|
Raster Vs. Vector ClipArt
Clipart comes in two flavors, raster and vector. Raster is a bitmap format (which I'll mostly refer to as bitmap instead of the less commonly used term raster) and is composed of colored dots. Common formats include .bmp, .jpg, .gif, and .tif. Raster images are edited in paint and photo programs like Adobe PhotoShop and MetaCreations Painter. Vector images are mathematically defined with coded instructions that define the angles and relationships between every line in the image. Common vector formats include .wmf and .cgm. Vector images are edited in drawing programs like Adobe Illustrator and CorelDraw. |
||
 |
This was taken from the Corel MegaGallery clipart package. | |
|
The real difference between the two formats is how they are used. Vector images, because of their mathematical origins, are readily scaleable without distortion. They can be stretched in size without losing any clarity or sharpness. Bitmap images, since they are composed of dots, lose their clarity when they are increased in size because the dots get bigger. Take an image that's 10 pixels wide by 10 pixels high, stretch it to 100 x 100 pixels and it looks like it's made of big squares. As an example of the difference between between the two formats, below is what happens when the Santa Claus image is zoomed to four times it's original size. The bitmap format is on the left, the vector on the right. At only a four power zoom, the bitmap image is already starting to look blocky and fuzzy while the vector image has retained its crisp look. |
||
 
Vector clipart has the advantage when it comes to rescaling the original
image. On the other hand, it's mathematical origins don't lend vector clipart
to artistic effects. Vector art is primarily composed of lines and color
fills. While a clever artist can get a vector image to approach
photographic quality, it's a trick somewhat akin to the occasional artist
who does a fancy drawing on an Etch-a-Sketch. With enough time and
practice, it can be done, but it's not the most efficient means of getting
the effect. The bitmap format is the best for an artist who wants to paint. |
||
| Drawing and Bitmap programs usually allow using both bitmap and vector images, but it's an uneasy alliance. Drawing programs allow very few things to be done with bitmap images. Bitmap programs have a limited set of vector editing tools to modify vector images. Painter can use vector images, but they eventually have to be turned into a bitmap to be fully used by the program. Painter's brushes cannot be used on vector art until they've been turned into bitmap floaters (using Collapse on the Objects Menu). Scaling of the image should be performed with the clipart as a vector image so that the image quality is maintained. Once the image is turned into a bitmap, it cannot be resized without losing some of the image quality. | ||