Digital Image File Types

In Computer Graphics and Design various file types are used to save the image. Each type of file offers advantages and limitations. It is important to know which file type is the most appropriate to use, depending on the circumstances.

  • JPEG (Joint Photographic Experts Group) is mostly used format for internet and digital cameras because of its lower file size. JPEG files are compressed to reduce the size of the digital file, but this process loses some of the information reducing the quality of the image slightly. For this reason JPEG is referred to as a 'lossy' file type. Normally the reduction in quality is not visible, but repeated copying and editing increases the data loss. JPEG is not as suitable for images with text, large blocks of colour, or simple shapes, because crisp lines will blur and colours can shift.
  • PNG Short for Portable Network Graphics, is a graphics standard supported by the Web (though not supported by all browsers). PNG was developed as a patent-free answer to the GIF format but is also an improvement on the GIF technique. PNG uses lossless compression, file so saving, restoring and re-saving a PNG image will not degrade its quality. PNG files are small without loss of quality, as are good for web graphics. They also provide for levels of transparency and 16 million colours.
  • BMP Short for bitmap, the BMP format is a commonly used faster graphics format for saving image files. It was introduced on the Windows platform, but is now recognized by many programs on both Macs and PCs. The BMP format stores colour data for each pixel in the image without any compression. For example, a 10x10 pixel BMP image will include colour data for 100 pixels. This method of storing image information allows for crisp, high-quality graphics, but also produces significantly larger file sizes than the compressed file types. The large files sizes make BMP files unsuitable for web pages but BMP images are often used for high quality printable images.

  • GIF Short for Graphics Interchange Format, a gif image is an image file used in web pages. GIF is a bitmap image format that was introduced by CompuServe in 1987 and has since come into widespread usage. The format supports up to256 colours. The colours are chosen from the 24-bit RGB colour space. It also supports animations and allows a separate palette of 256 colours for each frame. The colour limitation makes the GIF format unsuitable for reproducing colour photographs and other images with continuous colour, but it is well-suited for simpler images such as graphics or logos with solid areas of color. It's basically a moving picture on the web.
  • TIFF Short for Tagged Image File Format, is in principle, a very flexible format that can be lossless or lossy, although most graphics programs that use TIFF do not use compression and are lossless, consequently file sizes are typically quite big but of high quality. A limitation of TIFF is that the files are proprietary and no device will utillise all TIFF files. Web browsers do not support TIFF. TIFF is used for quality output from a digital camera and in the printing industry.
  • RAW is an image output option available on some digital cameras. RAW files are lossless and uncompressed. RAW format is proprietary and images cannot be transferred between devices in this format, also requiring proprietary software to edit or display them.

Comparison of file sizes

The table shows the size of this image file in different formats

File format File size (KB)
PNG 78
GIF 18
BMP 102
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