Glossary

3-point affine transform

A type of coordinate transformation that can be applied to images upon insertion. This option replicates the transform used on non-editable data types. This type of transform is a translate, rotate, independent x-y scale transform without sheer.

4-point rubbersheet transform

A type of coordinate transformation that can be applied to images upon insertion. This option provides an approximate transformation that is most accurate in the vicinity of the reference points, but contains some distortion in other regions of the image.

access key

The key that corresponds to an underlined letter on a menu, command, or dialog box.

active path

The location from which the current image file is actually being loaded. It can be a local path, a network path, or an Internet address.

Always Detach

An option in the Raster Design Options dialog box. If you erase the image frames, this option automatically detaches the images.

aperture

The square region, centered on the cursor crosshairs, where entity selection can occur when raster snap mode is active; also known as the snap window. You can also specify minimum and maximum pixel widths to snap to. See also snap window.

apparent intersection

The point where two entities would intersect if one, or both, were extended.

aspect ratio

The ratio of an image height to its width. See also bias.

attach

When you insert an image into a frame, the image is attached to the drawing. You can use the AutoCAD IMAGEATTACH command to attach an image, or you can use the AutoCAD Raster Design toolset iinsert command to attach an image. Attaching and inserting refer to the same process.

AutoInsert

A AutoCAD Raster Design toolset option for automatically inserting images in a drawing created with CAD Overlay ESP or GSX, which are earlier versions of AutoCAD Raster Design toolset.

AutoReplace

A AutoCAD Raster Design toolset option that replaces the image path of a previously inserted image by matching the drawing name.

AutoRub

A AutoCAD Raster Design toolset option that removes raster objects as you trace them with the vectorization tools. This option uses the Rub/Crop line width to determine the width of the raster that is removed.

base point

A point used for relative distance and angle when moving, copying, or rotating objects. Example: On the image, select the base point that you want to move to the destination point.

bias

The ratio of image width to image height, also called aspect ratio. You can change the bias of an image by using the AutoCAD Raster Design toolset ibias command.

bicubic

A pixel resampling method that computes the value for a new pixel based on interpolation of the values in a 4x4 block of surrounding pixels. This method provides a good compromise between accuracy and speed for most images.

bilinear

A pixel resampling method that computes the value for a new pixel based on linear interpolation of the values in a 2x2 block of surrounding pixels.

binary image

See bitonal image.

bitonal image

A two-color, 1-bit image, usually a line drawing such as a floorplan or parcel map. This image type is also called binary. The background color of a bitonal image can be transparent or solid. The foreground color can be any color.

blank distance

The distance between dashes in a dashed line.

blurring

In AutoCAD Raster Design toolset, a method for evenly weighing all pixels in the kernel, including the target. This filter, while similar to Low Pass #2, gives slightly brighter results.

blurring artifacts

A loss of image detail that can occur with image compression and resampling techniques. The symptoms include excessive smoothness where different colors meet, color bleeding, and a loss of color texture.

bitmap (BMP)

An image format. It can be compressed or uncompressed. Uncompressed BMP files contain raw data on a boundary of 4 bytes per raster. Compressed files are similar to the run length encoded PCX files, with minor variations. Only 4- and 8-bit files can be compressed.

boundary

See frame, image frame.

bounding outline

The visible element (usually a dotted rectangle) that is displayed when you select a region. Also called bounding box.

brightness

The luminance of pixels in an image. A higher brightness value makes all the pixels lighter.

CAD Overlay GSX and CAD Overlay ESP

Previous releases of AutoCAD Raster Design toolset.

CALS

Acronym for the raster image format Computer Aided Acquisition Logistics and Support. CALS files are black and white images used by the US Government as part of the transition to electronic media. CALS images are Fax Group IV compressed and are therefore a good way to store black and white line drawings and scans.

channel

A red, green, or blue color signal. Each AutoCAD Raster Design toolset color image is composed of one or more color channels. In a single-band 8-bit image, the color palette translates the index triplet for each color into a value for each color channel, with a limit of 256 total colors for any pixel. In a true color, or 24-bit image, separate red, green, and blue data bands provide color values to each channel, and each pixel can represent a value from 0 through 255 in each of the three channels.

