Problems desaturating an image in Indesign

[SteveIsHere]

I am unable to desaturate an image in Indesign. This is what I'm trying:

1. Select the image by clicking on its colored box in the Layers panel.
2. Select Window | Effects to display the Effects window.
3. Select Saturation in the first drop down menu.
4. Click on the Opacity ">" button.
5. Drag the slider to change the opacity.

Rather than changing the saturation, this changes the transparency (i.e., opacity). I.e., it makes the image "white" when on a white background. However, the color saturation (i.e., color vs B&W) doesn't change. I want to reduce the intensity of the colors.

Can you show me the error of my ways?

Thanks!

[Dov Isaacs · Accepted solution]

Unfortunately, you are confusing the Saturation Blending Mode of transparency for actually modifying the saturation of an image itself.

Although you can slightly modify the saturation of a placed color-managed RGB image by setting its rendering intent to Saturation when placing the image, that will not accomplish all that much for you. InDesign doesn't have a function for truly adjusting image hue or saturation.

The real solution is to edit the image directly in Photoshop and adjust its saturation therein. Then place the image again (or refresh the link) in InDesign.

          - Dov

[rob day]

You can do it by layering the same image on top of itself.

Something like this where I've set my document's Transparency Blend Space to RGB. The bottom version of my RGB image has its frame filled with RGB white or [Paper], and the image Blend Mode is set to Luminosity. The image is desaturated:

Then I clone the image (Copy>Paste In Place) and set the top image's frame fill to [None] and the image Blnd Mode to Normal:

I can then adjust saturation by changing the top image's Opacity: