Masonry Image Gallery
Follow these steps :
1: Add a Image Gallery VC Element to the Page.
2: Choose Image Grid Style in the "Image Gallery Settings" VC Options Popup.
3: Click on the '+' sign to add the Images
4: Select the Image you want and set the Image URL and select Masonry Sizing Option for individual Images .
5: Press Add Images when you have added multiple Images.
Make sure to select the "Image Grid Style" in the Dropdown field named "Gallery Type" . Only then would the step 4 options show up .
Also you need to be updated to Salient Theme Version 7.6+ as it has these Options .