Method of tracking movement of particles in bronchus
A method of tracking movement of particles in bronchus includes obtaining, from a video of the particles, a plurality of processed images, each of which contains a plurality of particle portions representing the particles, and implementing a tracking process for a reference image of the processed images. The tracking process includes, for each particle portion in the reference image, selecting a to-be-compared portion from among the particle portions in a next image immediately following the reference image, obtaining an expected range of movement of the particle represented by the particle portion according to a position of the particle portion, determining whether a corresponding position in the reference image that corresponds to a position of the to-be-compared portion in the next image is within the expected range, and storing the position of the to-be-compared portion into a track record that is associated with the particle when the determination is affirmative.
1. A method of tracking movement of particles in bronchus using a video of the particles that are moved by beating of cilia, the video containing a series of consecutive original images, the method comprising steps of:
processing the original images of the video to obtain a plurality of processed images, respectively, each of the processed images containing a plurality of particle portions each representing one of the particles; and
for a reference one of the processed images, implementing a tracking process including
for each of the particle portions in the reference one of the processed images, selecting a to-be-compared portion from among the particle portions in a next one of the processed images that immediately follows the reference one of the processed images,
for each of the particle portions in the reference one of the processed images, obtaining an expected range of movement of the particle represented by the particle portion according to a position of the particle portion in the reference one of the processed images,
for each of the particle portions in the reference one of the processed images, determining whether a corresponding position in the reference one of the processed images that corresponds to a position of the to-be-compared portion in the next one of the processed images is within the expected range of movement of the particle represented by the particle portion, and
for each of the particle portions in the reference one of the processed images, storing the position of the to-be-compared portion into a track record that is associated with the particle represented by the particle portion when it is determined that the corresponding position is within the expected range of movement.
2. The method as claimed in claim 1 , further comprising a step of, before implementing the tracking process, setting a value of a variable to one,
wherein the tracking process further includes
using an i th one of the processed images as the reference one of the processed images to implement the tracking process, where i is equal to the value of the variable,
after storing the position of the to-be-compared portion into the track record, adding one to the value of the variable and then determining whether the value of the variable is less than a total number of the processed images, and
repeating the tracking process when it is determined that the value of the variable is less than the total number of the processed images.
3. The method as claimed in claim 2 , further comprising steps of:
calculating, according to the track record, a length of movement of the particle that is associated with the track record; and
deleting the track record when the length of movement is not within a standard range.
4. The method as claimed in claim 3 , wherein the standard range is from an arithmetic average of the lengths of movement calculated respectively from the track records that are associated respectively with the particles to one half of the arithmetic average.
5. The method as claimed in claim 1 , wherein the step of processing the original images of the video to obtain a plurality of processed images includes, for each of the original images:
converting the original image to a grayscale image having a plurality of pixels; and
filtering the grayscale image to keep only those of the pixels each having a pixel value greater than a threshold value.
6. The method as claimed in claim 1 , wherein selecting the to-be-compared portion includes, for each of the particle portions in the reference one of the processed images, selecting a closest one of the particle portions in the next one of the processed images, where a position in the reference one of the processed images that corresponds to a position of the closest one of the particle portions in the next one of the processed images is closest to the particle portion in the reference one of the processed images.
7. The method as claimed in claim 2 , wherein the tracking process further includes:
when it is determined that the corresponding position is not within the expected range of movement, ignoring the to-be-compared portion from the tracking process to be performed with respect to the next one of the processed images.
8. The method as claimed in claim 7 , wherein the tracking process further includes:
when it is determined that the corresponding position is not within the expected range of movement, deleting the track record that is associated with the particle represented by the particle portion.
9. The method as claimed in claim 1 , wherein obtaining the expected range of movement of the particle is to, for the particle portion, defining a predetermined region surrounding a center of the particle portion in the reference one of the processed images as the expected range of movement.
10. The method as claimed in claim 9 , wherein, in a case where the particle portion is composed of only one pixel, the predetermined region of the particle portion has eight-connected pixels that are directly connected to the particle portion.
11. The method as claimed in claim 9 , wherein, in a case where the particle portion is composed of multiple pixels, the predetermined region of the particle portion has eight-connected pixels that are directly connected to a central pixel of the particle portion.
12. The method as claimed in claim 1 , further comprising a step of generating a plot showing tracks respectively of the particles according to the track records that are associated respectively to the particles.