How do professionals englarge photos?

When i put a small picture/image/photo into photoshop, or a general image resizing program---quality is lost dramtically, but when i give my pictures to Professional photographers, they some how find a way to enlarge pictures 20X, but also give me copies of small picture---all at the same great quality. HOW?

They take the original negative or print and use a special scanner to enlarge it to a large resolution, like 2000 pixels per inch. Then for the smaller pictures, they just shrink them down. You don't lose much quality when you shrink picture, just when you enlarge them because the computer has to "invent" pixel information where there is none.

If you want to have good quality prints at home, make sure you set your digital camera to take the pictures in the largest size possible, then shrink them down to your liking. Or if you're scanning film, scan it at a large resolution. (usually a picture is 300ppi, so if you want to make it twice as large, scan it at 600ppi)

Photos taking by a 35mm camera or by a high mega pixel digital camera are already very good quality and can be enlarged quite a bit w/o quality loss. You can do this yourself too. I'm not sure what you mean by a small picture/image/photo but once an image has been reduced in size and compressed to a small file size, it has to toss out a lot of information to get to that file size. Enlarging it again wont look like the original.

You can also use a scanner on a pic to scan at a very high quality that will enable it to be enlarged quite a bit.