In this paper, we present new algorithms for computing maximum perimeter and maximum area of the convex hull of imprecise inputs based on the parallel line segment model. The running time of our algorithms for maximum perimeter problem is O(n4 ) which improve over the previous results of O(n5 ) in [12]. For maximum are problem with different size of parallel line segments [12] gives O(n3 ) algorithms. We give O(n log n) algorithms with the assumption that all parallel line segments have the same size.