Is it possible to quickly change a picture from colour to B&W in indesign?
check this link.
https://www.g2.com/discussions/is-there-a-way-to-make-an-image-black-and-white-in-indesign-itself
thank you. it didn’t work for me…
here’s the answer:
InDesign doesn’t have a way to convert a color image to grayscale in the way that Photoshop does, but you can fake it pretty easily. 1. Set the Fill color of the image frame to paper. 2. Double-click on the image frame so that you have the content selected, not the frame. 3. Change the blend mode to “Luminosity.” Your image will now appear in shades of warm grey only. To make an entire document greyscale for output, create a new PDF output profile. In the “Output” panel, make the Color Conversion field “Convert to Destination” and the Destination field any of the “Dot Gain” profiles: 10% Dot Gain, 15% Dot Gain, etc… The PDF will be greyscale, perfect for monochrome newspaper ads and similar black-only purposes. To see what the PDF will look like while you’re editing in InDesign, turn on View>Proof Colors and make a custom profile with the same dot gain.
from that site. Not sure if it’s the only answer… 
i tried but didn’t work…
I didn’t try myself… Maybe l’ll try it out later. Why don’t you just pull it into photoshop?
Just wanted to say that I tried the instructions and it worked fine for me… Which part were you having trouble with?
ok, will try again, not sure what i did wrong…