- Also called:
- bitmap graphics
- Related Topics:
- computer graphics
- JPEG
- GIF
- pixel
- bitmap
raster graphics
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What are raster graphics?
Raster graphics are a type of digital image that uses tiny rectangular pixels arranged in a grid formation to represent an image. It is well suited for displaying continuous-tone images such as photographs or shaded drawings, along with other detailed images.
A raster graphic comprises tiny, uniformly sized pixels arranged in a two-dimensional grid of columns and rows. Each pixel contains one or more bits of information, depending on the image's detail degree. The number of bits stored in each pixel is known as the color depth.
Images from scanners and digital cameras are raster graphics, as are most images on the Internet. A commonly used graphics program for working with raster images is Adobe Photoshop.
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How are images stored in raster graphics?
Raster graphics store images as a grid of tiny pixels, each holding one or more bits of color information. For instance, a black-and-white image uses one bit per pixel, while a color image commonly uses 24 bits, known as truecolor, allowing over 16 million possible colors per pixel. The number of bits per pixel is the color depth, while the resolution is the number of pixels in a column times the number of pixels in a row. Popular raster file formats include lossy formats like GIF and JPEG, and lossless formats like BMP and TIFF.
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What is a pixel in a raster image?
In raster graphics, a pixel is the smallest element of a digital image, arranged in a grid formation to represent the image. Each pixel contains bits of information that determine its color and shading, with more bits resulting in a higher color depth. For instance, a black-and-white image uses one bit per pixel, while a truecolor image uses 24 bits, allowing over 16 million colors. The number of pixels in a display determines the image's resolution and level of detail.
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How does changing the resolution affect a raster graphic?
Changing the resolution of a raster graphic alters the level of detail in the image. Resolution, defined as the number of pixels in a display, impacts the detail that can be shown, and is expressed as the number of pixels in a column by the number of pixels in a row (e.g., 800 x 600).
Raster graphics use tiny rectangular pixels arranged in a grid to represent an image and are well suited for displaying continuous-tone images, such as photographs. Each pixel contains bits of information, with the number of bits per pixel known as the color depth.
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What are some common file formats for raster graphics?
Raster graphics use tiny rectangular pixels arranged in a grid to represent an image. They are well-suited for continuous-tone images, such as photographs, shaded drawings, and detailed images because they support a wide range of colors and depict subtle graduated tones.
Common raster file formats include:
* GIF (Graphics Interchange Format) A lossless data compression format that was popular for transmitting and storing graphic files.
* JPEG (Joint Photographic Experts Group) A lossy compression format widely used on the web and in digital cameras.
* BMP (Windows bitmap) A lossless format.
* TIFF (Tagged Image File Format) A lossless format.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How are raster graphics different from vector graphics?
Raster and vector graphics are two different ways to create digital images. Raster graphics use tiny, rectangular pixels arranged in a grid to represent an image, which is well-suited for continuous-tone images, such as photographs. Vector graphics use mathematical formulas to define lines, curves, and shapes, allowing images to be scaled without losing quality. Raster images are derived from television technology, while vector graphics were first used in computer displays in the 1960s.
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raster graphics, a type of digital image that uses tiny rectangular pixels, or picture elements, arranged in a grid formation to represent an image. Because the format can support a wide range of colors and depict subtle graduated tones, it is well suited for displaying continuous-tone images such as photographs or shaded drawings, along with other detailed images.
Raster graphics have origins in television technology, with images constructed much like the pictures on a television screen. A raster graphic is made up of a collection of tiny, uniformly sized pixels, which are arranged in a two-dimensional grid made up of columns and rows. Each pixel contains one or more bits of information, depending on the degree of detail in the image. For example, a black-and-white image contains only one bit per pixel (a binary bit can be in one of two states; thus, a single bit can represent white or black); an image with shading and color commonly contains 24 bits of information per pixel—with 224, or more than 16 million, possible states per pixel. Known as “truecolor,” 24-bit color can realistically depict color images. The number of bits stored in each pixel is known as the color depth. The number of pixels in a display, called resolution, affects how much detail can be depicted in an image. Resolution is often expressed as the number of pixels in a column times the number of pixels in a row (for example, 800 × 600).
Detailed images often result in large file sizes, although file size can be managed through data compression. Compression can be either lossy (meaning that some data is discarded) or lossless (no data is lost). Popular raster file formats include GIF (graphics interchange format) and JPEG (joint photographic experts group), which are lossy formats, and BMP (Windows bitmap) and TIFF (tagged image file format), which are lossless.
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Although raster graphics saw some use in the 1970s and ’80s, it was mostly limited to expensive graphics workstations (i.e., high-end computers that were specially optimized for working with graphics). As the graphics capability of personal computers improved in the 1990s, raster graphics became widely used. Images produced from optical scanners and digital cameras are raster graphics, as are most images on the Internet. A commonly used graphics program for working with raster images is Adobe Photoshop.
Another commonly used digital image file is the vector format. Unlike raster images, vector graphics can be resized without as much risk of blurring or distortion. This is because they are not composed of pixels; rather, these files are made through mathematical equations using a grid that allows for curves and assorted geometric shapes. While raster files are useful for digital photographs, vector graphics are typically used for fonts, logos, and other types of media that benefit from resizing for various purposes.