I am assuming the images will remain relatively static. The best way is to get them into SQL, in my opinion, again I am assuming your linked tables come from SQL.
I use something like this to pickup profile pictures and insert them into a SQL table, then use that table in PowerPivot.
CREATE TABLE [dbo].[TblImage](
[Image_Data] [image] NULL,
[Image_FileName] Varchar(128),
[User] Varchar(128))
INSERT INTO TblImage( Image_FileName, [User], Image_Data)
SELECT 'Feb2012.jpg', 'My Friend',
* FROM OPENROWSET(BULK N'C:\Backup\f1_SThumb.jpg', SINGLE_BLOB) as tempImg
INSERT INTO TblImage( Image_FileName, [User], Image_Data)
SELECT 'Feb2012.jpg', 'My Friend 2',
* FROM OPENROWSET(BULK N'C:\Backup\f2_MThumb.jpg', SINGLE_BLOB) as tempImg
If you can find a way to import the images in Excel as binary with VBA, please let me know, I have not yet found a reliable way to do so.
From MS a nice guide to working with images in PowerView
Or Dan English's
Using Database Images in Tabular BI Semantic Models with Power View
But if you want to go through the effort or embedding the data, SQL is by far the easier route to take. I will gladly admit that I have tried and failed on various occasions with Excel and VBA, but opted for the SQL route instead.