A digital document magnifier for scanning and digitizing printed information, processing the information, and displaying the processed information on a display screen is provided. The digital document magnifier software analyzes the contents of a document and then automates presentation of the document to a viewer. The system includes a microprocessor for processing the scanned information, and displayable video memory for storing information to be displayed. The video memory is organized as a two-dimensional circular display buffer. The two-dimensional buffer is used to zoom incrementally an image to the display screen as necessary. The magnifier can provide either one data bit per pixel for a monochrome display, or four data bits per pixel for a color or greyscale display. Methods for scaling coordinates between a source image bitmap buffer and a two-dimensional circular display buffer also are provided. The methods include dynamically re-mapping page geometry to obtain continuous line effects and continuous column effects.