I am trying to detect specific objects in images using Haar cascade in OpenCV.
Let's say I am interested in detecting stop signs in landscape images. When defining positive image samples for my training set, which would be the best kind of image: (a) full images with my object, (b) a medium crop or (c) a tight crop?
Similarly, what's best for negative images? Does this influence overfitting? I would also appreciate any other general tips from those with experience. Thanks.
Image ref: http://kaitou-ace.deviantart.com/art/Stop-sign-on-a-country-road-Michigan-271990933
You only want features that you want to detect in your positive samples. So the C image would be correct for positive samples.
As for negative samples you want EVERYTHING else. Although that is obviously unrealistic if you are using your detector in a specific environment then training to detect that as negative is the right way to go. I.e. lots of pictures of landscapes etc (ones that don't have stop signs in)