The Band Assignment color map for multispectral images assigns image bands to color channels.

clipped image

An image that has been cropped or reduced in area. The regions of the image that are outside the clip boundary are hidden from view. You can turn off the clip or you can delete the clip to redisplay all of the image. Unlike a crop, a clip is a display-only feature that you can use for viewing and plotting purposes. It does not permanently change image data.

color depth

The amount of information stored with each pixel to define its color or shade. Common color depths are as follows:

Color Depth	Type of Image	Available Color(s)
1 bit	Bitonal	1 color
8 bit	Grayscale	256 shades of gray
4 bit	Color	16 colors
8 bit	Color	256 colors
16 bit	Grayscale	65,536 shades of gray
24 bit	Color	16,777,216 colors
32 bit	Color	16,777,216 colors

color map

An assignment of colors to data values for the purpose of displaying the contents of a file in a meaningful way.

Users work with two main types of color maps. A palette color map is used with digital elevation models (DEM) to specify whether to display surface elevations or slopes, and how to distribute the set of colors across the range of data values.

A band assignment color map is used with multispectral data to select the data bands to display and to assign each band to a color channel (red, blue, or green). AutoCAD Raster Design toolset automatically assigns a color map to image files that are inherently displayable, such as aerial photos and bitonal images.

connected crossing polygon

A selection method for enhanced bitonal region objects. This method selects all raster entities that are within the polygon, crossing the polygon, or connected to entities that cross the polygon boundary. In the following example, note that the text in the upper right is not selected because it is the only entity not connected to entities that cross the polygon boundary.

Connected crossing polygon

connected crossing window

A selection method for enhanced bitonal region objects. This method selects all raster entities that are within the window, crossing the window, or connected to entities that cross the window boundary. In the following example, note that the text in the upper right is not selected because it is the only entity not connected to entities that cross the window boundary.

Connected crossing window

connected entity

1. An entity that is connected to an entity that is selected or otherwise referenced.

2. A selection method for enhanced bitonal region objects. This method selects a specified entity and all other entities connected to it. In the following example, note that a single click on the arrow in the upper right selects the entire connected structure except the two text entities, which are not connected to any other entity.

Connected entity

connected fence

A selection method for enhanced bitonal region objects. This method selects all raster entities that are connected to any entity that touches the selection line (fence) you draw. Entities enclosed by the fence but not touching it are not selected. In the following example, the two text blocks are not selected because they do not touch the fence and are not connected to any entities that touch the fence.

Connected fence

connected window

A selection method for enhanced bitonal region objects. This method selects only those raster entities that are entirely within the window you define and are not connected to any entity that extends outside the window. In the following example, note that the arrows are not selected because they are connected to lines that extend outside the window.

Connected window

connected window polygon

A selection method for enhanced bitonal region objects. This method selects only those raster entities that are entirely within the polygon you define and are not connected to any entity that extends outside the polygon. In the following example, note that the arrows are not selected because they are connected to lines that extend outside the polygon.

Connected window polygon

continuous tone

A shaded image, sometimes called halftone in traditional printing.

convolve filter

A type of image processing filter that can be used with grayscale images for various operations, such as smoothing or sharpening the image details.

copylast

An option that is available when vectorizing text. It displays the VText Edit dialog box, which contains the last text string you placed in the drawing. You can edit the text string if needed, and then click OK and pick an insertion point for the copy.

correlate

The process of positioning an image within the AutoCAD coordinate system so that the image dimensions and coordinates match AutoCAD units and coordinates.

crop

A selected area of a raster image. Pixel data outside the crop is deleted. The image frame size is adjusted automatically. A crop permanently alters an image.

data organization

The method of organizing the image data when the image is saved. The data organization can be stripped, tiled, or monolithic.

datum

A reference point, line, or surface.

decrement

To decrease by one.

DEM

Digital elevation model. A format for recording land elevations in a digital file. A regular grid of survey points is created over the surface, and the elevation of each point is recorded as a floating-point number.

density

The number of dots per linear unit at which an image is scanned or created. The more dots per unit, the higher the density and clarity of detail. Also called resolution or pixel density. See also DPI.

density units

The linear units on which the image density is based. Example: Inches are the density units of an image that was scanned at 300 dots per inch.

density value

The number of dots per unit that make up the image density. Example: An image scanned at 300 dots per inch has a density value of 300.

deskew

To rotate a raster image, usually for the purpose of aligning it orthogonally with the AutoCAD coordinate system.

destination point

The location to which you move an image. To move an image, you must pick a source point and a destination point.

detach

To completely remove an image from a drawing. To reverse a detach operation, you must insert the image from its source. Operations similar to detach but less permanent are erase, unload, and hide.

displace

To move an image from a source point to a destination point.

display

The visual output device and its technology, such as a CRT-based display, a flat-panel display, or the graphics portion of your monitor.

display order

The order in which images are displayed in AutoCAD. This sequence determines which images are above or below other images, and affects image visibility.

dither

The process of using a pattern of solid dots to simulate more colors than are actually available.

donut

A circle with a specified linewidth.

