Creating proper percentage of gold channel

Tech

Well-known member
Hi All,
Our vendor helped setup a test file for us to review. The problem is I can't replicate the process they did. I understand the concept of selecting only a certain percentage of highlights/shadows/midtone of an image, so they don't flood the entire channel with gold. The question is how does one select say only 10% highlight, 35% midtone and 65% shadows of an image or channel in photoshop???

I can't seem to find any tips/documentation regarding this technique. Is this an exclusively prepress secret no one talks about? Please help.


Thank you.
Tech

Edited by: Tech on Oct 22, 2007 10:23 AM
 

G_Town

Well-known member
Re: Creating proper percentage of gold channel

Command M for the curves adjustment?

That is if I understand what you are looking to do.
 

G_Town

Well-known member
Re: Creating proper percentage of gold channel

Right I'm familiar with metalfx but he makes no mention of it so I'm guessing based on this that he's a bit of a newbie to the prepress arena.

"I can't seem to find any tips/documentation regarding this technique. Is this an exclusively prepress secret no one talks about? Please help."
 

Tech

Well-known member
Re: Creating proper percentage of gold channel

It's not a simple curve adjustment because their photoshop channel isn't showing any adjusted curve info. We received a single layered file with 2 extra channels, one for gold and another for a red color art dept picked out.

The spot channels isn't a typical solid fill but looks more like a selection of shadow/midtone/hightlights of the image. The idea is to get gold ink into the image without flooding the entire plate.

Like I said, I understand the concept, but I need to replicate it to learn it for the future. No it's not MetalFX, I just reviewed their user guide... it looks nothing like the way this file is setup.

Thanks for the help.

Edited by: Tech on Oct 22, 2007 12:40 PM
 

G_Town

Well-known member
Re: Creating proper percentage of gold channel

So it looks like someone made a layer mask out of a selection and only that portion prints?



Edited by: G_Town on Oct 22, 2007 1:07 PM

Edited by: G_Town on Oct 22, 2007 1:08 PM
 

Tech

Well-known member
Re: Creating proper percentage of gold channel

Yes, that's what is looks like and hence it's confusing to me. BTW, the original art is grayscale converted into CMYK, so they aren't really making selection based on a certain percentage of CYM to make the compiled channel either.
 

Gregg

Well-known member
Re: Creating proper percentage of gold channel

Hi Tech.

If I am understanding you correctly I may have an explanation.

What it sounds like to me is that they convert the grayscale image to CMYK, in order to have some channels to select from. From there they choose one of the 4 channels that looks the closest to where they want the gold ink to be (lets say it's the Magenta channel). Then they would make a duplicate of the M channel, and if needed do a curves adjustment to that duplicated channel, to add density or take some away. Then they convert that channel into a Spot channel, save as a PSD or DCS or TIF and send it off.

Make sense? I do it alot for MIPP (Metalic Intergrated Printing Process) similar to the MetalFX post.

A little bit more complex, but on the same lines, they may have used Calculations or Apply Image to create the spot channel.

Hope that helps.

By the way, are you "TechBoy" from PPF? If so, good to see that you made the switch.

Gregg
 

Tech

Well-known member
Re: Creating proper percentage of gold channel

Hi Gregg,
Yes, this is Techboy.

We knew from start this would be an issue of selecting and making fine adjustments to spot channels. If we have an in-house printer that can output/simulate metallic ink correctly, I would have try and do this myself. Since we don't, this project test files were sent to our vendor oversea. Although, I wish we have a budget for using a local prepress shop to do this instead for faster feedbacks and no miscommunication. The concept is not difficult, incorporating metallic ink into CMYK images are common as long as one has the budget for it. We just don't know the technical name for it, but I'm glad you guys bring up MetalFX and Pantone's MIPP.

So after more poking around and trying to reconstructed what they did, as far as I could tell, in one file version, they did simply duplicate a black channel, delete info from CYM channels, used curve/level to adjust density/fill in black as well as spot channels. In two other files, they took a far more complicate way in making their selections and refining their adjustment. This is why I posted this thread seeking for advice. What they did here makes little sense and without exact specs, I can't replicate what they did nor apply this to future projects without calling upon them again. I dunno if this is a case of miscommunication or if this is a case of them guarding their jobs.

In short, what they did for us are faked 2-color images (grayscale/black + a red PMS spot channel) with gold metallic ink as 3rd color. There is a 4th PMS color in the project too but not in the images. The reason we tried incorporating metallic ink into what is essentially a duotone image is because the same metallic gold is used outside the images as well.

So yea, this isn't a typical MetalFX or MIPP, although I wish it is. LOL

Thanks.
Tech
 

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