https://developer.mozilla.org/en-US/docs/Web/API/Window/showSaveFilePicker#browser_compatibility
Using libjpeg-turbo via Emscripten.
Module.cwrap("encodeJPG","number",["number","number","number","number","number"])
Using fpng via Emscripten.
Module.cwrap("encodePNG","number",["number","number","number","number","number"])