DOQ

Digital orthophoto quadrangle raster image format, used for aerial photos that are processed to remove distortion. A typical DOQ represents one quarter of a USGS topographic map at 1:24 000 scale.

DPI

Dots per inch. A measure of image density. See also resolution, density, PPI.

Draft

An option in the Raster Design Options dialog box that does not dither the pixels. This setting is recommended for bitonal images.

drawing image

A raster file of a drawing, a photograph, a map, or a satellite image that you can edit, manipulate, and manage using AutoCAD Raster Design toolset.

drawing unit

The unit on which an AutoCAD drawing is based. Example: A common Imperial drawing unit is inches. A common Metric drawing unit is meters.

DTED

Digital Terrain Elevation Data. A grid-based file of elevation points. This format was developed by the U.S. National Imagery and Mapping Agency (NIMA).

ECW

Enhanced Compressed Wavelet. A highly-compressed image format from ER Mapper, Inc.

edge enhancement filters

Filters that improve the quality of an image by extracting individual elements, such as boundaries and property lines. You can also use these filters for object extraction or object recognition by higher-level algorithms.

EISA

Extended Industry Standard Architecture

embed

To store a raster image in a drawing, rather than as a file external to the drawing. Embedded images can be viewed in an AutoCAD-based application only if the application is installed with AutoCAD Raster Design toolset or the Object Enabler for AutoCAD Raster Design toolset.

Enable Mask

An AutoCAD Raster Design toolset option on the Image Mask Properties tab that enables an existing mask for display. Enabling allows you to view the image clip as defined by the image mask.

encoding

Compression method that is applied to an image when the image is saved. An encoding method can compress the image file to save disk space.

enhanced bitonal region object

A type of raster entity manipulation (REM) object that includes several lines, arcs, or circles within a bitonal raster image. For illustrated definitions of the types of enhanced bitonal region objects, see “connected” and “smart” in this Glossary.

equalization

A function that brings out details in an image. Equalization changes the darkest pixels in an image to black and the lightest pixels to white, then reassigns the remaining pixels to use all of the colors in between. Also called non-linear contrast stretch.

erase

To remove an image insertion from a drawing. This operation removes the image and frame from the drawing, removes the insertion object and its color map from the toolspace, but leaves an unreferenced data definition in the image data view. The color map is not erased from the image data view if it is used by other insertions. To reverse an erase operation, do a new insertion from the data definition object. Whether an erased image is also detached depends on how the Image Detach Options are set on the User Preferences tab of the Raster Design Options dialog box. See also detach.

ESRI Grid

An image format used in ESRI GIS products. This format is available in ASCII and binary versions.

Export

An AutoCAD Raster Design toolset command for saving an image to another file format and writing out correlation for the image. The correlation stores insertion point, scale, rotation, and density information for the image. When you export an image, you can choose what type of correlation to create. You can save the correlation data to a resource file, a world file, or to the image file. The type of correlation you can create depends on the type of image being exported.

fillet

A rounded corner where two lines meet. AutoCAD Raster Design toolset can apply fillets of specified radius to line intersections in bitonal images.

filter

An editing tool that can be used to adjust the appearance of an image. Example: The Invert filter reverses light and dark areas on an image. Also called editing filter.

FLIC

Acronym for the image format Animator FLIC.

follower

A vectorization tool that traces raster lines in a bitonal image and creates vectors that AutoCAD recognizes as individual objects.

foreground color

The color of the raster objects in a bitonal image. The other color in the image is the background color.

frame

A rectangular vector object that encloses an image. You can select the image frame by clicking it, or by using any AutoCAD selection method. The image frame is an AutoCAD object that you can assign to a layer, reposition, or scale, using standard AutoCAD methods. A frame can become an irregular shape if the image is cropped or clipped. See also image frame.

freq value

In a histogram image, the frequency value of a color or shade of gray: the number of pixels that use the indicated tone.

