Image File Formats
Have you ever wondered about the difference between a TIFF and a GIF, or if you should use a PSD or PDF? This guide will help solve some of the image format mysteries you may encounter.
BMP (Bitmap): “bitmap”
The first digital image format. It started with the Windows environment and produces larger file sizes with medium-high quality. Older and not as common now, but good for icons and high-contrast images.
TIFF (Tagged Image File Format): “tif”
TIFF files are large, but great for file storage and editing, because there is virtually no compression when saved. No longer common for digital cameras because jpegs are so much smaller. Adobe now owns TIFF, and patent restrictions may be an issue. There are over 50 different TIFF versions, so compatibility may be a problem. PNG-24 has now replaced TIFFs for many who want the same “lossless compression.”
GIF (Graphic Interchange Format): “gif” – hard or soft g is correct
Gif format is best used for text, line drawings, screenshots, cartoons, and animations. GIF is linked to a total number of 256 colors or less (or 8-bit colormap), so it is not as good for gradients. It is commonly used for fast loading web pages. It does keep transparency, but not as consistently as a PNG image. Designers may have to pay royalties for using GIFs.
JPG/JPEG (Joint Photographic Experts Group): “jay-peg”
Became popular with digital cameras. High quality images and huge compression is great for file storage, but not best for image editing. Every time a jpeg is saved, the quality is reduced as the file is recompressed. Good for blends and gradients, but compression can blur pixels and produce artifacts or squared pixels. Will not maintain a transparent background when saved.
PNG (Portable Networks Graphic): “ping”
Great overall image format because it utilizes “lossless compression,” which means quality will not be degraded with multiple saves. Good for computer-generated graphics and files containing text and images having sharp transitions, but not as good as JPEGs for photos because of larger file size. Will maintain a transparent background, unlike a JPEG. Designed to replace GIF and TIFF, because they come in 8-bit and 24-bit formats. PNG-8 Files are typically 20% smaller than GIFs. PNG-24 images are larger than JPEGs, but great if transparency is an issue. No royalties or patent restrictions come with PNG like the TIFF and GIF do.
PSD (Photoshop Document) “pee-es-dee”
The native image format for Adobe Photoshop. Great for image editing and full-quality saves, because it has no compression. Layers, selections, and effects are saved for future editing.
PDF (Portable Document Format) “pee-dee-ef”
Created by Adobe in 1993 for exchanging files from many native formats to one universal format. Versatile compression settings are extremely flexible, yet they can make it hard for users to save colors, transparencies, and gradients correctly.
DNG (Digital Negative): “dee-en-jee”
Created by Adobe as a universal RAW image format that is publicly available for saving digital photos in an uncompressed format. Every camera model can use a different raw format, and applications cannot read every raw file without constant updates and hassle. As a result, long-term archival storage and raw file sharing is problematic. Most image editing/management applications recognize DNG files, and Adobe provides free file converters for Mac and Windows. By addressing the lack of an open standard for raw files, DNG helps ensure that photographers will be able to access their files in the future.
Source: Caryn Esplin, 2011