Originally posted on February 8, 2012 1:08 PM by @RamyB
What’s up guys, I mentioned I would put together a halftone tutorial- I apologize for the extremely abrasive colors and abysmal handwriting in advance, but I think it demonstrates the points well enough If you have any questions about any part of this, I’ll try my best to answer, but I will preface by saying that this was mostly learned by trial and error and I am by no means an expert on halftones or printing. (Also, just to mention before you get your hopes up, this tutorial is only for photoshop users. I don’t know how to make halftones anywhere else, unfortunately.) Anyway, let’s begin.
Pt 1: The Basics
So here you see two boxes- the first shows a black to white gradient, the second is just black set to about 50% opacity. So now, let’s create halftones with these suckers
First, convert to grayscale. When asked to flatten image, say yes.
Your next step is to convert to bitmap- this will give you some nice options for your halftones.
Your next option is going to be your output resolution- What you choose here is relevant, but I think a lot of people have misconceptions about what this number means. At any time, you can change the resolution of your image without changing the quality or size at all- the difference is that it will print at a larger or smaller size depending on what you select, and the higher the resolution the cleaner the print will be (there are limits here though- over 300dpi is probably not going to get you much benefit).
Anyway, my point here is that the size of your image is what matters more than the resolution when you are working, because you can adjust the resolution later. If you want your shirt design to be 12 inches wide (which seems pretty standard for an across the chest design here on woot), make sure your file is 3600 px wide- That way, when you set it to 300 dpi, it will come out to 12 inches wide.
Anyway, I digress, and it will be easier in the long run if you just set everything to 300 dpi. Just make sure your file isn’t 800x600 px, because then your 300 dpi will do you no good 
Next, you select your frequency, your angle, and your shape. For now, I’m working at low resolution and selected 10. If you are not sure what size you can/should choose, see commentary below the next image.
For the angle, I remember reading somewhere that 67.5 and 22.5 are better for printing. I actually have no idea what the reasoning is here, but I just go with it. I think those angles look good anyway and simulate gradients better anyway. Shape, select as you want. I will comment about this later in the tutorial.
Ok, let’s see what we created
Time to discuss halftone sizing- On the right, you have a nice uniform halftone because you didn’t have any value variation within your original box. On the left, since we had a gradient, our halftone goes from basically a solid block of black to miniscule dots at the bottom. What does this mean for you? Basically, the frequency you can select for a uniform halftone is a bit higher. For a 50% opacity halftone, you can easily get away with 40 lines/inch with no problems at all. For a gradient, even 30 lines/inch can be pushing it. Keep in mind that, especially for women’s and children’s sizes, these will be scaled down and all your small halftones will either be distorted or just disappear entirely. Generally, when I create a design, I try to erase out all those 1 px dots that form everywhere to clean things up a bit. Like I said earlier, though, you don’t have to worry about this for a uniform halftone.
Full steam ahead!
So you can create a box. Now what?
Obviously boxes are great, but when it comes to doing halftones on a design, there are some complications. For one, getting the halftones to align properly with your original gradient or transparency can be a real pain the arse. So here is what you do:
Start with an ugly design of an apple. This is essential, your halftones won’t work unless it has a stupid face. I chose a cranberry color for the shading, and set the opacity to 67% to demonstrate this part.
Pay attention here, if you don’t know this trick already it will make your life really lovely. Lock your layer where you see the arrows. Change the cranberry color to black (if your layer is locked, you won’t be able to color anything else except the cranberry section).
Now insert a layer underneath there, fill it in white, and merge. You will now copy and paste this into another document, and follow the steps above to create your halftone (grayscale>bitmap>choose settings>voila).
Copy-paste this halftone back into your original document now.
Use the magic wand tool to select your white, and delete. Fantastico! Your halftones now align perfectly with your design.
I used large halftones to demonstrate here. This is a great demonstration of why you want to work at high res though, because these halftones look pretty awful as-is. Regardless, there are still lessons to be learned.
Wait a second, did you say you used Cranberry earlier? Isn’t that a shirt color?
Yes, great question! I’m so glad I asked. So now let’s talk about creating halftones using your shirt color.
Look, I can just insert a cranberry background, and now the halftone looks like the shirt color! Perfect!
NO. Don’t do this. Here’s the issue: Your cranberry is NOT an ink color. Therefore, you will have to delete out those sections from your red layer (you can do this with the magic wand tool, as we did with the white earlier). Now, look at what’s left of the red. Even though the cranberry halftone was nice and large for us, what we have left are these tiny, unprintable 1px red lines. This is not going to go well, especially if woot needs to print a white underbase for a dark shirt. Just don’t do this, it is a bad idea.
Instead of doing that, you need to convert your RED to a halftone, not your shirt color. What you do here is select your low opacity layer BEFORE making it a halftone with your magic wand. Erase this from your red. Now set the opacity to (100-your previous number)- in this case, my cranberry layer was set to 67%, so I want to change it to 33%. Now make this layer can be red, and it will look exactly the same. Basically what you’ve done is taken your cranberry shading, and turned it into red shading. Again, follow the steps above to turn this into a halftone.
Nice, now we have printable lines. Well done!
I am not sure if this part was clearly explained. Please tell me if you don’t understand this section because I felt like I couldn’t exactly put it into words for some reason.
Not all halftones are created equal
I promised earlier I would talk a bit about halftone shapes. Well here it is now.
I upped the size of the image so that I could show you what higher res halftones will look like. These two were created with the same angle and same frequency, but one is a line halftone and the other is a round halftone. With any halftones you create, you will get a slight textured look. It is inevitable. You are trying to convert a smooth transparency into dots or lines, there is only so much tricking that can be done with your eyes. So, choose your shapes wisely. I find that round halftones are great for flatter shading, while line halftones give a little more of a rounded look to me. So if you are using halftones to try to make something look three-dimensional, think about using a line halftone. For shadows on the ground, backgrounds, etc., a round halftone might serve you better. It really is a matter of personal preference though. I rarely find use for any of the other halftone types (I think I tried a diamond one once because I was bored).
Test these out- Having a variety of halftone types within a single design can be good or bad. If chosen effectively, it can separate your main subjects from background elements, for example. It can also be used to distinguish color changes from shading (for example, if I want to create a light blue mouse and I only have dark blue and white as colors, I might create a round halftone because I am looking for a basic color. I might shade my characters in the same image using a line halftone).
I know I didn’t talk very much about making halftone gradients, but you can do this with the same principle. Just make sure you never use more than one color on any given layer. If you want to do soft shading on a character, add a new layer, use your shadow color, convert to black, merge with a white layer, move to new document, bitmap, move back, your halftones are aligned. Now you can lock and change back to your original color. See? Same procedure, different results.
This thing is way too long, sorry about that, but I wanted to explain as much as I could. Hope someone can find this useful at least.
) Halftone is my preferred option, but I lowkey love the look of halftones.