Whether issued from a scanner or from any digital camera (P&S as DSLR) the original jpeg, tiff, raw, pictures have a color "world" profile.

Often camera settings allow to set it to say: Adobe RGB, ColorMatch, ProPhoto, sRGB, and many others, often brand proprietary profiles (i.e. Nikon RGB).
The web, as a whole is more text then picture oriented. Few file format are allowed as a "natural" display for your browser without special plug-ins.
Tiff is not recognized on web while it's a current file format in digital photography. GIF, JPEG are the favored formats.
A jpeg in sRGB should be the same viewed on your screen as viewed by anybody on a web site?
Most softwares allow for photo retouching in more elaborate profiles or gamuts (ex: ProPhoto in 16 or 32 bits) because you have a maximum of colors and shades... But when for web use, it is necessary to translate the resulting file in jpeg and sRGB !

You'll find more explanations in Bob's site ... :-)


"What can I do, What can I write, Against the fall of Night". A.E. Housman