Vector and Raster Graphics
All computer images are divided into two basic types: raster images (also known as the bitmap) and vector images. In some cases it is recommended the use of vector graphics, in others, depending on the nature of the project it’s recommended to use bitmap images. Sometimes, the two formats can be used together. An understanding of the advantages and limitations of each technology and the relationship between them will lead to their optimal use.
What is a raster image (bitmap)?
Raster images are created by digital cameras (pictures), are scanned or they are created on PC in different programs such as Adobe Photoshop. Raster images are composed from lots of pixels. The resolution of a raster image or a scanned image is expressed in terms of dots per inch or dpi. A scanner or printer resolution is also measured in dots per inch.
A raster image is complex in terms of applied effects, retouching, color variations, etc.
To accurately reproduce an raster image file the software must keep track of large quantities of information, including the exact location and color of each pixel of the combination of pixels. This results in huge file sizes for raster graphics. Higher resolutions (dpi) and higher color depth gives larger files.
When a raster image is created or scanned, the file size becomes a serious problem because large files tend to make your computer processor and hard drive to work overtime.
Raster files extensions are: BMP, GIF, JPEG, JPG, PNG, PICT (Macintosh), PCX, TIFF, PSD (Adobe Photoshop).
What is a vector image?
Vector is a synonym for the word line. The vector image is a collection of connected lines and curves that make up objects. When a vector image is created into a vector illustration program the lines and curves are connecting points. Each node, line and curve is defined graphically by the software using a mathematical description.
Vector elements have the great advantage to not lose quality when enlarged or reduced. For this reason they are used mostly for print. Vector files have small sizes and can be easily transmitted via email.
A drawing program will enable a user to click on an object and define its color. Coloring vector images is much easier than bitmaps.
With vector graphics it’s possible to create logos, illustrations, elements for websites or print and vector art (composition). Vector extensions are: CDR, AI, EPS, SVG.
