CMYK Colou Seperation

7/21/2019 CMYK Colou Seperation

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Creating great looking photographic prints or full color range prints onto a garment can be

accomplished using CMYK process printing. By only using the process colors you can

accomplish millions of colors onto a garment.

I just wanted to share with you the process of creating color seps used for CMYK screen

printing, here we go.

Artwork. The first and most important step is the artwork. Nothing can move forward with this

process without artwork. I have my artwork here that I will be working on. With all thesecolors, and gradients its a perfect fit for CMYK printing. without CMYK printing for this

design, It would require so many screens and set up time that the print job would just break the

bank.My artwork was created using Photoshop and a Wacom tablet. This piece has a hand drawn

element to it, and a chalk look almost like pastels. Be sure to create the art at the size to be

printed and at least 300 dpi!scaling artwork up or just snagging a low res picture off the web

results in horrible printsdont do it

Art to screen print showing image size settings

If your art isnt already in CMYK mode now is the time to change that. Go to Image > Mode >CMYK. Then flatten by going to Layers > Flatten Image.
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Layer > Flatten Image
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Image > Mode > CMYK

Note* you will lose some color detail if you are changing from RGB mode to CMYK. RGB has

a far higher color range than CMYK, most of the time it wont be too noticeable, but can really

change some colors. Just keep that in mind.

Our next step will be to separate the colors; Cyan, Magenta, Yellow, and Black (Key).

Bring up the Channels Pallet. You can access the channels pallet either method shown below.
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Channels from Window Menu

Use the method on left if you dont see the tab next to Layers.

Click the Channels tab next to Layers
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Photoshop has made it really simple for screen printers and artists to separate their CMYK

channels into separate files.

on the Channels pallet, click the fly-out button on the top right to access our channel

options. Click on Split Channels.

You should now have 4 files that each contain grayscale images for each color. That was pretty

simple huh!

See the pictures below for visual guides if your lost on that last step.

Note* You cannot undo split channels. So if you mess anything up you will have to re-open

your original artwork again.

Select Split Channels from the fly-out menu options

New Files for the Split Channels

Now that we have all the separated colors its time to make them ready for screen

burning. Because a printer will just print the newly separated files in line gradients, a screen willnot burn out properly. We will need to convert the grayscale images into a Halftone Screen

setting. The halftone dots will vary in size depending on the percentage of black. A 100% black
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area of the design will have a solid black printout, whereas a 50% black area of the design will

have a more spread out halftone pattern.

Lets start with the black or K file. Go to Image > Mode > Bitmapto bring up the bitmap

settings.

Bitmap Options

For the output I am selecting 300ppi which is the same as the dpi settings I have for this image

file.For the Method choose Halftone Screen.

The next window for our bitmap settings now comes up.

Halftone Screen Options

This is the part that will take some trial and error. These settings that I use may not work for

each design, or setup. I will explain how I came up with what I have used here.

Frequency:I use a formula to come up with this number. Screen Mesh/4=Frequency.

305/4 = 76.25 I have rounded down to 75. In most cases I just keep my frequency between 4555. For screen printing going any higher might be considered overkill.
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Angle:I like to keep all my screen angles the same @ 22.5. This is a topic that many have

debated over the years and I dont want to go into too many details. Some would consider

starting with 45 and adding 30 to each new halftone screen. So you would start with K=45,C=75, M=105, and Y=135. With screen printing presses holding really tight registration

keeping all the angles the same is not a problem.

Shape:I choose to use Round, but many like ellipse. Ellipse has its advantages, the screen mesh

can hold an oval shape better than a round shape. Play around with each different settings to find

which method you prefer.

After applying these settings your Black plate is now in a halftone screen, almost ready for

printing onto your transparencies and burning the screens! Just a few more steps and were done.

In the black plate you will now want to convert the image back to grayscale, Image >Mode >

Grayscale.

Your black file should be looking similar to this when you zoom in.

Halftone Pattern when Zoomed In

Now grab the magic eraser tool. We want to remove the white from the background. Be sure to

zoom in so that when using the magic eraser tool you dont accidentally click anywhere that hasany black. Heres the settings for the magic eraser tool that I use.
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Magic Eraser Settings

Setting the tolerance to 10, and making sure to deselect Contiguous.Now just click any white are of the file to remove all white.