Gap Width

A setting that defines the maximum gap (from 0 to 10 pixels) that AutoCAD Raster Design toolset can ignore as it follows a raster line, polyline, or contour. AutoCAD Raster Design toolset ignores any gap that is equal to or smaller than the Gap Width. This setting is useful for scanned images that have many disconnected raster lines or in which pixels are missing as a result of imperfect scans.

geo-referenced image

An image that references real-world coordinates in its correlation source. Example: Geo-referenced images include GeoSPOT, GeoTIFF, and images that use world files as their correlation source.

GeoSPOT

An image format from SPOT Image Corporation that supports georeferencing information.

GeoTIFF

A type of tagged image file format (TIFF) that supports geo-referencing information.

GIF

Graphics Interchange Format. A raster image format created by Compuserve.

GIS (Geographic Information Systems)

Computerized decision support systems that integrate spatially referenced data. These systems capture, store, retrieve, analyze, and display such data.

global coordinate system

A method for defining points on the earth in a Cartesian coordinate system, taking into account the curvature of the earth's surface.

gradient directional edge enhancement filters

Filters that improve the quality of the line where an object begins or ends by extracting individual elements. These filters use the vector sum of the three coordinate variables X, Y, and Z, taking into account their direction in space. You can use the gradient directional edge enhancements filters in any one of the eight compass directions. Use of these filters results in a black background with white outlines of the objects in the image.

grayscale image

An image usually created by a scanner in which continuous tones are represented as uniform shades of gray. Each pixel uses eight bits of information, producing 256 shades of gray.

grip(s)

Small boxes displayed at various points on a selected object that can be used to edit the object. Select a grip and then specify a grip editing function.

hide

To remove an image from the display while retaining it in active memory. The image frame remains visible. To reverse a hide operation, select the image frame or the toolspace object, then right-click and select Show. See also detach.

high pass filters

A means for enhancing the edges of images. Images that do not appear clear may also be sharpened by high pass filtering.

histogram

A bar graph that shows the number of pixels for each color in the selected image or images. An aid for image editing operations.

hybrid

A type of drawing that includes both raster and vector data.

IG4

Acronym for the image format Group 4 data with IST headers.

IGS

Acronym for the image format Image Systems Gray Scale.

image

A graphic that is composed of raster data. See also drawing image.

image format

The method in which an image was created and saved, such as bitmap, CALS, RLC, or GIF. Some image formats, such as PICT, are read-only.

image frame

A frame that encloses each image you insert (also called a boundary). If you select an image frame, grips appear and hatch marks are drawn over the image to indicate that you have selected it. See also frame.

Image Properties

The properties of color, layer, and frame linetype settings of each image.

image selection

A collection of data treated by AutoCAD Raster Design toolset as a unit. Example: When you select an image by clicking its frame, the image moves to the top of the display order, obscuring any vectors that intersect with it.

image unit

The unit at which an image was scanned or created. Example: If you scan an image at 300 dots per inch, the image unit is inches.

Index Color (8-bit)

An image type that contains up to 256 colors.

index value

The numeric identifier (0 to 255) of a color or shade of gray. These values are used in the Histogram and the Palette Manager.

invert

A filter used to reverse position, order, or relationship. Example: You can invert the image to create a positive image. Use the Invert filter to reverse the dark and light areas of an image.

JFIF - JPEG

Acronyms for image formats created by Joint Photographics Expert Group. JFIF is JPEG File Interchange Format. It uses a compression scheme that gives preference to compression rather than data preservation. Best suited for 24 bit images.

JPG2000

An advanced raster image format from Joint Photographics Expert Group, featuring options for lossless compression, wavelet compression, incremental decompression, and support for up to 48-bit color.

Lanczos

A pixel resampling method that computes the value for a new pixel by interpolating the value of a 6x6 block of surrounding pixels.

Landsat FAST L7A

A multispectral image format used by Landsat 7 satellite, which was launched in 1999.

layout

Management of images, to determine how they are displayed and in what order they are listed in the Image Management dialog box.

linetype

The display style of a line, such as continuous or dashed.

low pass filter

A means of extracting individual elements in areas where pixel intensities change rapidly, thereby reducing high-frequency detail. The effect is a slightly blurred image.

LZW

A file compression algorithm, commonly used with TIFF and GIF files.

