Imaging Glossary


The word "Imaging" encompasses a wide variety of topics ranging from photography and medical devices to scanning, capture, image manipulation, and image conversion and viewing. This glossary provides definitions for document and web imaging, in addition to terminology specific to Snowbound products and complementary technologies.

To navigate the glossary use the Alphabetical listing below to located terms by the corresponding letter. 

Document and web imaging is an increasingly important factor in how businesses manage information. Understanding the jargon and important concepts related to document and web imaging enables you to make informed decisions on your company's imaging software needs.

For a complete list of supported imaging formats for viewing, manipulation or conversion, please see our image formats section. Can't find a word? We are continually looking to enhance our online resource center for our visitors. If you know of additional words that should be added to our glossary, please contact us to suggest words for inclusion in our glossary.


ActiveX is a loosely defined set of technologies developed by Microsoft for sharing information among different applications. ActiveX is an outgrowth of two other Microsoft technologies called OLE (Object Linking and Embedding) and COM (Component Object Model). One of the major features of ActiveX is its ability to be used by a number of development environments. ActiveX is supported in RasterMaster for Windows.

Alias All

Alias All turns scale to gray and scale to color on at display time. All 1-bit black and white and color documents are anti-aliased in Snowbound Software's RasterMaster for Java SDK.


Annotations are used to mark up text and attach notes and comments to images and documents. In Snowbound's VirtualViewer web viewers, annotation objects are created through an interface and then stored in one or more annotation layers as a separate file. The annotation objects are registered as an underlying image permitting zooming and scrolling of the overall display without losing registration of the annotation information. You can set the foreground, background, and font color as well as line width and style for annotations.


Anti-aliasing is a method of making graphics and text easy to read and pleasing to the eye on-screen. Black and white or color images, if displayed at a lower resolution than 1:1 (image pixels to screen pixels), cause the image to look unreadable. This is because linear interpolation methods used for display skip pixels in the horizontal and vertical directions. Thus, some information is lost on display. Anti-aliasing corrects for this by producing an average of neighboring pixels. The effect is to give the document a soft, grayscale look. The underlying image is unaffected if used for display purposes. However, functions also exist to permanently modify black and white images to grayscale.


Application Program Interface (API) is the command-set for a set of routines that invoke a library or toolkit. It is a set of instructions that contain the rules that must be followed for two computer programs to talk to each other. For instance, a computer program can (and often must) use its operating system's API to allocate memory and access files.


An applet is a small Java application that can be sent along with a Web page to a user, much the same way an image is included. It is a software component that runs in the context of another program, for example a web browser. The applet must run in a container, which is provided by a host program, or through a plugin. It enables a variety of web browsers to accomplish many tasks, including viewing and manipulating images in many formats. When you use a Java technology-enabled browser to view a page that contains an applet, the applet's code is transferred to your system and executed by the browser's Java Virtual Machine (JVM). Snowbound's VirtualViewer Java viewers are available as an applet only or applet/servlet combination. The RasterMaster for Java imaging SDK can also be used to create an applet.


ASCII is an industry standard which assigns letters, numbers, and other characters within the 256 slots available in the 8-bit code. ASCII defines codes for 33 non-printing control characters (which mostly affect how text is processed) plus 95 printable characters.

Aspect Ratio

The aspect ratio of an image is the proportion of the image's size given in terms of the horizontal dimension versus the vertical dimension. An aspect ratio of 4:3 indicates that the image is 4/3 times as wide as it is high. Maintaining aspect ratio is important when viewing images so that they do not appear ‘squished’ or ‘stretched’.


An attribute is a defining characteristic of an object and is part of a tag. It can be set to different values.

Background color

The background color refers to the color in the background of the image display container.

Batch Conversion

Batch conversion is the ability to convert large quantities or groups of images from one format to another. Batch conversion is usually done in an automated manner. Snowbound's SnowBatch application is an automated batch converter that can run on the desktop or server.

Bayer Dithering Algorithm

The bayer dithering algorithm is a simple matrix dithering algorithm. Bayer dithering is sometimes used to make color images printable in black and white. It reduces 8, 24, or 32-bit images to 4-bit color.

Bicubic Interpolation

Bicubic interpolation is used for resizing an image by taking a 4 pixel by 4 pixel block and producing an average of those pixels by weighting the value of the pixel in the average based on its distance from the origin pixel. Pixels farther away have less effect on the resulting pixels value than do it's nearest neighbors. It resizes 8 and 24-bit images.

