Create a new Adobe InDesign layout and place an image. This will be used as a demonstration of how to desaturate images in InDesign.
Next, grab the "Rectangular Frame Tool" from the toolbox and then draw a frame over the image and of the same size as the image.
The next step you need to do in order to desaturate images in InDesign is to fill the frame with a solid color. This seems to work best when you use the "Swatch" panel to do this.
With the solid colored frame above the image selected, open the the "Effects" window and set the blending for the frame to "Hue."
The "Hue" blending retains the original luminosity and saturation from the placed image, so you will notice that the most affected areas in the frame are the ones that have the most color. You can change the blending mode to "Color" for a more uniform effect. This setting keeps the luminosity of the original only because the "Color" blend affects both hue and saturation.
Moving along, you now should change the blending mode to "Saturate." Depending on your choice of blending color, this might not look much different from the original.
Finally, return to the "Swatches" panel and adjust the tint. You will see that you are now in full control as you desaturate images in InDesign. Just select the level of desaturation you want. In this example, the image is completely desaturated.
Image Credit: Wikimedia Commons/Uwe H. Friese
Image Credits: Screenshots taken by Bruce Tyson