Maintain Drawing Link

An AutoCAD Raster Design toolset export option that, if selected, overrides the image you selected to export.

mask

An object used to display and plot a subset of the images in your drawing. A mask clips the images inside the mask boundary and hides or unloads the images completely outside the mask boundary. The mask boundary is an AutoCAD object that you can move, stretch, scale, and erase, like any other AutoCAD object.

median filter

A convolving filter that removes random visual speckles from an image by changing each pixel value to match the average value of the neighboring pixels.

merge commands

AutoCAD Raster Design toolset commands used to merge images, merge vectors into raster images, and select raster pen widths.

merge images

To group two or more images into a single image file.

mirror

To create a new version of an existing object by reflecting it in relation to a line or plane. Example: Scanning software might mirror a drawing, or you might scan the back of a drawing by mistake. You can correct these problems by mirroring the image.

Mitchell

A pixel resampling method that uses a cubic spline technique. It is widely considered to provide a good compromise between ringing and blurring artifacts on most images. See also blurring artifacts, ringing artifacts.

monolithic

Encoding method for TIFF files. Saves image data in one piece, and may result in slower processing time. See also data organization.

multispectral image data

Data recorded in the form of multiple bands. Each band records the values in a specific range of the spectrum, such as infrared, visible, or ultraviolet. Data gathered by satellites is typically provided in multispectral format. A band assignment color map is used to create false color images from these bands. The color map can be configured to highlight surface features, such as vegetation and water.

native capture

Copies a REM object using the image data directly from the image file, ignoring display scale and rotation of objects. Used only for the REM Copy To Clipboard command.

nearest neighbor

A pixel resampling method that assigns to a new pixel the value of the closest pixel in the original image. This is the fastest resampling method, but it produces the crudest results.

Never Detach

An option in the Raster Design Options dialog box that does not detach an image even if all image frames that reference the image are erased from the drawing.

NITF

National Imaging Transmission Format. This multiframe image format is commonly used by US federal agencies and NATO.

node

In AutoCAD Raster Design toolset, a link end point that can be represented as a block or point object. Example: You can force the line follower to ignore the intermediate nodes and draw a single straight line between the start and end points of a line.

noise

Random pixels that can result from poorly scanned images.

non-georeferenced image

An image that does not include real-world coordinate information.

non-linear contrast stretch

See equalization.

non-orthogonal image

A graphic representation that intersects or lies at angles other than right angles. Also called non-ortho image.

ortho-corrected image

An image that is corrected so all pixels represent their true locations on the face of the earth, making directions and distances accurate. Errors resulting from parallax, lens distortion, and other causes are corrected.

orthogonal

Intersecting or lying at right angles (0, 90, 180, or 270 degrees).

palette

The range of up to 256 colors used in an 8-bit image.

parallax

The apparent displacement of position of an object, caused by a shift in the point of observation.

PCX

A simple run-length encoded image format.

Pick <

An AutoCAD Raster Design toolset device for selecting points on the screen.

PICT

An image format created by Apple Computer.

pixel

A single dot on the screen. Pixels are the building blocks of raster images, and are individually assigned different colors or shades of gray. Image pixel size varies depending on the resolution of the image. A 2X2 pixel in a 400 dpi image is one quarter the area of a 2X2 pixel in a 200 dpi image.

pixel size

Image density expressed as the area of a pixel, typically used with aerial photography and satellite imagery.

PNG

Portable Network Graphics. A raster image format.

positive image

An image in which the light and shade areas correspond to the original image.

PPI

Pixels per inch. Also called dpi, or dots per inch. See also DPI.

projection

Data devised by cartographers and mathematicians to depict three-dimensional shapes (like the earth) on two-dimensional surfaces with known distortion.

quad sheet

A device for reducing image file size. Many maps are broken up into quadrants, which are square and are called quad sheets. When a group of quad sheets is inserted into a drawing, the drawing is considered to be tiled.

