Make all text in pdf slightly thicker/fatter. (Simulating the dotgain in offsetprint)

[Niclas]

Hi
We're shifting towards digital printing (b/w books) in our plant and since our old customers are used to the normal dot-gain of everything that was printed on our offset-presses, they spot the difference, since our digital press produces very close to what they see on their screens.

So my question is, how can we make our digital printed books, look the same as the books produced in our offset presses?

Our digital press is based on Kodak Stream InkJet, but nothing in the Kodak system seams to help us, since we want to make 100% text fatter/thicker and not increase halftones.
Using PitStop, we have experimented with converting all text to outline and then adding a stroke on the outline.
But that is to much manual work, and gave us letters that was fatter than others in the same sentence (I think it's the outline precision that gives us that result)

I've tried GhostScript, and converting pdf's to outlined text and it looks better than when PitStop outlined text. But from GhostScript I can not see how to add stroke to the outline/make the text fatter.

Another thing I was thinking about, is if it is possible to manipulate the font, so to say, make it fatter, and then using that font instead of the original.

Any ideas/suggestions?

Best Regards
Niclas Rådström

 

[gordo]

Hi
We're shifting towards digital printing (b/w books) in our plant and since our old customers are used to the normal dot-gain of everything that was printed on our offset-presses, they spot the difference, since our digital press produces very close to what they see on their screens.

So my question is, how can we make our digital printed books, look the same as the books produced in our offset presses?

Our digital press is based on Kodak Stream InkJet, but nothing in the Kodak system seams to help us, since we want to make 100% text fatter/thicker and not increase halftones.
Using PitStop, we have experimented with converting all text to outline and then adding a stroke on the outline.
But that is to much manual work, and gave us letters that was fatter than others in the same sentence (I think it's the outline precision that gives us that result)

I've tried GhostScript, and converting pdf's to outlined text and it looks better than when PitStop outlined text. But from GhostScript I can not see how to add stroke to the outline/make the text fatter.

Another thing I was thinking about, is if it is possible to manipulate the font, so to say, make it fatter, and then using that font instead of the original.

Any ideas/suggestions?

Best Regards
Niclas Rådström

Can you use a trapping function instead of an outline. That's what I used to do back in the day to slightly fatten or skinny text.

 

[mastegman]

I doubt Trapping would work as text would have to be printing alongside another colour. If there was no background then there would be no effect. Trapping also usually applies the 'spread' or 'choke' to the lighter colour. You can customise the effect and reverse the setting but it's still a 'messy' and editors process. I've never used Trapping in the way Gordo describes.

As the name implies Dot Gain refers to the result of appliing ink under pressure to a substrate (as you seem to understand) when printing halftone images and is relative to the size of the halftone dot and screen ruling. Dot Gain may also result from the effect of low viscosity inks 'bleeding' into a substrate especially on uncoated stock (just as ink is absorbed by blotting paper). As text is almost always rendered as linework using a solid ink I haven't considered the effect of type 'fattening' as a result of the same effect as I have not encountered it as an issue. Traditional methods of compensating for DG are to build it into the press profile and then apply customised tone adjustments to the tonal quality of the halftones in the RIP for different printing conditions (otherwise known as 'plate curves') but these would have no effect on areas of solid ink as there are no halftones to adjust.

The only solution I can see is to recommend to your designers that they choose different fonts of the same typeface. For example, set 'Regular' for digital and 'Light' for offset or Bold for digital and Regular for offset. Not sure if the result would be acceptable. Designers call. They could create two separate documents for each printing process using font substituion.This is obviously dangerous as it would probably lead to problems resulting from the text reflowing over multiple pages and text boxes.

 

[Stephen Marsh]

Have you asked Kodak for advice on DFE settings, or only looked at this yourself? If this is a big deal, chances are they are come across this before at other Prosper or Stream sites. Apart from your clients spotting a difference, is this a really a problem looking for a solution? Do they complain or is it just a “difference” that is noted? Have you tried stating that this is an inherent difference in technology? Is the text harder to read? You would have the benefit of cleaner illustrations and reversals.

On most “lower resolution devices", simply outlining fonts to vectors (with no stroke) creates a thicker/fatter result as the fonts lose their hinting and other properties. However in this case it does not sound like the result is enough to offset.


Stephen Marsh

 

[Niclas]

gordo: I'will look into what trapping can do for us, but as mastegman says, it might not work as expected. Or how did you use the trapping tool?

mastegman: I can see that problem also with trapping, however, it might be able to trick the trapping function by making all white background to black, and then all text to yellow. I'm not a prepress guy, so I don't have much experience of the trapping utility we use. (I'm the digital printing machine operator)
As to changing fonts, we get the problem with reflowing text so thats not an option.

Stephen Marsh: I've contacted Kodak about this, but they could not help us with a solution. The only thing we could play with is dot-gain on the substrate-profile, but thats only for half-tones, not solid black from what I could understand. And also saturation/brightness/contrast at the DFE, but that doesn't help on solid black.
Some customers complain about the difference, and we would want to be able to print the same book in either offset or digital and get the same result, so that customers don't spot the difference.
The customers that are complaining, normally uses a very thin font for all their publications and that font is being "more difficult" to read in digital printing.
What you say about making fonts to vectors and resulting in fatter/thicker fonts is exactly what we noticed, because even if we didn't add strokes, the text became thicker (good enough for our customer). However, outlining text can give various results. Some can be fatter than others and som might also be thinner at parts of the font.
I personally noticed that the letter k stood out (was fatter) at all pages (in a book with a certain font), but my colleagues could not see that. Also it was more visible when looking at the text from certain angles.
When talking to Kodak, they recommended us to not convert text to outline, because of what they said gav is us unexpected results.
In most cases, outlining text might give us what we want, but I'm afraid of the unexpected results that we might miss when printing a book.

Thanks for all the input and suggestions!

Niclas R

 

[gordo]

gordo: I'will look into what trapping can do for us, but as mastegman says, it might not work as expected. Or how did you use the trapping tool?

This is how I remember using trapping way back when to slightly thicken text. I don't know if you could apply the concept using today's tools using other methods. My point was that using the trapping function in your RIP might allow you to do what you need. I just don't have access to the tools to experiment with.
I used QuirkExpress:
If you have a text box with fill of "none" and black text partly over the transparent part of a spot-colour Illustrator EPS: the trapping will default to .144pt - the text effectively fattens. (but if the text box background is white: the trapping defaults to knockout). Because the type had not been converted to outlines the font attributes like hinting were preserved and you didn't get variation in the various letters.

 

[abc]

I noticed you tried the stroke technique with PitStop, you should be able to do this with an Action List and automate this, I'm not sure if you want a universal value for all text or if the value needs to change depending on the font size?
You mentioned you had tried it and had problems with precision, there is a way to change the precision on line thickness with regard to the number of decimal places it works to for rounding.
It would be interesting to see how a more 'precise' value would work.
If you would like to contact me to discuss, please feel free. [email protected]

 

[David Milisock]

If you're getting that much dot gain you may want to re-vist all your technology.