If you wasnt reading FLARToolKit mailing list, here is short summary: FLARToolKit converts color image to “binary” image before doing any magic on it, using fixed threshold filter. In fact, this threshold is simply hard-coded to be 80 in many examples, and you will need to write more code to detect good values for threshold if you want your application to run regardless of lighting settings. The filter in this experiment avoids the problem by using local average brightness as a threshold for every pixel; the downside is that it enables FLARToolKit to “see” far more details, thus wasting even more CPU time. As a work-around, I tried to narrow down search area in the image using last detected square, but this only helps when marker motion is limited.
Well, check it out, play with it, and let me know what you think.