Photoshop :: How To Remove Excess Gray Space Within Image

I have some large collections of images: columns of 8 to 10 images across with as many as 40 to 60 rows. These are exported from a program called CatDV Pro. Between each row is gray space -- my problem is that I need to reduce that gray separator between the rows to make a better visual display and also to get it to fit on the page of the book. I have about 30 to 40 of these image collections to process.
 
Some things I cannot do:  reduce the size of the gray separators in CatDV Pro -- not possible.  It is only possible to export the entire page of images together. Sure I could export each individual image but that would be a garganuan task -- not practical.
 
I don't want to cut and paste indivdual images or rows. Sure, it's possible but not at all practical.
 
I have tried Content Aware Scaling and it is not uniform enough. Some rows squish before others. I know about protecting some area in Content Aware Scaling but that doesn't seem practical either, not with 40 rows. Maybe I'm missing something there.
 
Here is a small sample of what I start with:

And here is what I want to end up with.  (keep in mind the actual files have many more rows):