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Saracroft
08-10-2006, 02:33 AM
Hey all! I have a few questions about trapping.
See, I don't trap my colors. I never have. So I don't know a lot about it.
I just know that it was first described to me, I was told that it took like 6 hours of something to complete. That when I decided that I wasn't going to do it. LOL I don't have that kind of attention span.

So, what exactly does trapping do for your colors? Is it nesseccary to trap colors? Or is it just as fine not to? Any info would be greatly appreciated!

Splash!
08-10-2006, 08:01 AM
Hey all! I have a few questions about trapping.
See, I don't trap my colors. I never have. So I don't know a lot about it.
I just know that it was first described to me, I was told that it took like 6 hours of something to complete. That when I decided that I wasn't going to do it. LOL I don't have that kind of attention span.

So, what exactly does trapping do for your colors? Is it nesseccary to trap colors? Or is it just as fine not to? Any info would be greatly appreciated!

I have never heard of such a thing, but I am interested, does anybody know what this means?

BKMDog
08-10-2006, 09:08 AM
As far as I know, what with modern, digital presses, trapping is no longer something to be concerned about. I'm not even sure I ever understood what it meant and why it was necessary, and never really worried about it. By the time I got into using a computer for doing art / illustration ( not all that long ago ), as I said, you didn't need to worry about it. A local guy that I commune with who's a prepress maniac told me that and he's been into doing digital work via computer for output to film and print since day one.

His print jobs for things like magazine ads, beer companies - he designs killer photo-related art for billboards and their packaging - and major food companies like Nestle for example, always look amazing.

But hey, if anybody has any better info than that, I'm all ears---

eDuke
08-10-2006, 10:18 AM
http://www.stickmangraphics.com/trap.htm
and a more detailed explanation of trapping and why:
http://www.trapping.org/tips.html

L Jamal
08-10-2006, 10:55 AM
so you don't have to read all the last link Ed posted
Trapping is not required in the four color process, when overprinting is used or when either black or white margins are placed around the object.

Black frames are used in the borders of colored areas in comic books.

crozonia
08-10-2006, 11:21 AM
I still trap my ink work. It's still good to know. and takes less than a minute to do. Don't blame your printer when your black inks aren't as crisp as the stuff you see in Top COW, or if the inks shift. So many people ask me who my printer is when they have a close look at my comic book. And while my printer is top notch, it's the trapping and support method that makes my inks look so sharp.

A couple of things.
-Black Ink layer should ALWAYS be 100 K. Anything less, and you get a screen.
- No Anti Alias on your black ink! Convert to bitmap and bring it back!
-ALWAYS muliply the Ink Layer on top of the coloured art.
- Have a support layer that is a couple of pixels thinner than the ink layer. This traps the lineart. Rule of thumb - don't trust technology!
- The support layer I use is normal settings - 60,40,40,0 for rich black inks. You can play around with this to give you a warmer or cooler black ink.

Jim

crozonia
08-10-2006, 11:25 AM
If you go to any fast food restaurant, usually the printing on drink cups is very shifty but are great examples of professional trapping inks and over print methods.

As far as I know, what with modern, digital presses, trapping is no longer something to be concerned about. I'm not even sure I ever understood what it meant and why it was necessary, and never really worried about it. By the time I got into using a computer for doing art / illustration ( not all that long ago ), as I said, you didn't need to worry about it. A local guy that I commune with who's a prepress maniac told me that and he's been into doing digital work via computer for output to film and print since day one.

His print jobs for things like magazine ads, beer companies - he designs killer photo-related art for billboards and their packaging - and major food companies like Nestle for example, always look amazing.

But hey, if anybody has any better info than that, I'm all ears---

Saracroft
08-10-2006, 11:45 AM
Okay, so (let me see if I got this straight)...Trapping is good, but not nesseccary. Especially since I'm dealing with coming books. I don't have any areas of solid color touching one another without being bordered by black lineart. The black lineart itself acts as the trap.
Right?

