Here is a color palette based on your request for a high contrast typographic poster featuring white, black, and green:

json
{
  "palette_name": "High Contrast Typographic",
  "colors": [
    {
      "name": "White",
      "hex_code": "
          
          #FFFFFF
       "
    },
    {
      "name": "Black",
      "hex_code": "
          
          #000000
       "
    },
    {
      "name": "Green",
      "hex_code": "
          
          #00FF00
       "
    }
  ]
}

This palette is designed to create a striking contrast, perfect for typographic posters. The combination of white and black provides a classic, clean aesthetic, while the bright green adds a vibrant accent that draws attention.

Would you like to explore more colors or perhaps different shades of green?