morphological filters affect the shape they mostly work on binary images the most common are erode, dilate, close and open algorithm with which you can make a "pepper or salt removing filter" to remove black or white isolated pixels
concerning background subtraction, if you use a fixed background (you make a snapshot at startup and subtract it to the video stream) you will have defects due to light change, some background part could be interpreted as a foreground feature adaptive background technique use a dynamic image reference, which could be made with a low-pass filter, this image is then subtracted to the video stream this makes a high-pass filter -- do it yourself http://antoine.villeret.free.fr 2013/4/18 Ska Frenz <skafr...@gmail.com> > Hi, thank you for the suggestions, I'll check openCv. Can you explain how > to use "morphological filters" to clear up the noise in the image? Are > there examples around? Also, could you please explain me better what do you > mean with "adaptive background subtraction method"? > > Thank you for your time :) > > francesco > > > 2013/4/17 Antoine Villeret <antoine.ville...@gmail.com> > >> hi, >> >> the segmentation method (how you extract what is your interest from the >> rest of the image) is very critical in video tracking >> background subtraction is a basic way to extract blob and it works only >> in certain conditions of light (if you want to track something outdoor, you >> should use an adaptive background subtraction method) >> moreover, there is no general method to do video tracking, it depends on >> what you want to track and how it is filmed >> >> so, the first thing is to have a good image, with not too much lighting >> changes, good contrast between background and features to track >> then you can start thinking about segmentation, and the >> segmentation accuracy depends on the quality of the video >> you may need to do something more than just background subtraction, for >> example, you could apply some morphological filter to remove noise >> after that, you can start tracking >> you could also apply a threshold on the blob size to not track very small >> blob >> blob of interest are often surrounded by very small blobs due to >> segmentation noise >> >> but you can have a look at pix_opencv objects, >> there is [pix_opencv_blobtrack] which implements a whole processing >> chain, including foreground extractor, blob detector, blob tracker and >> follower >> I'm not sure it's included in pd-extended, but you can find some binaries >> on build server >> >> hope this help >> >> antoine >> >> >> -- >> do it yourself >> http://antoine.villeret.free.fr >> >> >> 2013/4/17 Ska Frenz <skafr...@gmail.com> >> >>> Hi everyone, this is my first time on the pd-list so I hope I won't do >>> anything wrong. >>> I'm writing here to get some help about pd tracking objects >>> (pix_blob..). I'm using the background subtraction method, to track objects >>> and I need help to understand how I can track multiple objects with >>> multiples different blobs. I'm trying the pix_multiblob and yes, it show 2 >>> blobs..but they track the same object. Then basically I do not understand >>> how can I make the first blob to follow just one object for all the time >>> that specific object is inside the webcam rectangle, and the second blob to >>> track another separate object. I cannot find any material that clearly >>> talks about this.I attached the patch I'm working on. I'd love to see some >>> well-explained examples if you know where to get them. >>> Thank you very much for your help :) >>> >>> Francesco >>> >>> _______________________________________________ >>> Pd-list@iem.at mailing list >>> UNSUBSCRIBE and account-management -> >>> http://lists.puredata.info/listinfo/pd-list >>> >>> >> >
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