The GIF (Graphics Interchange Format) file format, created by Compuserve in 1987, uses a lossless compression algorithm (LZW) and is limited to a 256-color palette. GIF also supports transparency, and interlacing. One of the issues surrounding the GIF format is that the LZW algorithm was protected in the USA by a patent held by the company Unisys. The Unisys LZW patent expired in the USA on June 20, 2003.
The PNG (Portable Network Graphics) image format was developed in 1995 as the successor to the GIF format. PNG uses a more efficient compression algorithm than GIF, is patent-free and supports true color images. Alpha channels (variable transparency), gamma correction (cross-platform control of image brightness), and two-dimensional interlacing are other important features of this format. While support for PNG images in browsers has been low in the past, they can now be safely used in all modern browsers, including Mozilla Firefox, Opera, Safari, and Internet Explorer. Internet Explorer supports binary transparency in PNG files, just like with GIF, but lacks support for alpha channels.
TIFF (Tagged Image File Format) is the most widely supported graphics file format for printing. Although TIFF is not suitable for viewing in Web browsers, it has other strengths: it is a highly flexible format which is supported by numerous image processing applications. TIFF was designed to be independent of the hardware platform and the operating system on which it executes.
The BMP format (Windows Bitmap) is compatible with most Windows programs, including older programs, but is not recommended for Web browsers, because BMP cannot compress images. BMPs are sometimes preferred for images in computer software when speed is more important than reduced file size, because uncompressed bitmaps can be displayed more quickly.
|Save your graph as:|
|PNG||if you want to share the graph on the Web or to use in your documents (recommended)|
|GIF||if you want the smallest resulting file|
|BMP||if you want to use the file in older Windows programs|
|TIFF||if you want to print the graph or to use the file on Mac/Unix|
Plot graph for e^x-sin(1/2^x) on [-4, 6].
|PNG||7.05 KB||27 colors|
|GIF||4.78 KB||9 colors|
|BMP||299.12 KB||27 colors|
|TIFF||10.5 KB||27 colors|
You can open and edit the saved images using IrfanView, the best free image viewer for Windows.