Color tracking - what are the best colors to use?

hi, ive currently just started doing some research into colour tracking, where i’ll be tracking a number of coloured objects and trying to work out what colours will work best

so that,

  1. the objects are clearly distinguishable from one another
  2. and they are brighter then the average person’s clothes who will be holding the objects.

initial thoughts were to use Red, Green, Blue as the colors.
but then i know that Green as a colour is much brighter compared to the other two.

so now thinking of using Green with Cyan and Yellow
as Cyan and Yellow both have a full value of Green in them with a combination of Blue and Red.

just thought id put it out to the forum and see what people think or have had experience with.

many thx,
L.

hey L,

short answer: it depends.

your camera might respond better to different colours, or your scene might have something in the background that makes particular colours more appropriate.

just try different colours and see what happens.

i’ve ended up going with fluro colours since the last post.
they are a lot brighter and less likely to clash with clothing, unless you’re at a 90s rave :slight_smile:

promising results so far, tracking 3 colours in OF and passing the data to a flash application.

will post any findings regarding colour tracking as the project progresses.

thx,
L.

good work! looks very nice :slight_smile:

Just out of interest; are you tracking them in RGB space? If so you may find it more successful to track in HSV or YCbCr since they both have a specific lightness channel (which you can ignore) and therefore make them more robust to lighting variation.

M.

hi mhax,
yeah im doing the tracking in the HSV color space.
if anyone is interested, the project lives in,
http://julapy.googlecode.com/svn/trunk/openframeworks/colorTracker/trunk/

its basically an amalgamation of examples i found on the forum with added contour analysis and TCP connection to flash.

referenced examples include,
http://www.berio.alg-a.org/Tracking-colors-tracking-laser
http://gamuza.d3cod3.org/

L.

I have a live voting system running with bright pastel colours that I track. It works pretty well so far on a 200 person room. I picked a pink and blue and they work well as you can narrow down the spectrum and also check for size. I do a calibration routine regulalry for light changes as well.

I am not sure of your scenario, but for mine it was all about lighting. Getting good, neutral bright diffuse lighting with no hotspots in the tracking area took a while and some clever lighting folks.

The other big deal is the camera. If you can find a camera that captures 4:2:2 you will be better off, I did not have the gear to try a 4:4:4 colour space but imagine it would be better again. Most cheaper cameras are 4:2:0, a pretty restricted colour space that makes it hard to differentiate close colours and gave a lot of false positives. Also getting a really neutral white balance and not overly hot gamma keeps the image getting into your computer more like the outside world and not crushed. A high qality camera with manual control will help a lot.

My experience was getting it right was way more work outside the computer than I thought, but it can work great.

Fred