Object size

This is used to determine the region of the image that will be loaded in each time-point. The size of the region will be: Object size * Window size (see also the help for the next text field). The reason you can specify the object size separately is due to the "center of mass" tracking algorithm, which for each time-point iteratively computes the center of mass, starting in a region of size "Object size * Window size" and then 'zooming in' until the region is of Object size.

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Window size

The factor determines the window in which the algorithm will search for the object in the next time-point.
Tracking window size = Object size * Window size
This needs to be large enough to cover the distance that the object moves between subsequent time-points. If the objects moves out of the "Tracking window" the algorithm will not find it.

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Tracking sub-sampling

You can specify binning (linear interpolation) in x and y, as well as sub-sampling in z and t. Especially when streaming from tiff stacks sub-sampling in z significantly speeds up the process, because only every dz plane will be loaded.
For center-of-mass based tracking x/y binning makes no sense.
For correlation-based tracking however x/y binning is recommended as it increases the speed and reduces the noise.

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Track length

Here, you can specify the number of frames that you would like to track the object. Please note that you do not need to start tracking at the first frame. Simply move the time slider on the image forward and then select an object and click 'Track selected object'. Also note that you can track different objects for different lengths.

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Intensity gate

The tracking might be distracted by background noise and/or spurious bright regions (dirt). Use the intensity gate to only select gray values that are well above the background noise and well below too bright image features. Using values of -1 for either the minimum or maximum [min, max] will deactivate the respective gate.
Please note that the lower gate is subtracted from the whole image, and pixels above the upper gate are set to zero. Examples:
100,-1 will subtract a value of 100 from all pixels in the image.
-1,3800 will set all pixels >3800 to zero.

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Show first N regions

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Expand/crop the tracked region

The factor determines the size of cropped object view. The size is: Object size * Cropping factor.
If you put all instead of a number it will show the whole image.

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Set nx, ny

Place a rectangluar selection on the image and click this button to read its width and height.

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Set nz

Click twice at different positions of the image's z-slider to set the z range.

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Track selected object

Use ImageJ's Point Selection tool to select an object in the image and then hit this button to start its tracking. You do not have to wait for the tracking of one object to be finished; you can immediately start tracking another object.

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Cancel tracking

Stops all tracking threads.

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Show track table

Shows a table with the current tracks.
Newly computed track positions will be added on the fly.
All columns can be sorted by clicking on the column names.
The currently selected object will be highlighted in the image.

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Save track table

Saves the table as a text file for further processing, e.g. in R or Excel.

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Clear track table

Removes all tracks from the track table.

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Show tracked objects

Opens as many new image windows as there are completed tracks. Each image window shows the data locally surrounding the respective track. The size of the shown region can be adjusted by the changing the values in 'Cropping radii'.

Main ideas behind this functionality

One often wants to observe morphological changes of moving objects. It is however very challenging for the human brain to focus on the morphological changes as it is distracted by the object's motion. Thus, having a 'stabilized view' on the object, where its translocation is eliminated is very helpful. In addition, the 'stabilized view' also reduces the amount of data needed to further study the object.

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Report issue

Opens the github issue web-site.

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Enhance features

You can choose between 'None' and 'None'.

None

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None

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Tracking Method

You can choose between 'center of mass' and 'correlation'. For both methods, the manually entered background intensity is subtracted before the computations are done.

center of mass

The center of mass is very fast to compute. For 'center of mass' the position at each time-point is determined by an iterative (n=10) center-of-mass computation, where the size of the region in which the computation happens gradually shrinks from "Object size * Tracking factor" to "Object size".

correlation

For 'correlation' the position of the first time-point is determined as its center of mass. The position of subsequent time-points is determined relative to the previous time-point by computing the shift that yields the maximal cross-correlation between the signals.

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