Part 5: I should start by saying I have covered the topic of using graphic arts densitometry to evaluate inkjet proofs once before. Back in July ’05 GN#5 addressed this same issue so you may wish to refer back to it. I considered changing this topic, because the title is a bit inflammatory. Understand that my frame of reference is users of our software who rely upon density and TVI as process control measurements for inkjet proof production.
Far too many times I have seen the density and TVI values stay within tolerance, and yet the Delta E shifts can be huge. Those of you who follow the blogging I do at JimRaffel.com (yes, I write more than once a week sometimes), saw a graph of the spectral response of the Red, Green, Blue, and Visual filters used in graphic arts densitometry. Those filter responses are specifically designed to address the spectral response of process cyan, magenta, yellow and black. While I was not able to find them for this week, I have seen graphs which compare the spectral response of offset printing inks with typical inkjet inks. By next week I will either find the curves or reproduce them myself once I am back in the office. A picture will be worth a thousand words when I post those graphs at JimRaffel.com.
Coming next… How important is Gloss?