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In this work, we propose refinements to the difference-smoothing algorithmfor measurement of time delay from the light curves of the images of agravitationally lensed quasar. The refinements mainly consist of a morepragmatic approach to choose the smoothing time-scale free parameter,generation of more realistic synthetic light curves for estimation of timedelay uncertainty and using a plot of normalized $\chi^2$ computed over a widerange of trial time delay values to assess the reliability of a measured timedelay and also for identifying instances of catastrophic failure. We rigorouslytested the difference-smoothing algorithm on a large sample of more thanthousand pairs of simulated light curves having known true time delays betweenthem from the two most difficult `rungs' -- rung3 and rung4 -- of the firstedition of Strong Lens Time Delay Challenge (TDC1) and found an inherenttendency of the algorithm to measure the magnitude of time delay to be higherthan the true value of time delay. However, we find that this systematic biasis eliminated by applying a correction to each measured time delay according tothe magnitude and sign of the systematic error inferred by applying the timedelay estimator on synthetic light curves simulating the measured time delay.Following these refinements, the TDC performance metrics for thedifference-smoothing algorithm are found to be competitive with those of thebest performing submissions of TDC1 for both the tested `rungs'. The MATLABcodes used in this work and the detailed results are made publicly available athttps://github.com/rathnakumars/difference-smoothing

Crash testing difference-smoothing algorithm on a large sample of simulated light curves from TDC1