Files created with a Drawing image type can be edited easily in an image editor. Photo is used for images with many shades of gray or color. A photo image type is used to scan images that are to be printed or displayed on imagesetters or color screens. Also, use a photo image type to scan an image that is to be edited. Original photographs and pictures in books, magazines, and newspapers are examples of the kind of images to scan.
Halftone is used to optimize the quality of scanned photos when printed on desktop printers.
Images scanned as a halftone image type are processed in a way that simulates the many shades of color in the image when it is printed. The halftone process is needed for images printed on desktop printers because they can only print a small range of colors. Millions of Colors is used to scan images that are to be displayed or printed on 24-bit color displays or imagesetters. Files created with the Millions of Colors setting often contain more than a megabyte of data. For example, a half-page scanned image creates a 12 MB file.