System and method for gesture interface

1. A method for automatically remotely issuing commands to a medical imaging workstation comprising the steps of:

determining a change in a background of an image from a plurality of images;

determining an object in the image,

identifying a gesture according to a trajectory motion pattern of the object;

determining if the motion pattern corresponds to a valid command by classifying the motion pattern along windows in time; and

if the motion pattern corresponds to a valid command, the workstation automatically executing the command resulting in translational and rotational manipulation of a virtual visualization tool based on the command.

2. The method of claim 1 , wherein the step of determining the change in the background further comprises the steps of:

determining a gradient intensity map for the background from a plurality of images;

determining a gradient intensity map for the current image;

determining, for a plurality of pixels, a difference between the gradient intensity map and the gradient intensity map for the background;

determining a comparison between the difference and a threshold; and

determining a pixel to be a background pixel according to the comparison.

3. The method of claim 1 , wherein the object includes a user's hand.

4. The method of claim 1 , wherein the step of identifying a gesture further comprises the steps of:

determining a reference point;

determining a correspondence between the trajectory and the reference point; and

translating the trajectory according to one of a plurality of commands.

5. The method of claim 1 wherein the step of determining an object in the image further comprising the steps of:

obtaining a normalized color representation for a plurality of colors in each image;

determining from training images an estimate of a probability distribution of normalized color values for an object class; and

determining, for each pixel, a likelihood according to an estimated probability density of normalized color values for the object class.

6. The method of claim 1 wherein the step of executing the command further comprises the steps of:

determining the duration of the gesture; and

correlating the duration of the gesture to an intensity and scale in which the command is executed.

7. The method of 6 wherein repetition of a command increases the intensity of the corresponding command response.

8. The method of claim 1 wherein the virtual visualization tool is a virtual endoscope.

9. The method of claim 8 wherein the command corresponds to rotation of the virtual endoscope.

10. The method of claim 9 wherein the gesture is rotation of a user's hand.

11. The method of claim 8 wherein the command corresponds to moving the virtual endoscope in a right to left direction.

12. The method of claim 11 wherein the gesture is waving of a user's hand from right to left.

13. The method of claim 1 , wherein the step of determining the trajectory of the object through the plurality of images further comprises the steps of:

determining, for each pixel, a temporal likelihood across a plurality of images; and

determining a plurality of moments according to the temporal likelihoods.

14. The method of claim 1 wherein the identified gesture is a valid command if it detects object pixels moving in a predefined pattern.

15. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for automatically remotely issuing commands to a medical imaging workstation, the method steps comprising:

determining a change in a background of an image from a plurality of images;

determining an object in the images;

identifying a gesture according to a trajectory and motion pattern of the object;

determining if the motion pattern corresponds to a valid command by classifying the motion pattern along window in time; and

if the motion pattern corresponds to a valid command, the workstation automatically executing the command resulting in translational and rotational manipulation of a virtual visualization tool based on the command.

16. The method of claim 15 , wherein the step of determining the change in the background further comprises the steps of:

determining a gradient intensity map for the background from a plurality of images;

determining a gradient intensity map for the current image;

determining, for a plurality of pixels, a difference between the gradient intensity map and the gradient intensity map for the background;

determining a comparison between the difference and a threshold; and determining a pixel to be a background pixel according to the comparison.

17. The method of claim 15 , wherein the object includes a user's hand.

18. The method of claim 15 , wherein the step of identifying a gesture further comprises the steps of:

determining a reference point;

determining a correspondence between the trajectory and the reference point; and

translating the trajectory according to one of a plurality of commands.

19. The method of claim 15 , wherein the step of determining the object in the image further comprises the steps of:

obtaining a normalized color representation for a plurality of colors in each image;

determining from training images an estimate of a probability distribution of normalized color values for an object class; and

determining, for each pixel, a likelihood according to an estimated probability density of normalized color values for the object class.