How to impose 1 Bit Tiff files

[helmuttgutenberg]

I would like to impose 1 Bit Tiff files to get a print in offset in a same sheet with different dot (fm,Am dot in a same signature)

 

[Marko]

re:How to impose 1 Bit Tiff files

I would like to impose 1 Bit Tiff files to get a print in offset in a same sheet with different dot (fm,Am dot in a same signature)

the main purpose of a 1 bit tif is that its already screened with a set of dots, line screen and resolution.

Do you have something to do your screening. If so, try a pdf or contone tiff.

mark

 

[pcmodem]

If your RIP software has the ability to create a Low-Res link FPO file of your 1-bit tiff. You should be able to create an impo from your FPO files, then send the impo back to the RIP to link back up with the High-Res files.

 

[imagesetting]

We used to have a customer who used something called Iceworks (I need to check that) - it did exactly what you wanted - ie it created a 1 bit tiff, screened, FM or conventional.
We would output film for him from his files he'd set up.

The RIP wouldn't screen his files as it treated it like line work.
So you would be able to lay up your files imposed with different screen types on the same signature.

 

[gordo]

We used to have a customer who used something called Iceworks[SNIP]

I believe that you are thinking of IceFields: ICEFIELDS

To the OP.
Many RIPs have the ability to export 1 bit screened tiffs of your documents which can then be imposed just like any other file using your imposition application or placed and imposed in a page layout application and exported as a PDF.

Your RIP may have this ability as a licensed option. If this is a one-time test then your vendor may give you a temporary trial license (usually 30 days) so that you can do your testing.

Kodak's Prinergy has a utility called "DotShop" which allows you to apply different screening to different areas of a PDF prior to RIPping. Perhaps other workflows also have this ability.

A word of caution, mixing different screening types (especially FM and AM) on the same press form can be problematic because they have different ink/water requirements. If you must mix them then you should try and impose the press form so that halftone screens of the same kind are inline with one another.

best, gordo

 

[Al Ferrari]

Different ink/water requirements?

Different ink/water requirements?

A word of caution, mixing different screening types (especially FM and AM) on the same press form can be problematic because they have different ink/water requirements. If you must mix them then you should try and impose the press form so that halftone screens of the same kind are inline with one another.

best, gordo

Hi Gordon,

Other areas of a plate such as a large screen area in line with a large solid also have different ink/water requirement. Yet these are handled routinely. Why do the different ink/water requirements of AM/FM areas of the plate behave specially differently?

Please explain at greater length.

Thanks,

Al

 

[gordo]

Other areas of a plate such as a large screen area in line with a large solid also have different ink/water requirement. Yet these are handled routinely. Why do the different ink/water requirements of AM/FM areas of the plate behave specially differently?

I'm not so sure that a large screen area in line with a large solid has a different ink/water requirement.

Basically, all things being equal, for any given tone value, the dots of an AM/XM screen have smaller perimeter to area ratios as well as carry a thicker and less even film of ink than typical FM screens. In contrast, FM screens have a larger perimeter to area ratio and carry a thinner more homogeneous film of ink. That makes the FM screen susceptible to over emulsification or attack by the fountain solution if the ink/water balance on press is set up to print AM/XM.
That's not to say there will be problems running AM/XM on press with FM - but there may be, and it may be sufficient to invalidate a comparative test (if that's being done in this case).

best, gordo

 

[imagesetting]

Ahh yes, IceFields it was.

I would second the mixing of screen types on the same job (if possible), would introduce complications for the press minder.
You maybe able to print something, but how acceptable the results would be is down to you and your customer to establish.
http://www.imagesetting.com

 

[Al Ferrari]

"For a given tone value" is the key.

"For a given tone value" is the key.

After sleeping on this, I am starting to understand the potential problem suggested by Gordon.

This could be tested with a plate form consisting of a row of 10 - 90% AM screen test patches across the plate followed a row of aligned 10 - 90% FM screen test patches, followed by a solid bar.

How would a given pair of AM/FM patches compare when an even density was achieved across the plate for the solid bar? This form could be used for testing different ink and fountain solution formulations.

Perhaps there is a published report of some such test that someone could point us to.

Al

 

[gordo]

After sleeping on this, I am starting to understand the potential problem suggested by Gordon.[SNIP]
Perhaps there is a published report of some such test that someone could point us to.

Al

The difference in lithographic performance was written about in the article "The Lithographic Impact of Microdot Halftone Screening" published by the Technical Association of the Graphic Arts in the 2003 TAGA Proceedings.

It's also alluded to or mentioned in most technical documents about screening.

Unfortunately there's very little published technical information, or proper research done, on such basic subjects as ink/water balance, solid ink density,grey balance etc. There's a great deal of opinion, anecdotal experience, and parroting of so-called industry truths, but.....oooops! I'm starting to rant.....sorry!

best, gordo

 

[Al Ferrari]

Now someone has to step up to the plate.

Thanks for the rant.

Al

 

[Deleted member 16349]

After sleeping on this, I am starting to understand the potential problem suggested by Gordon.

This could be tested with a plate form consisting of a row of 10 - 90% AM screen test patches across the plate followed a row of aligned 10 - 90% FM screen test patches, followed by a solid bar.

How would a given pair of AM/FM patches compare when an even density was achieved across the plate for the solid bar? This form could be used for testing different ink and fountain solution formulations.

Perhaps there is a published report of some such test that someone could point us to.

