I’ve chosen the name for this post so that hopefully, if you’re here, you know about halftones and are looking for something beyond the standard CMYK halftone separation.
We’ll start with the four-color separations which include CMYK, and work our way down the list to separation models with fewer and fewer colors.
CMYK is pretty much the standard for ‘full-color halftone’ printing. It’s been around for over a century. The trick is that the light hues cyan, magenta and yellow give you all the hue and saturation you need (when layered over a white background–which is key) and then the black gives your eye all the information about the value. I would use a four-tone CMYK stencil about 75% of the time. In so many situations, it JUST WORKS.
Test all the variants with downloads of the best all-around taste test: the hamburger stencil.
But you know sometimes you want to key into the vibe of a different color palette. When I’m working with comic book characters (think Superman or Wonder Woman), I want to use the colors that are ‘native’ to these drawings.
The colors we use here are evoking an era when comic book hero costumes were in simple, identifiable colors. The CMYK doesn’t show them at their best, although the flesh tones and grays are quite a bit better there. But the primary blues and yellows of the RBYK version are definitely more in the direction we want to go.
CMYK is the traditional subtractive color model. We typically use RGB for additive color applications. But if you lighten your red, green and black you can still use them for subtractive color and get close enough to ‘true’ color while achieving a really different vibe.
The one place I’ve found that I reliably get better results from RGBK is when I want an expanded range of earth tones. Browns, tans, darker skin tones always seem to pop more with RGB. In this example the blue sky is so light that it even misses the lightest pass with cyan. But it’s the foreground that really improves in this case.
Note: When there is no specifically blue component, RGK (red-green-black) is also really good for capturing many shades of browns and earth tones.
Things start to get more interesting with three-color separations. For one thing, you’re saving one stencil. For another thing, you are favoring some colors over others because your ‘dual’ colors (assuming the third one is always black) are typically hues that are across the color wheel from each other.
Red and green are the two colors that human vision sees best in opposition to one another.
Without context, I don’t have a clear favorite here. But if my context is autumn harvest, I might prefer to go with the RGK halftone, because the RGK pears look earthy and the CMYK pears look less real to me.
Orange and light blue are natural complements to each other. Because they aren’t exactly opposite each other on the color wheel, this color separation leaves yellow-greens out in the cold. (But most compositions don’t have a lot of this yellow-green in them because it’s an uncommon color.)
In the 120-line halftones above, the Orange-Blue-Black definitely gets my vote. It’s easier to parse the landscape, and even the greenish tinges are more realistic (although theoretically the way you’re getting to green is a complex combination of orange, blue and black). And, of course, it’s three layers compared to four layers.
With two-color separations, we’re usually leaving out the black and instead forcing one of the two colors to be the darker one. That way we can get some hue variation, and at the same time preserve the dark-light to capture most of the value range.
Yellow-Navy separations go back to the way our (human) eyes work: we detect and transmit differences in red-green and differences in yellow-blue to our brains. So if the primary colors of your image are more along the yellow-blue axis, this color separation method should work well.
Compare the 2-layer stencil above on the right to the four-layer halftone stencil in the middle. C3PO might look a little better with the extra colors, but R2D2 definitely comes out ahead with the navy.
Try it yourself with the R2D2 and C3PO stencil.
Pink-green also leverages the way our human color perception works, this time along the red-green axis. The trick here is that we get rid of the black (K) and skew the green to dark (so, dark green) and skew the red to light (aka pink). It’s hard to find an example of an image that gets very accurately reproduced with pink and dark green halftones.
Of course, if you use a single halftone on a white background, there aren’t so many different ways to do this.
Grayscale (black on white)
The halftone you can put on a white background to get the greatest contrast is black. But you could always use a dark color different from black: like hunter green or dark brown or navy blue. In our experience, you have to be careful about how you cover the surface with these dark colors, because you often can’t tell the difference between the dark color and black. Sometimes it’s best to use (for example) a royal blue as your dark color, and then to use a very light black spray on top of the royal blue until you get the navy look you’re looking for.
We painted a halftone portrait on a car recently, and because the color of car was dark, we used the reverse grayscale halftone to paint white spray chalk on the dark blue paint of the car.
Black on background other than white
If you choose a background other than white, you’ll have less contrast, but you’ll have the option of color keying your background to something else you like. Bright pastel backgrounds work best. You can even vary the textures and colors of your background to get interesting effects.
Arbitrary color palette for halftoning?
At Bay Stencil, we thought it might be cool to support a way of halftoning to support an arbitrary color palette. We even tried out a version of an interface that lets you select five arbitrary colors to include in a halftone painting.
What we found out was that many, many combinations that we tried (using intuition and some science to pick the colors) just didn’t result in any useful output. Given that it actually costs something to compute all these halftones, we didn’t think it made sense to have users waste a lot of time (and us cooking a lot of servers) looking for a color palette to halftone over, when we could provide a few presets that get you 95% of the good outcomes you’re looking for. So, as of right now, you can choose from the following color palettes for your halftone:
- Reverse grayscale
And we’re in beta with the additional models we’ve featured in this post:
Contact us to request halftone downloads using these unusual color separation methods.
We don’t claim to know anything about halftone *printing*; everything here pertains to halftone line stencils in resolutions that are realistic to be cut on craft cutters or laser cutters (so, 80-120 lines per image). There are lots of differences between halftone stenciling and halftone printing: Dot halftones used in printing have slightly different properties. Also, you have a different kind of flexibility when you apply spray paint than you do when you’re applying printer’s ink. (You can cover some areas and some layers more thickly than others when you spray, for example, regardless of what the stencil is like.)
So, please enlighten me about halftone *printing*–just know that this post is not about halftone printing. 🙂