on decompression and is preferred for graphics applications. Lossy compression results in some data modification and may be used where "good enough" quality is acceptable. Some industry groups recommend that lossy compression not exceed an 8:1 compression ratio. TIFF and PDF formats support JPEG compression.
	TO TOP	When do I use a PICT file?
		The PICT (abbreviation for picture) format is one of the earliest file formats. Avoid saving files as PICT. If you print a page containing a PICT graphic, the graphic must be converted by the RIP during output into Postscript's native bitmap form and this is error-prone and time-consuming.
	TO TOP	What is a PDF?
		Several software applications create portable document format (PDF) files or digital paper format (DPF) files. These applications are variations of page description languages such as Postscript and employ an object-oriented structural design that incorporates vector, raster and text elements as objects and provide for portability between computer platforms and software applications. A PDF file describes the relationship of elements to one another in a device- and resolution- independent manner which greatly reduces the chance for errors when files are RIPPed to an output device. PDF files are small, nearly uneditable, and very transportable. Although it is in the early stages of adoption, many in the graphic arts industy are convinced that this format will be accepted as the de facto standard for digital delivery.
website by eIMPRESS	TO TOP	What are postscript files?
		In most drawing, paint, image-editing and page-layout programs, when the operator selects "Save", the file is written to a hard drive, floppy disk etc as a file in native format. If the operator selects "Print" and chooses destination printer, the file is written across a network to an output device such as a laser printer. If the operator selects "Print" however and chooses destination file, the digital information is written to disk as a postscript file. Two very different results from two seemingly similar actions. The major difference is the actual format of the data that is created.
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