# $ K Imaging Concepts
The following terms describe the imaging concepts that are associated with Imaging OLE controls:
Images
What Is an Image?
Bitmap Image
Black-and-White Image
Color Image
File Types
Gray-Scale Image
Image Files
Image Page
Image Types
True Color Image
Units of Measure
Annotations
What Are Annotations?
Annotation Functions
Annotation Groups
Annotation Tool Palette
Annotation Types
Compression
What Is Compression?
Compressed Image
Compression Options
Compression Type Support
Compression Types
Uncompressed Image
Display
What Are Display Functions?
Display Types
Palettes
What Is a Palette?
Common Palette
Custom Palette
Scanning
What Is Scanning?
TWAIN Specification

# $ Units of Measure
Dots Per Inch
Pixel
Resolution

# $ Annotations
The following terms describe the annotation concepts that are associated with Imaging OLE controls:
What Are Annotations?
Annotation Functions
Annotation Groups
Annotation Tool Palette
Annotation Types

# $ Compression
The following terms describe the compression concepts that are associated with Imaging OLE controls:
What Is Compression?
Compressed Image
Compression Options
Compression Type Support
Compression Types
Uncompressed Image

# $ Display
The following terms describe the display concepts that are associated with Imaging OLE controls:
What Are Display Functions?
Display Types

# $ Images
The following terms describe the image concepts that are associated with Imaging OLE controls:
What Is an Image?
Bitmap Image
Black-and-White Image
Color Image
File Types
Gray-Scale Image
Image Files
Image Page
Image Types
True Color Image
Units of Measure

# $ Palettes
The following terms describe the palette concepts that are associated with Imaging OLE controls:
What Is a Palette?
Common Palette
Custom Palette

# $ Scanning
The following terms describe the scanning concepts that are associated with Imaging OLE controls:
What Is Scanning?
TWAIN Specification

# $ Annotations
The following terms describe the annotation concepts that are associated with Imaging OLE controls:
What Are Annotations?
Annotation Functions
Annotation Groups
Annotation Tool Palette
Annotation Types

# $ Compression
The following terms describe the compression concepts that are associated with Imaging OLE controls:
What Is Compression?
Compressed Image
Compression Options
Compression Type Support
Compression Types
Uncompressed Image

# $ Display
The following terms describe the display concepts that are associated with Imaging OLE controls:
What Are Display Functions?
Display Types

# $ Images
The following terms describe the image concepts that are associated with Imaging OLE controls:
What Is an Image?
Bitmap Image
Black-and-White Image
Color Image
File Types
Gray-Scale Image
Image Files
Image Page
Image Types
True Color Image
Units of Measure

# $ Palettes
The following terms describe the palette concepts that are associated with Imaging OLE controls:
What Is a Palette?
Common Palette
Custom Palette

# $ Scanning
The following terms describe the scanning concepts that are associated with Imaging OLE controls:
What Is Scanning?
TWAIN Specification

# $ Annotation Functions
Annotation functions provide tools for drawing and manipulating annotation marks.  Depending on how you implement them in your application, the end user can:
{bmc bullet.bmp}	Create, move, resize, edit, and delete annotation marks.
{bmc bullet.bmp}	Modify annotation attributes (such as color, size, text, and visibility).
{bmc bullet.bmp}	Group annotation marks and control their visibility.
{bmc bullet.bmp}	Save annotation marks as part of the image or separately.

# $ Annotation Groups
Annotation groups make it possible to organize and manage annotations, giving the end user the capability to:
{bmc bullet.bmp}	Logically organize annotations into functional groups; for example, Accounts Payable Group, Accounts Receivable Group, Purchasing Group, Receiving Group, and so on.
{bmc bullet.bmp}	Toggle the visibility of the groups; for example, to Turn On Accounts Payable Comments, Turn On All Comments, and so on.
A group can contain one or more annotation marks and multiple groups can be associated with a single image.

