subject: Learning Digital Photography - All About Aliasing [print this page] Learning Digital Photography - All About Aliasing
One thing you'll find about photography is that there is a lot of confusing vocabularly words. Aliasing, which is a common word in the world of digital everything (video games, CGI, photography), is one of those words that everyone has heard, but may not quite understand. And the anti-aliasing feature found on many digital cameras doesn't do much to explain why you should use it. Not to worry though, for anti-aliasing is no where near as complicated as it may sound.
Understanding Pixels
Most digital images are made up of square units known as pixels. When you look at your digital images and zoom in a few times, you'll find that the closer you get, the more "blocky" the image appears. This is the result of the individual pixels becoming more pronounced as the image increases in size.
Your camera's resolution is directly related to the number of individual pixels it can capture in a given frame as is often referred to as the mega pixel value. The higher the resolution, the more pixels you get. The more pixels you have, the smoother the lines in your image. For example, think of a staircase where it looks blocky up close but as you move further away it looks more like a diagonal line. This is how pixels work to create shapes in an image.
Understanding Aliasing
Aliasing refers to the edges of round or diagonal lines in your images, which are all made up of square pixels. When these pixels are drawn rigidly and carry only one color, these lines will appear pronounced and jagged. You may not notice this initially if the pixel is surrounded by other similar colors, but as the colors increase in contrast the pixel will appear more pronounced.
Aliasing is not usually obvious unless an image has been taken at a very low resolution. Luckily, most digital cameras these days take pictures at resolutions that make aliasing difficult to see under normal conditions, however it can be seen as soon as the image is enlarged. All digital photographs have some level of aliasing, no matter how good the camera may be.
So What is Anti-Aliasing?
Anti-aliasing allows the colors at the edge of pixels to bleed into one another, creating a sort of blurred effect. This causes a blurring of the edges of each individual pixel and creates smoother lines and more natural color differentiation resulting in sharper images.
To test this out, take one of your digital images and reduce it in size. You will no doubt notice that as the size decreases, the lines of objects in the photograph will seem smoother. As the pixels in the image shrink, they become less visible to the naked eye. This reduction in size of your picture, is similar to the effect of anti-aliasing because it slightly blurs each pixel allowing it to better blend into the rest of the image.
Most good digital cameras will come with a built in anti-aliasing feature so your pictures won't have the "blocky" look. Anti-aliasing will make your photographs look more natural and will help to offset any loss of quality caused by a lower resolution camera or setting. Although it is always good idea to shoot at the highest resolution possible, anti-aliasing will help to make sure your images look great.
Although you may not have realized how important anti-aliasing was before, once you understand the impact on your pictures you won't want to shoot without it. Anti-aliasing really helps to bridge the gap between expensive super high resolution cameras and the price of the average digital camera by eliminating the rough, jagged lines of aliasing. If your camera has an anti-aliasing feature, turn it on and leave it on your photos will thank you.
