| 摘要 |
<p>This invention provides a feature extracting circuit (Fig. 1) including a shift register section (6) arranged to store an image for a predetermined number of lines, the image consisting of a predetermined number of bits, and then to shift the image; a look-up table section (7) for transforming a set of partial image data for a predetermined number of pixels supplied from the shift register section into a direction index and then for outputting the direction index; and a counter section (8 to 19) for counting the direction index output from the look-up table section (7). The feature extracting circuit receives a binary digital image and extracts, as a parameter of the image, a direction index which indicates the direction in which the boundary between adjacent black and white pixels extends. In the preferred arrangement the image data is sampled 4 x 4 pixels at a time, and consecutive 16-bit addresses applied to the look-up table section. Each 4 x 4 pixel sample includes a relevant pixel, a 2 x 2 array including the pixel, and nearest neighbour pixels. In this arrangement direction index data can be generated without any need for preliminary filtering for smoothing correction.</p> |
