问题
I need a collection of sample images to train a Haar-based classifier for face detection. I read that a ratio of 2 negative examples for each positive example is acceptable. I searched around the web and found many databases containing positive examples to train my classifier (that is, images that contain faces), however, I can't any database with negative examples. Right now, I have over 18000 positive examples. Where can I find 2000 or more negative examples?
回答1:
use http://tutorial-haartraining.googlecode.com/svn/trunk/data/negatives/
or any other image set that has no objects you need to recognize
NOTE: the number of samples you mention is too big, you don't need so much to obtain high accuracy
来源：https://stackoverflow.com/questions/32429150/where-to-get-negative-sample-images-for-haar-training