The Ghetto Method for Spot Color in Photoshop

Say you have a rgb image of a logo that needs to be printed two color. Ok so you could recreate the image in Illustrator and apply spot colors in that.

Or... You could convert the rgb file to cmyk in Photoshop and delete the contents of two color channels, say the cyan and yellow channels leaving you with the k (black) and the magenta channels which would seperate into two color plates.

But seldom is life that simple. Many times the black portions of the rgb file will be present in all the cmyk channels. BUT! you could go to the color settings in Photoshop choose Custom CMYK setup and change your black generation to maxium. Ahh much better. Just remember to change it back to your previous settings before you do any other cmyk conversions :)

You probably want to use the Levels or Curves image adjustment to increase the contrast in the color channels so you get nice solid spot colors in your print output.

Or you could just bite the bullet and recreate the sucker...but what fun is that?