Disclosed is an automated staining apparatus (autostainer) capable of staining sample on a microscope slide. The autostainer is capable of limiting the amount of reagent used through a process including image acquisition and processing techniques, wherein an image of the slide is acquired and used to determine a region on the slide to be stained. Also disclosed are methods of using images acquired by the autostainer in sample processing. In addition, a system having the autostainer functionally linked to an imaging system is provided.