Make your separation

1. Open your image in Photoshop

Your image should be sized to the correct size of output and a dpi of 170. All images must be sized BEFORE printing. You cannot change the size/dimensions/resolutions after; the results will be not good.

• To check: Top Menu > IMAGE > IMAGE SIZE
  
  

Save it as a new image because you will be doing destructive image editing.

• Top Menu > SAVE > SAVE AS

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2. Change your image mode

IMAGE > MODE > CMYK

Look in the Channels Menu at the right side. If not visible, Top Menu > WINDOWS > CHANNELS.


This shows you the 4 colors are separated. You need to turn each one of these layers into a Bitmap.

3. Split Channels

Click on the small channels menu (4 lines on top R of menu).

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Select SPLIT CHANNELS.

If this button is greyed out, you have to Flatten your image. Go to : TOP MENU > LAYER > FLATTEN IMAGE

This will turn each layer of the CMYK into its own image. See the top tab bar for all your separations.

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Below is my Black Layer. It shows up as a series of Greys. We want to only have black and white values.

With each individual file, we are turning it into a Bitmap (only needed for exposure units, i.e. silkscreen, photo litho, etc. the image will be made up of a series of dots that the screen can recognize when
exposing). Do this to each file.

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4. Change to bitmap (silkscreen, platemaker, photo litho only)

IMAGE > MODE > BITMAP

The frequency and Angle are important. You are more than welcome to experiment with these settings to see the size and range of dots that can be made to alter the final look of your image. However the following are the “Industry Standard” for most print shops. When in doubt, follow below and you cant go far wrong.

Resolution

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This is the first menu. Make sure your output is 170 (0.75 x your screen mesh count) and that you choose Halftone Screen. The value of OUTPUT RESOLUTION must be the same for each layer: Cyan, Magenta, Yellow and Black.

Screen

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This is the second menu.The angle values will change for each color layer. For CMYK, keep the dots set to Round.

Note: If you get and "alpha" or "transparency" layer, you can discard it.

Press OK!

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→ Example of the black separation converted to a bitmap.

Repeat these steps for each color layer until you end up with 4 bitmaps. They will be black and white, but you will silkscreen them in color.

5. Save & Upload

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1. Press File > Save As
2. Name your file and save as Photoshop (PSD) on the Format menu.
3. To print your transparency: Ask your teacher where they want you to save your final file. If unsure, save on your USB drive, or to the Short-Term Storage Box Folder.
   1. Personal Backup: Files will automatically delete from the school computer when you are logged out. If you are on a shared computer, make sure to save a backup for yourself by: emailing to yourself, uploading to a cloud service, putting on a personal USB.

7. PRINT!

Silkscreen, photo litho: Get a TA, monitor, tech or faculty to help you print your transparencies.

Riso: print your separations yourself using the UT Computer Printers.

Preview your separation in Photoshop

All of your bitmaps will be black to print, but you can preview them in Photoshop using color overlays.

Original:

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CMYK:

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Method 1: Download CMYK template (shorter, more advanced)

If you are comfortable with Photoshop, you can use this template which saves you a lot of work.

Usually, you don't even have to remove the white. Try it out! You can also change the overlay colors for experimentation.

Method 2: Use Image Overlays (longer, easier)

1. Save a COPY of each of your layers (File > Save As...). The editing we will do is destructive.
2. For each separate Bitmap file that you have, change it back to CMYK. You have to do both the below steps:
   
   1. IMAGE > MODE > GREYSCALE > SIZE RATIO: 1 > OK
   2. IMAGE > MODE > CMYK > OK


3. Then you have to remove the white color information so you are only left with the black dots. Do this by: LAYER > DUPLICATE LAYER
   1. Turn off the bottom layer by clicking on the eye
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   2. Then click on the top layer.

      From the top menu choose:

      TOP MENU > SELECT > COLOR RANGE

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      Use the eye dropper to click on the white of your image. Then DELETE.

      You are now left with just the black information

4. 
   

   To add the color overlay go to the Top Menu > LAYERS > LAYER STYLES > COLOR OVERLAY
   Choose your color to best represent the layer.
   If you are using true CMYK colors, you can use the percentages at the bottom right. Just do 100% for the layer color (e.g. this one is cyan so 100% cyan) and 0% for the other colors (M,Y,K)
   
   Tip: You can experiment with other colors! Great for Riso and experimenting with silkscreen.

   
   

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5. Hit OK.
   
   

6. Go Back to the LAYERS menu and right click on your overlay. Pick "Rasterize style"
   
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7. You can now drag or copy all four layers into the same file to see them layered on top of one another. You can play with the order and the opacity!

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