Since Marked Responsive Images requires a specific naming convention to parse variants correctly, I wrote a short PowerShell script to automate the process using ImageMagick.
You just provide an image path and an output destination, and it creates appropriate files and spits out the exact markdown string you need:
./generate-responsive-images.ps1 -InputFile "C:/AbsoluteOrRelative/PathToYour/File.png" -DestinationFolder "AbsoluteOrRelative/Output/Folder" -OutputName "root-file-name"This will generate all the correct images and provide you with the corresponding markdown image snippet, like this: