PDF with grayscale images getting huge

[Matbathome]

I have file I created in Indesign that has a lot of grayscale images. It's true grayscale and I made them grayscale in Photoshop. For whatever reason, this pdf is ballooning up to 18 meg and it's only 10 pages. It didn't start happening until I converted the images to grayscale.

Any ideas?

[Willi Adelberger]

What is your color management policy for CMYK?

What are the PDF export settings? You export?

[rob day]

The export of grayscale images is handled differently than export for color images. Check Export>Compression and look at your settings for Grayscale