You can define the chart structure just by changing the number of patching in the rows and columns, then using QTR linearize-data, you can parse the measurement file and it will average the readings for you.
When I do this for the 21x4 I can measure the standard 21 step target (not the 21x4 random or 21-step random) 4 times and then run the measurement file through the qtr linearize data app and it will spit out the graph, averaged Lab, and density measurements that you can plug into whatever you might need the averaged measurements for. This is what I do for the the 51-step target now too. It is 3 rows of 17, so I define the measurement chart in i1 profiler as 9 rows of 17 columns. I measure the whole chart once, then go back to the top and measure it again 2 more times.
Hope that helps,
Richard Boutwell