1. A computer-implemented method for detecting and growing isolated dots in a document image having a plurality of pixels, wherein the method is implemented in a computer system comprising one or more processors configured to execute one or more computer program modules, the method comprising: receiving a document image having a plurality of pixels therein; isolating the pixels of the received image to form a plurality of windows, each window comprising a target pixel and a plurality of pixels surrounding the target pixel; detecting an isolated dot in the received image; identifying a dot growth factor to grow the isolated dot in the received image; using the dot growth factor to identify tiered pixel patterns from a plurality of predefined, tiered pixel patterns, wherein each of the tiered pixel patterns having a predetermined dot growth factor; comparing the pixels within each window to the pixel patterns within the identified tier to identify a match between the pixels within the window and at least one of the pixel patterns; and changing a pixel value of the target pixel, when a match is identified, to grow the detected isolated dot in the image by the dot growth factor.