Hello ...
The text "50x50-150x150" is just a language variable ... you dont have to go off those dimentions.
X-Cart does have a setting in the General Settings > Appearance options section called:
Thumbnail width in the products list. As default it's set to 125.
Meaning if the uploaded thumbnail image is smaller than 125px in width, it will strech it to 125px or if it's bigger than that it will scale it down (not physically how something like imagemagick does, but just by some html paramaters)
Hope that helps (and made some sence
)
Regards
Shafiq :sK
__________________
Developing in 4.7.x now (Dipping into v5 - Slowly!)
Have used 4.1.x, 4.2.x, 4.4.x, 4.5.x, 4.6.x & 4.7.x
Multiple Instances of X-Cart
MySQL 5.6.37
CentOS 7.4
Chamber Internet - Lancashire, United Kingdom
http://www.chamberelancs.co.uk