Bitonal Image

A bitonal image is an image comprised of pixels that contain only a single bit of information. Each pixel is either on (white) or off (black). Fax image formats and Group 4 image formats are bitonal images. 1-bit images are typically compressed using Run Length Encoding (RLE), also known as monochrome, bitonal, or black and white.


Bits-per-pixel, or the color depth, is defined by the number of bits-per-pixel that can be displayed on a computer screen. The more bits-per-pixel, the more colors that can be displayed. Bits-per-pixel describes the number of bits used to represent the color of a single pixel in a bitmapped image.

Boolean Operations

Boolean operations consists of operators such as “and”, “not” or “or”. Generally Booleans are used in programming and Internet Search engines.

Bounding Box

The bounding box of an image refers to the smallest upright rectangle which surrounds the image and includes all of the pixels that are not fully transparent.


Brightness is an attribute of visual perception in which a source appears to emit a given amount of light. Changing the brightness of an image makes the entire image lighter or darker.


The buffer is a data area shared by program processes that operate at different speeds or with different sets of priorities. The buffer allows each device or process to operate without being held up by one another. A buffer is memory used to temporarily hold output or input data. The data can be output to or input from devices outside the computer or processes within a computer.


A byte is the unit most computers use to represent a character such as a letter, number, or typographic symbol. It consists of a unit of data that is eight binary digits long.

CAB file

The CABinet (CAB) file is the Microsoft Windows native compressed archive format that contains a compressed and archived applet for Microsoft's Internet Explorer users. It supports compression and digital signing. It's used in a variety of Microsoft installation engines.

Check 21

The Check Clearing for the 21st Century Act (Check 21) was signed into law on October 28, 2003, and became effective on October 28, 2004. Check 21 is designed to foster innovation in the payments system and to enhance its efficiency by reducing some of the legal impediments to check truncation. The law facilitates check truncation by creating a new negotiable instrument called a substitute check, which permits banks to truncate original checks, to process check information electronically, and to deliver substitute checks to banks that want to continue receiving paper checks. A substitute check is the legal equivalent of the original check and includes all the information contained on the original check. The law does not require banks to accept checks in electronic form nor does it require banks to use the new authority granted by the Act to create substitute checks.


Class is a definition for the methods and variables of an object. It describes the rules by which an object behaves. A class can have subclasses that can inherit all or some of the characteristics of the class. The structure of a class and its subclasses is called the class hierarchy.


Classpath is an environment variable that tells the Java compiler where to look for and interpret class files .

Clipboard (Windows)

The clipboard is an area used to exchange data between applications. Applications place data on the clipboard so other applications can access it. This storage is meant as a short-term volatile place to keep information that will be used again shortly. These operations are typically referred to as cutting and pasting data.

Color Conversion

Color conversion is the process of changing from one color model to another.

Color Correction

Color correction is the process of removing unwanted casts or tints from an image.


Compiling is a process statement which turns a particular programming language into machine language or “code” that a computer’s processor uses. (e.g. an executable .EXE or .COM file that may run on a computer or virtual machine.)

Component Application

An application that performs a specific function and is designed in such a way to easily operate with other components and applications. The term is sometimes used interchangeably with applet.


Compression is a process of encoding an image or other data so that it occupies less memory or disk space than its uncompressed version. Image compression can be lossy or lossless. The goal is to achieve the best image quality at a given bit-rate (or compression rate). Compression techniques for 24-bit color images usually do not work well on 1-bit or bi-level images. Similarly, compression for 1-bit images do not compress well for 24-bit color images. Examples of compression formats include ABIC, Group3/Group4, JPEG, JPEG2000, JBIG, JBIG2, MMR, ZIP, and LZW. Snowbound's products handle image compression directly and rapidly without having to invoke a print driver or any other external application.

Compression Ratio

The compression ratio is the ratio of a file’s uncompressed size compared to its compressed size. Because the user has control of the amount of loss, JPEG is one of the few formats that permits the user to control the compression ratio of the information.

Content Management System (CMS)

A content management system (CMS) is a computer software system for organizing and facilitating collaborative creation of documents and other content. A content management system is frequently a web application used for managing web sites and web content, though in many cases, content management systems require special client software for editing and constructing articles. Snowbound's VirtualViewer web viewer can integrate with CMS systems enabling users to easily access, view, convert, manipulate, annotate, and print document and image formats within the repository through a single universal viewer.


Contrast is the variation of the lightest or brightest in comparison to the darkest portions of an image. In imaging, contrast depends on the image source, the medium, and the ambient lighting. Control Array A control array allows you to dynamically add menu items to a Visual Basic form during program execution.


