A printing industry blog focusing on color measurement, printing, ink, paper, spectrophotometers, and densitometers.
One reader made a comment at JimRaffel.com that density is also a good indicator of ink film thickness on a printing press. Just remember that two inks with different pigment loads can record the same density and have different ink film thickness.
Coming next…Part 5 Measuring TVI of Inkjet proofs in meaningless
Part 3: TVI in and of itself is not a bad thing: Back when TVI was called Dot Gain, I remember going into print shops and having pressman tell me “No, we don’t have any dot gain.” This was not ignorance (they knew they did), but instead a misconceived notion that TVI was a bad thing. I always countered this by saying that Dot Gain is not bad; however, NOT knowing what you Dot Gain is, is a bad thing. Think of it as trying to get from one city to another in a car without a map. We need to know where we are in order to get where we are going.
Coming next…Part 4. Density is king
Part 2: GRACoL 7 appears to be taking our pressrooms in a direction where TVI will be significantly less importance in monitoring production run stability. Instead GRACoL 7 is based on maintaining gray balance utilizing density and L*a*b* values. Over all, I feel this is the right direction to go and from what I have heard and seen several test press runs have proven this to date. Even GRACoL 7, however, recommends taking a look at CMYK TVI values when the system does not seem to be working as intended. TVI and TVI variation are still incredibly powerful and simple measures of press stability. I have watched real pressroom experts track down loose blankets and other press problems by first taking a look at TVI numbers, then looking for the actual mechanical problems. (NOTE: If you have not read the GRACoL 7 draft quite frankly you must. This methodology will become a barrier to entry very quickly.)
Coming next…Part 3: TVI is not a bad thing.
This is Part 1 of a 5 part series from Jim Raffel’s TVI notebook.
Part 1: Tone Value Increase (TVI) really is a better term than Dot Gain: My short answer for this is that a densitometer (or spectrophotometer acting as a densitometer) does not actually measure dots, so how can we really call it Dot Gain? Add to this the fact that some systems being used for proofing result in continuous tone images with no dots and my position becomes a bit clearer. Those on the SWOP committee that spearheaded the initiative to change this misleading term (which I resisted early one) should be commended. After all, when a 50% patch of a color increases to an apparent 65% patch of that color the tone value has in fact increased regardless of whether that patch is made up of dots or not.
Coming next…Part 2: GRACoL 7 & TVI