Trying to control hue in black & white photos in a cmyk file?
mividaloca (5 pencils) | Wed, 2008-01-23 22:09I have created a photoshop file that has a silhouetted "black & white" photo with a colored background (needs to be cmyk to print for magazine ads).
How do I control the color of the black and white photo so that it doesn't run too brown or green? It looks fine on screen (which is supposedly calibrated), but my tear sheet came back with a really green hue... the client won't do a color proof.
Also, I have three more ads in the series, with different photos, but same background. I need to make sure that the hue in the photos are consistent.
Also, my blacks have too much ink (adding up to over 300%).
Any thoughts/suggestions? Thanks!
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In a perfect world I would do this.
1) Ask printer which CMYK space they use. Usually, they say U.S WEB SWOP COATED.
2) Convert your B&W image to Grayscale in Photoshop. Then, convert to profile U.S WEB SWOP COATED (or whatever the printer said).
RESULT = Perfectly neutral image at perfect TAC amount.
Of course, the world is not perfect but I do have a technique that would guarantee a neutral 4C image called an UBER-K separation. Contact me if you'd like to explore that option.
Without color proofs from the printer, nobody can be held accountable for the print job except the client himself (and what client wants to hear that?).
Cheers.
Without my sense of direction, I don't know where I'd be.
I am facing the same problem with b&w and cmyk color shifts on prints.
Does converting B&W images to Grayscale in Photoshop. Then, convert to profile U.S WEB SWOP COATED garanty the image will show the same as on my screen (calibrated with Spyder2Express )? As for colored image do I just assign the US SWOP profile?
Or do I manually knock down 25% cmy through the channel mixer? What is the UBER-K separation?
Its the first time I work with prints....any help would be highly appreciated!
Why not just tell us what that option is?
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Powerpoint is not a design application
My latest web design work
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Dirt and Rust
The pre-press trick is to manually create your own CMYK separation through channel mixer in Photoshop. Instead of having the black plate function as a helper (for neutrality balance, density and achieving TAC), you make the CMY inks the helper plate.
Using the channel mixer function of Photoshop you take a CMYK file and 'push' the information OUT the CMY plates and INTO the K plate. The end result is a K plate that looks like a grayscale and CMY plates that give the grayscale an overall boost in density.Since it's mostly a B&W image, the press can drift pretty radically and the neutrality will not be affected.
I have several ICC profiles I custom created that does this 'auto-magically'. I'd be happy to make the separation to show you what it's doing and how it prevents unwanted color shifts on press. One of the key features of this pre-press trick is removing the CMY values of the 1/4 tones of a 4C image as you may notice that traditional separations will not have any black in the 1/4 tones at all. This means that CMY alone must acheive neutrality in this crucial part of the image, and that's a pretty tough even in the best of press conditions.
Without my sense of direction, I don't know where I'd be.
I'd say that sounds like a pretty good trick. :)
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Powerpoint is not a design application
My latest web design work
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Dirt and Rust
Nifty! Will this work with just one wants-to-be-K photo in an otherwise 4C job, or does it affect the whole layout? You're doing this in Photoshop, not the layout app, I assume, yes? I've never bothered with ICC profiles. How do you do that?
Mara
(Slowly sliding a nice plate of warm chocolate chip cookies over toward caomimghgin's keyboard...)
Mara
hahah! I love chocolate chip cookies.
Yup! You'd do this in Photoshop, either manually (as described) or 'auto-magically' through a UBER-K separation profile. It would only affect that single image.
ICC profiles are kinda scary to tell the truth but I'll tell ya a few simple and inexpensive ways to enter into that weird world.Don't worry so much about understanding it, but give yourself an opportunity to experience what it does and the concepts should come pretty easily.
Open a nice photographic image in Photoshop. Admire it for a moment, then go to Assign Profile under the edit menu. Select anything in that pop-up. You'll see the color change on the image. Do it again and you'll see another color change. Repeat until tired of seeing colors change. Notice that the numbers (RGB/CMYK) didn't move, but you affected real color changes when assigning different profiles.
Now, this experiment is a bit counter-intuitive. We tend to think numbers mean colors but in fact they really don't. That's what color management tells us. Now, during your excersises you may have found that you LIKED one of those profiles. That's totally valid.
If you liked one of the profiles better then do the following steps....
Assign that profile and convert image to LAB mode. Convert image back to RGB (or CMYK. Whatever it originally was.) Viola! Now you notice that the colors stayed the same BUT the numbers changed.
This little exercise is color management in a nutshell. I didn't explain WHY any of this is true or whats happening behind the scenes, but maybe the first step is to just use it then figure things out as you need to.
Let me know how it goes! Oh. Can I have a cold glass of milk too?
Without my sense of direction, I don't know where I'd be.
Cold milk sliding your way! (Well, Rice Dream, but who's counting?)
Thanks!
Since asking my questions earlier today, I had occasion to visit a favorite printer of mine. He was telling me, very excitedly, how a new press of his works, and mentioned some stuff that sounded a lot like your ICC profile idea. Smug in my newfound (and of course totally nonexistent) knowledge, I said, "Oh yeah, like assigning ICC profiles when you..."
He cut me off with a vigorous nod and dragged me over to show me some proofs he was especially proud of. "Yeah!" he said. "Same kinda thing exactly."
So thanks double :-)
Now all I have to do is try your trick so I'll actually know what I'm talking about next time. I have a brochure project coming up next week for which this might come in handy.
What a great little community we are.
Now don't leave crumbs on the keyboard, there's a good designer.
Mara
How is it printing? Offset?
I'd adjust your channels in Photoshop.
as a prepress guy myself...
Ideally, you don't want to send them any photoshop files. you want to send them a CMYK PDF or Postscript file made from a Quark, Indesign, Illustrator file with the B&W image embedded in it as Greyscale, rather than send the entire ad as a single CMYK image. and if you can do it without any bitmaps at all, for example if the entire piece is just text with a simple logo, you don't even need photoshop. Print quality will be much better and the file size much smaller.
Prepress software can then combine the greyscale with the K (black) channel accurately.
If all you have is this photoshop file, then you're stuck screwing with the other options as described previously in this thread.
"...and mamma cried: Watch out where the huskies go, don't you eat that yellow snow" - Frank Zappa