Some reasons to convert images are to reduce their sizes, for use in other software, for use in a protected format like a PDF file, and for sending to other people who may not know how to use the picture in the format it is in.
There are many different image file types available. To name a few of the more popular ones, these are JPEGs, GIFs, and BITMAPs. JPEGs are used for static images using compression in order to make the file size smaller. This file type has become very prevalent in recent years with the popularity of digital cameras as JPG is generally the default file format. GIF can be used for animation and still images. BITMAP files have a .bmp extension and sore images with no compression, and thus are much larger file sizes.
Compression schemes can be considered either lossy or lossless. Lossy compression stores all the image's color at a lower resolution but the eyes should not even notice it. A lossless compression keeps all information pertaining to the image, color, and size.
An image's file type can generally be determined by its file extension. That is the dot and three letters at the end.
Additional file formats are available giving you a better selection on how to save your pictures or graphics. Some of the newer ones include WMF, EMF, TIFF, PNG, and ICO. Converting between formats many times is as simple as opening the file in your favorite editing software and saving to the desired format. Some programs feature a batch fiction that will convert many files at once. When converting image files, remember that many file types employ compression, possibly reducing their image quality.
Not all formats are compatible for you to be switching back and forth with them. Raster formats generally can be converted back and forth, and vector based formats generally can be converted to a raster based format. You simply pull up the image and right click for SAVE AS, and save the image as the program requires. Converting raster formats to a vector format is not as simple as other conversions and may require additional, more specialized software.
How do you choose between all the different file types that are used today? TIFF can be used for flexibility and with a lossless format. GIF has 256 colors that it creates, and if your picture has less that 256 different colors in it, it can be saved exactly. If it is more than 256 colors, GIF will use the closest color match. PNG is also lossless, but it does look for areas that can be compressed in the image. BMP is an uncompressed format and is hardly ever used. JPG is good for images that have many rich and vibrant colors.
The Internet can be a good resource for finding free ware, shareware, and demo versions of software converting images. Some of these are very specialized ans geared to converting one specific type to another, while others will take a file in any dozen or more different formats and convert it to just about any other format. Some of these programs may also be able to help determine what type of image that “mystery” file is that's missing its extension.