Instead of sectioning off a large region of computer memory and mapping that to the display device, vector display devices use a variable number of lines to create images—hence the term "vector graphics." Since vector display devices can define a line by dealing with just two points (that is, the coordinates of each end of the line), the device can reduce the total amount of data it must deal with by organizing the image in terms of pairs of points.
Vector graphics are commonly found today in the SVG
types of graphic file formats
, and are intrinsically different from the more common raster graphics file formats such as JPEG
The term "vector graphics" is mainly used today in the context of two-dimensional computer graphics. It is one of several modes an artist can use to create an image on a raster display. Vector graphics can be uploaded to online databases for other designers to download and manipulate, speeding up the creative process. Other modes include text, multimedia
, and 3D rendering
. Virtually all modern 3D rendering is done using extensions of 2D vector graphics techniques. Plotters
used in technical drawing still draw vectors directly to paper.
This vector-based image of a round four-color swirl displays several unique features of vector graphics versus raster graphics: there is no aliasing
along the rounded edge (which would result in digital artifacts
in a raster graphic), the color gradients
are all smooth, and the user can resize the image infinitely without losing any quality.
The World Wide Web Consortium
(W3C) standard for vector graphics is Scalable Vector Graphics
(SVG). The standard is complex and has been relatively slow to be established at least in part owing to commercial interests. Many web browsers now have some support for rendering SVG data but full implementations of the standard are still comparatively rare.
In recent years, SVG has become a significant format that is completely independent of the resolution of the rendering device, typically a printer or display monitor. SVG files are essentially printable text that describes both straight and curved paths, as well as other attributes. Wikipedia prefers SVG for images such as simple maps, line illustrations, coats of arms, and flags, which generally are not like photographs or other continuous-tone images. Rendering SVG requires conversion to raster format at a resolution appropriate for the current task. SVG is also a format for animated graphics.
There is also a version of SVG for mobile phones. In particular, the specific format for mobile phones is called SVGT (SVG Tiny version). These images can count links and also exploit anti-aliasing. They can also be displayed as wallpaper.
Detail can be added to or removed from vector art.
Modern displays and printers are raster
devices; vector formats have to be converted to raster format (bitmaps – pixel arrays) before they can be rendered (displayed or printed).
The size of the bitmap/raster-format file generated by the conversion will depend on the resolution required, but the size of the vector file generating the bitmap/raster file will always remain the same. Thus, it is easy to convert from a vector file to a range of bitmap/raster file formats
but it is much more difficult to go in the opposite direction, especially if subsequent editing of the vector picture is required. It might be an advantage to save an image created from a vector source file as a bitmap/raster format, because different systems have different (and incompatible) vector formats, and some might not support vector graphics at all. However, once a file is converted from the vector format, it is likely to be bigger, and it loses the advantage of scalability without loss of resolution. It will also no longer be possible to edit individual parts of the image as discrete objects. The file size of a vector graphic image depends on the number of graphic elements it contains; it is a list of descriptions.
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. (June 2018)
Vector art is ideal for printing
since the art is made from a series of mathematical curves, it will print very crisply even when resized.
For instance, one can print a vector logo on a small sheet of copy paper, and then enlarge the same vector logo to billboard
size and keep the same crisp quality. A low-resolution raster graphic
would blur or pixelate excessively if it were enlarged from business card size to billboard size. (The precise resolution of a raster graphic necessary for high-quality results depends on the viewing distance; e.g., a billboard may still appear to be of high quality even at low resolution if the viewing distance is great enough.)
If we regard typographic characters as images, then the same considerations that we have made for graphics apply even to the composition of written text for printing (typesetting
). Older character sets were stored as bitmaps. Therefore, to achieve maximum print quality they had to be used at a given resolution only; these font formats are said to be non-scalable. High-quality typography is nowadays based on character drawings (fonts
) which are typically stored as vector graphics, and as such are scalable to any size. Examples of these vector formats for characters are Postscript fonts
and TrueType fonts
- Because vector graphics consist of coordinates with lines/curves between them, the size of representation does not depend on the dimensions of the object. This minimal amount of information translates to a much smaller file size compared to large raster images which are defined pixel by pixel. This said, a vector graphic with a small file size is often said to lack detail compared with a real world photo.
- Correspondingly, one can infinitely zoom in on e.g., a circle arc, and it remains smooth. On the other hand, a polygon representing a curve will reveal being not really curved.
- On zooming in, lines and curves need not get wider proportionally. Often the width is either not increased or less than proportional. On the other hand, irregular curves represented by simple geometric shapes may be made proportionally wider when zooming in, to keep them looking smooth and not like these geometric shapes.
- The parameters of objects are stored and can be later modified. This means that moving, scaling, rotating, filling etc. doesn't degrade the quality of a drawing. Moreover, it is usual to specify the dimensions in device-independent units, which results in the best possible rasterization on raster devices.
- From a 3-D perspective, rendering shadows is also much more realistic with vector graphics, as shadows can be abstracted into the rays of light from which they are formed. This allows for photorealistic images and renderings.
- an indication that what is to be drawn is a circle
- the radius r
- the location of the center point of the circle
- stroke line style and color (possibly transparent)
- fill style and color (possibly transparent)
Vector formats are not always appropriate in graphics work and also have numerous disadvantages.
For example, devices such as cameras and scanners produce essentially continuous-tone raster graphics
that are impractical to convert into vectors, and so for this type of work, an image editor will operate on the pixels rather than on drawing objects defined by mathematical expressions. Comprehensive graphics tools will combine images from vector and raster sources, and may provide editing tools for both, since some parts of an image could come from a camera source, and others could have been drawn using vector tools.
Some authors have criticized the term vector graphics
as being confusing.
In particular, vector graphics
does not simply refer to graphics described by Euclidean vectors
Some authors have proposed to use object-oriented graphics
However this term can also be confusing as it can be read as any kind of graphics implemented using object-oriented programming
Typical primitive objects
Any particular vector file format supports only some kinds of primitive
objects. Nearly all vector file formats support simple and fast-rendering primitive objects:
Most vector file formats support:
A few vector file formats support more complex objects as primitives:
If an image stored in one vector file format is converted to another file format that supports all the primitive objects used in that particular image, then the conversion can be lossless.
Vector graphics editors
typically allow translation, rotation, mirroring, stretching, skewing, affine transformations
, changing of z-order
(loosely, what's in front of what) and combination of primitives into more complex objects.
More sophisticated transformations
include set operations
on closed shapes
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Last edited on 16 June 2021, at 21:42
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