Method of determining the orientation of an image
View Patent ↗The orientation of an image such as a radiographic image is deduced from the digital representation of the image. In one embodiment the curvature is calculated and a decision on the orientation of the image is obtained on the basis of the value of the calculated curvature.
1. A computer implemented method of determining the orientation of an image comprising:
determining, via a computer for processing a digital representation of said image, the orientation from direction and magnitude of normal vectors associated with local curvature in a set of points associated with the digital representation of said image by:
performing a first and second derivative vector computation for one or more pixels of said digital representation;
quantizing a direction and magnitude of the computed first and second derivative vectors;
weighted voting the quantized first and second derivative directions into analyzing coordinate system orientations to determine a maximum vote; and
selecting the image orientation having the maximum vote.
2. The method according to claim 1 wherein said image is represented by a digital edge representation.
3. The method according to claim 1 wherein said image is a thoracic image, the method further comprising determining curvature of at least one of ribs and ribcage in said thoracic image.
4. The method according to claim 1 wherein said image is a mammographic image and wherein a curvature is calculated for skin border edge segments of said image.
5. The method according to claim 1 wherein collimation areas are excluded from said digital representation.
6. The method according to claim 1 wherein direct exposure areas are excluded from said digital representation.
7. The method according to claim 1 further comprising orienting the image represented by the digital representation into a desired orientation by subjecting said image to an orientation modifying geometric transformation to yield said desired orientation of the image.
8. A computer readable medium having stored thereon computer executable program code for carrying out the steps of claim 1 .
9. The method according to claim 1 wherein said orientation is deduced from an addition vector of said normal vectors.
10. The method according to claim 1 wherein said image is represented by an iso-intensity representation.
11. The method according to claim 1 wherein said direction and magnitude of the computed first and second derivative vectors are quantized according to four Cartesian plane quadrants.
12. The method according to claim 1 wherein said direction and magnitude of the computed first and second derivative vectors are quantized according to eight Cartesian space octants.