Method and system for fast detection of lines in medical images

A method for detecting lines in a digital image, comprising the steps of:

• selecting a spatial scale parameter, said spatial scale parameter corresponding to a desired range of line widths for detection;
• convolving said digital image with a first one dimensional kernel and a second one dimensional kernel to produce a filtered image array, said first one dimensional kernel and said second one dimensional kernel each having a size related to said spatial scale parameter;
• producing a line image based on second-order spatial derivatives of said filtered image array;
• wherein said line image is produced from said digital image using a number of computations that is substantially proportional to the spatial scale parameter such that, as the spatial scale parameter is increased, said number of computations increases at a rate that is less than the rate of increase of the square of the spatial scale parameter.

A method for detecting lines in a digital image, comprising the steps of:

• selecting a spatial scale parameter, said spatial scale parameter corresponding to a desired range of line widths for detection;
• convolving said digital image with a first one dimensional kernel and a second one dimensional kernel to produce a filtered image array, said first one dimensional kernel and said second one dimensional kernel each having a size related to said spatial scale parameter;
• separately convolving said filtered image array with a first, second, and third second order difference operator to produce a first, second, and third resulting array, respectively;
• computing a direction image array comprising, at each pixel, a first predetermined scalar function of corresponding pixel values in said first, second, and third resulting arrays;
• computing a line intensity function array comprising, at each pixel, a second predetermined scalar function of corresponding pixel values in said first, second, and third resulting arrays;
• and
• computing a line image array using information in said line intensity function array.

A computer-readable medium which can be used for directing an apparatus to detect lines in a digital image, comprising:

• means for directing said apparatus to filter said image to produce a filtered array;
• means for directing said apparatus to convolve said filtered image array with a plurality of second order difference operators designed to extract second order directional derivative information from said filtered image array in a predetermined set of directions;
• means for directing said apparatus to process information resulting from said step of convolving to produce a line image;
• wherein said predetermined set of directions is selected to correspond to an aspect ratio of said second order difference operators.

An apparatus for detecting lines in digital images, said apparatus comprising:

• a first memory for storing a digital image;
• a first convolution device capable of convolving said digital image with a first one dimensional kernel and a second one dimensional kernel to produce a filtered image array, said first one dimensional kernel and said second one dimensional kernel each having a size related to the size of lines being detected;
• a second convolution device capable of separately convolving said filtered image array with a first, a second, and a third second order difference operator to produce a first, second, and third resulting array, respectively;
• a first processing device capable of computing a direction image array comprising, at each pixel, a first predetermined scalar function of corresponding pixel values in said first, second, and third resulting arrays;
• a second processing device capable of computing a line intensity function array comprising, at each pixel, a second predetermined scalar function of corresponding pixel values in said first, second, and third resulting arrays;
• and
• a third processing device capable of computing a line image array using information in said line intensity function array.