The Difference Between Vector and Raster Images & Why It Matters
Even though Hidden Woods Media is primarily a video production company, we do a lot of animation work as well. Sometimes it’s as simple as creating lower thirds or animating our clients’ logos. Sometimes we’ll do a full sequence or even an entire video of full-screen animations. And when it comes to animation the format of the source images that we’re moving around the screen is very important. (Here’s a hint: No, a doodle of your logo on a cocktail napkin isn’t going to work.)
Let’s say we’re doing an animation of your logo as the intro to your new promo video. Whether the animation is 2D or 3D, the first thing we’re gonna need from you is a vector file version of that logo. If your response to that last sentence is “What’s a vector, Victor?” then this post is for you. So here it is: the definitive guide to the difference between vector images and raster images.
First, let’s lay out just what a vector image is not.
Raster (more commonly known as bitmap) images are the most common image files you’re likely to encounter in your daily life. Raster images are pixel-based – think of a digital photograph. If you zoom into it far enough, you’re going to see a grid of tiny, individualized boxes known as pixels. Each pixel is an individual color or shade and when you zoom back far enough you get an image. It’s basically a mosaic with thousands and thousands (or more) little colored tiles. When you hear that a video camera shoots 1920×1080, that means that each video frame is made up of 1,080 rows of 1,920 pixels (or 2,073,600 little colored squares in total). Raster images can be scaled down, but cannot be scaled up without reducing the image quality. Think about when you scale up a photo, the pixels are more obvious and the photo seems stretched or fuzzy. The most common file extensions for raster or bitmap images are .jpg, .bmp, .png, .tiff, and .gif.
(Photo source: gen3printing.com)
Vector images are a less common file type in most people’s daily experience. Common file extensions are .eps or .ai (or sometimes .obj if we’re working in 3D). Rather than being made of square tiles or pixels, vector images are mathematically based. Essentially the source code of a vector image is a series of mathematical equations which your computer reads and turns into paths, shapes, colors, etc., which in turn create the image. Vector images tend to be of logos, illustrations or computer generated graphics. They don’t come out of a camera…it’d be pretty difficult to make a vector photograph. The central reason that vector images are easier to animate is because they can be expanded infinitely – the image isn’t made up of pixels, so when you stretch it the computer just recalculates the equation. This stuff sounds complicated, but it really isn’t. One example you’ll probably recognize from daily life is the use of fonts in your word processing software. If you type something in 12pt font, and then expand it to 150pt font, it doesn’t look pixelated does it? That’s because the letters are made of equations, not pixels.
The best way to visually explain this is a side-by-side comparison between blown up versions of images from one of our recent projects:
(Notice also how the vector file above has more depth to the colors.)
Another reason that vector files are much easier to animate than rasters is the fact that these file types contain various layers – while every element of a raster image is flattened into one. Let’s say we’re trying to animate a scene of two people having coffee at a restaurant. A vector file of this scene will have each person, each coffee cup – basically each element of the scene – on a separate animate-able layer. When we pull it into After Effects, we can manipulate the scale, position, rotation, etc. of the coffee cup without affecting the people or the table or the background. If all of these things are on one layer, changing the scale, for instance, will change the scale of every single thing in the image.
(The above photo shows how various layers of one single image look when they are individually animate-able).
All in all, when you’re working with video production companies, animators, or graphic designers, be sure to discuss with them what needs to be done with your logo. Do you want an animation for the intro/outro? Is the entire video going to be animated? More likely than not, if the image/logo/illustration needs animation, the best choice is to use vector files, rather than raster. If you’re not sure where to find a vector version of your logo, your graphic designer is 99% likely to have one and to know exactly what you’re asking for.