Eliminating Small Dots on Cyrel Fast Plates

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Eliminating Small Dots on Cyrel Fast Plates

Postby graciesmom » Tue May 20, 2008 1:18 pm

Until recently, my company used Film to make plates. Then we got a Digital Cyrel Fast Plate making system. The minimum dots that this is holding are sometimes too small. What is the best method of eliminating dots from PDF's, with embedded images, that dirty up bright colors and pastels? Should we increased Systems Value or change the drop everything below number. I have not had much success with the drop everything below method. But I am afraid of the loss of grey levels by using, a Systems value such as 10. I do not think that the 3% and below dots are needed in some colors. The colors just get dirty, and without the links to modify, it gets tricky. Plates are linearized , Symphony curves are used for overall color correction, 1300 line / 2.5 bcm aniloxes , but those small dots are killing the colors. Bight blue skies look overcast and grey with the 1% dots of MYK. Thanks
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby exflexo » Tue May 20, 2008 4:25 pm

Yeah, you can't leave everything up to a machine to decide.. because in the end it doesn't know that you don't need any yellow in a blue sky.

I only relied on the rip to make those decisions on minor issues, such as where sharp vignettes would fall off etc. Otherwise, we made sure that the file was "clean" in photoshop. It really requires going through each channel of the file and deciding what to leave in and what to take out. A computer can't possibly know what color an object should be, it is simply doing what it was programmed to do and treating ALL things equally. You have to have someone who understands color, photoshop and an eye for detail to handle those decisions... then you can leave the little details to the rip. You definitely do not want to be shaving off dots on the plate for all the obvious reasons. And when it comes to isolated highlight dot like you are addressing, it really needs to be handled in photoshop and not at the rip level.
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby graciesmom » Tue May 20, 2008 5:12 pm

What if you are not given the photoshop links, does exporting the embedded links to photoshop out of a PDF and then relinking it deminish the photos quality?
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby exflexo » Tue May 20, 2008 6:24 pm

Well, you can open the PDF file in photoshop.. but its re-rastering the data. But on the other hand, your rip is also doing the same thing.. so its six of one and a half dozen of the other. Personally, I'm not confortable with imaging high end process files from just a PDF, I would prefer to have the Adobe Illustrator file and the accompanying PSD support docs. I'd recommend requesting those as an S.O.P.
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby ramirez » Tue May 20, 2008 10:21 pm

Hi guys.
To me it looks like the minimum dot on the plate is not setup properly in the rip curves. I think that graciesmom is getting smaller dots than the plate can safely hold. Also, even is he's using a 1300 line anilox, the 2.5 bcm is unusually big. I think you should also try to reformulate your ink for a lower bcm anilox, as you know the print is done with solid dots. This way you'll be able to get lighter and cleaner highlights.

The dots below the minimum dot should be removed by setting up the curves properly and eliminating the first 2 levels of grey, by example, 0.4 and 0.8. A 2% digital dot in the SWOP profile should print as 4% measured with a reflective densitometer and Murray Davis formula. A 5-6% measured dot at 1% should make you happy, if you go above 6% you need improvements, you'll be able to see a hard edge at the end of your gradations. No one mentioned hybrid screening yet.

Can you describe the settings from your curve in the rip, how did you determined the minimum dot and how do you cut in the curve or rip setting the desired levels of grey.

About the blue sky or any other image, you should try to separate your images with a light black (black body curve), this way you will not have black in highlights. The defects caused by the printing of the black channel will be hidden in shadows. Your customers should be convinced to separate their RGB images to your supplied CMYK profile, generated from your press/inks/paper. Using a uncontrolled unmanaged color separation I is a waste of time, you'll waste time and money on the press. As we know, we don't usually even get the profiles attached to the images.

CMY in the right amount will generate gray, if you get a small dotgain in the highlights you'll be able to achieve amazing images.
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby graciesmom » Wed May 21, 2008 1:38 pm

Great help so far. I appreciate all of your comments.

We have gone to great lengths and output test plates to get the Cyrel Plates Linear, before we use Symphony on them. We use a System Value of 2 and drop everything below 1%. There are no small dots on the plate that can not hold. We print a .7% dot after curve on the low end with ease. The dot prints clean and holds up fine. I guess my biggest thing is the files. I was hoping to adjust the color of embedded files, that we do not get links to, on the rip end. Instead of having to export embedded images into photoshop and re-link them back into the original PDF, that has been opened in Illustrator for stepping and distortion.... While were are thinking about it, why does the link even after it is embedded back not always have the same color breakdown as the photoshop file? Profiles are the same in both programs. Thanks
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby dennisctan » Thu May 22, 2008 8:01 am

IMHO, a bitmap editor such as Esko's FlexoPerfection may be the answer for part of your quetions; It allows you to control the numbers of pixels to be imaged on your digital images after ripped and you can use the software to get rid of those unwanted isolated dots . Check out: http://www.esko.com/web/site.aspx?p=376
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby Snow » Thu May 22, 2008 9:24 am

