Unreliable HEX codes when converting swatch from CMYK to RGB

[dagingen]

Unless i am missing something, this must be some kind of bug. (See attached video)

1. I duplicate a cmyk-swatch.

2. Doubble-click it and scitch mode to rgb

3. Adjust rgb-values if neccesary

4. Copy the hex-value and use it to name the swatch for easy refferance before clicking OK

5. When i edit the swatch again, the hex value has changed.

[Peter Spier]

in your video I'm not seeing the values for either hex or RGB changing after the swatch is saved?

[dagingen]

Look at the HEX-code in the swatch Options at 30 sek (#D4DAEA) an then again at 40 sek (#D4DBEA)

[rob day]

Hi @dagingen , I think InDesign’s hex value for RGB 212|219|234 (#d4dbea) is correct. The math to get the 16-bit hex values can be scripted:

var ca = [212,219,234]
alert("RGB " + ca.toString() + " HEX value = " + rgbToHex(ca))

function rgbToHex(c){
    var hs = "";
    for (var i = 0; i < c.length; i++) {
        var hex = Number(c[i]).toString(16);
        if (hex.length < 2) {
            hex = "0" + hex;
        } 
        hs += hex;
    }
    return hs;
}

Returns this:

Photoshop also returns #d4dbea for 212|219|234:

[dagingen]

Hey! 🙂 Thank you for the detailed response.
Yeah, you're right. #d4dbea should be the right code. It lines up with eerything else.

The main reason i posted was more to submit this as a bug-report - but this might be the wrong place to do that? (Sorry, I usually just lurk in the forums).  

[rob day]

The main reason i posted was more to submit this as a bug-report

I don’t think you will get very far with a bug report. Your chart assumes there are single, universal RGB and CMYK color spaces, which is not the case. This might help:

https://community.adobe.com/t5/indesign-discussions/branding-color-guide/td-p/10818696

[rob day]

Also, InDesign’s color conversions are color managed, so the conversion from a set CMYK value to RGB would produce different values depending on the document’s assigned RGB and CMYK color profiles, and the current Color Settings’ Conversion Options Intent.

Looks like the chart you are using is not color managed, and assumes some unknown CMYK and RGB color space for its conversions.

[Peter Spier]

@rob day  shouldn't the hex values be static, though, for any RGB color space when you type numbers into the RGB fields? After all hex is just a different representaion of the decimal value. I would expect color appearance to change, but not the numbers.

[rob day]

Hi Peter, Yes hex is just a different RGB notation. I get #D4DBEA for 212|219|234 in InDesign, Photoshop, and via math. The chart in @dagingen ’s clip is a bit blurry, but seems to be listing #D4DBEB for 212|219|234, which I don’t think is right.

Also the chart is showing CMYK 29|11|4|0 and RGB 212|219|234 (#D4DBEA) as colors with a matching appearance. I can’t find any CMYK and RGB profile combination that come close to displaying a match, so I’m guessing the chart values are from some website conversion and are not color managed conversions.

A few profile combinations for the 2 values:

[dagingen · Accepted solution]

@Peter Spier Yes, that was my main point. I should be able to trust that the RGB and HEX numbers are one to one at all times when using the color dialog.

Thanks for the info on color-conversion @rob day 
I had a look at the InDesign-files vith converted PMS-colors - great job! This wil be usefull in the future.