QuickBird TIFF

A multispectral image format produced by DigitalGlobe from its QuickBird satellite.

raster data

A series of dots, or pixels that form an image. This type of data is produced when you scan a paper drawing, a blueprint, or a photograph. A raster image is composed of pixels.

raster entity

A series of contiguous pixels that form a single entity such as a line, rectangle, or circle. AutoCAD Raster Design toolset can recognize such entities and create vector entities or regions that can be more easily edited than the raster originals.

raster entity manipulation (REM)

An object-oriented method of editing raster entities in bitonal, color, and grayscale images. REM handles raster entities much like vector objects. There are three types of REM objects: region objects, enhanced bitonal region objects, and primitive objects.

raster impact point

The point where a vector polyline intersects a raster entity.

raster object

A distinct line, circle, or arc in a bitonal raster image. Raster objects can be vectorized or edited using raster entity manipulation.

raster pen

A tool that allows thickening of vector objects when you merge them into the image. Thicknesses are assigned according to the specified entity color.

raster snap

A setting that automatically places the cursor at the end, center, corner, intersection, or edge points on a bitonal raster entity. If you choose more than one snap mode, then the crosshairs snap to the closest of the possible snap points.

resolution

The number of dots per unit at which an image is scanned or created. Example: An image scanned at 600 dots/inch (dpi) has a higher resolution than one scanned at 300 dpi.

resource file

A file used by AutoCAD Raster Design toolset to store image correlation data such as insertion point location, scale, and rotation. Resource files have a .res extension. They can be created by the Export command and can be read only by AutoCAD Raster Design toolset. See also world file.

ringing artifacts

A loss of image detail that can occur with image compression and resampling techniques. The symptoms include ripples or similar interference along edges where two dissimilar colors meet. The sharpness of the edges is degraded.

RFT

Revisable form text.

RGB

Red-green-blue color channels.

RLC

Run-Length Coding raster image format. AutoCAD Raster Design toolset can read RLC1 and RLC2. RLC 1 is a plain RLC with no header. RLC2 is an RLC1 with IST headers. See also run-length coding.

RLC2

Run-Length Coding raster image format with IST headers. See also run-length coding.

rotation angle

The angle at which an image is being revolved about its axis.

RTF

Rich text format

rub

To remove a line or area from an image with a AutoCAD Raster Design toolset Rub command (e.g., irubline, irubarc). A rub changes the pixels in a selected area to the transparent color. When background transparency is turned on for the image, the rubbed area becomes transparent. Rub permanently alters your image.

rubbersheet

To match points in an image to known reference points in a coordinate system by warping the image using a triangular or polynomial transformation.

run-length coding

A data compression method that replaces a run or sequence of identical data units (such as pixels) with a single unit and the length of the run.

saved path

The image file name saved in the drawing. It can be a simple file name, a local path, a network path, or an Internet address.

scale

The defined dimensional relationship between units of linear measurement on the earth’s surface and those on a map or aerial photo.

scaling

A method of proportionally changing the size of a raster image in reference to existing raster or vector entities without rotating it.

shading

The use of marking made within outlines to suggest three-dimensionality, shadow, or degrees of light and dark in a picture or drawing. Example: You can use the sharpening filters on grayscale images to make differences in shading more distinct. It may be necessary to use sharpening filters to extract the highest amount of useful data from a low- resolution scan.

sharpening filters

A device for enhancing details in images. Sharpening filters, with the exception of the matched filters, use spatial filtering with a 3x3-pixel kernel.

Show Image Frame(s)

An option on the Image Mask tab of the Raster Design Options dialog box. Shows the frames of the images that are hidden or unloaded.

SID (MrSID)

Multiresolution Seamless Image Database. A highly-compressed image format from LizardTech, Inc.

Single Image Optimization

An AutoCAD Raster Design toolset feature that automatically selects your image when you run a AutoCAD Raster Design toolset command that requires an image to be selected. You are prompted to select an image only if you are working with multiple images.

smart crossing polygon

A selection method for enhanced bitonal region objects. This method selects all raster entities that lie within or cross into the polygon you draw. If any part of the entity crosses the polygon boundary, the entire entity is selected. In the following example, note that the horizontal lines and the circle are selected because they cross the polygon boundary.

Smart crossing polygon

smart crossing window

A selection method for enhanced bitonal region objects. This method selects all raster entities that lie within or cross into the rectangular window that you draw. If any part of the entity crosses the window boundary, the entire entity is selected. In the following example, note that two horizontal lines that cross the window boundary are selected.

Smart crossing window

smart fence

A selection method for enhanced bitonal region objects. This method selects all raster entities that touch a selection polyline (fence) that you draw. Entities enclosed by the fence but not touching it are not selected. In the following example, the text 8.94 is not selected because it does not touch the fence.

Smart fence

smart window

A selection method for enhanced bitonal region objects. This method selects only the raster entities that lie entirely within the rectangular selection window. In the following example, the arrow and number within the window are selected, but the horizontal lines that cross the window boundary are not selected.