Coordinates are a pair of numbers that represents a specific location in a two-dimensional plane. Crop Cropping is an image processing method to remove a region of an image or text. It can be used to remove an extraneous information or subject matter to improve the final composition.


Desktop Color Separation (DCS) is a standard QuarkXPress format based on EPS and developed by Quark, Inc. It enables non-Quark applications to pre-separate images into individual C, M, Y, K, and master/composite files allowing the exchange of bitmap images between prepress applications. It is used to speed up the printing process because only the information for the plate being printed is sent to the printer rather than the entire CMYK file.


A Device Dependent Bitmap (DDB) is a bit map dependent upon a particular hardware device where the bitmap will be displayed. This is usually a computer screen or printer. DDBs tend to display at a high speed however when printing a DDB it may be necessary to convert to a DIB in order to see the bitmap because not all printers support DDB.


Decompression is the method or process of decoding image data which is stored in a compressed data stream or file. Decompression methods automatically detect the file format.


Depth is defined by the number of bits-per-pixel that can be displayed on a computer screen. RasterMaster automatically converts the pixel depth to the appropriate value, based on the output format specified. Device Dependent Device dependent is the software written to work on a particular set of hardware platforms.

Device Driver

The device driver is the set of software routines that work with and control a specific hardware device. Each device including printers, keyboards, mouse, monitors, disk drives need to have a driver in order to work with the system.


A Dev ice Independent Bitmap (DIB) is an image format specification independent of all hardware devices and platforms. All high-level and low-level functions that decompress or import images convert the data and store it in memory as the MS Windows DIB format, which consists of the following: header (DIB_Head), palette, and image data. All formats are converted to either 1, 4, 8, or 24-bits. All 1, 4, and 8-bit images have a palette. The raw uncompressed image data follows the palette specification.

Distributed Application

An application made up of components running in separate runtime environments, usually on different platforms, that are connected through a network. Distributed applications can be a relatively simple client/server set-up, requiring a single client computer and a single server, or more complex allowing many client computers and multiple servers. The server-side software manages shared resources and contains the main processing capability for the application. The front-end (client) software handles user interface functions and displaying output to the screen.


Dithering is a method of using similar colored and sized pixels to display or print a different color or resolution. In a dithered image, colors not available in the palette are approximated by a diffusion of colored pixels from within the available palette.


The Dynamic Linked Library (DLL) is a compiled and linked collection of computer functi ons that are not immediately bound to an executable, but are called during program execution. Dynamic linking means that the data in a library is not copied into a new executable or library at compile time, but remains in a separate file on disk. Snowbound's RasterMaster for Windows is available as DLL.

Document Viewer

A document viewer enables a document to be opened and displays the contents of a file. A document viewer could be considered the application that created the file such as Microsoft Word or Excel. Or it could be a separate application that displays the content as it would appear if viewing it in the creator application. These viewers often require that the original format be converted to something else in order to open and view such as PDF for Adobe Reader. Snowbound's VirtualViewer web viewers support over 40 document and images formats eliminating the need to convert to a different format in order to view. VirtualViewer also eliminates the need for the user to need the native (creator) application on their system.

Documentum® WDK

The Documentum Web Development Kit (WDK) created and offered by EMC Documentum provides an application framework, a set of components, a set of user-interface controls, and a set of URL-addressable commands that leverage DFC services. The framework provides the infrastructure used by WDK components to operate and interact. The WDK makes it fast and easy for developers to include content management functionality in their Web-based applications. Snowbound offers a version of its VirtualViewer web viewer that supports the WDK enabling users to easily access, view, convert, manipulate, annotate, and print document and image formats within the Documentum repository through a single universal viewer.

Documentum® Webtop®

Documentum Webtop is an easy-to-use interface created by EMC® Documentum that allows users to access the EMC's repository and content management system using a standard browser application. EMC Documentum Webtop is ideal for users who prefer the point-and-click navigational ease of a Web interface, particularly when content is accessed from remote locations across the Internet. Snowbound offers a version of its VirtualViewer Webtop web viewer that is configured to integrate specifically with Webtop, enabling users to easily access, view, convert, manipulate, annotate, and print document and image formats within the Documentum repository through a single universal viewer.


Dots Per Inch (DPI) is a measure of printing resolution. It usually refers to the number of printer dots that can be printed in one inch. Higher values indicate higher resolution; usually equal to 1/72nd of an inch. The more dots per inch, the higher the resolution. For example, if you print on a laser printer at 600 DPI your output will show the image with 600 dots across and 600 dots down. In total you will have 360,000 dots per square inch resulting in a crisp image vs. if you print at 300 DPI.


