The JPG File Format

JPEG files (pronounced: “jay-peg”) are the most commonly used format for digital images. Regardless of the industry or workplace, you are sure to come across jpegs. Facebook photos, email signatures, cat pictures—most likely they are all jpegs.


Jpegs are the most widely used format for both photographers and on the internet. Most digital cameras, by default, save images in the jpeg format. Almost every word processing and image editing software (Adobe Photoshop, Microsoft Paint, Word, Pages) can open jpegs; however they are not an editable format. What you see is what you get. When a jpeg is saved, all information in condensed into one image layer. Think of them as a final format ready to be uploaded to a website or sent to a friend.

You can recognize a jpeg by the file ending of .jpg or .jpeg. Jpegs are a type of raster file, meaning they are made up of tiny colored pixels. Most jpegs contain 300 of theses pixels per inch. Web jpegs are usually reduced to 72 pixels per inch to minimize file size. One of the major benefits of jpegs is their ability to be downsized into smaller files sizes, but that comes with some draw backs.

Jpegs do not support transparency and are always in a rectangle shape. A jpeg can remain clear and crisp when reduced in size, but scaling the image larger will result in a blurry and fuzzy image (see images below). Most image editing applications will allow you to control the size of the file by adjusting the image quality when exporting. You can see in the example below. When working with a jpeg remember to never stretch the file larger than it’s initial size and be careful resizing the image too many times.

bird

Notice how the image above gets blurrier as it is scaled larger. Jpegs should never be resized larger than the initial files size.

When to Use:

  • Jpegs are the right choice when you are working with an image—like the ones you might take with a camera.
  • Jpegs are the right format for designed graphics that contain images.
  • It’s the right choice when uploading an image to the web that contains complex coloring.

History:

The term “JPEG” is an abbreviation for the Joint Photographic Experts Group, which created the standard for the file in 1987.