System and method for elimination of irrelevant and redundant features to improve cad performance

• US 20050281457A1
• Filed: 05/27/2005
• Published: 12/22/2005
• Est. Priority Date: 06/02/2004
• Status: Abandoned Application

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Inventors: Dundar, Murat
• Application Number:
  US11/140,290
• Publication Number:
  US 20050281457A1
• Time in Patent Office: Days
• US Class Current: 382/159
• CPC Class Codes: G06F 18/2115 by evaluating different subsets according to an optimisation criterion, e.g. class separability, forward selection or backward elimination
• CPC Class Codes: G06F 18/21322 Rendering the within-class scatter matrix non-singular

Abstract

A computer-implemented method for processing an image includes identifying a plurality of candidates for an object of interest in the image, extracting a feature set for each candidate, determining a reduced feature set by removing a least one redundant feature from the feature set to maximize a Rayleigh quotient, determining at least one candidate of the plurality of candidates as a positive candidate based on the reduced feature set, and displaying the positive candidate for analysis of the object.

Claims

1. A computer-implemented method for processing an image comprising:

identifying a plurality of candidates for an object of interest in the image;

extracting a feature set for each candidate;

determining a reduced feature set by removing a least one redundant feature from the feature set to maximize a Rayleigh quotient;

determining at least one candidate of the plurality of candidates as a positive candidate based on the reduced feature set; and

displaying the positive candidate for analysis of the object.

2. The computer-implemented method of claim 1, wherein determining the reduced feature set comprises:

initializing a discriminant vector and a regularization parameter; and

determining, iteratively, the reduced feature set.

3. The computer-implemented method of claim 2, wherein determining, iteratively, the reduced feature set comprises:

determining the reduced feature set according to the discriminant vector, wherein features of the feature set with an element of the discriminant vector greater than a threshold are selected as the reduced feature set;

determining a class scatter matrix and mean in a reduced dimensional space defined by the reduced feature set;

determining a transformation vector;

updating the class scatter matrix and means according to the transformation vector; and

determining the discriminant vector.

4. The computer-implemented method of claim 2, further comprising:

comparing, at each iteration, each element of the discriminant vector to a threshold; and

stopping the iterative determination of the reduced feature set upon determining that all elements are greater than the threshold.

5. The computer-implemented method of claim 4, wherein the threshold is a user defined variable for controlling a degree to which features are eliminated.

6. The computer-implemented method of claim 2, wherein the transformation vector and the discriminant vector can be determined as:

$\begin{array}{cc}{\min }_{\mathrm{\alpha <br><br>},a\in <br><br>R^d}<br><br>\text{\hspace{1em}<br><br>}& {\mathrm{\alpha <br><br>}}^T<br><br>\left(S_w*\left({\mathrm{aa}}^T\right)\right)<br><br>\mathrm{\alpha <br><br>}\\ s.t.& {\mathrm{\alpha <br><br>}}^T(\left(m_{+}-m_{-}\right)*a=b\\ \text{\hspace{1em}<br><br>}& {\mathrm{\alpha <br><br>}}^T<br><br>e_l\le <br><br>\mathrm{\gamma <br><br>},\mathrm{\alpha <br><br>}\ge <br><br>0\end{array}.$

7. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for processing an image, the method steps comprising:

identifying a plurality of candidates for an object of interest in the image;

extracting a feature set for each candidate;

determining a reduced feature set by removing a least one redundant feature from the feature set to maximize a Rayleigh quotient;

determining at least one candidate of the plurality of candidates as a positive candidate based on the reduced feature set; and

displaying the positive candidate for analysis of the object.

8. The method of claim 7, wherein determining the reduced feature set comprises:

initializing a discriminant vector and a regularization parameter; and

determining, iteratively, the reduced feature set.

9. The method of claim 8, wherein determining, iteratively, the reduced feature set comprises:

determining the reduced feature set according to the discriminant vector, wherein features of the feature set with an element of the discriminant vector greater than a threshold are selected as the reduced feature set;

determining a class scatter matrix and mean in a reduced dimensional space defined by the reduced feature set;

determining a transformation vector;

updating the class scatter matrix and means according to the transformation vector; and

determining the discriminant vector.

10. The method of claim 8, further comprising:

comparing, at each iteration, each element of the discriminant vector to a threshold; and

stopping the iterative determination of the reduced feature set upon determining that all elements are greater than the threshold.

11. The method of claim 10, wherein the threshold is a user defined variable for controlling a degree to which features are eliminated.

12. The method of claim 8, wherein the transformation vector and the discriminant vector can be determined as:

$\begin{array}{cc}{\min }_{\mathrm{\alpha <br><br>},a\in <br><br>R^d}<br><br>\text{\hspace{1em}<br><br>}& {\mathrm{\alpha <br><br>}}^T<br><br>\left(S_w*\left({\mathrm{aa}}^T\right)\right)<br><br>\mathrm{\alpha <br><br>}\\ s.t.& {\mathrm{\alpha <br><br>}}^T(\left(m_{+}-m_{-}\right)*a=b\\ \text{\hspace{1em}<br><br>}& {\mathrm{\alpha <br><br>}}^T<br><br>e_l\le <br><br>\mathrm{\gamma <br><br>},\mathrm{\alpha <br><br>}\ge <br><br>0\end{array}.$

13. A computer-implemented detection system comprising:

an object detection module determining a candidate object and a feature set for the candidate object; and

a feature selection module coupled to the object detection module, wherein the feature selection module receives the feature set and generates a reduced feature set having a desirable value of a Rayleigh quotient, wherein the object detection modules implements the reduced feature set for detecting an object in an image.

14. The computer-implemented detection system of claim 13, wherein the feature selection module further comprises:

an initialization module setting an initial value of a discriminant vector and a regularization parameter;

a reduction module determining the reduced feature set according to the discriminant vector, wherein features of the feature set with an element of the discriminant vector greater than a threshold are selected as the reduced feature set;

a discriminant module determining a class scatter matrix and mean in a reduced dimensional space defined by the reduced feature set;

a sparsity module determining a transformation vector; and

an update module updating the class scatter matrix and means according to the transformation vector, wherein the sparsity module determines the discriminant vector given the updated class scatter matrix and means.