diff --git a/helpers/qr.helper.js b/helpers/qr.helper.js
index 7473b6e..9152978 100644
--- a/helpers/qr.helper.js
+++ b/helpers/qr.helper.js
@@ -4,6 +4,29 @@ const moment = require("moment");
 
 const config = require("../config");
 
+const luma = (color) => { // color can be a hx string or an array of RGB values 0-255
+  const rgb = (typeof color === 'string') ? hexToRGBArray(color) : color;
+  return (0.2126 * rgb[0]) + (0.7152 * rgb[1]) + (0.0722 * rgb[2]); // SMPTE C, Rec. 709 weightings
+}
+
+const hexToRGBArray = (color) => {
+  if (color.length === 3)
+    color = color.charAt(0) + color.charAt(0) + color.charAt(1) + color.charAt(1) + color.charAt(2) + color.charAt(2);
+  else if (color.length !== 6)
+    console.debug('Invalid hex color: ' + color);
+
+  const rgb = [];
+  for (var i = 0; i <= 2; i++)
+    rgb[i] = parseInt(color.substr(i * 2, 2), 16);
+  return rgb;
+}
+
+const calculateContrastingColor = (color) => {
+  const _color = (typeof color === 'string') ? color.replace('#', '') : color;
+  return (luma(_color) >= 165) ? '#000' : '#fff';
+}
+
+
 module.exports.getInscriptionQRCodeUrl = function (inscriptionId) {
   return encodeURI(`${config.server.public_url}/inscriptions/${inscriptionId}/qrimage`);
 };
@@ -34,7 +57,7 @@ module.exports.getInscriptionQRCode = function (params) {
       options = _.assign(options, {
         color: {
           light: params.color ? colourNameToHex(params.color) : "#000000",
-          dark: "#ffffff",
+          dark: calculateContrastingColor(params.color), //"#ffffff",
         },
       });
     }
diff --git a/modules/events/marketing_list.service.js b/modules/events/marketing_list.service.js
index 7867240..0cd8d4f 100644
--- a/modules/events/marketing_list.service.js
+++ b/modules/events/marketing_list.service.js
@@ -42,7 +42,7 @@ function _generateMarketingDTO(dataInscription) {
     inscriptionDTO.validated = inscription.validated;
 
     inscriptionDTO.reservation_code = reservation ? reservation.reservation_code : null;
-    inscriptionDTO.color = reservation ? reservation.color : 'green';
+    inscriptionDTO.color = reservation ? reservation.color : "darkgreen";
     inscriptionDTO.description = (reservation ? reservation.description : "Entrada").toUpperCase();
     inscriptionDTO.qrConfig = null;
     inscriptionDTO.qrCode = null;