These blocks can seperate an image into two images, one defining shape and the other defining color, as well as combine the images back together. The use of this is to work with the shape or the color of an image without changing the other. Here is a link to the my snap mod which I coded the project in.
You can save the project to your snap account, then share it (open > project name > share), then copy the link to the project, and post that here. The link should look something like this
https://snap.berkeley.edu/snap/snap.html#present:Username=morkley&ProjectName=[project name]
Will that work with the blocks from my mod that become undefined blocks in snap?
probably, unless their custom blocks.
Could be simpler to export your project and then upload it so a site and just publish the link to it.
I see you've put a link up but I'm getting 404 on it - have you made the file shareable on your Google Drive?
I think I fixed it now.
OK - got your project loaded into your mod 
Couple of questions
- What is it trying to achieve?
I get this
and I'm having trouble relating the two images
- Could it not be done with Snap! with the standard Colors and Crayons library?
The variables are how the images are related the shape is in model then by using pallet 1 you get the image on the left and with pallet 2 you the image on the right, every time you run it pallet 2 is randomized but pallet 1 stays the same. As to whether it could be done with colors and crayons it definitely could but when I tried it gave me
so I stoped.