Among the variety of graphic formats, there are two key categories such as vector and raster images. They serve different purposes, have a peculiar structure, and complement each other. Vector images, in contrast to raster ones, are described by geometrical formulas, not pattern dots. Therefore, they can be increased or decreased without loss of quality since the formula remains the same, and only the scale changes.
In bitmap images, each square called raster has its color and brightness, composing a mosaic. The more points on the plane and the smaller they are, the more one sees the image. Looking at the screen with thousands of dots of different colors and shades, people identify objects and images composed from them (McAndrew, 2015). For example, any digital photo consists of these multicolored dots. A raster image, unlike a vector image, is capable of transmitting a realistic image with a lot of small details.
The computer remembers the colors of all the squares in a row in a certain order, which explains why bitmaps require more memory to store information. According to McAndrew (2015), the mentioned images are also difficult to scale and even harder to edit. To enlarge an image, it is necessary to increase the size of the squares, and then it becomes stepped. To reduce the raster pattern, one has to transform several neighboring points into one or throw away extra points. As a result, the image is distorted, and its small details become illegible.
Vector images do not consist of dots containing color information, but reference points and vector lines connecting them. A vector image contains information about the positions of points as well as data about the line passing through the reference points. In other words, a vector image includes information in the form of formulas and mathematical calculations, having a small size regardless of the actual scale of the depicted canvas (McAndrew, 2015).
Vector images are especially useful when there is a need to increase a photo or any other picture without losing its quality. For example, various logos, business cards, and banners for websites need vector images in terms of design. Although Adobe Photoshop allows working with vector images, it is still a raster editor. The Adobe Illustrator and CorelDraw programs are more appropriate for working with vector images.
Thus, vector images are based on geometrical formulas, while raster pictures have pattern dots. It is noteworthy that vector graphics can be easily transferred to raster format. A vector image can be converted into a bitmap image of the required resolution, but it is rather difficult to convert the bitmap image into a vector without loss of quality. In general, vector images require less memory to store necessary data compared to raster images.
Reference
McAndrew, A. (2015). A computational introduction to digital image processing (2nd ed.). Boca Raton, FL: CRC Press.