Join Taz Tally for an in-depth discussion in this video Making dot gain adjustments, part of Photoshop CS5: Prepress and Printing.
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In this segment, I'd like to address how to correct for dot gain in a grayscale image. Later on in the course, we'll talk about accounting for dot gain and color images when we go through color gamut conversions. But for grayscale, there is a couple of different ways to adjust for dot gain. Sometimes when you send your images to a printing company, they'll automatically adjust for dot gain on press. So you can send them the standard image and they know what their dot gain is. But you absolutely want to ask the question, ask them if they're going to dot gain adjust the image for you, because strangely enough, a lot of printing companies or some may not.
They'll do it for color images, because that occurs during the gamut conversion. But for grayscale images, they may print them as is. So first is to ask the question of whoever is going to print your image. If you're printing your own image, a couple of things you can do. One, I recommend doing a test print on the small like 3 x 5 piece of paper and see what it looks like. Then if you want to do a manual dot gain adjustment, you can do this. We're making an assumption here that we've already set our highlights and shadow points. We have them the way we want to. For an overall dot gain adjustment, we typically do this from the midtone.
We do it from the midtone because the midtone is where you very often get the maximum amount of dot gain adjustment. The reason for that is that's where the halftone dots start to merge into each other in a conventional halftone dot printed image. So what you can do is you can do some test runs. Try it at 5% and 10% and 15%, and just try a couple of tests. You can just do a curve like this, just a dot gain correction curve. You can actually label this as your dot gain correction. If you have more than one kind of paper, you can make a different dot gain correction curve for each kind of paper that you're using.
The nice thing is since we're doing non-destructive editing using a Curves adjustment layer is you can change this if you need to for different output devices. If that's the way you want to do it, or you can make a separate curve for each kind of paper in an output device. Well, that's how you can do the correction manually. There is also a way that when you save your image, you can also apply a dot gain correction to it. To do that, we'll come underneath Edit, and we're going to leave this at this Color Settings dialog box that we have here. If you remember, we tackled this a little bit earlier when we talked about setting up Photoshop just as an initial setup.
So we set our Working Spaces for RGB and CMYK. Well, now we're going to move down to the third version here. This is for grayscale, where we can set a dot gain here. Notice there are some built-in dot gains of 10, 15, 20, 25 and 30%. What you can do here in the default is to set your dot gain to say at 20%, and then print your image. If it's not light enough, then you can go to a dot gain of 25% or 30%. Don't worry so much about what those numbers mean. All you want to be able to do is match up a setting here with a particular output device and paper.
So you can set your dot gain at 20% and then click OK. Then when we go to save this image, we go to File, right, and then do a Save or a Save As. Then notice down here underneath Color, Embed Color Profile: Dot Gain 20%. When you do that, then it keeps that color profile with the image and applies 20% dot gain when that images are actually printed on a printing device. So you can do it manually and/or you can also control your dot gain percentage for grayscale overall right here in the Color Settings dialog box.
Then when you go to save your image, make sure that you embed that color profile for 20% dot gain. Through those methods, you can both manually and through color profiles control your dot gain when you print your image. But remember the first thing you want to do when you're sending out your grayscale images to a printing company or to any kind of service or output device is asked them, if they're going to correct the image for dot gain. If they don't know what you're asking about or you can't get a good answer, say hey, do just the small test print for me, so I can see what the image looks like. That gives you a starting point from which to correct your overall dot gain.
Because believe me if you don't do that, if you don't ask some of those questions, almost always your images will print a good deal darker than what you expect them to. With dot gain correction, one final point on screen, when you do an overall dot gain correction, it should look a little bit lighter on screen than it's actually going to print.
- Understanding RGB and CMYK bit depth
- AM versus FM screening
- Working with device color gamuts and profiles
- Making image adjustments before printing
- Choosing the correct file format for output
- Assigning spot and process colors
- Comparing editable and raster type
- Sharpening for print
- Printing to grayscale
- Proofing images
- Recording actions to automate printing-related tasks