matching a higher line screen

[prepress_brillance_43]

I have a job, one of very few that comes through here, that is extremely color critical. We are supposed to be running it to match a previous sample from another printer. I ran my plates at 200lpi. The dots are way bigger than the previous sample. I can assume from that that the line screen on the previous printing obviously is higher than the 200lpi I ran mine at. The color of their logo is only a very little bit off in color. According to the version of Trueflow I have, 200lpi is the highest I can run.. what can be done to match this job??? any ideas?? they are saying they cant do it on press because the screening is different. Can they not adjust pressure? or run it a little hot on the blue or something??... any ideas??... would a considerable dot gain cause a huge difference in size of the dot if the previous sample WAS run at 200lpi(even though it looks to be more)...

any help is appreciated greatly.. thanks..

[prepress_brillance_43]

more info.. I dont know how true, but will I ever without asking the pressman who ran the previous one AND him remember.., I think the previous set was run with the pressure way light, and the inks way heavy.. but now that crap printing has become this company's "must match"..

how are some of you dealing with issues like that??...

...still thinking the line screen is higher, though, and I think our press has more dot gain that is compounding the results...


please help.. my head is killing me.


btw, I guess what Im asking is... do any of you old-schoolers know any tricks??... apparently my pressman and production manager dont.. it doesnt help that our owner doesnt know printing, so he thinks we are all just making a bunch of excuses... he actually said just a little bit ago.."I just find it hard to believe that the size of the dot and the screening being different would cause a difference in color.." :? ...uh dude, the dot is EVERYTHING.(really what I said to him!!) :roll:

[LoganBlade]

my asumption would be that the other printers had a different curve biuld in the rip? THey may print it with an open curve that prints cleaner. say a 80 print on sheet at 70 to dot gain up? What is really the match problem that your experienceing. If you put it on press and it doesn't match maybe set up a curve to make it look pretty. open the cyan or one of the other colors. Not sure if i am hitting your problem but that is what I can give you right now.

[prepress_brillance_43]

see, go and open my mouth and make sure I shove foot in, because it always shows my ignorance... we are not running ANY profiles on any jobs, but I will be looking into, what I can possibly do within trueflow.. its pretty much WYSIWYG in this shop because like I said... we dont deal with this type of color critical job but evey blue moon..

[clod]

FM screening can certainly render different color due to the screening/dot size...is that what you're dealing with (check out a midtone dot)? Of course simply crappy printing can render color difficult to reproduce as well. Are there any colorbars on your sample?

If too much dot gain on your end is the issue, you could make a cut-back curve at the CTP Rip to match the gain of the sample...hard to troubleshoot this from a distance though.

We don't re-print anything without it going through a proofing cycle, or that we've printed ourselves, so I can't say that we deal with this often.

[prepress_brillance_43]

Originally Posted by clod

FM screening can certainly render different color due to the screening/dot size...is that what you're dealing with (check out a midtone dot)? Of course simply crappy printing can render color difficult to reproduce as well. Are there any colorbars on your sample?

If too much dot gain on your end is the issue, you could make a cut-back curve at the CTP Rip to match the gain of the sample...hard to troubleshoot this from a distance though.

We don't re-print anything without it going through a proofing cycle, or that we've printed ourselves, so I can't say that we deal with this often.

Thanks Clod for the response. I have looked it over at the RIP and I could apply a cutback curve for the dotgain. However we(manager and I) have talked it over and the dotgain is not the problem.. also, there is no colorbar on the preprinted piece, it is a finished(cut and folded) sample... really the major problem is that we are not a color-managed shop, and yet the sales reps at our mother company think we are, even though we have told them multiple times. The other problem is that when we explain this issue to the owner and/or the sales reps, they begin to tune us out because in their mind, we are making excuses and they don't care to understand "WHY"... they just "want it done"...

looking at the dot on the previous piece, I would guess the lpi is 250 or 300. The version of trueflow we have is max of 200lpi. Our owner had the opportunity when we purchased to go higher, or to get a different screening package.. I remember specifically asking him, are we going to be running Ad Agency Color Critical work ANYtime in the future?? His response was "No, we do not want to deal with that type of work." So I and the rep for screen helped him save thousands of dollars worth, and bought lower grade. Now here we are 8 months later with a Color Critical job, and when we try to explain the situation, the owner doesnt want to even try to understand.. he wants to say things like what I said above about not believing the dot would make the difference. So really we have ended up with a shop that is the ignorant leading the ignorant who is leading the production.. :roll: I probably have worked this topic into the ground here in the shop, overthought it, and over worked trying to get a valid solution, when they have already decided at press that what they have is close enough(owner approved) and we are going on.. but that doesnt mean I, Mr. PB_43(not really very brillant) has to stay without answers or a solution. If for nothing else, I want to gain the knowledge for myself.

