Image types: JPG files in a nutshell
If you work in a marketing role at your organization, you’ve probably been asked for a specific file type when sharing an electronic image. In my next few blog posts, I’m going to share several of the major file types, an overview of the uses, advantages and drawbacks of each, and how you can use this information to improve the quality of the graphics you use and produce. We’ll start with…
An overview of JPEG files
| HIGH RESOLUTION |
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| MEDIUM RESOLUTION |
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| LOW RESOLUTION |
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JPEG (or JPG) is one of the most common file types, used both online and offline for a huge variety of applications. You can identify a JPEG file by its extension of -.jpg.
JPEG stands for Joint Photographic Experts Group. JPEGs were created because image files are large and consume a lot of computer resources. JPEG is a compressed file that reduces an image to a series of pixel-based color data. To create and open a JPEG, your computer uses algorithms to deconstruct and reassemble the digital image based on the color data. The greatest benefit of using a JPEG file is that in its decompressed state, the image is only a fraction of its original size—which saves space on your computer, helps image-heavy websites load faster, and is more email friendly.
Your digital camera allows you to choose image quality settings—low, normal, fine, super-fine, etc.—that affect the amount of data (and quality) that is stored when you take a picture. Similarly, when your camera or image editing software saves a JPEG, there are different settings that affect the image quality. These settings will instruct the camera or software to deconstruct an image with varying degrees of accuracy which, in turn, determines how well the image can be reconstructed when viewed later. Higher settings require more memory; lower settings require less. You should set the JPEG image quality according to your needs (see table at right).
Interpolation and loss of image quality
The process of reconstructing a JPG is called interpolation. No matter what setting you save with, the opened JPEG is technically never as good as the last time it was saved/deconstructed. In other words, reconstruction is never 100% accurate to the original image. At higher settings, the difference is almost imperceptible. Still, you should always save a copy of your original image before saving over a JPG. Each time you open and save over a JPEG, you are applying a round of deconstruction and imperfect reconstruction; the effects can stack and slowly degrade the quality of an image. The payoff is extremely manageable file size. Volumes of images can be saved this way and the results can remain picture perfect, so long as you pay attention.
