Image File types
TIFF is, in principle, a very flexible format that can be lossless or lossy. The details of the image storage algorithm
are included as part of the file. In practice, TIFF is used almost exclusively as a lossless image storage format that uses
no compression at all.So, file sizes are quite big.
PNG is also a lossless storage format. However, in contrast with common TIFF usage, it looks for patterns in the image that
it can use to compress file size. The compression is exactly reversible, so the image is recovered exactly.
GIF creates a table of up to 256 colors from a pool of 16 million. If the image has fewer than 256 colors, GIF can render
the image exactly. When the image contains many colors, software that creates the GIF uses any of several algorithms to
approximate the colors in the image with the limited palette of 256 colors available. Thus, GIF is "lossless" only for images
with 256 colors or less.
JPG is optimized for photographs and similar continuous tone images that contain many, many colors. It can achieve
astounding compression ratios even while maintaining very high image quality. GIF compression is unkind to such images.
JPG works by analyzing images and discarding kinds of information that the eye is least likely to notice. It stores information
as 24 bit color. Important: the degree of compression of JPG is adjustable.
RAW is an image output option available on some digital cameras. Though lossless, it is a factor of three of four smaller
than TIFF files of the same image. The disadvantage is that there is a different RAW format for each manufacturer.
BMP is an uncompressed proprietary format invented by Microsoft. There is really no reason to ever use this format.
PSD, PSP, etc. , are proprietary formats used by graphics programs. Photoshop's files have the PSD extension, while Paint Shop
Pro files use PSP. However, be sure to save your end result as a standard TIFF or JPG, or you may not be able to view it
in a few years when your software has changed.