This is an InDesign/Photoshop error but the problem itself is coming from Photoshop.
I made a silhouette pic in Photoshop CS6 after rasterizing some layers and what I have is a black background with a white figure in the foreground. I could not convert it to a JPEG, but I opened it up in Bridge and I wanted to import it into InDesign, but then I got an error message that said:
"This file uses an unsupported color space. Only RGB, CMYK, L*a*b*, grayscale, indexed and bitmap formats are supported by the Photoshop filter"
I tried to fix it in Photoshop but there's no way to unlock the Background layer in order to edit it. Any answers?
Editing a layer isn't going to result in a different colour space, anyway.
Open the problem black and white document in Photoshop.
Image > Mode > Grayscale
Save or Save As.