Drag is a term used to describe when an object or text is selected and then moved to an alternate location. Duplex Scanning Duplex scanning is the ability to scan both sides of a sheet of paper at the same time.

Edge Detection

Edge detection is a method of locating and isolating an optical edge in a digital image. For instance, most high-speed scanners scan with a black background. An edge-detection algorithm will look for this black edge and remove it leaving only the original page data. The goal of edge detection is to mark the points in an image at which the intensity changes sharply.


Encoding is the format for storing uncompressed data, how it is packed, and the set of symbols used to represent the range of data items. File compression allows you to limit an image's size by encoding the image's data more concisely and efficiently.


Encryption is the conversion of data into a form that cannot be easily understood by unauthorized people. Encryption/decryption is a good idea for sending sensitive information over the web, such as an online credit-card purchase, patient records, and financial data.


Equalize is an image-processing algorithm that redistributes the frequency of image pixel values allowing equal representation for any given continuous range of values.

Fat Client/Thick Client

Fat client/thick client is a client/server architecture where the client performs the bulk of the data processing or imaging operations. The data itself is stored on the server. Snowbound's VirtualViewer applet/content server is an example of a fat client. All of the image processing such as zooming, redaction, and manipulation is executed on the client side. Because everything is happening on the client it is very fast since it is not necessary to call back to the server for every action.

File Format

A file format is a specification for storing image data. The format dictates what information is present in the file and how it is organized, including headers, directories and compressed data. Snowbound's products import and convert file formats to Snowbound's internal formats at decompress time. The format is a simple uncompressed DIB format stored in memory. This format is decompressed or imported and can be saved out to any supported format.


A filter is a block of code which is used to handle a particular file format or compression algorithm.


Flipping results in swapping pixels along the X-axis or along the Y-axis, depending on the operation. It is used to change the orientation of an image.


A font is a complete collection of all the characters and typefaces in a specific family. A typeface is usually comprised of an alphabet of letters, numerals, and punctuation marks.

Foreground Color

The foreground color is the color to use for the foreground data, such as text. It is also used for the fill-in color for rectangles, ellipses, and polygons and is the highlight color for highlighted rectangles and text color for Post-its and edits.


A frame is the edge or border that resembles a border or picture frame. Frames are often used in word processing and graphic arts to help focus the viewer's attention. In data or network communications, a frame is a block of data that begins with a header to indicate the beginning of the block of data and a trailer to indicate the ending of the data.

Gamma Correction

Gamma correction is the compensation for the response curve of the monitor and video card. The lower values of the curve appear blacker than they actually should. Gamma displays the lower level values a little brighter and the high clauses a little darker for better contrast on 8-bit grayscale and color images.


Grayscale is the color created by dots and shades of white to black to form images. They have a maximum color depth of 8 bits. When defining shades of gray in terms of RGB, each of the 3 red, green, and blue components must be equal to each other. Thus, grayscale images have a maximum color depth of 8 bits.


The U.S. General Services Administration (GSA) is a federal agency of the United States government, established in 1949 to help manage and support the basic functioning of federal agencies. Snowbound Software is a GSA contract holder, providing imaging solutions to government agencies.


A Graphical User Interface (GUI) is a computer interface that uses graphical objects. GUIs display visual elements such as icons, windows, and other gadgets. Snowbound's VirtualViewer web viewers have configurable GUIs.


The half-tone is the reproduction of a contiguous-tone image on a device which does not directly support continuous output. This is done by displaying or printing a pattern of small dots which from a distance can simulate the desired output color or intensity. This is typical of black and white newspaper photos.


The intent of the Health Information Portability and Accountability Act (HIPAA) is that all electronic transactions for which standards are specific must be conducted according to the standards. These standards were not imposed by the law, but instead were developed by a process which included significant private sector input. HIPAA also addresses the security and privacy of health data.


A histogram shows the distribution of colors in an image. For a 256 color image, it shows how many times a particular pixel intensity occurred in that image. It is a graphical version of a table which shows what proportion of cases fall into each of several or many specified categories. The categories are usually specified as nonoverlapping intervals of some variable.


Hyperlink Text Markup Language (HTML) is a tag-based language used to create documents for the Web. HTML forms are often used to capture information from web sites.

Huffman Coding

Huffman coding is a method of data compression that is derived by how often elements appear within the data. Windows uses ICO Microsoft Icon format files (multipage file) to display its icons. It contains a standard device independent bitmap with a new header on top. The header indicates the type of resource and number of icons. Huffman coding supports 1 and 4-bits of uncompressed data.


The Amiga Interchange File Format (IFF) is used to transfer documents to and from Commodore Amiga computers for native bitmap formats. It allows images and text to be stored inside the file.

