COMPUTER SCREEN IMAGE MAGNIFICATION SYSTEM AND METHOD

An image magnifying method and apparatus magnifies a portion of an image displayed on a computer display device. The user of the computer selects a first region (called a magnification window) of the displayed image, for instance using a mouse or trackball pointer device. Image data from the screen buffer for the user selected magnification window is copied to a first buffer. A magnified image is generated from the copied image data and the magnified image is stored in the screen buffer so as to replace the copied image data. When the user moves the screen cursor, or otherwise selects a second magnification window that overlaps with the first, the magnification application copies image data for a combined window, covering both the first and second magnification windows, from the screen buffer to a second buffer. The image data stored in the first buffer is copied into the portion of the second buffer corresponding to the first magnification window, at which point the second buffer contains unmagnified data for the entire combined window. The application generates a magnified image for the second magnification window and stores it in a portion of the second buffer corresponding to the second magnification window. Finally, the portion of the second image buffer corresponding to the combined window is copied into the corresponding portion of the screen buffer. As a result, the magnification window moves smoothly from the first to the second window, without creating any flashing artifacts.