def sortForSameExpTime(expTimes, img_paths):
    '''
    return image paths sorted for same exposure time
    '''
    d = {}
    for e, i in zip(expTimes, img_paths):
        if e not in d:
            d[e] = []
        d[e].append(i)
    d = OrderedDict(sorted(d.items()))
    return list(d.keys()), list(d.values())