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Easy RGB, CIELCH and Munsell

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Z
 Z
(@zoriana-m-morozewych)
Active Member
Registered: 2 years ago
Posts: 6
Topic starter  

I’m trying to understand how the CIELAB/LCH (Lightness, Chroma) numbers correspond to Munsell LCH numbers. Using Dunne Edwards Santa Fe Sunrise as an example, how does one convert EasyRBG’s  C=34.629 to DE’s Chroma of 5.9? The same question for L=65.689 to Value of 6.4? How do these 2 systems work with each other or is there a way to convert them to each other?

Detail:

Name

#

hue°

 

Hue

Family

Value

Chroma

LRV

L

A

B

Santa Fe Sunrise

DET468

62.266

62

5.8

YR

6.4

5.9

34

65.689

16.115

30.651

                                  L              C           H

CIE-L*Ch(ab) =   65.689   34.629   62.266°

GLIDDEN Notations

Similar question - how does one convert the Chroma on a Glidden color to a Munsell Chroma Notation? For example, 80YR 48/274 - Soft Copper Orange has a Chroma value of 274 in Glidden, but how would one convert it to Munsell? 

Thank you


   
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Lori Sawaya
(@lorisawaya)
Estimable Member Admin
Registered: 2024 years ago
Posts: 164
 

Yes. CIELAB and Munsell 'work together' because Munsell was the template for the CIELAB color space.

Transforming color data values CIELAB to Munsell isn't rocket science but it is complex. Only because there are standards and processes that must be understood and followed. Because it's consistency that makes the notation results as accurate as possible.

I teach those processes and standards and the details of transformation in The Four Pillars of Color course.

However, there are hacks that you might find useful:

One color hack (for lack of a better term) is you can divide CIELAB L* by 10 to get Munsell Value. Some color scientists argue that this is better than the standard equation that involves interpolation.

Similarly, you can divide CIELAB C by 5 to get an estimation of Munsell Chroma. Emphasis on estimation. This Chroma color hack doesn't work as well as the L* hack - because math.

The Glidden/Dulux/ICI's The Master Palette notation is a completely different animal. It's based on the brilliant Acoat Codification Color system designed specifically for paint colors in 1978.

The ACC system has a similar premise based on the 3 dimensions of color: hue, chroma and luminance. However, the the ACC dimensions notated in the notation are hue, chroma and LRV. There is no direct correlation to LCh or Munsell.

The ACC notation is equally as useful and powerful as LCh or Munsell.

Because hue is an interval scale with no defined point of zero, you can divide - and label - hue families many different ways. The ACC hue notation is different from LCh/Munsell but it works just as well and exactly the same way.


   
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Z
 Z
(@zoriana-m-morozewych)
Active Member
Registered: 2 years ago
Posts: 6
Topic starter  

Thanks for reminding me that there are various systems, which has now given me a headache. 😀 

I have another question about Easy RGB.

Using SW 6477 Tidewater as an example, which you have detailed out in your list of colors, hue=188, hue2 is 6.35 F=BG, V=8.34 and C=1.43. 

I compared the numbers by selecting Munsell in EasyRGB -- and the value and chroma numbers were close. The hue° is the same, of course. Hue 2 closest is 7.5G at a ΔE 3.3 (which is wrong), but the V=8 and the C=2 is close to both what you have and the formulas you shared. Could a non-professional homeowner like me use it as a quick and easy reference to get an idea of where the color is on the Munsell system, especially if we are using your color wheel to know where it should approximately fall? Or, is this a dangerous assumption?

Looking at the list, it also showed the closest match to your numbers at 5 BG with a ΔE of 5.4 or 7.5 BG with a ΔE of 7.0. Can ΔE be used (and how) to get what the hue 2 and family is? (And, do I even want ΔE in my life?)

Thanks again for your time and having this fascinating website. I now have enough knowledge to get into real trouble! Seriously, I now can impart standardized color information when talking to designers, etc. thanks to you. Your expertise is appreciated.


   
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Lori Sawaya
(@lorisawaya)
Estimable Member Admin
Registered: 2024 years ago
Posts: 164
 

ΔE applies to the CIELAB Color Space. L*a*b* and LCh are just two different formats to notate colors in the CIELAB Color Space. L*a*b* are cartesian coordinates and LCh are cylindrical. LCh is more useful because it superimposes nicely on to a familiar color wheel. Lab notations are about redness/greeness and blueness/yellowness - great for comparing how colors differ.

Not so great for simply describing color appearance for regular people - which is why I include LCh hue angle in The Color DNA Table.

Posted by: @zoriana-m-morozewych

Could a non-professional homeowner like me use it as a quick and easy reference to get an idea of where the color is on the Munsell system, especially if we are using your color wheel to know where it should approximately fall? Or, is this a dangerous assumption?

No. There isn't a quick and easy way. You have to know your way around a color space and standards to get Munsell notations that describe color as accurately and objectively as possible.

Which is why I created The Color DNA Table - we do the work and worry about, illuminants, white points, conversions, process and standards, etc.

You can't transform from Munsell to other formats/notations. Because math.

Chroma and Value are more straightforward than figuring out what Munsell hue family a color belongs to AND where within that hue family it fits in. So that's why there will always be a greater degree of consistency with Value and Chroma.

Hue is always going to be from the perspective of two different color appearance models/spaces: Munsell and CIELAB .

Again, that's a good thing because it's representative of how real people perceive color - human perception doesn't align nice and tidy either.

What's important is to pick a lane for comparing hue and stay in it. Munsell or CIELAB. Because color comparison is relative and that's why you don't want to toggle between the two when comparing. To be clear, no harm in considering both and Munsell when getting a read on how a color could actually show up. Because two perspectives are better than one.

It's when you want to quantify the difference between colors that you want to stay in one color model/space lane.


   
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Z
 Z
(@zoriana-m-morozewych)
Active Member
Registered: 2 years ago
Posts: 6
Topic starter  

Thank you for your sage advice. It seems CIELAB the way to go (for me) to compare all these diverse systems. It was helpful comparing Glidden paint colors against PPG and other colors that I'm interested in which are not listed on your site. BTW-I contacted PPG to see which of their colors match some of the Glidden colors I was looking at and how. The information they gave me was that a PPG closest match was "slightly darker" or the same PPG color matched 3 different Glidden colors. It was only when I converted the Glidden colors to CIELAB and sorted by L'Ch or Value that I was able to "see" what the differences are. It also helped me sort the 4 PPG  and 3 SW samples I have on the wall, and how they stack up against each other either by L*Ch or Value in the 52-61 Hue range. I think I understand now, but if not- I'm sure you'll set me straight! 🤔 


   
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Lori Sawaya
(@lorisawaya)
Estimable Member Admin
Registered: 2024 years ago
Posts: 164
 

@zoriana-m-morozewych Sounds like you have it figured out! Great job.


   
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