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Graphic images on your computer come in two different forms, raster images
and vector images. Raster images are made by programs such as Photoshop and
Corel Photopaint. Vector images are produced by Adobe Illustrator, Freehand,
and CorelDraw. While the results from these different programs can look similar,
the ways in which they are made are very different.
Raster images are made up of millions of individual squares, or pixels, of
various colors. The more pixels you have, the better the image will look. The
number of pixels, or resolution, is usually expressed in dots per inch (dpi).
Images on the Web are shown at 72 dpi. A high-resolution image would run 300
dpi or higher. Some types of printing can get into the 1600 dpi range. Much
like a mosaic, a raster image can look smooth from a distance but as you zoom
in closer you can see the individual pixels.
A vector image is drawn from mathematical formulas for lines and curves and
is redrawn each time you zoom in for a closer look. The quality of the image
stays the same regardless of the level of magnification. Vector files, since
they are formulas instead of information on millions of individual pixels, tend
to use less memory than raster files.
The edge of a circle, rendered as a raster image, may look smooth initially,
but eventually as you zoom in you will see a jagged stairstep edge of the individual
square pixels that make up the image. A lower resolution image will look jagged
or pixellated much sooner than a high resolution image. A circle's edge in vector
form will always be smooth no matter how close you zoom in since it is recalculated
each time you change the view.
Raster based programs are best at working with photo-realistic images and make
subtle (or bold) changes in color, shadow and texture. Vector based programs
excel at easy control of edges and tend to produce a more graphic style of art.
Regardless of the type of image, higher resolution is always better for producing
a good result. While your image may be vector or raster, or even a combination
of the two, the Art Staff at ExpertShirt.com will work hard to translate it
into the best textile printing possible.
About the Author:
Mandar is a graphic artist and man-about-town with Expertshirt.com. Design your
own custom tshirt online at http://www.expertshirt.com |
