Edge detecting device

An edge detecting device comprising:

• an image pickup unit including an image pickup device which receives an optical information from an object and converts said optical information into an electrical image signal;
• sampling means electrically connected with said image pickup unit for converting said image signal into digital image data including a train of data elements;
• a first calculation block for obtaining preliminary edge data, electrically connected with said sampling means and comprising:
• Fourier transformation means for converting said digital image data obtained by said sampling means into data in a spatial frequency region by performing a high-speed Fourier transformation;
• filtering means for filtering said data in a spatial frequency region obtained from said Fourier transformation means to remove at least a zero order spatial frequency component therefrom;
• and
• inverse Fourier transformation means for converting the data in the spatial frequency region with said at least a zero order spatial frequency component thereof having been removed by said filtering means into data in real space to be output as the preliminary edge data, by performing a high-speed inverse Fourier transformation;
• a second calculation block for detecting rough edge location, electrically connected with said sampling means and comprising:
• a low pass filter, constructed and connected to remove high frequency components from said digital image data obtained by said sampling means to provide filtered data including a train of filtered data elements,
• first calculation means for calculating at least a difference in value between each pair of the filtered data elements located adjacent to each other in the train of said filtered data obtained by said low pass filter, in a range of at least one partial train of said filtered data obtained by said low pass filter, to provide difference data including a train of difference data elements;
• second calculation means for zeroing each value of a plurality of the difference data elements contained in two partial trains located at respective ends of said difference data obtained by said first calculation means to produce processed difference data elements;
• and
• third calculation means for raising each value of the processed difference data elements from said second calculation means to a higher power to obtain rough edge data;
• edge detecting means, electrically connected with each of said first calculation block and said second calculation block, for detecting an ultimate edge location information corresponding to edges contained in the optical information from the object, based on a correlation between the preliminary edge data obtained through said first calculation block and the rough edge data obtained through said second calculation block;
• and
• signal transmitting means for transmitting said ultimate edge location information obtained by said edge detecting means to external devices.