# $ Annotation Types
Imaging OLE controls support the following annotation types: 
Annotation Type	Description	
Attach-a-Note	Enters text into a background rectangle on an image	
Filled Rectangle	Covers a portion of an image	
Freehand Line	Draws a freehand line on a section of text or a portion of an image for emphasis	
Highlighter	Draws a transparent, filled rectangle for highlighting emphasis (available as a discreet annotation type on the Annotation Tool Palette)	
Hollow Rectangle	Places a border around areas of an image for emphasis	
Image Embedded	Embeds an actual copy of another image in an image file	
Image Reference	Includes another image in an image file by reference (that is, it links to an external file that contains the image)	
Image Stamp	Places an image stamp directly on an image	
Rubber Stamp	Places an image or text stamp directly on an image (available as a discreet annotation type on the Annotation Tool Palette)	
Select Annotations	Selects annotation marks for deleting, modifying, moving, or resizing	
Straight Line	Underlines text, demarcates a section of a page, or draws callout lines	
Text	Places text directly on an image	
Text From File	Places text from a file on an image	
Text Stamp	Places a text stamp directly on an image	

# $ What Are Annotations?
Annotations are digitized versions of the marks commonly used on documents in a paper-based environment; for example, highlight, rubber stamps, and text notes.  Like their paper-based counterparts, digitized annotation marks are typically used to prepare documents for subsequent handling in a business process.  However, digitized annotations provide additional benefits that paper-based tools do not:
{bmc bullet.bmp}	Digitized annotations can be added, moved, and deleted at will.
{bmc bullet.bmp}	The attributes of digitized annotations (such as color, size, text, and visibility) can be readily modified.
{bmc bullet.bmp}	Groups of digitized annotations can be named.  The named groups can then be selectively acted upon.
Annotation marks can be saved within a TIFF image file as annotation data that is kept separate from the image data.  The marks can also be merged with the image data in a process known as burning-in.  To save annotations to any file type other than TIFF, the annotations must be burned-in.
Burning-in converts the annotation marks into image pixels and merges them with the underlying image pixels in the process.  Once annotations are burned-in, they become part of the base image and can no longer be manipulated by the annotation functions.

# $ Black-and-White Image
A Black-and-White image is a type of image where each pixel is either on (black) or off (white).  This type of image is typically used in fax transmissions.

# $ Bitmap Image
A Bitmap image is a representation of a graphic image, displayed by setting individual pixels to white, black, or a color.  This type of image is typically used by the Windows Paintbrush applet and has a filename extension of .BMP.

# $ Color Image
A Color image is a type of image that contains various colors.  Imaging OLE controls support 4- and 8-bit palettized images, as well as 24-bit color images.

# $ Compressed Image
A Compressed image is an image that is stored using a technique that reduces the size of the image, thereby saving storage space.

# $ What Is Compression?
Compression is the process by which image data is reduced to require less storage space.  Employing compression is particularly important when saving gray-scale or color images because of their large size.

# $ Compression Options
Compression options are bitwise values that dictate how image data is compressed.  A relationship exists between compression options and compression types, where certain compression options apply only to specific compression types.
Whenever a compression option and a compression type are specified as arguments to an Imaging OLE method, the software checks the relationship for validity.
Compression Option Support

# $ Compression Option Support
Imaging OLE controls support the following compression options:
Compressed LTR -- Compressed bit order, Left-To-Right.  The compressed data codes begin at the most significant bit of each byte and are ordered from the most significant bit to the least significant bit.  The Compressed LTR compression option applies to all compression types that support black-and-white images, except the PackBits compression type.
EOL -- End Of Line.  Each line of data is terminated with a standard end-of-line bit.  The EOL compression option applies to the Group3(1D) and Group3(2D) compression types.
Expand LTR -- Expanded bit order, Left-To-Right.  The expanded data codes begin at the most significant bit of each byte and are ordered from the most significant bit to the least significant bit.  The Expand LTR compression option applies only to image data that is being read; it is therefore meaningless when writing or converting images.  The Expand LTR compression option applies to all compression types except JPEG.
Negate -- A high-level request to invert black-and-white data.  The Negate compression option applies to all compression types that support black-and-white images.
Packed Lines -- The compressed data is packed into bytes with no padding at the end of each line (the data is not byte-aligned).  The Packed Lines compression option applies to the Group3(1D), Group3(2D), and Group4(2D) compression types.
Prefixed EOL -- Each strip of data is prefixed by a standard end-of-line bit sequence.  The Prefixed EOL compression option requires that the EOL compression option be set as well.  It applies to the Group3(1D) and Group3(2D) compression types.
JPEG Options -- Joint Photographics Experts Group compression options.  JPEG compression options comprise all combinations of high, medium, or low compression and high, medium, or low quality (resolution).
The higher the compression, the lower the disk space requirement; the higher the resolution, the greater the image quality.  An image compressed with the Low Compression/High Quality option has the highest disk space requirement and the highest image quality.  Conversely, an image compressed with the High Compression/Low Quality option has the lowest disk space requirement and the lowest image quality.
The JPEG compression options apply to the JPEG compression type, which can be used with JPG and TIFF file types.

