Screening for printing smooth skintones

[WharfRat]

I would try something as simple as running the M and C at the same angle
and placing the Y at the C angle.

(Please - no "dis"ing until you have tried it.)

MSD

 

[gordo]

I would try something as simple as running the M and C at the same angle
and placing the Y at the C angle.

Yikes, you're braver than me - I wouldn't even try doing that. There's a fair bit of on-press published research that would disqualify that option. But if it works for you....

When skin color predominates, printers will sometimes switch angles from the N American standard: 15C 75M 0Y 45K and use 15C 45M 0Y 75K (avoids M/Y conflict/moiré but introduces C/Y conflict).

More info on screen angle options here:
Quality In Print: Halftone screen angles - part 2 of 3

best, gordon p

 

[marktonk]

Gordo,


To be fair, we usually are in agreement
Mark

Seems I have a talent for being disagreeable.

best, gordo

 

[otherthoughts]

For what it's worth?

For what it's worth?

Thanks for the feeback. We have run Staccatto 20-micron for about 2 years now and really like the smoothness and the ability to hold detail in most cases. Only issue we have run into has been single-color tints (such as 50% black only screens). We don't run a tremendous amount of flesh tones, but the some of the flesh tones that we do run seem kind of grainy to me.

The darker skintones seem to reproduce great, but very light colored skin (particularly in smoother areas such as the cheeks) seem to show some grain. Haven't heard any complaints from existing clients though. It's just that we are approaching a new client and they are making a huge deal about smooth skin tones. That is why I am staring at previous work we have printed and noticed this grain.

Now I am thinking that maybe the graininess is coming from the digital images themselves. It could be that they were not very good captures to begin with....

With regard to the first item emphasized above that relates to 50% Black Screen Tints.
Image-quality/capture would, of course, have no role to play regarding screen tints. So this particular issue points directly to the multitude of Screening and or Printing considerations that have been most superbly argued by the talented pool of posters so far.


With regard to "very light colored skin (particularly in smoother areas such as the cheeks)".I have a few suggestions that may help to discern whether you are dealing with a screening issue or an image issue

We are all aware that a decent offset press is capable of printing a 5% to 95% dot range. The best I'd ever encountered, some years ago was 2% to 97%.

Now lets say that your very light skin tone of the cheek is 40%Yellow 33%Magenta 5%Cyan and 2% Black(due to heavy GCR). If your press is only capable of the 5% to 95% range, what happens to your 5% Cyan dot in the light skin tone? Less than regular I would suspect. What about the 2% Black dot with a press capable of a 2% to 97% range?

Now lets remove the GCR effect in the light flesh-tone, the Cyan printer grows to 8% and the 2% Black dot is eliminated. Wouldn't this result in a smoother flesh-tone?

What I am suggesting, is that when you bump up against the limitations of your printing processes, there will be inconsistencies. I am also emphatically saying that there is nothing wrong with using GCR. I only used GCR here to illustrate a point.

So what does this mean? If you closely inspect your light flesh-tones and happen to notice that your Cyan printer is dropping in and out, resulting in a grainy effect. Well that can't be good can it? Everyone that performs color-corrections at your shop should know the printing range of your press(s). I've seen many operators set their image highlights to 3%C, 2%M, 2%Y, 0% K, totally unaware of whether their presses/work-flow was capable of reproducing it.

With regard to graininess associated with film-speed/shutter-speed/aperture settings. This type of graininess is typically most prevalent in the shadows.

And lastly, masking off the flesh-tones areas you are concerned with and reducing the "Unsharp Masking" signals of the gray components(Cyan and Black channels) might also help to smooth things out

Best Regards
OT​

 

[CFPrinting]

The troublesome area with Traditional screening is the 0 angle on the Yellow. Both the 15 and the 75 angles have a visible moire' against the 0, verses a mild pattern with the 45 and 0. Once the Yellow becomes a little dirty, that moire' shows up on the image. Since flesh tones usually involve the yellow and magenta, it is always a good idea to put the magenta at 45. Teal colors would have the cyan at 45.

 

[CFPrinting]

I would try something as simple as running the M and C at the same angle
and placing the Y at the C angle.

(Please - no "dis"ing until you have tried it.)

MSD

Wouldn't this result in extreme color shifts throughout the run?