Monday, March 07, 2005

Bad registration

Coming from the world of print, registration of images when printing is a big deal. The different colors of ink have to hit in the correct spot to look good, especially with a 4 color CMYK print.

However, when the registration is off, it creates a bit of an effect, showing the hidden pieces of the image. This can be cool if controlled. So, I set out to figure out a good way to simulate this kind of effect with photoshop and illustrator. It turns out to be extremely simple.

The first step in the process is to take the channel of an image to isolate the part of the image. To do this, first start by making sure your image is in CMYK, not greyscale or rgb.

  1. Then click on the channels palette and choose a channel.

  2. Then select all and copy it into an Illustrator file. Make sure the color of the document is RGB.
  3. Select the copied image.
  4. Adjust the color:
    You need to adjust the color of the image and tell it to be the color that it was. To do this go to the 'Filter' menu and choose 'Adjust Colors' Option
  5. This will open a dialog boxwhere you can tweek the color. Check both the 'Preview' and 'Convert' checkboxes.
  6. Then choose the 'RGB' from the dropdown list.

  7. Now you can adjust the color of the selected image. Follow this guide:

    • CYAN
      • set Red = 0
      • set Green = 63
      • set Blue = 78
      • set Red = 100
      • set Green = 0
      • set Blue = 50
    • YELLOW
      • set Red = 100
      • set Green = 100
      • set Blue = 0
    • BLACK
      • set Red = 0
      • set Green = 0
      • set Blue = 0

  8. Now just set the transparency mode to 'Darken' on all of the items, and knock them out of register as you see fit.

What's cool is that you can play with other colors if you don't want to use the traditional CMYK. You can also use just a few channels for a duo-tone effect.