# $ Compression Type Support
For each file and image type, the Imaging OLE controls support the following compression types:
File Type	Image Type	Compression Type Supported	
BMP	Black-and-White
Palettized4
Palettized8
BGR24
	None	
DCX/PCX	Black-and-White
Palettized4
Palettized8
RGB24
	PCX proprietary	
JPG	Gray8
RGB24
	JPEG	
TIFF	Black-and-White
Gray4
Gray8
Palettized4
Palettized8
RGB24	None, Group3(1D), Group3(2D), Group3(MH), Group4(2D), LZW, PackBits
None, LZW
None, JPEG, LZW
None, LZW 
None, LZW
None, JPEG, LZW	
XIF	Black-and-White	None, Xerox-proprietary	
Notes:  The DCX/PCX, JPG, and XIF file types are read-only.  For TIFF file types, the Palettized4 image type is read-only.  The Group3(2D) and LZW compression types are read-only.

# $ Compression Types
Imaging OLE controls support the following compression types:
Group3(1D) -- A compression type based on the CCITT Group3 fax standard, Group3(1D) is used to compress black-and-white TIFF image files.  Group3(1D) encodings are designed to provide reliable delivery of image data over inherently unreliable data links.  It is commonly used to compress images for fax transmission.
Group3(2D) -- Similar to the Group3(1D) compression type, Group3(2D) is used to compress black-and-white TIFF image files for fax transmission exclusively.  Group 3(2D) encodings provide a high degree of error recovery during fax transmission.  Read-only.
Group3(Modified Huffman [MH]) -- Also similar to the Group3(1D) compression type, except Group3(MH) provides no end-of-line characters.  It is used to compress black-and-white TIFF image files.
Group4(2D) -- Based on the CCITT Group4 fax standard, Group4(2D) is used to compress black-and-white TIFF image files. Group 4(2D) encodings are designed to provide delivery of image data over reliable data links, such as ISDN or X.25.  It provides superior compression for non-dithered images when compared to the Group3(1D) compression type.
JPEG -- The Joint Photographics Experts Group compression type is used to compress 24-bit color (RGB24) and 8-bit gray-scale (Gray8) image files.  JPEG produces a high compression ratio, but some image data is actually lost during compression.
LZW (Lempel-Ziv-Welch) -- A lossless compression type (that is, no data is lost during compression).  It is used with black-and-white; BGR24, RGB24, Palettized4, and Palettized8 color images; as well as Gray4 and Gray8 gray-scale images.  Read-only.
PackBits -- A simple, byte-oriented, run-length compression type, PackBits is used to compress black-and-white TIFF image files.
PCX -- A ZSoft-proprietary compression type, PCX is used to compress multipage DCX and single-page PCX black-and-while and color images.
Xerox-proprietary -- The Xerox-proprietary compression type is used to compress XIF images.

# $ Common Palette
A common palette is shared by all images being displayed.  It is a special, 8-bit palette that has a variety of colors, chosen because they give generally good results for both color and gray-scale images.  While the resulting image display is not as good as a custom palette rendition of the image, the common palette has the advantage of permitting any number of images to be displayed simultaneously with good overall quality.

