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There are two categories of computer images: Raster and Vector. Rastor pictures are the representation of a digital image as a matrix of picture elements (pixels) on a grid. All images acquired by digital cameras and camcorders, scanners and screen capture programs are bitmapped images. Also known as "raster graphics, images created in paint programs are also bitmapped images.
Vector images are representations of a digital image as points, lines and other geometric entities based on mathmatical concepts. All computer-aided design (CAD), drawing and diagramming programs create vector images. Vector graphics and "bitmapped graphics" are the two fundamental structures for digital images. However, vector images are very space efficient compared to bitmapped images, and they maintain all their detail when zoomed in and out.
The defining difference between the two types is in how they form an image. Vector images are object-oriented while raster images are pixel oriented. A raster image is a collection of dots called pixels. Each pixel is a tiny colored square. When an image is scanned, the image is converted to a collection of pixels called a raster image. Scanned graphics and web graphics (JPEG and GIF files) are the most common forms of raster images.
In contrast, vector images are a collection of connected lines and curves that produce objects. Images are created when node or drawing points are inserted and lines and curves connect notes together: "connect the dots" in principle. Every aspect of a vector object is defined by math included node position, node location, line length and on down the line. . A vector object will have a "wireframe" underneath the colors in the object. In a vector object, colors are like clothes over the top of a skeleton. CorelDRAW and Illustrator create text and objects using vectors that can be easily manipulated.
Image qualities, such as color, resolution, image quality when resized, are considerations to consider when choosing what type of image to use. Below is a listing of the two types of images, along with advantages and disadvantages of each. This is only introductory, not inclusive or extensive.
~~ Debra Contreras
Raster Pictures: The representation of a digital image as a matrix of picture elements (pixels). All images acquired by digital cameras and camcorders, scanners and screen capture programs are bitmapped images. Also known as "raster graphics, images created in paint programs are also bitmapped images.
There are two categories of computer images: Raster and Vector. Rastor pictures are the representation of a digital image as a matrix of picture elements (pixels) on a grid. All images acquired by digital cameras and camcorders, scanners and screen capture programs are bitmapped images. Also known as "raster graphics, images created in paint programs are also bitmapped images.
Vector images are representations of a digital image as points, lines and other geometric entities based on mathmatical concepts. All computer-aided design (CAD), drawing and diagramming programs create vector images. Vector graphics and "bitmapped graphics" are the two fundamental structures for digital images. However, vector images are very space efficient compared to bitmapped images, and they maintain all their detail when zoomed in and out.
The defining difference between the two types is in how they form an image. Vector images are object-oriented while raster images are pixel oriented. A raster image is a collection of dots called pixels. Each pixel is a tiny colored square. When an image is scanned, the image is converted to a collection of pixels called a raster image. Scanned graphics and web graphics (JPEG and GIF files) are the most common forms of raster images.
In contrast, vector images are a collection of connected lines and curves that produce objects. Images are created when node or drawing points are inserted and lines and curves connect notes together: "connect the dots" in principle. Every aspect of a vector object is defined by math included node position, node location, line length and on down the line. . A vector object will have a "wireframe" underneath the colors in the object. In a vector object, colors are like clothes over the top of a skeleton. CorelDRAW and Illustrator create text and objects using vectors that can be easily manipulated.
Image qualities, such as color, resolution, image quality when resized, are considerations to consider when choosing what type of image to use. Below is a listing of the two types of images, along with advantages and disadvantages of each. This is only introductory, not inclusive or extensive.
~~ Debra Contreras
Raster Pictures: The representation of a digital image as a matrix of picture elements (pixels). All images acquired by digital cameras and camcorders, scanners and screen capture programs are bitmapped images. Also known as "raster graphics, images created in paint programs are also bitmapped images.
Types of Raster Pictures:
BMP: A computer image that is stored and displayed as a set of colored points in a rectangular grid; the representation of a digital image as a matrix of picture elements (pixels).
BMP: A computer image that is stored and displayed as a set of colored points in a rectangular grid; the representation of a digital image as a matrix of picture elements (pixels).
Advantages
1-bit through 24-bit color depth
Widely compatible with existing Windows programs, especially older programs
Disadvantages
No compression, which results in very large files
Not supported by Web browsersVector Pictures
No compression, which results in very large files
Not supported by Web browsersVector Pictures
PCX - PC Paintbrush: also called Z-Soft bitmaps, store a single raster image at any color depth. Paintbrush pictures are more widely used in earlier Windows and MS-DOS-based programs, and are still compatible with many newer programs. PCX pictures support internal Run Length Encoded (RLE) compression.
Advantages
Standard format across many Windows and MS-DOS based programs
Internal compression
Standard format across many Windows and MS-DOS based programs
Internal compression
Disadvantages
Not supported by Web browsers
Not supported by Web browsers
PNG - Portable Network Graphic: PNG pictures store a single raster image at any color depth. PNG is a platform-independent format that supports a high level of lossless compression, alpha channel transparency, gamma correction, and interlacing. It is supported by more recent Web browsers.
