The code (ds2.imagePath = path) should be added in the demo.py

[XJhaoren]

ds2 = deepcopy(ds)
# Nordland winter dataset
ds2.name = 'winter'
#ds.imagePath = '../datasets/nordland/64x32-grayscale-1fps/winter'
try:
    path = os.environ['DATASET_2_PATH']
except:
    path = '../datasets/nordland/64x32-grayscale-1fps/winter'
    print "Warning: Environment variable DATASET_2_PATH not found! Trying '"+path+"'"
ds2.imagePath = path
ds2.saveFile = '%s-%d-%d-%d' % (ds2.name, ds2.imageIndices[0], ds2.imageSkip, ds2.imageIndices[-1])
# ds.crop=[5 1 64 32]
ds2.crop=[]