What do all these graphics file extensions mean?
Vector files store images as a series of simple shape descriptions. They will divide an image into lines, rectangles, circles, etc. and it will describe the positions and colors of all these shapes on the page, and then rebuild the image when the file is opened.
There are advantages to using vector files, since you have a description of a scene, you can increase its size indefinitely, and still have enough information to maintain a high-quality image. Some programs use a vector format by default. All PowerPoint drawings are in vector format, as are all Microsoft clip art. Vector images are suitable for putting simple images into documents and presentations, but should not be used on web pages.
Bitmap images are analogous to taking a photograph. The entire image is divided into a grid of tiny squares, called pixels, and the color of each pixel in the entire image is recorded. This format allows extremely complex images (such as photos) to be described, but can produce extremely large file sizes.
Unlike vector files, you cannot enlarge a bitmap file without losing resolution. One last point about these two formats is that it’s easy to convert a vector file to a bitmap (that’s what happens when you look at it on your screen!), but it’s rarely possible to convert a bitmap to a vector. BMP files are usually not compressed, so they are large; the advantage is its simplicity, wide acceptance, and use in Windows programs.
JPEG or Joint Photographic Experts Group (DOS file name extension is JPG) files suffer generational degradation when edited and saved repeatedly. The JPEG format is also used as the image compression algorithm in many Adobe PDF files. Advantages of JPEG images:
o Huge compression ratios mean faster download speeds
o JPEG produces excellent results for most photos and complex images
o JPEG supports full color (24-bit, “true color”) images
The Graphics Interchange Format, or GIF, is limited to an 8-bit or 256-color palette. This makes the GIF format suitable for storing graphics with relatively few colors, such as simple diagrams, shapes, logos, and cartoon-style images. The GIF format supports animation and is still widely used to provide image animation effects. Advantages of GIF files:
o GIF is the most compatible graphics format on the Web
o GIFs of schematic images look better than JPEGs
o GIF supports transparency and interlacing
TIFF or Tagged Image File Format is a flexible format that typically saves 8-bit or 16-bit per color (red, green, blue) for 24-bit and 48-bit totals, respectively, using the file names TIFF or TIF. The TIFF image format is not widely supported by web browsers. TIFF remains widely accepted as an archival standard for photography in the print business.
The PNG or Portable Network Graphics file format was created as the free and open source successor to GIF. The PNG file format supports true color (16 million colors), while the GIF only supports 256 colors. The PNG file excels when the image has large areas of solid color. JPG files are smaller than PNG files. Many older browsers currently do not support the PNG file format. However, Internet Explorer 7 and all current web browsers fully support the PNG format.
