What is aspect ratio?

Aspect Ratio (AR): For photography, aspect ratio is an expression of the width of an image compared to the height of that image. All digital images are rectangles (or they are square).

What does aspect ratio apply to? All cameras, computer monitors, movies, TVs and even photo paper have a specific aspect ratio. The different aspect ratios can give the photographer or printer headaches. I hope this information helps!

The 2 common aspect ratios: The images produced by most digital cameras are 4:3 aspect ratio, as are most monitors and TV sets. The common image sizes for cameras:
2048 x 1536, 1600 x 1200, 1024 x 768 all are 4:3 aspect ratios. So, on 8.5 x 11" photo-paper, they would print at 10" x 7.5". However, many cameras also offer 3:2 aspect ratio, the same as the popular 35mm film. This is to support the popular snapshot photo-paper of 4" x 6", fashioned for 35mm film, with its 3:2 aspect ratio.

Must maintain aspect ratio! When an image is resized, the aspect ratio must not be changed. This would either distort (turn a circle into an egg) or crop the original. The most frequently-occurring scenario of cropping is shown below.

Beware of image-cropping! When you present common 4:3 AR images to Walmarts, Staples, or on-line services to print 4" x 6" snapshots, they will be cropped, as their photo-machines are set for image width and must crop the top/bottom to create the 3:2 AR for the 4" x 6" photo-paper! So make sure there is extra room for head and feet on the 4:3 AR images.

High-aspect ratio: HD (High-Definition) TV screens and computer monitors are featuring a wider 16-9 aspect ratio to fit DVD movies. This may affect aspect ratios of digital cameras in the future!


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© 2005 Fred Hall