When you're editing, combining, or otherwise manipulating digitized photographs. It's also important to note that because Flash uses vector images, Web sites created in Flash are often entirely vector-based. Keep in mind that as Web browsers moves more towards standardized support of vector-based image formats such as SVG, Web designers will have more flexibility in terms of using vector images in their Web designs. Though most Web designs created in vector imaging programs must be exported to raster before being programmed, retaining a vector original allows the designer to keep absolute power of the resizing and editing of the original to fit the current trends in screen resolutions or user needs. Many Web sites that utilize geometric shapes and lines are perfectly suited for vector images.
However, for reasons of longevity and portability I've been recommending that professional graphic designers create Web site graphic design references as vector images. This is usually because raster imaging programs are generally easier to use and learn, and most people have a basic understanding of how the bitmap system works. Keep this in mind when creating images that you might have to modify later.Īnd yet when designing for the Web, many designers will work only with raster-based images. You'll have to alter the wording by changing the individual pixels themselves. Chances are the image is stored in a raster formatted image file, so the change won't be as easy as they think. This distinction between raster and vector can loom large, for example, when clients or coworkers ask you to alter the text on an image. The W3C has produced an XML-based format called Scalable Vector Graphics (SVG), but browsers do not yet widely support it.įor creating and editing images, Adobe Illustrator is still the reigning king of vector imaging program.Ī raster image loses quality when enlarged, as it is limited by a set number of pixels per inch. In an attempt to make Flash an industry-wide standard, Macromedia opened its Flash file format in April 1998, making it freely available to content and tools developers. PostScript is a popular vector format for printing, but so far Macromedia's Flash is the closest thing to a standard vector format on the Web. Here's a good example: in most desktop applications, fonts are vector (or, more accurately, vector-like) images.
Vector images are easier to modify without losing quality, because the components can be moved, resized, rotated, or deleted independently. On a computer screen, vector images are forced into a bitmap display. Vector images are ideal for print, as their quality is not limited by any size definition, and are printed as smooth lines and shapes. Vector image files record images descriptively, using mathematics to identify lines and geometric shapes.
Photoshop and Paint Shop Pro are two of the most popular bitmap editors, though The GIMP is a great GNU licensed editor. You can edit raster graphics only by altering the pixels directly with a bitmap editor. Though it's been around for half-a-dozen years, it's still not supported by all Web browsers. PNG is sort of in between JPEG and GIF, mixing the best of both. On the Web the most widely used raster file formats are JPG, which is used primarily for photo-realistic images with many colors, and GIF, which is used primarily for line and shape images with limited colors. The most popular raster file formats are BMP, TIFF, JPEG, GIF, and PNG. This makes sense as photos are a collection of organic, not geometric shapes. In fact, any true digitized photo must be a raster image. Here's a good example: digital cameras record raster images. When printed, raster images are limited in quality by the resolution, or number of pixels per inch, that is recorded in the image file. Raster images are ideal for the computer screen, which display a certain number of pixels per inch of screen (resolution). Raster images are image files where the format records exactly how many pixels are used in what colors, and in a certain order. RasterĪs we know, digital images displayed on a computer screen are nothing more than colored pixels. These types refer to how the image data is recorded by the computer, and determines your options for changing the image. In the world of digital imaging there are two types of graphical image files that you need to be aware of: raster and vector.
Creating Web Designs Raster Versus Vector Graphics