JS converter to change image palette to Unified dyes-like one and export its pixels to JSON or Lua tables.
Clone this repo or download a zip file, open index.html, select options and image, check if preview looks good.
If it does, a list of param2 values for unifieddyes blocks will be available in "output" area.
You can add more data to the output by selected "advanced" option. It will add filename, width and height attributes.