JPEG always uses lossy JPG compression, but its degree is selectable, for higher quality and larger files, or lower quality and smaller files. JPG is for photo images, and is the worst possible choice for most graphics or text data.
For TIF files, most programs allow either no compression or LZW compression (LZW is lossless, but is less effective for color images). Adobe Photoshop also provides JPG or ZIP compression in TIF files too (but which greatly reduces third party compatibility of TIF files). "Document programs" allow ITCC G3 or G4 compression for 1-bit text (Fax is G3 or G4 TIF files), which is lossless and tremendously effective (small). Many specialized image file types (like camera RAW files) are TIF file format, but using special proprietary data tags.
24-bits is called 8-bit color, three 8-bit bytes for RGB (256x256x256 = 16.7 million colors maximum.)
Or 48-bits is called 16-bit color, three 16-bit words (65536x65536x65536 = trillions of colors conceptually)
Supports transparency in regular indexed color, and also there can be a fourth channel (called Alpha) which can map RGB graduated transparency (by pixel location, instead of only one color, and graduated, instead of only on or off).
PNG also supports animation (like GIF), showing several sequential frames fast to simulate motion.
PNG uses ZIP compression which is lossless, and somewhat more effective color compression than TIF LZW. For photo data, PNG is somewhat smaller files than TIF LZW, but larger files than JPG (however PNG is lossless, and JPG is not.) PNG is a newer format than the others, designed to be both versatile and royalty free, back when the patent for LZW compression was disputed for GIF and TIF files.
One color in indexed color can be marked transparent, allowing underlaying background to be seen (very important for text, for example). GIF is an online video image, the file contains no dpi information for printing. Designed by CompuServe for online images in the days of dialup and 8-bit indexed computer video, whereas other file formats can be 24-bits now. However, GIF is still great for web use of graphics containing only a few colors, when it is a small lossless file, much smaller and better than JPG for this. GIF files do not save the dpi number for printing resolution.
GIF uses lossless LZW compression. (for Indexed Color, see second page at GIF link at page bottom).
GIF also supports animation, showing several sequential frames fast to simulate motion.
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