Join Russell Viers for an in-depth discussion in this video Finding CMYK blacks, part of 11 Things Every Newspaper Should Know About PDFs.
A real problem in working with PDF is sometimes these blacks that look great on our monitor are really made out of cyan, magenta, yellow and black inks. Well, that's not a problem if you can keep it in perfect register on the press. That didn't happen, especially for a newspaper that has a press run of 1,000. 2,000. By the time they get that up to speed, they're looking at a few key parts, and then they're shutting the press down. This ad might be on page seven and it's just going to get lost.
So, it's very important that we learn how to diagnose where are there CNYK blacks and how do we fix those. I'm back in Acrobat 9 and I'm going to go to Advanced > Print Production > Output Preview. In Acrobat 10, it's View tools > Print Production and click on the Output Preview button. All right. Now, two ways that we can check for these rich blocks. And one way I don't, I don't ever use, but I'm going to show you this because I want you to know its there, so that you know, you can see what it does and its limitation.
If I go to Color Warnings and I say show me all the rich blacks, look at that text hm. Let's go back to Separations Preview and let's look at it. Yep. Sure enough, that black right there is made up of cyan, magenta, yellow, black inks, that's a problem. Okay, so in this case, that color warnings worked. Let's go to a different ad, though. Let's go to this ad color warnings rich black. Mm? Everything seems to be okay. Don't see any problems there. Let's just see what happens if I bump this down to 50%, nope, 10%. Nope, everything seems fine on this ad.
Got a little bit of a highlight where the outline of that is bleeding to the background there, but, you know, that's, that's nothing, that's nothing for what we're doing here. So, let's put this back on 80, the default. Yep. Looks like this ad is fine, right? No. If I go to Separations and turn off black, in theory, everything in this ad that's black should just disappear. But it doesn't. This photograph is CMYK. You can see it, right there. Plain as day. And if your printer only output the black plate, that's what you're going to get instead of that, which is a real problem. Okay, so we can see that that color warnings doesn't really do the job, and here's the reason, this is looking for things that really are cyan, magenta, yellow, black with what we call, impure numbers or impure grays or impure blacks. This is a photograph.
Well, can you imagine the confusion of the software if every time it saw a photograph that had black in it or text that had more than one color of black, how does it know the difference? Well, Photoshop has some algorithms, we'll say, that it uses to create black. You can see that anytime you open a gray scale image in Photoshop and you go Image mode CMYK and convert it back to color, you can see that those blacks are distributed across the CMYK plates. And that's an algorithm that Photoshop, it's just the way they do it.
Acrobat recognizes that. So, it's smart enough to say, okay, we're going to tell you if there's rich black in text or objects, but if it's rich black in a photograph, we're not going to warn you. Well, that doesn't help us does it? Because in this case, I've got a photograph that's got RGB or CNYK data in it and I need to fix that. So, what I tend to do is one of two things. I either only turn off the black plate, give it a quick glance, or I also move my mouse over. Notice how down here, right here in this information, it's telling me that it's 100% black.
Up here, it's telling me, see those values, even the darkest isn't even 100% black. That's an example of that algorithm I was talking about that Acrobat recognizes and says, oh, that must be a photograph. And so, it's going to be fine, we're not, we're not, we're going to leave it alone. All right, so now that we know there's a problem, how do we fix it? Well, I'm going to go to my Advanced Editing > TouchUp Object tool or in Acrobat 10, what they call the Edit Object tool now. And in this case, I'm going to select this photograph.
Now, I could edit the image, and open it in Photoshop. But I'm too lazy for that, I'm just going to go to Properties, go to color, and I'm going to tell it something like, let's just try generic gray profile, and see what happens. Convert Colors. Close. Hmm, looks okay, let's see what happened. Print Production > Output Preview. Well, if I just move my mouse over it, I can see what it looks like there. If I go and turn off the black plate, I can see that I got what I wanted, okay? So now, it's a spot and black, there's no CMYK blacks in there.
Now, this other one though, because it's vector art, I could try doing it that other way. Let's just see what happens. If I go to tools > Advanced Editing > TouchUp Object tool and click, notice that I'm getting more of this art than just that text. Let's see if, yeah. See, I've got red as well. So, I can't do it that way. I can't just sit there and say convert the color to gray scale, cuz then I'll lose the color, you know, the spot color in this. So, I'm going to right-click, go to Edit Object.
And now, I've got it open in Illustrator. I'm going to select that text right there. See, 100, 100, 100, 100. Boom. Now, it's only black. Let me save, Cmd+S, and let me go back to Acrobat. Hm, it doesn't look like anything changed. Advanced > Print Production > Output Preview. Let's check. Yep. What's Black is Black. Everything else is distributed across those other plates. So, that's an example of finding the rich blacks very quickly and using either TouchUp Object to correct it or going to Properties and changing the color space for that.
Either way, we can get those CMYK blacks out of there.
- Checking out the PDF
- Digging deeper with the Output Preview panel
- Simple fixes with the TouchUp tools
- Converting colors
- Managing transparency
- Working with fonts
- Preflighting PDFs
- Repairing PDFs with Photoshop and Illustrator
- Exporting vs. printing and distilling