Why do grayscale images turn out lighter when exporting a PDF from Indesign than how I see them in Photoshop?

I converted RGB images to grayscale in Photoshop, placed them in my InDesign doc, exported it as a PD, and the end result is much lighter grayscale images than what I had worked on originally in Photoshop.Why do grayscale images turn out lighter when exporting a PDF from Indesign than how I see them in Photoshop?
Well it depends on where the 'much lighter' is showing up; your screen or your printing? If it is just your screen I wouldn't be too concerned, as InDesign probably converted the color profile when you created the PDF, especially if your PDF contains other CMYK art.





It also depends on what type of pdf you created, whether it's color profile is CMYK, RGB or Grayscale and if you changed the resolution of your image in the PDF'ing process.





Really, the only place you need to be concerned about this is in your proofs. If you print the art from Photoshop directly, and then using the same printer, print it from your PDF, is there a difference? There shouldn't be.





But if it is inconsistent, I would check what PDF format you're using and make sure it has a color profile in the PDF export dialog. Next I would try assigning a color profile to the image in Photoshop (Go to Edit %26gt; Assign Profile) first.