Thursday, October 29, 2009

What is the Difference in Raster and Vector Images?

Sometimes I get asked this question or a variation of it so I thought I would include a response here on the blog for everyone else who may have wondered about this topic.

"What is the difference between pixel-based images and vectors? When do you use a vector instead of pixels? Or, when would you use a pixel-based image instead of vectors?"

To make things easier in answering this question I will refer to 'pixel based images' as 'raster images'. I am more accustomed to thinking of images composed of pixels as raster format files as that is the correct terminology. Now to the nitty-gritty of this discussion. Raster images are like Vectors, unique because of the way the file types store information. They both produce a visual result but they do so by different means.

Raster images are sometimes referred to as bitmap images. The information contained in this file type is stored with a bit by bit comparison of the images that you see on your computer's monitor. Each individual pixel is part of a larger collection of pixels that compose a giant grid.
Each one of those pixels contains information from the file that the screen shows you in an identical location on the grid when it is viewed on the screen. These grids represent points of color with-in an image. And based on the number of color bits assigned to the file, your color
depth can show more or less of the color variety available in the overall image. Since each one of these little rectangles combine with all the rest to provide the information for the image, the file can become quiet large especially the more the color depth increases.

When zooming in very close to the image you will notice the little jaggy stair step type edges that are formed by the shapes of the edges of the combined pixels. In a way this is similar to the process in which the Impressionist painter, George Suerat combined tiny dots of various
hue to form the desired visible color and light in his images. Each tiny brush dot may have been composed of a slightly different shade or tint but when all were combined they formed the visual color the artist desired by letting the viewers eye mix the colors while actively viewing the

These blending hues, 'contones' as the print industry refers to them, are a 'continuous tone' in appearance, though when you zoom in the differences of each pixel becomes visibly apparent.
You can find raster graphics used more with images like photographic files or files of an image like a fine art painting. Many of the newer applications for working with raster images now contain a selection of built in vector tools for things like typography so that this hybrid format
can maintain the crisp edge found in vector files.

Vector files are nothing like Raster images because as we said earlier, the file types both store information in different ways. Vector has a method of information storage that involves lines, points and curves. This is all done with mathematical equations that represent the image we
are working with.

Since less information is stored in this format, the file size is considerably smaller than Raster files. And unlike Raster files you can stretch and re-size Vector images and the image will stay crisp and clear. If we zoom in close we do not get a grid full of colored rectangles but just a zoomed in view of the image we are looking at.

While a photograph saved as a vector would require very large amounts of processing time, simple toned images and type work better with the vector format. Vector formats are also very popular in animation file types like flash animation files or the older .gif format. Even the most
basic, the .gif file can contain a stack of vector images that sequence through based on a time line and create an animated image like those found in many web sites. Since the vectors contain the information in a compact system all of the continuous toned parts of the images do not have to have information for every individual pixel the area is composed of thus saving much file space and keeping the overall size small for the information it contains.

This can translate into more data being included in distribution via the internet by faster download speeds or even in being able to fit more files into a back-ups device like a CD or DVD for example.

Depending on the type of image you are working with and the ways in which you need to store it, distribute it, or transform and re-size it through reduction or enlargement; you should be aware of the positive and negative elements of each file type and how they work with the
information contained with-in.

Tuesday, October 27, 2009

Test For Title #2

I'm working through the title posting issues on
New Changes Today^Today I set up new services to be reached via This is a test post to check their status, please ignore.