The PDF component in ImageGear allows you to securely create, display, edit, annotate, format, organize, and search PDF and PostScript (PS) documents. ImageGear is also a complete, high-performance, image processing toolkit; so, it allows applications to seamlessly integrate advanced image processing techniques into PDF documents.
This topic provides information about the following:
The Adobe Portable Document Format (PDF) is the native file format of the Adobe Acrobat family of products. PDF relies on the same imaging model as the PostScript page description language to describe text and graphics in a device-independent and resolution-independent manner. A document can be converted straightforwardly between PDF and the PostScript language; the two representations produce the same output when printed. To improve performance for interactive viewing, PDF defines a more structured format than that used by most PostScript language programs. PDF also includes objects, such as annotations and hypertext links that are not part of the page itself but are useful for interactive viewing and document interchange. However, PDF lacks the general-purpose programming language framework of the PostScript language.
The PostScript (PS) language is a simple, interpretive programming language with powerful graphics capabilities. Its primary application is to describe the appearance of text, graphical shapes, and sampled images on printed or displayed pages, according to the Adobe imaging model. A program in this language can communicate a description of a document from a composition system to a printing system or control the appearance of text and graphics on a display. The description is high-level and device-independent.
"PostScript" refers to a widely-supported general-purpose computer language that encodes text and graphics files for sharing with the many different hardware devices that support it. The full name for this language is "PostScript Page Description Language" (PDL).
An Encapsulated PostScript file stores (encapsulates) graphical or photographic images from a larger PostScript file. ImageGear currently supports the reading of EPS image of any bit depth as long as the preview image is TIFF, uncompressed. ImageGear currently supports the writing of monochrome (1-bit), grayscale (8-bit gray level), and color RGB (24-bit) EPS images only.
The EPS file format begins with a PostScript language header. The data herein identifies the format as EPS, and gives the image title, creator, creation date, size, and position of the image. Each line begins with a percent sign (%), which is normally interpreted in the PostScript language as the beginning of a comment line. Within the context of the EPS header, it takes on a different meaning.
Following the header is a block of PostScript code, which accomplishes the actual creation of the image.
The format proceeds with the bitmap data, or "graphics screen representation".
The EPI version of the EPS format, the version supported by ImageGear, contains an abridged interpretation of the image that is appended to the end of the file. It is usually smaller, and contains a lower resolution. One of the benefits of a preview image is that an application does not need to be able to interpret PostScript in order to display the image. Preview images are created with one of four file format types: TIFF, WMF, MAC PICT, and EPS.
PDF support is compatible with Adobe PDF v1.7 as defined in the Portable Document Format Reference Manual Version 1.7, distributed by Adobe Systems, Incorporated. It provides reading capability up to the PDF v1.7 and writing of PDF v1.7 documents.
PostScript support is compatible with Adobe PostScript (TM) 3.0 language as defined in the PostScript Format Reference Manual, distributed by Adobe Systems, Incorporated. It provides reading capability up to the PostScript 3.0 Language, Level 3, and writing of the PostScript 3.0 files with Language Levels 1, 2 and 3. This includes writing of Encapsulated PostScript (EPS) files with standard and extended preview as well as without preview at all.
We have an entire set of samples that illustrate common PDF functionalities and uses cases. See a list of PDF Samples and Demos.