Solid Ink Density on proof

[rwolfe54]

Ideally should the densities be the same or close to what is targeted at press? We have some debate as to whether the SID on proof correlate to press SIDs.

[Erik Nikkanen]

Ideally should the densities be the same or close to what is targeted at press? We have some debate as to whether the SID on proof correlate to press SIDs.

A density value is determined from a specific reflection profile from the image. One can not see density. It is not a colour or even a level of darkness. When measuring density with the same system of ink and paper, density is a relative measure of reflectance recalculated where D = log 1/reflectance. (reflectance has a range of 0 to 1)

When measuring different ink sets on different papers etc. there is no direct relationship with the density values. Metameric pairs can look the same but their density values can be different. The aim is to get a metameric pair match and not a density match for same locations in the images.

Also the SID patches on a press is different than on a proofer. The SID on a press is more directly related to the ink films on the press for the printing condition. On a proofer, since there is more independence of ink deposit anywhere in an image, the patch does not have to have a fixed relationship to how the image is determined.

[Stochast]

Ideally should the densities be the same or close to what is targeted at press? We have some debate as to whether the SID on proof correlate to press SIDs.

In a word, NO. In today's digital proofing, we traditionally lose sight of what the proof is for - color. If your proofer is set up to or at least near ISO/GRACoL/SWOP, then you will have a better result doing a visual comparison than allowing yourself to be misguided by a densitometer.

Once your shop invests in a G7 linearisation, the G7 Expert will thoroughly train you in printing spectrally, and in doing so, will explain why densitometric comparison doesn't work. If you have any type of Spectrophotometer, eg: X-Rite Eye-One, 528 HH, etc., perhaps you can utilize it and develop your QC methods with L*a*b*. Check out Measure Tool, a piece of X-Rite's GMB Profile Maker Suite. It has a spot reading tool that is undongled, and will give you DeltaE. Further, go to xrite.com and search "colorguide" and download and print the PDF. It will explain L*a*b* very well, and set you on your way...

[rich apollo]

Typically, no.

[jkoors]

The item to pay attention to in the proof is Tone Value Increase (TVI). Density isn't a factor, instead what you should pay attention to color similarities (gamut), tone and reproduction of the proof to closely match the final press results.

[meddington]

The item to pay attention to in the proof is Tone Value Increase (TVI). Density isn't a factor, instead what you should pay attention to color similarities (gamut), tone and reproduction of the proof to closely match the final press results.

For the same reason that Erik pointed out, TVI on a proof can be dissimilar to production printing. TVI, afterall is based on density measurements. Often there is similarity, but not a guarantee.

[jkoors]

Well, not really... TVI was coined and used particularly by SNAP organization so that it could be referred to in both the printed density environment and the proofing environment. In actuality it's not solely a measurement, rather also a visual understanding of how the tone has increased (darker, lighter, mid-tone increase etc...) and without measurement you can "visually" reproduce similarly. I also stated, "Close representation of proof to press". I never stated a guarentee of exact proof to press match.

[Erik Nikkanen]

The item to pay attention to in the proof is Tone Value Increase (TVI). Density isn't a factor, instead what you should pay attention to color similarities (gamut), tone and reproduction of the proof to closely match the final press results.

Unfortunately TVI is based on density values and is also not totally comparable between two different ink and paper systems.

Even when comparing in offset printing, printing a screen of the same single ink and paper combination, one can have the print of FM and AM have the same TVI value but they will not necessarily look the same. One has to be careful. When measuring TVI of any ink other than black, the TVI value is not directly related to what you see.

Comparing colormetrically so far is the best way to compare.