As shown below, the Four-Color Overlay subdues images while allowing color to show through.

The use of the Four-Color Overlay treatment creates contrast between the full-color image on the left of the spread and the typographic information to the right.
Pretreated Images
A collection of pretreated images using the Four-Color Overlay treatment are available for download. These images may be used across print and web applications.
Photoshop Action
A Photoshop action has been created and available for download. Photoshop actions streamline the process of producing these effects in an easy and efficient way. Instructions on how to use the action are available.
To Create This Effect in Photoshop

Blue Version
1) With your full-color image opened in Photoshop, make sure it is set to CMYK (Image -> Mode -> CMYK Color).
2) Create a new layer and fill in with Jefferson Blue (C:98 M:83 Y:13 K:46). Set layer blending mode to Overlay with an opacity of 40%.
3) Duplicate the Jefferson Blue layer and change the blending mode to Multiply with an opacity of 70%.
Feel free to adjust the opacities on either/or blue layers to produce desired effect.
TIP: Adjusting the levels/curves of the image will help bring more details out of imagery.

Orange Version
1) With your full-color image opened in Photoshop, make sure it is set to CMYK (Image -> Mode -> CMYK Color).
2) Create a new layer and fill in with Rotunda Orange (C:0 M:68 Y:100 K:0). Set layer blending mode to Overlay with an opacity of 45%.
3) Duplicate the Rotunda Orange layer and change the blending mode to Multiply with an opacity of 90%.
Feel free to adjust the opacities on the orange layers to produce desired effect.
TIP: Adjusting the levels/curves of the image will help bring more details out of imagery.