1. A digital image processing method implemented in a computer for generating an erosion image from a corresponding original digital image having a plurality of pixels, the method comprising: inputting the original digital image; generating an extended binary image by adding pixels to a boundary of the original image based on a structuring element and binarizing, utilizing a threshold value, each of the plurality of pixels of the original digital image and the pixels added to the boundary, wherein in the binarization process, each pixel is binarized in parallel; obtaining a processing image (b) from the extended binary image, wherein each pixel in the extended binary image having a value of 1 is identified as a pixel of interest in the processing image (b); obtaining a target image (T) from the extended binarized image, the target image being a same size as the original input image; generating an erosion image utilizing the processing image (b) and the target image (T), the erosion image being obtained by processing each target pixel in the target image in parallel by performing the following steps on the target pixel: a target pixel coordinate determination step of determining coordinate values for the target pixel in the target image (T); a surrounding pixel area determination step of determining a surrounding pixel area in the processing image (b) surrounding a processing image pixel corresponding to the target pixel, the determination being made based on the coordinate values (TCol, TRow) for the target pixel and a size (height and width) of a structuring element; a surrounding pixel processing step of performing processing on each pixel in the surrounding pixel area in a predetermined order to determine whether or not to update the value of the target pixel, wherein the processing on each pixel in the surrounding pixel area comprises the steps of: a pixel of interest determination step of determining whether or not a current pixel of the surrounding pixel area being processed has been identified as a pixel of interest in the processing image; in a case where it is determined that the current pixel has not been identified as a pixel of interest, determining that the target pixel is not to be updated based on processing of the current pixel in the surrounding pixel area, and commencing processing of a next surrounding pixel in the predetermined order, thereby returning to the pixel of interest determination step for the next surrounding pixel; in a case where it is determined that the current surrounding pixel has been identified as a pixel of interest, performing the steps of: a structuring element pixel determination step of determining which pixel element in the structuring element overlays the target pixel when an origin of the structuring element is located at the current surrounding pixel; a pixel value obtaining step of obtaining a pixel value for the structuring element pixel element determined in the structuring element pixel determination step as overlaying the target pixel; a target pixel update determination step of determining whether or not to update the value of the target pixel based on the obtained pixel value for the structuring element pixel element determined in the structuring element pixel determination step, wherein, if the obtained pixel value is a first value, a determination is made not to update the target pixel and processing commences for a next surrounding pixel in the predetermined order, thereby returning to the pixel of interest determination step for the next surrounding pixel, and if the obtained pixel value is a second value, a determination is made to update the value of the target pixel; updating the value of the target pixel if the target pixel update determination step determines to update the value of the target pixel; a target pixel value determination step of determining whether or not the updated value of the target pixel is equal to a predetermined value (N); in a case where the target pixel value determination step determines that the updated value of the target pixel is equal to the predetermined value (N), terminating processing of remaining pixels in the surrounding pixel area and setting the value of the target pixel as the predetermined value (N); in a case where the target pixel value determination step determines that the updated value of the target pixel is less than the predetermined value (N) and all surrounding pixels have been processed, setting the value of the target pixel in the target image based on the number of updates performed in the updating step; in a case where the target pixel value determination step determines that the updated value of the target pixel is less than the predetermined value (N) and additional surrounding pixels remain to be processed, returning to the pixel of interest determination step for a next pixel of the surrounding pixels to be processed in the predetermined order; obtaining an output image by, after all target pixels in the target image have been processed according to the foregoing steps, thereby resulting in an updated target image, setting a value of pixels in the updated target image having the predetermined value (N) to a first binary value and setting pixels in the updated target image having an updated value less than the predetermined value (N) to a second binary value; and outputting the obtained output image.