image aspect ratio: definition

The aspect ratio of a digital photograph is the relationship between the width and height of the photograph. There are two common aspect ratios produced by digital cameras: 3:2 and 4:3.

The number before the colon represents the width of the image and the number after is the height. Both numbers represent a relationship, not a specific measurement.

There are other aspect ratios besided the two mentioned here, but they are less common. Some examples of other aspect ratios are 5:4, 16:9 and 1:1 (a square image).

Different digital cameras will produce images with different aspect ratios, even if you don't change the camera settings. Aspect ratios will differ between camera manufacturers and even between different model cameras from the same company.

One Nikon camera will capture images that are 4:3 and another will be 3:2. A few digital cameras offer multiple aspect ratios and let you choose which one you want to use for any given photo.

 

aspect ratio chart

 

image aspect ratio examples

Let's say that there is an image with a 3:2 aspect ratio. The actual size of this image in pixels can be 300 x 200, 600 x 400 or 1350 x 900, and so forth. So long as the relationship between the width and the height is always 3 to 2, the aspect ratio does not change even though the size of the image does.

Now consider an image with a 4:3 aspect ratio. The horizontal and vertical size of this image in pixels can be 400 x 300, 800 x 600 or 1800 x 1350.

Below are some visual aids to illustrate the different aspect ratios as they compare to each other. The image shown is a 3:2 with all other aspects scaled to same height.

aspect comparison

As you can see as you change an image from 3:2 to any other, there is a portion of both sides that get cropped off. In the case of this image, eventually the caption will be clipped. Depending on the image, cropping to a different aspect will either help or maintain the feeling of the image, or deter or ruin the intended feeling.

Below are two examples of the effects of cropping.

Example 1: cropping that maintains the "closeness" feel of the flower

aspect good

Example 2: cropping that chops off copy and changes the feel of the photographer's intent

aspect bad

As you can see, with Example 1 the feeling of closeness you get with the macro shot of the flower is maintained, and can be argued helped by the cropping effect of going from the wider 3:2 to the tighter, more boxed feel of the 5:4.

As with Example 2, you can see that the caption on the right is chopped off as well as the second chair, and the window on the left is mostly gone. First, the caption could be resized to fit the new space, but at a cost of reduced size to maintain the two lines it occupies; or it would have to be reformatted, which would effect the "feel" of the original intended composition of the image. Also, the lose of the chair and the window reduce the feeling of this being a empty, "quiet" waiting room.

Cropping, especially, affects the feeling of wide angle shots (as shown below).

aspect bad 2

 

images printed without cropping

Maintaining the two example aspects from above, 3:2 and 5:4 (which demostrate the greatest difference between listed aspects), you can look below and see how your print will look when no cropping is done and the full image is proportionately fitted into the widest, or tallest dimension the paper allows. As you can see, there will be white, unprinted margins on either both the sides, or top and bottom depending on the image aspect and paper size (essentially the paper's aspect ratio).

aspect printed