Fixed import issue and replaced uniform_filter with a simple mean in test_images.py
Fixed import issue and replaced uniform_filter with a simple mean in test_images.py

mikarubi/thunder,pearsonlab/thunder,poolio/thunder,broxtronix/thunder,poolio/thunder,jwittenbach/thunder,mikarubi/thunder,kunallillaney/thunder,kcompher/thunder,j-friedrich/thunder,pearsonlab/thunder,j-friedrich/thunder,oliverhuangchao/thunder,zhwa/thunder,oliverhuangchao/thunder,kcompher/thunder,broxtronix/thunder,thunder-project/thunder,kunallillaney/thunder,zhwa/thunder