How do you add color to a halftone image in Photoshop?

Two of the most popular ways of creating a halftone from an image is to convert the image to a bitmap and apply a halftone line screen (2). The other method is to use the Color Halftone filter (4). You should take into account how the final image is going to be reproduced before you colorize as this will save you a massive headache when it comes time to print it. If it's meant for online use or will be converted to CMYK to print, then you don't have to worry about much.



I'm assuming that you're looking to accomplish something similar to (3). If this is the case:

1. Once you convert to a halftone, convert back to an RGB image and copy the image to an alpha channel.

2. Use the alpha channel to select the black in the image and fill with the foreground color.

3. Invert the selection (command-shift-i) and fill with background color.

From there you can use masks to segment parts of the image and hue-shift contrasting colors to your heart's content.