The same question is how to determine the Min dot on the plate. No matter what is FAST or solvent process at digital plate, we have to choose the Min dot. Some one likes to view the dot on the plate by 100X microscope. Some one likes to see the fingerprint by press. I think, both are ok. It 's good to test each one. Choose what you like.
Some time, we like to add some marks at the side of the job. 0.5% must have. When you have ripped the PS or PDF files, you can see the .5%. If .5% not on the job. All of the dots less than 0.5% will be lost. We use Harmony to adjust the bump curve.
About the image in Illustrator. I also find some bug. When you are looking at Photoshop CS2 by straw tool, you will find every channel is upper to 1%. After you have ripped, and upload bump curve. The same question will be appearing. There 're some scattered dots in some area. All of them are less than the Min dot.
Okay, We check the ICC, bump curve, etc... All are ok. At last, we found, the troubles is Photoshop CS2. We up all channel to 10%, don't apply, and then down to 1%, all will be solved. There 're no scattered dot appear.
I don't know what I said is your troubles.

I hope it will be helpful to you.

Snow in PRC
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby ramirez » Sat May 24, 2008 12:41 pm

Hi guys

You're looking at CMYK as beeing a 0 to 100% steps of gray, which in fact in the way the data is ripped, they are 255 levels of gray. Do the levels adjustment layer in Photoshop and you'll see. With levels you'll be able to match the first level of gray from your images with the levels of gray from the rip.
Also, when you find the min dot, you should have your test file done in levels of gray, same values as in the rip, 0.4, 0.8, 1.2, 1.6, 2.0, 2.4 and so on ... In both Nexus (in Optirange) and Esko (in Intellicurve) you setup how you drop your levels of gray. Usually you should drop everything below 1, so you'll drop the first 2 levels of gray. The 0.4 and 0.8 levels will print too dark compared to how they should print.

If you're talking about scum dots, they can be removed in Photoshop, and the procedure is not complicated. Also, FlexoPerfection will do a good job, but probably is better to have a cleaned image right from start.
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby pvanderh » Sat Jul 26, 2008 12:17 am

I know this is a shot in the dark but we went through a similar situation when we started doing some jobs as digital samba. If possible kill 1.8% and below. 1.8% seems to be the magic number for our system. We have a different system but the principal could be the same. When we killed 1% we would randomly get scum dots on plate and press. For those jobs we notice that if the RIP file was opened in PhotoShop and if we would dig closely we would be able to see dots that PS registered as 1% though they we honestly under that, more like less than half a percent. Some how setting the kill % to 1.8 manages to remove those .5 and under % scum that we saw but does not effect the 2% +-^ and above that you want to hold to have clean drop shadows and such. Open the file in PS and dig closely. You should see those 1% areas. Then try to up the kill % to 1.8. Open that file in PS and see if you can find the same 1% areas. If that works you have not had to do very much to find the solution.
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Re: Eliminating Small Dots - NEW QUESTION

Postby flexomap » Thu Oct 08, 2009 1:29 pm

I'm resurrecting this post because I'm experiencing a similar situation and some of these responses may be applicable. I am receiving low-end scanned artwork that has a lot of very small "noise" pixels that cannot be visibly detected in Photoshop at the highest zoom but when sent to our Esko FlexRIP they are showing up in the separated .len files and we're holding these dots on the plates, resulting in a very dirty print. I believe this is due to the bump curve increasing the value of these less than 1% dot artifacts. We do not have Esko's Flexo Perfection software (expensive!!) so I'm wondering if there is a way to address this issue since we cannot see these "noise" pixels in Photoshop. I'm thinking that perhaps the post regarding "killing" the % to 1.8 might be worth trying but I'm not sure how to execute this in Photoshop. Also, has anyone used the Reduce Color Noise Filter in Photoshop for this type of problem? Any further input/ideas would be appreciated.

Thanks!!
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby cheapthrills » Thu Oct 08, 2009 6:33 pm

I may have missed it with all the back and forth but I would certainly employ a "Bump curve" for your minimum dots.
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby flexomap » Fri Oct 09, 2009 8:15 am

Cheapthrills,

Thanks for your input. We do employ a bump curve but my concern is that I don't want these dots on the plates in the first place so I'm looking for a way to get rid of them. The problem is that I can't see them in Photoshop at full zoom because they're so small so it's impossible to remove them prior to the RIP. Hope that helps clarify.
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Re: Eliminating Small Dots on Cyrel Fast Plates

Postby Luc St-Pierre » Wed Oct 14, 2009 12:45 pm

If so, then use (under filters in Photoshop) noise-dust and scratches and enter 1 pixel. This will remove seen and unseen speckles in the file.
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