BOM Line-Item Pictures that show up in the Part Items Grid and on Line Item quotes.
You will need to make sure that you have "Show [picture in the BOM Items Grid" checked. This is located in "Tools", Configure User Settings", Personal Settings".
Option #1 (Read Pictures in from Project Matrix)
You need to have a valid Project Specifier License and have the catalogs downloaded to be able to add these.
Right click on the selected Part(s) and click on "Read Pictures From Pmatrix".
To have the picture come in as rendered image, you will need to right click on the Part Preview in Spec, select "Display Mode" and "Rendered".
Option #2 (Manually add a custom image)
Right click on the part you want to add the custom image and click either "Paste Image from Clipboard to BOM Item" or ""Add / Modify BOM Part Picture".
Right click → Paste or use the Paste Image icon in the upper right corner.
This will update the image for the line item for just this one part. If you modify in the Master Parts List, it will update the part for all future uses. See here for additional details.