Image Format

Image format refers to how the image is saved. There are a wide variety of formats used today ranging from proprietary to standard formats. Proprietary formats are specific to an application, company, or industry (i.e. AFP) and standard formats are note (i.e. JPEG). Snowbound's products support over 100 image formats including proprietary formats.

Image Processing

Image processing includes the steps involved in getting an image uploaded to a computer, modifying, printing, and saving it as a digital image. Image processing functions include resizing, sharpening, brightness, and contrast.

Image Repository

An image repository is a central place where images are stored and maintained. A repository can be a place where multiple databases or files are located for distribution over a network, or a repository can be a location that is directly accessible to the user without having to travel across a network. Snowbound's VirtualViewer web viewers enable users to easily access, view, convert, manipulate, annotate, and print document and image formats within the repository through a single universal viewer.

Image Viewer

An image viewer is an application with the ability to automatically detect and read image formats. The application usually renders the image according to properties of the display such as color depth and display resolution. Snowbound offers VirtualViewer web viewers that are ready to integrate with existing applications. Viewers can also be created using Snowbound's RasterMaster Imaging SDK.

Imaging Applet

The imaging applet is an image viewer in which the application for viewing, manipulating or converting images is built as a Java applet. This enables users to perform these functions through a standard Web browser. Snowbound offers a stand alone imaging applet and an applet/servlet combination within its VirtualViewer product family. Applets can also be created using Snowbound's RasterMaster Imaging SDK for Java.

Imaging Toolkit

The imaging toolkit is an SDK designed specifically to build image and document viewing or conversion applications. It gives developers the necessary library calls and features so that they can build functionality into their application including viewing, conversion, manipulation, printing, saving, annotation, redlining, text extraction, and scanning. Snowbound's RasterMaster Imaging SDKs are available for a variety of platforms including Java, Windows, .NET, and UNIX.


The IMNET G4 compressed format is a medical image format. Snowbound's RasterMaster Imaging SDKs support IMNET.

Indexed Color Image

An indexed color image is an image which does not define colors in terms of their actual RGB or CMYK values and which derive its colors from a “palette” known as “Indexed Color”. Because the palette is limited to a maximum of 256 colors, they are not considered “true color”. Colors in the palette are referenced by index numbers which are used by the computer to identify each color.


Interleave defines how data is arranged in memory. For instance, an RGB image may have the following pixel arrangements (every 3 characters of ‘R’,’G’, or ‘B’ is one pixel): Pixel Interleave: RGBRGBRGB, RGBRGBRGB, RGBRGBRGB Raster Interleave: RRRGGGBBB, RRRGGGBBB, RRRGGGBBB Frame Interleave: RRRRRRRRR, GGGGGGGGG, BBBBBBBBB. Interleaving arranges data in a noncontiguous way to increase performance.

Internal Format

The internal format is the way the data is stored inside the system. All RasterMaster products import and convert file formats to Snowbound's internal format at decompress time. The format is a simple uncompressed DIB format stored in memory. This format is decompressed or imported and can be saved out to any supported format. Invert For a 1-bit image, inverting changes all black pixels to white and all white pixels to black.

JAR file

A JAR file contains the class, image, and sound files for a Java applet. They are all gathered and compressed into a single file for faster downloading. Combining the class files into a JAR file is more efficient than letting the Virtual Machine download the classes individually from the webserver on demand. Jar files can be created and extracted using the jar command that comes with the JDK or with zip tools.


The Java platform is the name for a computing environment, or platform, from Sun Microsystems which can run applications developed using the Java programming language and set of development tools. In this case, the platform is not a specific hardware or operating system, but rather an execution engine called a virtual machine, and a set of standard libraries which provide common functionality. Java is a reflective, object-oriented programming language. Snowbound's VirtualViewer web viewers and RasterMaster for Java are all built on 100% Java.

JPEG Interleave Factor

The JPEG interleave factor decimates the blue and red chroma planes when writing out a JPEG image. It specifies how many pixels to skip in the X and Y direction when compressing the image.


The layer is the organization of programming into separate functional components that interact in some sequential and hierarchical way, with each layer usually having an interface only to the layer above it and the layer below it.


The library is a collection of software functions that can be called by a higher level program. Most libraries are collections of similar routines such as those used for graphical or image processing.

Linear Interpolation

Linear interpolation is used for resizing an image. It takes 2 pixels, separated by x pixels, then averages the x + 2 pixels to create an intermediate value. This resulting value is then used to represent the entire range of pixels. Linear interpolation is not very effective for resizing 1-bit documents since much of the visual data is lost.


