Problem
1. Write a function to blend two pictures of the same size together, with the weight of the first picture changing linearly from 1 in the first row to 0 in the last row in the final picture, and with the reverse happening for second picture.
2. Write a function to interleave two pictures of the same size together in k horizontal strips of equal width (k is given as input). The first strip should be of picture 1, the second strip of picture 2, the third of picture 1, and so on to the end.