Advantages
High-level lossless compression
Alpha channel transparency
Gamma correction
Gamma correction
Interlacing
Supported by more recent Web browsers
Disadvantages
Lack of support for PNG files in older browsers and programs
As an Internet file format, PNG provides less compression than the lossy compression of JPG
As an Internet file format, PNG offers no support for multi-image or animated files, which the GIF format supports
JPG - Joint Photographic Experts Group (JPEG): JPEG pictures store a single raster image in 24-bit color. JPEG is a platform-independent format that supports the highest levels of compression; however, this compression is lossy. Progressive JPEG files support interlacing.
Advantages
Superior compression for photographic or realistic artwork
Variable compression allows file size control
Interlacing (for Progressive JPEG files)
Widely supported Internet standard
Disadvantages
Lossy compression degrades original picture data
When you edit and resave JPEG files, JPEG compounds the degradation of the original picture data; this degradation is cumulative.
JPEG is not suitable for simpler pictures that contain few colors, broad areas of similar color, or stark differences in brightness.
GIF - Graphics Interchange Format: GIF pictures store single or multiple raster image data in 8-bit, or 256 colors. GIF pictures support transparency, compression, interlacing, and multiple-image pictures (animated GIFs). Animated GIFs are supported in the GIF89a version of the GIF file specification.
Advantages
Widely supported Internet standard
Lossless compression and transparency supported
Animated GIFs are prevalent and easy to create with a large number of GIF animation programs
Disadvantages
256-color palette; detailed pictures and photo-realistic images lose color information and look paletted
Lossless compression is inferior to the JPG or PNG formats in most cases
Limited transparency; no semi-transparent or faded effects like those provided by alpha channel transparency
TIFF - Tagged Image File Format: TIFF pictures store a single raster image at any color depth. TIFF is arguably the most widely supported graphic file format in the printing industry. It supports optional compression, and is not suitable for viewing in Web browsers. The TIFF format is an extensible format, which means that a programmer can modify the original specification to add functionality or meet specific needs. This can lead to incompatibilities between different types of TIFF pictures.
Advantages
Widely supported, especially between Macintosh computers and Windows-based computers
Optional compression
Extensible format allows for many optional features
Disadvantages
Not supported by Web browsers
Vector Pictures: The representation of a digital image as points, lines and other geometric entities. All computer-aided design (CAD), drawing and diagramming programs create vector images (see graphics formats). Vector graphics and "bitmapped graphics" are the two fundamental structures for digital images (see graphics for basic concepts). However, vector images are very space efficient compared to bitmapped images, and they maintain all their detail when zoomed in and out.
Types of Vector Pictures:
DXF - AutoCAD Drawing Interchange File: The DXF format is a vector-based, ASCII format that Autodesk's AutoCAD program uses. AutoCAD provides highly detailed schematics that are completely scalable.
Advantages
AutoCAD allows you to create highly detailed and precise schematics and drawings
AutoCAD files are popular in the architectural, design, and engraving industries
Disadvantages
Limited support in Office 2000, which supports versions up through R12
AutoCAD has a steep learning curve; however, other graphics programs are also capable of exporting DXF pictures
CGM - Computer Graphics Metafile: The CGM metafile can contain vector and bitmap information. It is an internationally standardized file format used by many organizations and government agencies, including the British Standards Institute (BSI), American National Standards Institute (ANSI), and the United States Department of Defense.
Advantages
International standard format
CDR - CorelDRAW!: The CorelDRAW! metafile can contain both vector and bitmap information. It is a widely used, artistic design file format.
Advantages
Widely used in the prepress and artistic design industries.
Disadvantages
Limited support in Office 2000, which supports version 6 and earlier
WMF - Windows Metafile: The Windows Metafile is a 16-bit metafile format that can contain both vector and bitmap information. It is optimized for the Windows operating system.
Advantages
Windows standard format that works well with Office 2000
Windows standard format that works well with Office 2000
EPSF - Encapsulated PostScript Format: The Encapsulated PostScript Format is a proprietary, printer description language that can describe both vector and bitmap information.
Advantages
Accurate representation on any PostScript printer
Industry standard format
Disadvantages
The on-screen representation may not match the printed representation; the on-screen representation may be low-resolution, a different image, or only a placeholder image.
EPS files are designed to be printed, not necessarily looked at. They are not the most suitable format to display information on the screen.
EMF - Enhanced Metafile: The Enhanced Metafile format is a 32-bit format that can contain both vector and bitmap information. It is an improvement over the Windows Metafile Format and contains extended features such as:
Built-in scaling information.
Built-in descriptions that are saved with the file
Improvements in color palettes and device independence.
The EMF format is an extensible format, which means that a programmer can modify the original specification to add functionality or meet specific needs. This can lead to incompatibilities between different types of EMF pictures.
Extensible file format
Improved features compared to WMF
Disadvantages
Extensibility results in many different types of EMF pictures
Not all EMF files are compatible with all programs that support the EMF standard.
PICT - Macintosh Picture: The PICT file is a 32-bit metafile format for the Macintosh. PICT files use Run Length Encoded (RLE) internal compression, which works reasonably well. PICT files support JPEG compression if QuickTime is installed (Macintosh only).
Advantages
Best file format for on-screen display on the Macintosh
Best printing format from the Macintosh to a non-PostScript printer
Disadvantages
Fonts may be represented incorrectly when moved cross-platform
QuickTime must be installed to view some PICT files correctly
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