A look-up-table is an indexed list of numbers used to change pixel values in a predefined way. A look-up-table is used to determine the colors and intensity values with which a particular image will be displayed.

Lossless Compression

Lossless compression is a method of image compression where there is no loss in quality when the image is compressed or uncompressed. Lossless compression is used when it is important that the original and the decompressed data be identical. Some image file formats, notably PNG, use only lossless compression.

Lossy Compression

Lossy compression is a method of image compression where some image quality is lost during higher compression. A lossy data compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original, but is close enough to be useful in some way. The advantage of lossy methods over lossless methods is that in some cases a lossy method can produce a much smaller compressed file than any known lossless method, while still meeting the requirements of the application. The most common lossy image compression method is JPEG.


Lempel Ziff Welch (LZW) is a lossless image compression method found in the popular GIF format and patented by Unisys. Two commonly-used file formats in which LZW compression is used are the GIF and TIFF format. LZW compression is also good for compressing text files. It only supports up to 8-bit data.

Managed Code

Code that is executed by a common language runtime environment rather than directly by the operating system. Managed code applications gain common language runtime services such as automatic garbage collection, runtime type checking and security support, and so on. These services provide uniform platform- and language-independent behavior of managed-code applications.

Memory Buffer

The memory buffer is a temporary space in memory for working storage.

Memory Pointer

The memory pointer is a variable that points to the location in memory of some data. This is also known as indirect addressing.


Merging is the process of taking two or more images and combining them into one.


A method is a programmed procedure that is defined as part of a class and included in any object of that class. A class can have more than one method.


The Microsoft Paint program bitmap file format (MSP) supports 1-bit images (black and wh ite images). It uses a type of RLE compression found also in compressed .BMP files, therefore they can be converted to BMP file formats. MSP is used most often by Microsoft Windows applications, but may be used by MS-DOS-based programs as well.

Multipage Image

A multipage image is a graphic or picture that appears on screen that consists of more than one page.

Native File Format

The native file format is a file format specific to an application. Native files can typically be recognized only by the application that produced the file. For example, a PowerPoint file can usually be opened only in PowerPoint. Snowbound's VirtualViewer web viewers and RasterMaster Imaging SDKs support a wide variety of files in their native format including MS Word and Excel.


NCR is a simple header with CCITT group 4 data. It is a unique black and white image compression format.


Noise consists of dark spots that can appear when using a digital camera with bad lighting conditions, or when there is static build-up on the scanning array element in a high speed scanner.


Objects are units of code that are eventually derived from a process. An object is what actually runs in the computer. Objects can share models and reuse the class definitions in their code.


Octree is a color reduction algorithm used to reduce the number of colors in an image from 24-bits or 8-bits to 4 or 8-bits. An octree is a tree data structure mainly used for organizing 3-dimensional space.


Orientation determines which edge of the image is displayed in the positive X direction (up) and which edge is displayed in the negative Y direction (left).

Overlay file

When used in imaging, an overlay file is generally text data that when displayed at a fixed position above a blank form fills in the fields for that for m. The form is usually a scanned image. This is most common with MO:DCA and PTOCA images. Snowbound Software's annotation options permit the creation of text and graphic overlays to an underlying image.


A package is a collection of Java classes which are typically stored in the same directory, one class to a file.


A palette is a designated subset of the total range of colors supported by a computer graphics system. Each color in the palette is assigned a number, and for each pixel, one of these numbers is stored. This number determines the color of the pixel. Palettes allow images comprising a small number of colors to be stored using a relatively modest amount of graphics memory. A digital image palette is a collection of 3 look-up-tables, which are used to define a given pixel's display color. One table is for red, one for green, and one for blue.

Pan Window

The pan window is a window containing a smaller version of the image. Used in conjunction with the mouse pointer and a cropping rectangle, it can simulate scrolling around the image quickly.


A parameter is an item of information, such as a name, a number, or a selected option that is passed to a program by a user or another program. The parameters affect how the program operates. With simple HTML parameter changes in Snowbound Software's VirtualViewer web viewer, user permissions can be enabled or disabled.


A pixel which is short for Picture Element is a single point in a digital image. An image is made up of many rows and columns of points. An 8-bit pixel can take on one of 256 values. A 24-bit pixel image usually has three 8-bit components for each of the primary colors; red, green, and blue. Depending on the resolution used for viewing or printing may or may not be able to see the individual pixels. High resolution will make the pixels appear as though they are seamlessly interlaced showing now space around the pixel. Low resolution will make the image appear blurry and not as defined.

