In the last post, we dealt with compression and the TIFF file format. Now, let's talk about JPEG,PDF and XPS.
JPEG (pronounced jay-peg) is another imaging standard and stands for Joint Photographic Experts Group. JPEG is a lossy compression format for photographic images. It is designed for use with either full color or gray-scale images. JPEG is best when used with photographs rather than text. JPEG specifies how an image is transformed into a stream of bytes, but not how those bytes are ecapsulated in any particular storage medium. JFIF (JPEG File Interchange Format), created by the Independent JPEG Group, specifies how to produce a file suitable for computer storage and transmission over the Internet from a JPEG stream.
JPEG/JFIF is commonly used to store and transmit photographs over the Internet. It is not suitable for use with line drawings or text because its compression method does not perform well with these types of images. PNG and GIF are used in these instances. JPEG is best used with photographs and paintings of realistic scenes with smooth variations of tone and color. In many cases, JPEG will produce a much higher quality image than other common methods.
With the increasing use of multimedia technologies, image compression requires higher performance and new features. JPEG2000 is intended to advance standardized image coding systems to serve applications for years to come. JPEG2000 is a new image format based on state-of-the-art wavelet compression. It is applicable for a number of different applications in the digital imaging market including digital cameras, pre-press, medical imaging and others. JPEG2000, Part 1 (ISO 15444) offers both lossless and lossy compression and provides better image quality at smaller file sizes than JPEG. JPEG2000, Part 2 (ISO 15444/6) is used to compress scanned color documents containing both bitonal elements as well as images.
The development of JPEG2000 is the result of collaboration between the International Organization for Standardization (ISO), the International Telecommunications Union (ITU-T, formerly CCITT) and input from a multitude of industry experts.
Usually, when you think of PDF, the first thing that comes to mind is Adobe Acrobat. But did you know that there are over 2000 PDF product suppliers? PDF, Portable Document Format is a file format originally developed by Adobe Systems for representing documents in a manner that is independent of the original application software, hardware, and operating system used to create those documents. PDF is an open standard and anyone may write applications that can read or write PDFs royalty free. In 2008, the PDF specification was published as ISO 32000-1:2008. A PDF document is a self-contained cross-platform document. It is a file that will look the same on the screen and in print, regardless of what kind of computer or printer someone is using and regardless of what software package was originally used to create it. Although they contain the complete formatting of the original document, including fonts and images, PDF files are highly compressed, allowing complex information to be downloaded efficiently.
There is also another file format, XPS, XML Paper Specification. XML Paper Specification or XPS is a document storage and viewing specification developed by Microsoft that describes electronic paper in a way that it can be read by hardware, software and the human eye. XPS provides a page view of the way the document will print. It describes the appearance of fixed format documents by using an XML based format so that the layout won't change. XPS is viewed as a potential competitor to PDF (Portable Document Format) but will not replace PDF in the instances where dynamic content capabilities are required which XPS cannot handle. By dynamic content, we mean the type of content that may be contained in a drop-down on a form. Microsoft released XPS with a royalty-free patent license to encourage wide adoption by the industry. The XPS document format is included with Windows Vista and 2007 Microsoft Office System products. The XPS viewer is included with Windows Vista and is available for Windows XP and Windows Server 2003. The viewer allows users to open, read and apply digital signatures to XPS documents without needing the full XPS generating software. XPS allows electronic documents to print better, be shared easier, archived and better maintain the security of the information in the document.
XPS relies on two additional specifications - the Open Package Conventions which describe the method for creating packages of content, resources, and metadata in a compressed ZIP file and Open XML Markup Compatibility Specification that describes the mechanism to support versioning and extensibility of XML. Ecma International's TC46 chaired by Martin Bailey, Global Graphics, will continue the work on the XPS standard and facilitate its fast track processing at ISO to become an ISO standard. XPS is platform independent.
There are a multitude of image file formats to choose from. Whatever image file format and compression that your organization chooses, is dependent on the application you are using. It is important to take into consideration the type of documents you will be scanning, the graphical content contained in the documents and how they will be used. The file format you select should meet the inteded use and be capable of including the compression scheme you choose.