Smart window

smart window polygon

A selection method for enhanced bitonal region objects. This method selects only the raster entities that lie entirely within a polygon that you draw. In the following example, the circle and horizontal lines that cross the polygon boundary are not selected.

Smart window polygon

smoothing filters

A device for removing details or unwanted speckles in images. Smoothing filters use spatial filtering with a 3x3-pixel kernel.

snap window

The square region, centered on the cursor crosshairs, where entity selection can occur when raster snap mode is active; also known as the aperture.

snap window

You can also specify minimum and maximum pixel widths to snap to. The snap window snaps only to the bitonal objects that are between the minimum and maximum pixel widths.

source point

The location from which you move an image. To move an image, you must select a source point and a destination point.

spatial resolution

Image density expressed in pixels per unit, typically used with scanned images.

speckle

An unwanted random spot in an image. Speckles or stray pixels can often appear in an image when you scan drawings or blueprints that are dirty or wrinkled. You can remove speckles from your bitonal images by using the Despeckle filter.

stripped

Encoding method for TIFF files. Breaks up image data into strips for quicker processing. See also data organization.

supported image types

AutoCAD Raster Design toolset supports bitonal, grayscale, and up to 24-bit color images, along with digital elevation models (DEM), multispectral imagery, and generic integer data in 16- and 32-bit format.

supported image types

AutoCAD Raster Design toolset supports bitonal, grayscale, and up to 24-bit color images, and generic integer data in 16- and 32-bit format.

TARGA

A raster image format created by Truevision Inc. Usually 16-bit or 24-bit true color. Can be 8-bit grayscale or simple run-length coded.

Threshold

An AutoCAD Raster Design toolset operation for converting color or grayscale images to bitonal format. Within the range of grayscale values in an image, the threshold marks the upper limit of black pixel values and the lower limit of white pixel values. AutoCAD Raster Design toolset can set the threshold value automatically, but you can manually adjust it before conversion, using the Threshold tab of the Histogram dialog box.

thumbnail

A miniature representation or preview of an image. Thumbnails are used in the AutoCAD Raster Design toolset Insert Image dialog box, the Histogram dialog box, and the AutoCAD Image Adjust dialog box.

TIFF

Acronym for the tagged image file format.

tiled

Encoding method for TIFF files. Breaks the image data into rectangular, tiled regions for quicker processing. See also data organization, quad sheet.

toggle

To switch between two options of an electronic device, usually by pressing a single button. Example: The AutoCAD Raster Design toolset Toggle command changes the visibility of the image frame.

transparent color

A selected color that is transparent in a grayscale or color image. If background transparency is turned on for the image, all pixels of the transparent color become transparent. Any time you use a Rub command, the color of the rubbed area is changed to the transparent color.

true color (24-bit) image

An image that can contain up to 16.7 million colors. This image type is composed from three 8-bit data bands: red, green, and blue.

unembed

To remove an embedded image from a drawing. The unembedded image must be saved as an independent file. See also embed.

unload

To remove image data from the display and the working memory of a drawing. The image frame remains visible, and the image object remains in the Image Manager Toolspace tree. To reverse an unload operation, do a reload. See also detach.

vector

A mathematical object with precise direction and length, but without specific location. Vector data is stored as XYZ coordinates that form points, lines, areas, and volumes.

vectorize

Converting a bitonal raster image to vector data. You can use the AutoCAD Raster Design toolset vectorization tools to vectorize a raster image. See also follower, VTools.

VTools

AutoCAD Raster Design toolset vectorization tools used to manually convert bitonal raster arcs, circles, lines, or rectangles to equivalent vector objects.

VTools Removal

A setting on the VTools General tab of the Raster Design Options dialog box that controls what happens to the underlying raster entity when vectorization tools are used to vectorize the raster entity. Depending on the Removal Method setting you choose, the raster entity can be rubbed or REM deleted.

wavelet

Multiple resolution image files compressed to a small fraction of their original size.

world file

A file that stores correlation information for an image, consisting of scale, rotation, and insertion point. World files can be created by the Export command to correlate an image in another graphics application. The world file is in ASCII format that you can view using Notepad. World files are saved in the folder where the image is located. Their extensions vary, depending on file type, but always end in w. Examples:

• BMP - bpw
• GIF - gfw
• IG4 - i4w
• TIFF - tfw

X Y and Z coordinates

Any of a set of numbers used to specify the location of a point on a line, on a surface, or in space.