Pixel Depth

Pixel depth is the number of data bits each pixel represents. In 8-bit contexts, the pixel depth is 8, and each display pixel can be one of 256 possible colors or shades of gray. With a 24-bit raster, the pixel depth is 24, and 16,777,215 colors are possible.


A plugin (or plug-in) is a computer program that can, or must, interact with another program to provide a certain, usually very specific, function. Typical examples are plugins to display specific graphic formats (e.g., SVG if the browser doesn't support this format natively), to play multimedia files, to encrypt/decrypt email (e.g., PGP), or to filter images in graphic programs. The main program (a web browser or an email client, for example) provides a way for plugins to register themselves with the program, and a protocol by which data is exchanged with plugins.


A pointer is a way to grab an instance of an object and then either pass that instance a message or retrieve some data from that object. A pointer is actually just an address of where an instance is held in memory.


Postscript is a programming language that describes the text and graphic elements of a printed page. The PostScript language is a programming language spoken by desktop software after the print command is issued. These PostScript instructions created by the software (in partnership with the printer driver) are sent to a PostScript laser printer to describe the page the user wishes to have output. The PostScript laser printer has an interpreter inside (called a RIP) that takes that page description and instructs the laser printer how to image the page.

Preserve Black

Preserve black checks neighboring pixels for any black pixels so that any small black lines are not removed when scaling a large black and white image. This type of anti-aliasing is best used for engineering drawings. In Snowbound's products preserve black creates a 1-bit pixel based on neighboring pixels. It forces the snowbnd object not to skip black pixels when being scaled down for display.

Printer Driver

The printer driver is a piece of software th at converts the data to be printed to the form specific to a printer. The purpose of printer drivers is to allow applications to do printing without being aware of the technical details of each printer model. All Snowbound products for Windows print to any device with a valid Windows printer driver installed.

Public Attributes

An object’s public attributes are those properties of that object required by other simulations that want to interact with it. Public attributes are inherited from other classes and are therefore visible to those classes.


Raster describes a single row of pixel data for a digital image. Thus, a raster image is one that is made up of rows of pixels. A raster image is a data file or structure representing a generally rectangular grid of pixels, or points of color. The color of each pixel is individually defined. For example RGB images consist of colored pixels defined by three bytes—one byte each for red, green, and blue. Less colorful images require less information per pixel; an image with only black and white pixels requires only a single bit for each pixel. Raster images differ from vector images in that vector represents an image through the use of geometric objects such as curves and polygons.


Redrawing re-displays the current image.


Render means to draw the image into a device context, such as a printer or monitor. It generates an image from a model, a description of three dimensional objects in a strictly defined language or data structure. It contains geometry, viewpoint, texture, and lighting information.


Resizing changes the X and Y size of the actual image data to the coordinates given.


Resolution is the number of pixels per unit of length along the x and y axis. It designates the sharpness and clarity of an image. The term is most often used to describe monitors, printers, and bit-mapped graphic images.


Rotating changes the image angle. An image may need to be rotated because a document may have gone through a scanner at an angle. This process permanently changes the image. Sometimes image data is scanned or photographed upside down. Rotating the image 180 degrees corrects this problem.


Scale adjusts how image intensities are scaled for display.

Scale To Color

Scale to color is used when displaying scaled-down color images. It prevents loss of visual data, creating a smoother rendering of th e image. It works best for color images with text, such as brochures, magazines, and newspaper flyers.

Scale To Gray

Scale to gray is used when displaying scaled-down (zoomed out) black and white images. It prevents loss of visual data, particularly for straight lines of text, creating a smoother rendering of the image. It converts the image to gray scale values. It converts the neighboring pixels to an 8-bit gray scale value. Scale to gray obtains the best results on text type documents.

Screen Coordinates

Screen coordinates are the coordinates of the graphics display controller. The origin is a lmost always at the upper left hand corner of the display and pixel rows are numbered downward.


A Software Development Kit (SDK) is a set of development tools that allows a developer to create applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar. SDKs also include sample code and supporting technical notes or other supporting documentation to help clarify points from the primary reference material. Snowbound's RasterMaster Imaging SDKs are available for a variety of platforms including Java, Windows, .NET, and UNIX.


Sepia are reddish brown monochrome tints. When applied to a photo, they give the picture a warm, antique feeling.


A servlet is an object that receives requests and generates a response based on the request. The API defines HTTP subclasses of the generic servlet requests and responses as well as an HTTP session object that tracks multiple requests and responses between the web server and a client. Servlets may be packaged as a Web application. Moreover, servlets can be generated automatically by Java Server Pages (JSP), or alternately by template engines such as WebMacro. Often servlets are used in conjunction with JSPs in a pattern called "Model 2", which is a flavor of the model-view-controller pattern.

