Segmentation method of document images by two‐dimensional fourier transformation
Masahiko Hase, Yasushi Hoshino · Systems and Computers in Japan · 1985
Abstract A processing method is described for the document image composed of characters, graphics and photographs, extracting those regions by the following procedures. (1) Two‐dimensional Fourier transformation is performed for the entire image, the angle of the character lines is corrected utilizing the peak coordinate of the transform result, and the period of the character lines is calculated. (2) Based on the real and imaginary parts of the transform result, the coordinates for the characters are calculated. (3) The two‐dimensional Fourier transformation is performed for the subpictures determined by the character period. The entire document is scanned and the regions are detected by determining the existence of the peak corresponding to the character‐line period. It is shown by experiment that the angle of the line can be detected with accuracy within 2 degrees between ‐45 and +45 degrees. An experiment was performed for the image (journal article and patent document) composed of graphics and photographs, and it is verified that the method can extract the regions with sufficient accuracy.