# $ Custom Palette
A custom palette is optimized for the display of a particular image.  An image displayed using a custom palette results in an image that is most like its original.
Using the custom palette has one disadvantage, which is only noticeable when displaying multiple images using a monitor and controller that display 256 or fewer colors.  The disadvantage is that background images can appear in lower quality than their originals.  This occurs because Windows shares the active palette of the foreground window, which may not be suitable for displaying background images.

# $ What Are Display Functions?
Display functions provide the ability to show and manipulate images within an image window.  Typical display functions include:
{bmc bullet.bmp}	Copying, cutting, and pasting to the Clipboard
{bmc bullet.bmp}	Flipping
{bmc bullet.bmp}	Rotating
{bmc bullet.bmp}	Scrolling
{bmc bullet.bmp}	Zooming
These display functions manipulate the image data in the display memory of the PC.  The image file data is not modified unless the image is saved.

# $ Display Types
The display type pertains to the way in which data is presented to the monitor.  It does not alter the original image in any way.  Imaging OLE controls support the following display types:
Black-and-White (Bi-Level) -- Displays an image as black and white.  The Black-and-White display type is typically used for applications that manage black-and-white documents exclusively.
Common -- Displays an image using the common palette.  The Common display type permits the display of multiple images simultaneously while maintaining reasonable image quality.  A monitor and controller capable of displaying 256 colors are recommended.
Custom -- Displays an image using the best palette possible.  The palette used depends on the type of image being displayed, as described in the following list:
Image	Palette Used	
Black-and-White	Binary	
4-Bit Gray-Scale	Common	
8-Bit Gray-Scale	Gray8	
24-Bit Color Images	Common	
Because the palette used is designed specifically for the type of image being displayed, the custom display type is best suited to application programs that display one image at a time.  A monitor and controller capable of displaying 256 colors are recommended.
Gray8 -- Displays an image using a linear-scale palette of up to 128 shades of gray.
RGB24 -- Displays an image by letting Windows map the image directly to the monitor.  With suitable hardware, the RGB24 display type produces the best color at the optimum speed.  Further, it allows multiple images to be displayed with no loss in background image quality.  A monitor and controller capable of displaying 32,000 colors are recommended.

# $ Dots Per Inch
Dots Per Inch (dpi) indicates the number of dots (or pixels) per inch in an image.  The more dots per inch in an image, the higher its density and quality.

# $ File Types
Imaging OLE controls support the following file types:
BMP -- The file format used by the Windows Paintbrush applet.  BMP (bitmap) supports single-page color images.  Compression of BMP files is not supported.
DCX (read-only) -- The file format for multipage ZSoft PaintBrush images.  DCX supports both black-and-white and color images.  DCX files are compressed using PCX compression.
JPG (read-only) -- The file format for Joint Photographics Experts Group (JPEG) images.  JPG supports single-page 8-bit gray-scale and RGB24 color images.  JPG files are compressed using JPEG compression.
PCX (read-only) -- The file format for single-page ZSoft PaintBrush images.  PCX supports both black-and-white and color images.  PCX files are compressed using PCX compression.
TIFF -- The file format for Tag Image File Format (TIFF) images.  TIFF supports multipage black-and-white, gray-scale, and color images; several compression types; and a variety of options.  TIFF is compatible with all image densities.
XIF (read-only) -- The file format for Xerox images.  XIF supports multipage black-and-white images only.  XIF files can be uncompressed, or compressed using Xerox-proprietary compression.

# $ Gray-Scale Image
A Gray-Scale image is a type of image that contains various shades of gray.  Imaging OLE controls support 4- and 8-bit gray-scale images.

# $ What Is an Image?
An image is a photograph, line drawing, or text document that has been converted to digitized form, usually by a scanning device.  A scanned image is saved in a particular image file format.
Typically, an image is displayed in a window that can be sized or moved.  Images can also be annotated, e-mailed, faxed, or printed.

# $ Image Files
Images are stored in image files, which are standard Windows files.  Image files can be organized in folders, copied, renamed, deleted, and so on, using standard Windows commands.
Depending on the file format, image files can contain one or more images.  In multipage image files, each image is stored in a single image page.  Image files can be stored on the hard drive of a local PC, or on redirected network drives.  Applications can access any available image file by specifying its proper path (drive, folder, and filename).

