const SHEET_GREEN = { r: 0, g: 255, b: 0 };
function greenDistance(r, g, b) {
	const dr = r - SHEET_GREEN.r;
	const dg = g - SHEET_GREEN.g;
	const db = b - SHEET_GREEN.b;
	return Math.sqrt(dr * dr + dg * dg + db * db);
}
console.log('sheet green (34,139,34):', greenDistance(34, 139, 34).toFixed(1));
console.log('brown (139,90,43):', greenDistance(139, 90, 43).toFixed(1));
console.log('threshold at s=50:', 150 - 50);