Desaturate Image in InDesign
Put a black rectangle over the image
TO Desaturate Image in InDesign, Click the “Window” menu and select “Transparency” to open the Transparency menu. Click the “Blending Mode” menu at the top of the panel and select “Hue.” Click the “Opacity” menu in the Transparency panel, then drag the slider to about 50 percent. The image colors are desaturated.
Select different colors from the Swatches panel to change the color being used to filter the image. Black will give the image a uniform desaturation, whereas yellow will give the image a yellowish tint. Blue gives the image a bluish tint.