# $ Image Page
Image pages provide a way to organize multiple images in an image file.  Each page contains or stores one image.  The following file types support multiple pages:
{bmc bullet.bmp}	DCX
{bmc bullet.bmp}	TIFF
{bmc bullet.bmp}	XIF

# $ Image Types
Imaging OLE controls support the following image types:
BGR24 -- This type of image uses 24 bits of data per pixel (eight bits-per-pixel for each of the three primary colors -- Blue, Green, and Red).  This translates to 256 shades of each primary color to provide up to 16 million colors for each image.  To display BGR24 images, the monitor and controller must be capable of displaying at least 32,000 colors.  The BGR24 image type is typically encountered in BMP files.
Black-and-White (Bi-Level) -- The Black-and-White image type displays one bit of data per pixel on the screen as either black or white.
Gray Scale -- There are two types of gray-scale images:  Gray4 and Gray8.
	Gray4 -- A Gray4 image uses 4 bits of data per pixel.  Every pixel on the screen can be displayed in 16 shades of gray, giving the image much better clarity than black-and-white images.
	Gray8 -- A Gray8 image uses 8 bits of data per pixel.  Every pixel can be displayed with 256 shades of gray, producing better image clarity than Gray4.  Gray8 images are particularly effective for storing pictures and photographs.
Palettized -- There are two types of palettized images:  Palettized4 and Palettized8.  
	Palettized4 -- A Palettized4 image uses 4 bits of data per pixel to reference a palette of 16 RGB (Red, Green, Blue) colors. These images can use a custom palette only.
	Palettized8 -- A Palettized8 image uses 8 bits of data per pixel to reference a palette of 256 RGB colors.  These images can use either a custom or common palette.
RGB24 -- Also known as true color, an RGB24 image is the same as a BGR24 image, but with the colors (Red, Green, and Blue) in a different order.

# $ What Is a Palette?
A palette is a look-up table that is used to translate an index value into a color value (known as an RGB value, for Red, Green, Blue).  There are two types:  Common and Custom.
Color images are often stored using a palette so that they take up less space.  Such an image is said to be palettized.  A complex image that has been palettized is often of lower quality than the original image.  This is due to the fact that the eye can distinguish many more colors than are usually available in the palette.
Windows reserves 20 palette entries to use for window backgrounds, borders, and so on.

# $ Pixel
The pixel is the smallest graphic unit on a screen or image.  It is equal to one screen dot or picture element.

# $ Resolution
Resolution is the overall measurement of image quality.  It is expressed as the number of dots- or pixels-per-inch.  It is possible for an image to have different horizontal and vertical resolutions.  For example, images received from fax transmissions typically have resolutions of 200 by 100 pixels-per-inch.  The more pixels-per-inch, the higher the resolution.  Image quality increases in proportion with the resolution value.  Therefore, the higher the resolution, the greater the image quality.

# $ What Is Scanning?
Scanning is the procedure for capturing data as images in electronic form.
An image acquisition device (typically a scanner) is connected to the PC and controlled by an application program.  The application program communicates with the scanner through an interface called the scanner data source (driver), which is usually supplied by the manufacturer of the scanner.  Imaging OLE controls support TWAIN, the industry-standard specification for image capture.

# $ True Color Image
A True Color image is a type of image that mixes shades of red, green, and blue to provide over 16 million colors.  These color images are also known as BGR24 or RGB24 images.

# $ TWAIN Specification
TWAIN is an industry-standard, open specification that defines the way in which an image acquisition device (typically a scanner) communicates with an application program.  With TWAIN, an application program can acquire images through any device that complies with its specification.
For your scanner, or other image acquisition device, to function properly, you need the TWAIN data source from its manufacturer as well as the latest 32-bit TWAIN DLLs.  You can obtain the latest 32-bit TWAIN DLLs from the following sources:
World Wide Web -- At http://www.twain.org
FTP -- At ftp.twain.org

# $ Uncompressed Image
An Uncompressed image is an image that is stored as is, without compression of any kind.  This type of image is usually larger than a compressed image; it may therefore require a greater amount of storage space.