I have to go now I have to go meet a man about a design job.. but thanks for the help and info.

[LoganBlade]

Whay are you not trying to a color managed work flow. So you just use a linear screening to print? Does your shop proof from a proofer. How close to you come to them. It took me a day of prepress and press time to get a press to run so that it matched the proofer. Only beause the proofer is very conistant with color were the presss is not. I did a proof put in a Curve for the dot gain then manages the curve to match the proof working a color at a time. Takes time and a good pressman but can be done easily. then it would be a color manage shop no problem...untill another thing comes up.

later

[prepress_brillance_43]

my understanding of color management is that you make the proofer match the press, not the way you said.. You run the exact same set densities on press on every job and profile the proofer to that. ..but that is my understanding.
We installed a generic SWOP profile to our proofer and run proofs, get signoff and then pressman chases color.. yes that is backwards the way we do it, but we get extremely close on 99% of our jobs because we dont usually get jobs like this one where we have to match something printed somewhere else. At the time of purchase of our ctp, ourowner said he wasnt interested in this kinda work... then he goes and sells and his reps sell this kind of work... I dont get it... I was told that in order to be TRULY color managed you have to reprofile every time something changes on press, ie blanket, inks... but maybe I was told wrong.. I just thought the objective of color managing is to make the press the constant.

I think ultimately the owner thinks or thought he could skimp on the purchases and we could still do the color management right... I think at this point, because there has been a densitometer ordered, that's the first step, once we have it, the install guy for our color proofer will be called back out to train me to create my own profiles with our unused copy of Monoco XRIte and OPTIX XR... these pieces were included in our "package" deal from Enovation/Screen but when the guy was out to do install last july, we had no densitometer and he couldnt footprint the press... why create profiles to use, if the pressman wasnt going to be able to run to a set density... so we went the generic route and it has been fine until now..

hope this answers your question..

here's another question...

Can someone explain in "technical" terms what applying a curve actually does to the dot on each plate??.... I want to be able to explain to the owner(who really will never understand and doesnt want to) and the production manager who doesnt want to deal with it. but if I understand and can do it I become more valuable... thanks.

[MarkTonk]

Hey 43,

I took this from a post I had earlier and edited some of the info. Applying a curve is a way of controlling dot gain, one of the great features of CtP.

If you look at it as you would a scanner, gradation needs to be established before you worry about color. Gradation effects color but color will not effect gradation. So, with CtP, you first need to establish your gradation or tone curve. This should match your house standard. Typically, with sheetfed, on a decent coated stock, it will be 18 to 20 % dot gain. Now, plate dependent, a 50% on plate may only gain 13% on paper (50 is now 63%). There is nothing wrong with this in a closed loop system but most programs generated tints will be too light and so will most color separations if they are based on average dot gain for this combination. Also, repeat jobs that were printed via analog methods will also look too open. So, before you decide on color, you have to decide on gain. Once you program your curve to match the gain you are looking for on the printed sheet, then you will print your target to read with your profiling software. So your gain or tone shpe needs to be established first, then you can profile for color.

This ICC profile will then be used to color manage the ink jet proof to the press sheet. Again, dot gain has to be established before color. And it makes sense for the low cost proofer to match the more expensive press. This is only accomplished by printing to a standard. The proof then can match closely to the press. This saves money in that press makeready will be accomplished in less time with a properly profiled proofer.

Now, a higher screen ruling will have more dot gain then a lower screen ruling. So, the same job with out a compensation curve to match a standard will gain more at 300 line then at 150 line. These will not look the same. However, if you reduce the curve on the 300 line to match closer to the dot gain you get at 150 line, they will look more alike but the 300 will have more of a continuous tone look and more detail. The curve allows you the digital capability of controlling dot gain.

I hope this helps. If you need more info, e-mail me a phone number and I can call you to discuss.

Best regards,

Mark

[MarkTonk]

43,

I forgot, the screening used can be from a different manufacture. so not only can the dot gain be different, the screening algorithms maybe be different. Also, the dot shape can effect the look. If you use eliptical dot and they used round, you will have a different look even with the same screening/rip. Here is a link to our guides Expert Guides. See the one on screening, it may help explain some of this.

http://www.heidelberg.com/www/html/e...s_products_a_f


Regards,

Mark