Kep!
08-10-2006, 11:52 AM
Like the man said, it takes less than a minute and CAN make the difference of seperating the good from the great. Hell, not that hard to write macros.

illojik
08-10-2006, 01:03 PM
I've got an action in photoshop for anyone who wants it. just shoot me an email. it sets up your files for coloring for you, including a trap layer underneath your lineart layer (some call this an undercolor layer), and a color hold layer over top of your lineart layer. Nothing easier than opening an inked page, dropping it into your page template and hitting play on an action :D The results are unmistakable. Also, in PS you can go to Image/Trap, and select .5 points on your final CMYK files. Lots of pros do this now as well as the undercolor layer beneath the lineart. For pages straight from pencil work, you don't need an undercolor layer, all you have to do is use the Image/Trap feature after you've flattened your file. those are some good articles Ed linked to though, worth your time :)

L Jamal
08-10-2006, 02:10 PM
A couple of things.
-Black Ink layer should ALWAYS be 100 K. Anything less, and you get a screen.
- No Anti Alias on your black ink! Convert to bitmap and bring it back!
-ALWAYS muliply the Ink Layer on top of the coloured art.
- Have a support layer that is a couple of pixels thinner than the ink layer. This traps the lineart. Rule of thumb - don't trust technology!
- The support layer I use is normal settings - 60,40,40,0 for rich black inks. You can play around with this to give you a warmer or cooler black ink.


This is not trapping, it's underprinting. It's totally different. Underprinting produces a rich black and is necessry for all full color process printing.

Trapping is mostly used for spot colors when you're not using full color process.

Multiplying your ink layer can produce over saturated ink levels.

crozonia
08-10-2006, 03:24 PM
Have a support layer that is a couple of pixels thinner than the ink layer. This traps the lineart.

This part is trapping your undercolour to your inks. That's what we're talking about, no?
You want sharp 100 K lineart. The trapped undercolour prevents your lineart from shifting.
As for oversaturation, that's why the undercolour is 60,40,40,0. That's a safe threshold.

L Jamal
08-10-2006, 03:59 PM
The purpose of the decreasing the selection is to keep the underprinting color (60,40,40 in your case) from showing if the black plate has a slight shift. Because comics have black ink bordering most colors trapping is not needed in most cases as the article ed linked to pointed out. Underprinting blacks and trapping are 2 different subjects. With trapping you are concerned about how shift in the non black plates will effect colors, so you do knockouts and overprinting to stop color bleed. If you are coloring a comic with no black line art (like the most recent Plastic Man series) then traping is important. Otherwise, you just need to worry about underprinting your blacks correctly.

crozonia
08-10-2006, 04:34 PM
Okay - having reread the first post, the question was trapping colours. But I hope someone learned something about lineart preparation!

Biofungus
08-10-2006, 07:00 PM
Cro: are you sending layered files to your printer? It sounds like you are. A composite tiff or PDF are most likely your best bet, because you don't have to worry about the printer mucking around with individual features (layers) of your art.

For the record: I always thought trapping was used on the non-black colors because they used to print the colors first, then the black, but they couldn't print them together because the black ink would bleed into the color otherwise. (IOW, if they printed at the same time, the black edge would bump up against the colored edge and either bleed, or there would be a halo around it because of shrinking the black areas to prevent bleeding).

crozonia
08-10-2006, 07:34 PM
No, I don't send layered psd files.

Cro: are you sending layered files to your printer? It sounds like you are. A composite tiff or PDF are most likely your best bet, because you don't have to worry about the printer mucking around with individual features (layers) of your art.

For the record: I always thought trapping was used on the non-black colors because they used to print the colors first, then the black, but they couldn't print them together because the black ink would bleed into the color otherwise. (IOW, if they printed at the same time, the black edge would bump up against the colored edge and either bleed, or there would be a halo around it because of shrinking the black areas to prevent bleeding).

Saracroft
08-11-2006, 03:02 AM
Oh, no. My files are no longer layered by the time they make their way to the printer. I always send flattened files. Usually TIFF format, unless the creator specifies otherwise.

Is the trapping/underprinting/whatever still nesseccary if my files are already flattened? I was wondering that actually. I mean, I'm no printing expert but it doesn't make sense to me that my lineart layer and color layers would still slip if they're already compressed into a little colorful pancake.
But, as I said, not an expert.