CEI - File Types and Formats (Lesson)

 

File Types and Formats Lesson

Image File Formats

When saving images, you want to make sure that the quality of the image remains when the file is saved, opened, and applied to your website or presentation. Depending on the program the image is being designed from, where the image is downloaded or copied from, and how it is going to be used will determine how the image is stored. All computer images are stored as digital files with a file extension that indicates the file format. A file extension is the two to four letters preceded by a period at the end of a computer filename. When stored, the computer translates the image into a digital code. There are numerous image file formats, but they all fall into one of two categories: rasters and vectors.

Vector versus Raster Image

Raster Images 

Raster (or bitmap) images are pixel base images that work best when you need to store and display high-quality images. Each pixel is given a specific location and color value. Because their pixel number is fixed and they are resolution dependent, raster images cannot be drastically resized without appearing blurry and pixelated. This is the result of the pixels being stretched. Each raster image is limited to its individual dimensions and number of pixels, which affects its size and resolution. However, the more pixels a file contains and the higher the resolution, the sharper the image quality will be. Take a look at the raster image before and after it was resized.

Lion Raster Image Before and After

Raster images are best used for digital photography and are better when very sharp attention to detail is needed.

Raster image file formats include:

  • JPG- Joint Photographic Experts Group
  • TIFF- Tagged Image File Format
  • GIF- Graphics Interchange Format
  • PNG- Portable Network Graphics
  • BMP- Bitmap

Vector Images 

Vector images are created using mathematical equations, lines (known as paths), and curves rather than pixels. In comparison to a raster image, a vector image can be resized as large as a banner or infinitely scalable without it losing its quality and resolution. This is because they work based on algorithms rather than pixels. One downside to resizing a vector image is the larger the image the more polygons are needed to retain its quality. This results in a very large file.

Vector graphics are commonly used in illustration and graphic design because the images created are normally enlarged and are more conventional than realistic. They are also good for creating logos, layouts, icons, and video games.

Vector image file formats include:

  • EPS- Encapsulated Postscript File Format
  • SVG- Scalable Vector Graphics
  • PDF- Portable Document Format
  • AI- Adobe Illustrator
  • EMF- Enhanced Metalife

Description of Image File Format

image file formats infographic

Download Infographic Script Links to an external site.

 IMAGES CREATED BY GAVS