Converting image for web is again a skilled job needs a bit experience. Packages like photoshop have made this work fairly easy with its helpful commands. Images makes your page more alive at the same time it increases download time hence the use of images has to be economical both in time and designing aspect. If you need some good quality photographs you will get here . Again its free.
Image Processing It is also a very wide term used.
Generally image processing involves adjusting the technical properties of the image and modifying the actual content of the image may be to give totally new look to the image. Photoshop is the most popular program in this field. Font People love to work with fonts. It is a design of character. You have wide choice here.