Skewed Image

A skewed image is a crooked or warped image.

Text extraction

Text extraction is the ability to extract (pull out) text from a document or image. Snowbound Software's RasterMaster Imaging SDKs support extraction of both text and formatting data from MS Word, Excel, PDF, AFP, and PCL files. The extracted information can be used to create a data stream that can be processed by content aggregation tools to directly import the information into a database or repository. This data is then available to be re-purposed for publishing, archiving, or searching. Batch extraction eliminates old-fashioned manual processes of cutting and pasting information, thereby greatly reducing the amount of time it takes to gather and populate databases with document content. In addition to the large time savings, it also reduces the potential for errors since the content is automatically extracted without manual intervention.

Thin Client

A thin client is a computer (client) in client-server architecture networks which has little or no application logic, so it has to depend primarily on the central server for processing activities. The word "thin" refers to the small boot image which such clients typically require. This is perhaps no more than what is required to connect to a network and start up a dedicated web browser. Snowbound's VirtualViewer® HTML5 is an example of a thin-client. All of the image processing is done on the server and then rendered to the client.


A thumbnail is a small, typically low resolution representation of an image. It is usually used to display many images on the screen at once. It is intended to make it easier and faster to look at or manage a group of larger images. Thumbnails are reduced-size versions of pictures, used to make it easier to scan and recognize them, serving the same role for images as a normal text index does for words. Visual search engines and image-organizing programs normally use them, as can some modern operating systems or desktop environments, such as Windows XP, KDE, and GNOME.


Transparency displays the foreground color of an image and ignores the specified background color. It is commonly used for icons in Internet HTML documents. In Snowbound's products, transparency is currently supported for the GIF file format.

True Color

True color defines each pixel in terms of its actual RGB or CMYK values. Colors in the palette are referenced by index numbers which are used by the computer to identify each color.


TWAIN lets you scan an image directly into the application. The TWAIN driver runs be tween an application and the scanner hardware. TWAIN usually comes as part of the software package you get when you buy a scanner. It is also integrated into many image manipulation programs. TWAIN scans an image on the currently installed scanner or input device and returns the standard library image. Snowbound's RasterMaster SDKs support TWAIN Scanning.


Unix was designed to be portable, multi-tasking, and multi-user. The Unix systems are characterized by various concepts: plain text files, command line interpreter, hierarchical file system, treating devices, and certain types of inter-process communication as files, etc. In software engineering, Unix is mainly noted for its use of the C programming language and for the Unix philosophy. Snowbound's RasterMaster Imaging SDK is available for UNIX.

User Interface (UI)

The user interface (of a computer program) refers to the graphical, textual, and auditory information the program presents to the user, and the control sequences (such as keystrokes with the computer keyboard, movements of the computer mouse, and selections with the touchscreen) the user employs to control the program.


A variable is a value that can change, depending on conditions or information passed to the program.

Vector Graphics

Vector graphics describe objects according to their geometrical characteristics including points, lines, curves, and polygons t o represent images in computer graphics. You can move, resize, or change the color of a vector graphic without losing the quality of the graphic. Vector graphics differ from raster graphics, in that a raster graphic is the representation of an image as a collection of pixels (dots).

Virtual Machine

The virtual machine is software that acts as an interface between compiler Java binary code and the microprocessor that performs the program's instructions. Once a Java virtual machine has been provided for a platform, any Java program can run on that platform.

Web browser

A web browser is a software application that enables a user to display and interact with HTML documents hosted by web servers or held in a file system. Web browsers support by Snowbound Software products include Microsoft Internet Explorer 4.x and higher, Netscape Navigator 4.x and higher, Mozilla 1.0 and higher, and Mozilla Firefox 1.0 and higher.

Web Server

A web server is a computer permanently connected to the Internet, running an application allowing files to be transferred over the Internet to a client machine. Web server programs operate by accepting HTTP requests from the network, and providing an HTTP response to the requester. The HTTP response typically consists of an HTML document, but can be a raw text file, an image, or some other type of document.

Web Services

Web services provide a standard means of interoperating between different software applications, running on a variety of platforms and/or frameworks. Web services are characterized by their great interoperability and extensibility, as well as their machine-processable descriptions thanks to the use of XML. They can be combined in a loosely coupled way in order to achieve complex operations. Programs providing simple services can interact with each other in order to deliver sophisticated added-value services.
Definition provided by W3C Web Services Activity Statement


Zoom magnifies the size of an image as it appears in the editing window.

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