The process of digitizing an image into raster format is called 

White space on the outer edge of the book page

Half sheet work method used for printing book work is also known as

The lightest or whitest parts in a photograph

The process in which the least dominant process color is replaced with an appropriate value of black in areas where yellow, magenta and cyan overprint 

The process of adjusting the color in a scanned image so that it more closely matches the original image, or to compensate for flaws (such as overexposure, unexposure or color casts) in the original image