- Raster image
A raster image is based on a dot-matrix or pixel grid and requires a high resolution in order to be printed or adapted to multiple display formats.
Raster images use many colored pixels or individual building blocks to form a complete image. JPEGs, GIFs and PNGs are common raster image types. Almost all of the photos found on the web and in the print catalogs are raster images.
The raster image is not scalable; if you increase the size of it, this image will look blurry. To prevent this, all you can do is leave the image in its original size or make it smaller.
For example: Images intended for print need to have a resolution of 300 dpi (dots per inch), as the printing process allows for much greater detail. The images intended for web only need to have a resolution 72 dpi (dots per inch), which is the maximum resolution of monitors.
A short list of raster image formats:
- Vector image
A vector image allows you to maintain the quality of the design across multiple formats and resolutions. In a vector file, each point, line, and shape created is fully scalable. You may resize the vector image without losing its quality. Also, the vector images are ready for commercial printing.
Vector images, alternatively, allow for more flexibility. Constructed using mathematical formulas rather than individual colored blocks, vector file types such as EPS and AI are excellent for creating graphics that frequently require resizing. Your company logo and brand graphics should be created as a vector and saved as a master file so you can use it with smaller items such as your business card and letterhead, but also on larger surfaces, such as your corporate jet. When necessary, always create a JPG or PNG for use on the web from this master vector file. Just be sure to save the new raster file in the exact dimensions needed.
A short list of vector graphics formats:
- WMF, EMF