No way to grab LAB values using Illustrator script

Community Beginner ,
Apr 20, 2022 Apr 20, 2022

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Hi, I am trying to write javascript code that will run in Illustrator and tell me what the current value of L,A,B of a specific spot swatch I have.


I wrote a more complex script that uses this function, but the problem is with this code snippet:


var c = swatch.color;
    if (c.typename == "SpotColor") {
      c =;
    var colorComponents;
    switch (c.typename) {
      case "RGBColor":
        colorComponents = [,,];
      case "CMYKColor":
        colorComponents = [c.cyan, c.magenta, c.yellow,];
      case "LabColor":
        colorComponents = [c.l, c.a, c.b];
      case "GrayColor":
        colorComponents = [c.gray];
    var destColorSpace = ImageColorSpace["LAB"];
    var outputColors = app.convertSampleColor(
    var l = outputColors[0], // grabs l value
        a = outputColors[1], // grabs a value 
        b = outputColors[2]; // grabs b value
    var color;

Here is more of the code for context:

// edits existing LAB color values
function editSpot(swatch, l, a, b) {
  var spotColor =;
  spotColor.color = newLabColor(l, a, b);
  return swatch.color;
// creates new LabColor, which gives the color values to the spot
function newLabColor(l, a, b) {
  var newColor = new LabColor();
  newColor.l = l;
  newColor.a = a;
  newColor.b = b;
  return newColor;
// creates new spot swatch
function addSpot(name, l, a, b) {
  var newSpot = doc.spots.add(); = name;
  newSpot.colorType = ColorModel.SPOT;
  newSpot.color = newLabColor(l, a, b);
// retrieve swatch by swatch name
function getSwatch(colorName) {
  try {
    var swatchToChange = activeDocument.swatches.getByName(colorName);
  } catch (e) {
    if (placeholder) {
      alert("The swatch name " + colorName + " does not exist.");
    return undefined;
  return swatchToChange;

 The problem is within the first code snippet. Even though the PDF file is in LAB, and the swatch is in LAB, the variable c gives "RGBColor", which then is being converted to LAB in an unaccurate way.

Illustrator only uses integers and doesn't use decimals in color values, e.g. L=70, there isn't an option for L=70.45.
To my surprise though, when I try to preview/alert the value of variable l,a,b (outputColors[0],[1],[2]) - the output will show like this:

real values.png

But the swatch colors in illustrator GUI was like this:

fake values.png

Bug , Scripting







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