You will notice now that some of our black halftones have become uneven.

Before Magic Eraser
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After Magic Eraser

To fix this, switch over to the Layers Pallet if not there already, and duplicate the layer (I preferto hold ALT and then click and drag down my layer to create a duplicate, but you could right

click the layer and select duplicate layer that way as well). Then merge (CTRL+E on PC, or

command+E on mac) the 2 layers together to bring the black back to a solid fill.
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Merged Layers

Now we will want to convert our Black file into RGB mode. This might not make sense becausewe have been using CMYK mode and Grayscale mode throughout this article, but its ok

Move this file over so that we can start on the next colors. All we have to do now is exactly aswe did to our black.

- Image > Mode > Bitmap. Use the settings described earlier.

- Image > Mode > Grayscale- Zoom way in

- Use Magic Eraser tool on white area of image

- Duplicate Layer- Merge Layers

Now instead of changing the image mode to RGB we will drag the halftone for each color

directly into our Black file using the Move Tool.

Remember to label the layers after each move for the appropriate colors.
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Using move tool, click and drag in the artwork and drag over to the black file

Still dragging the art onto the black file
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The art is now inside the black file, in its own layer.

Now keep using the move tool to position the artwork in the exact spot as the Black layer. This

is important for registration when on the press. Newer versions of Photoshop will actually snap

to the correct spot once you have it close. To be certain try zooming into an area of the art where

you can easily tell if they are lining up correctly.

Here is the file I now have that shows the art lined up correctly and my Layers now labeled forclarity.
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After moving Cyan, lining up art, and relabeling my layers

Now we can close our Cyan file, no need to save the file. Do exactly the same process for the

remaining 2 colors.

Here is my file now that contains all 4 colors, each on their own nicely labeled Layers.
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All Colors in one file, nicely labeled

These files are ready to send to the screen printer! But were not done yet. We will actually be

applying color overlays to each layer, and then changing the blending modes so that we can see

what our new file looks like.

Right Click on the Cyan Layer (not the thumbnail) and select Blending Options.
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Right Click Cyan Layer and choose Blending Options

This brings up our layer styles, we wan to now click on Color Overlay
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In the Layer Style window, Click Color Overlay

Now we want to click the color Box to change our color, clicking the red color box brings up yetanother window that lets us choose our color. We will want to click the button for Color

Libraries for our color.
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The Color selection box appears, click on Color Libraries

In the color libraries make sure that PANTONE solid coated is selected. Now scroll up through

the colors to find the process Cyan color and select it.
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In the Color Libraries, scroll to the top to find our Process Colors

Our Cyan layer now has a color overlay of Cyan!

Move on to the next 2 color to select their appropriate PANTONE color using the same Blending

Options on each layer.

Heres how our file should now look. Notice in the layer pallet that each layer except for blacknow has a layer style.

All layers with their Color Overlays

Wait a minute! This looks nothing like our original file not to worry!

Create a new layer beneath each of the Cyan, Magenta, and Yellow layer.
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Create new layers under each color

Now we need to merge each color layer with the new layer under it. DONT MERGE ALL

LAYER TOGETHER! So in my example above we will merge Yellow with Layer 1 copy 2;

Magenta with Layer 1 copy; and Cyan with Layer 1.

So highlight Yellow and Layer 1 copy 2 (or similar to however you have your file now) and

merge the layers. This applies the color overlay to our halftone files that we created. Now wehave our yellow layer as halftones, in the correct color it will be printed with. This is important

and you will see why in a minute.
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In layers change the blending mode from normal to multipy for each color

Heres what we should get now that we changed each layer to Multiply.

The Image looks Great!
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It loos alot like our original now! This process actually simulates exactly what is happening on

the screen printing press. Because the process inks used for CMYK printing are transparent they

are blending together, meshing and mixing on the shirt to create all the different colors.

Closeup of whats happening on the file.

Closup of file

Before sending the file out for screen printing you could save your printer a step by creating

black color overlays for each color.

I hope this helps anyone looking for CMYK separations using Photoshop.

Leave a comment below if you thought this was useful, or if you have any suggestions.

Thanks for reading.
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CMYK Colou Seperation