Help
Author
Info This node comes with the addon pack. Get it here.

Credits
Warnings
Bugs

related discussions

start a forum thread about this node

about ColorTracker (FreeFrame DShow9)

open source

• code available via:https://github.com/vvvv/vvvv-sdk/tree/develop/vvvv45/src/nodes/freeframes/ColorTracker
• includes project files for the Code::Blocks c++ IDE
• depends on opencv 1.0 libraries

usage

When you use ColorTracker, the most important step is the fine tuning of the tracking parameters.

These are:

• Object Color (H, S, V) or (R, G, B)
• Hue(H), Saturation(S) and Value(V) Tolerances

To achieve an optimal tracking output, these parameters have to be adjusted to the lighting situation of the video scene (or vice versa) and to your object color.

If possible, turn off automatic gain control (AGC), automatic brighness ajustment etc. on your camera.

During fine tuning of the parameters you should have Show ThreshImage set to 1, so you can see which pixels of the image are considered as belonging to the object (i.e. those which are white). Also, set Show ROI to 1, to see the search frame. When nearly all pixels in the area of the object are white and the rest of the image is black, you're done.

Like a good linear minimizer, adjust one parameter at a time, then continue with the next one. Playing around will give you a feeling for this...

Contrary to  CamShiftTracker (FreeFrame DShow9), ColorTracker reinitialises itself when parameters are changed, so you get a direct feedback if your parameter change has a positive effect.

First, set H, S and V Threshold pins to a high value (>0,8): most of the image, including the object, is supposed to be white now. If your object doesn't show up as a cloud of white pixels in the thresholded image, increase all Thresholds a little (if you reach value '1.0' for all thresholds, all pixels, regardless of their original color, will be white).

Start decreasing 'H Threshold' value, until the white pixels on your object start to look noisy, then adjust the hue value of the input color ('Hue' pin on 'HSV Join' node in helppatch), until the object appears (mostly) white and the rest of the image is black. Repeat these two steps until there's no improvement.

Then repeat these two steps (decreasing threshold, adjusting input color value) with 'V Threshold' and V input color value, and 'S Threshold' and S input color value, respectively.

When you're done, you might repeat all steps until you don't see any improvement.

If all that doesn't help, you might have to improve the lighting situation.
Think about illuminating the object with a lamp, or adding a diffuser if the video image is too dark and the colors don't come out right.