Patent ID: 6418238
Filing Date: 2002-07-09
Classification: G06T

Abstract:
An image detection apparatus comprising:a filter operation unit for conducting an operation of calculating a synthetic produce between inputted image data and a plurality of filters, respectively, wherein said filters differ in direction and have respective orientations; a directional balance operation unit including an angle calculation unit for obtaining an angle made between a vector whose components are a plurality of outputs of said filter operation unit for each direction and a reference vector whose components are equal to each other; and a roundish shape detection unit for detecting roundish shapes within the inputted image data based on an output of said directional balance calculation unit, wherein said directional balance operation unit includes a standard deviation operation unit for obtaining a standard deviation of a plurality of outputs of said filter operation unit for each different direction of said filters; wherein said roundish shape detection unit detects said roundish shapes based on an output of said angle calculation unit and an output of said standard deviation operation unit; wherein said roundish shaped detection unit includes a feature calculation unit for calculating a feature of the inputted image data for each size of said plurality of filters based on the output of said angle calculation unit, the output of said standard deviation operation unit and a pixel intensity value of the inputted image data; and wherein said feature calculation unit calculates a first feature based on the output of said angle calculation unit and said pixel intensity value in accordance with the following mathematical expression: feature 1=f(xi, yi) cos 2&thgr;i where f(xi, yi) is a pixel intensity value on a pixel (xi, yi) and a second feature based on the output of said standard deviation operation unit in accordance with the following mathematical expression: feature&it;â€ƒ&it;2=1d&it;&LeftDoubleBracketingBar;g&af;(xi,yi)_&RightDoubleBracketingBar;&it;sin&it;â€ƒ&it;Î¸i&af;(=1d&it;&Sum;k=1d&it;â€ƒ&it;(gk&it;â€ƒ&it;&Sum;j=1d&it;â€ƒ&it;gjd)2)where gk(xi, yi)=a Gabor cosine filter output for a direction indexed by symbol k on the pixel (xi, yi), Î¸i=cos-1&it;(&Sum;k=1d&it;â€ƒ&it;gk&it;(xi,yi)d&it;&Sum;k=1d&it;â€ƒ&it;gk2&it;(xi,yi)),{square root over (d)}=a norm of a d-dimensional vector (1,1, . . . , 1,1), and, &LeftDoubleBracketingBar;g&it;(xi,yi)_&RightDoubleBracketingBar;=&Sum;K=1d&it;â€ƒ&it;gk2&it;(xi,yi).