Al

Hi Al,

I have been under the impression that the FM screens in the lower range were not affected much by the changes in ink film and therefore by changes in the solid density. This implies to me that some movement in density could be done and the FM screen (in the lower range) would be more consistent while the AM screen values could be moved a bit to some desired reading. This phenomena might be helpful if wanting to run both screens. Just conjecture on my part. Maybe Gordon has some practical experience on this.

In your test set up, comparing the difference in the screens is interesting. Gordon had some samples of FM and AM screening that I got from him that kind of showed this. The interesting thing to me was that even though the screens were printed with the same ink and paper, side by side, the colours were slightly different in some paired samples. This implies to me that colour management would be required if there was an interest to obtain matching pairs of patches or to run different screens on the same sheet. Single ink patches would not match but multi CMY screens would be required.

 

[gordo]

I have been under the impression that the FM screens in the lower range were not affected much by the changes in ink film and therefore by changes in the solid density.

There are two primary reasons that combine for the greater stability of FM screens when SIDs vary - the small surface area of FM dots don't allow for a greater ink film thickness, and the dot gain/TVI of FM screening is primarily optical so it is not as much affected by the spread of ink under pressure.

This implies to me that some movement in density could be done and the FM screen (in the lower range) would be more consistent while the AM screen values could be moved a bit to some desired reading.

Correct. The flip side is that the tones/color represented using AM/XM screens will vary more through the press run.

This phenomena might be helpful if wanting to run both screens. Just conjecture on my part. Maybe Gordon has some practical experience on this.

It would help you to match tones between the two screens however the different ink/water balance requirements could cause problems that would shift tones in opposite directions.[/QUOTE]

The interesting thing to me was that even though the screens were printed with the same ink and paper, side by side, the colours were slightly different in some paired samples. This implies to me that colour management would be required if there was an interest to obtain matching pairs of patches or to run different screens on the same sheet. Single ink patches would not match but multi CMY screens would be required.

FM screens have a larger and somewhat shifted gamut compared with AM/XM screens. With color management you could make FM screening match the color of AM/XM screening, but you cannot use color management to make AM/XM screening match FM colorwise.

And, for the sake of accuracy - it is not how the halftone dots are organized (AM/XM vs FM) that is the important issue - it is the size of the dots that makes the difference. I.e. FM performance is the result of the properties of micro-dots on press. If you print your AM/XM screen at 400+ lpi it will show many of the same lithographic properties as an FM screen.

best, gordo

 

[Deleted member 16349]

And, for the sake of accuracy - it is not how the halftone dots are organized (AM/XM vs FM) that is the important issue - it is the size of the dots that makes the difference. I.e. FM performance is the result of the properties of micro-dots on press. If you print your AM/XM screen at 400+ lpi it will show many of the same lithographic properties as an FM screen.

best, gordo

Yes, I discussed this phenomena of small dots in my 1997 TAGA paper. Glad to see that my analysis matches real results.

 

[Al Ferrari]

Well now that we are all Direct To Plate, is there a reason, aside from the increased file size, that the industry does not explore these stability benefits of 400+ lpi?

 

[gordo]

Well now that we are all Direct To Plate, is there a reason, aside from the increased file size, that the industry does not explore these stability benefits of 400+ lpi?

I don't know which side of the industry - vendors or printers - you are referring to but, some on the vendor side have already explored the stability of 400 lpi vs FM (FM is lithographically still better). The vast majority of printers aren't explorers ("Why fix it if it ain't broke?" "Customers aren't asking for it").

best, gordo

 

[imagesetting]

Lower line screens just give better latitude on press, 200lpi would be sufficient - and in the ever stressful production environment - you cant box yourself in.
It would have been great to experiment with FM screens, profile the workflow, but often their are just not the resources (time and money).
http://www.imagesetting.com

 

[SteveAgfa]

imagesetting:

Your comments reflect the reasoning behind hybrid or in our case Sublima XM screening.

At 175 lpi AM screening, a 2% dot is 2x2 pixels (21 microns). That's the smallest size dot
we use in an XM implementation. To get a lighter tone, we no longer make the dot smaller,
we make them fewer.

With Sublima, all the dots align along established ABS (AM) screening angles, and give the
smoothness of AM flat tints, the detail of a higher line screen (210, 240, 280, 340), and the
ease of use on press of a 175 lpi screen, since the smallest dots we generate are no smaller
than that 2x2 pixel dot.

Regards,

 

[J]

imagesetting:

Your comments reflect the reasoning behind hybrid or in our case Sublima XM screening.

Nice plug for Sublima - with a post totally irrelevant to the issues under discussion.

J

 

[gordo]

Your comments reflect the reasoning behind hybrid or in our case Sublima XM screening.

With Sublima, all the dots align along established ABS (AM) screening angles, and give the
smoothness of AM flat tints, the detail of a higher line screen (210, 240, 280, 340), and the
ease of use on press of a 175 lpi screen, since the smallest dots we generate are no smaller
than that 2x2 pixel dot.

Just to drive the point home:
:Sublima is Agfa ABS (their AM screening) but without a 1% sized halftone dot.
Other than the lack of 1% sized dots the screens are identical, indistinguishable, exactly the same, undifferentiated.

If your CtP, or plate, or press cannot image a 1% sized dot then :Sublima may help you to render a 1% tone using 2% sized dots.

Other than that, :Sublima when run at the same lpi as is no easier than any other AM screen at 210, 240, or 340 lpi since :Sublima is a conventional AM screen (minus the said 1% sized dots).

best, gordo