Black-and-White HDR: Colorize with the Photoshop Duotone Tool
Colorizing (often called tinting or toning) black-and-white high dynamic range (HDR) images overlays one, two, or more colors over the black-and-white image, resulting in an aged or other creative effect. Photoshop has many of the same features as Elements (Colorizing, Color Variations, and Color Layers), but offers more power-user features that give you greater control over colorizing.
The Photoshop color mode Duotone automatically applies colored tints in various proportions. Duotone is easy and powerful, and has a lot of options. You can choose the number of colors, specific toning curves for each color, and the colors themselves. (CMYK is available as well.) However, your image must be converted to grayscale, which is 8 bits per channel.
Although the name of this tool is Duotone (two colors), you can have one color (Monotone) or more: three (Tritone) or four (Quadtone).
To apply a duotone, start with an image already converted to black and white using your favorite method. It can still be an 8 Bits/Channel or 16 Bits/Channel RGB image at this point (that is, a black-and-white image in a color space).
The point is for you to have a chance to control the black and white tonality. If you want to quickly colorize an image and not spend a whole lot of time converting it to black and white first, jump right into the following steps.
Follow these steps to apply a duotone:
Convert your image to 8 bits per channel by choosing Image→Mode→8 Bits/Channel.
Convert your image to grayscale by choosing Image→Mode→Grayscale.
You need to have an 8 bits/channel image converted to grayscale to use duotone — it won’t work with any other format.
Convert your image to Duotone by choosing Image→Mode→Duotone.
The Duotone Options dialog box shows a monotone to begin with, or the settings from your last application.
In the Duotone Options dialog box, choose a preset from the Preset drop-down list.
You might prefer to find some presets you like and possibly modify and save them as your own. (Configure the settings you like, and then select the small drop-down list tucked between the Preset menu and the OK button — within this list are the Save and Load Preset options.)
This figure shows a preset loaded in the dialog box and the image visible onscreen. The BMY Sepia 4 option is selected in the Preset drop-down list, Tritone in the Type drop-down list.
To create your own colorized image, use these options:
Type: Select Monotone, Duotone, Tritone, or Quadtone.
Duotone Curve: Click the little graph beside each color to control how the tones are applied. Make them darker, lighter, increase the contrast, and so on. The process is similar to adding points on a histogram to brighten or darken, but you are limited to specific ink percentages.
Ink: Click the color swatch to open the Color Picker and choose a new color.
Color name: If you’re using a preset, the preset color name appears. If you selected a color from the Color Picker, you can name the color whatever you want.
Overprint Colors: Click the Overprint Colors button to open a dialog box where you can specify in what order the colors are printed. For example, the result of printing red over blue can look different than printing blue over red.
That’s it. You should save the colorized image as a separate file because it’s now an 8 bit-per-channel duotone image.