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CT&A RGB vs RGB L*a*b* input to Munsell. You can select any of the 4000 color chips in the Munsell Color Deck. You can convert to a combination of between two to. Munsell / #f2f3f4 hex color code information, schemes, description and conversion in RGB, HSL, HSV, CMYK, etc. Munsell to CMYK Conversion (Long Shot) Pages: 1 2. Does anyone know how to convert Munsell to CMYK (or an RGB colour space RAL colours to Pantone, CMYK, RGB. Jan 30, 2012 The Munsell Soil Color Space is a commonly used perception-based colour system with many applications in soil and earth sciences, geographic information systems (GIS) and even painting and interior design.
Color conversion. Color code converter. Color codes chart. Color conversions. Color code converter. HEX value is 6 digits (rrggbb). RGB values are in range of 0.255. Rgb To Munsell Converter. Munsell to RGB conversion tables. Virtual Munsell Color Wheel. Detailed information about Munsell as a color space can be found elsewhere on the web (I recommend The Dimensions of Color,Handprint, and Munsell). At the bottom of this tool you will see a circle of hue squares. Convert Munsell colors to computer-friendly RGB triplets The Munsell color system was designed as a series of discrete color chips which closely approximation to the color sensitivity of the human eye.
I'm looking at at document that describes the standard colors used in dentistry to describe the color of a tooth. They quote hue, value, chroma values, and indicate they are from the 1905 Munsell description of color:
The system of colour notation developed by A. H. Munsell in 1905 identifies colour in terms of three attributes: HUE, VALUE (Brightness) and CHROMA (saturation) [15]
HUE (H): Munsell defined hue as the quality by which we distinguish one colour from another. He selected five principle colours: red, yellow, green, blue, and purple; and five intermediate colours: yellow-red, green-yellow, blue-green, purple-blue, and red-purple. These were placed around a colour circle at equal points and the colours in between these points are a mixture of the two, in favour of the nearer point/colour (see Fig 1.).
VALUE (V): This notation indicates the lightness or darkness of a colour in relation to a neutral grey scale, which extends from absolute black (value symbol 0) to absolute white (value symbol 10). This is essentially how ‘bright’ the colour is.
CHROMA (C): This indicates the degree of divergence of a given hue from a neutral grey of the same value. The scale of chroma extends from 0 for a neutral grey to 10, 12, 14 or farther, depending upon the strength (saturation) of the sample to be evaluated.
There are various systems for categorising colour, the Vita system is most commonly used in Dentistry. This uses the letters A, B, C and D to notate the hue (colour) of the tooth. The chroma and value are both indicated by a value from 1 to 4. A1 being lighter than A4, but A4 being more saturated than A1. If placed in order of value, i.e. brightness, the order from brightest to darkest would be:
A1, B1, B2, A2, A3, D2, C1, B3, D3, D4, A3.5, B4, C2, A4, C3, C4
The exact values of Hue, Value and Chroma for each of the shades is shown below (16)
So my question is, can anyone convert Munsell HVC into RGB, HSB or HSL?
They say that Value(Brightness) varies from 0..10, which is fine. So i take 7.05 to mean 70.5%.
But what is Hue measured in? i'm used to hue being measured in degrees (0..360). But the values i see would all be red - when they should be more yellow, or brown.
Finally, it says that Choma/Saturation can range from 0..10 ...or even higher - which makes it sound like an arbitrary scale.
So can anyone convert Munsell HVC to HSB or HSL, or better yet, RGB?
8 Answers
The hue specification you've given here is incomplete (4.5 should be 4.5Y etc). Since the link is dead, if anyone is interested, the specs are still alive here:http://web.archive.org/web/20071103065312/http://lib.umich.edu/dentlib/Dental_tables/Colorshadguid.html
The only free utility for Munsell conversion I could find was this:
Very old as you can see, but seems to work well. Current programs that can do this are not free:
- http://www.babelcolor.com/main_level/download.htm (this one has a free 14 day trial)
The current holders of the Munsell products are X-Rite, they probably have some conversion solutions as well.
Further, note that the link you supplied includes definitions for the same colors in other color coordinates - namely Yxy and CIE lab*. Both can be freely converted online at http://www.colorpro.com/info/tools/convert.htm or offline with this free color converter
Ohad SchneiderOhad SchneiderIt is rather involved. The short answer is, converting Munsell codes into RGB involves interpolation of empirical data in 3D that is highly non-linear. The only data set that is publicly available was collected in the 1930's. Free or inexpensive programs that I have found on the net have proved to be flawed. I wrote my own. But I am jumping ahead. Let's start with the basics.
Munsell codes are different in kind than those other codes, xyY, Lab, and RGB. Munsell notation describes the color of an object - what people experience when they view the object. (Isaac Newton was the first to realize that color is in the eye of the beholder.) Munsell conducted extensive experiments with human subjects and ingenious devices.
The other codes, i.e. xyY, Lab*, and RGB, describe light that has bounced off an object and passed through a convolultion with a rather simple mathematical model of a human eye. Some google-terms are 'illuminant,' 'tri-stimulus,' and 'CIE standard observer.'
Munsell describes the colors of objects as they are perceived under a wide variety of illuminants. Another google-term is 'chromatic adaptation.' Chromatic adaptation in the brain is automatic if the lighting is not too weird. It is really quite remarkable. Take a piece of typing paper outside under a blue sky. The paper looks white. Take it indoors and look at it under incandescent (yellowish) lights. It still looks white! Munsell tapped into that astonishing processing power empirically. Munsell codes also preserve perceived hue at different chromas. A sky-blue and a powder-blue that Munsell assigns the same hue notation, e.g. 5RP, will appear to the typical human with normal eyesight to be the same hue. More on that in the footnote.
CIE xyY, Lab*, and RGB mean nothing unless an illuminant is specified. Chromatic adaptation for illuminants in the mathematical model is computationally difficult. (Rough but simple approximations can be done using the 'Bradford matrices.') The RGB that we use is by default 'sRGB,' which specifies an illuminant called D65. D65 is something like a cloudless day at noon. The Lab numbers listed by the OP are probably relative to D50, which is more like afternoon or morning light. The xyY numbers might be relative to D50, or they might be relative to an old standard called C. I am not going to check. C was the light from a standard lighting fixture that was relatively inexpensive to build in the 1930's. It is obsolete. But C plays a key role in the answer to the question.
In the 1930's, color scientists were developing the mathematical models. One of the things they did was to take a standard Munsell Book of Color, shine illuminant-C light on the colored chips in the book, and record the data in xyY format. That is the only one that is freely available. Others surely exist, but they are closely held secrets.
Good news though. The data set works good. The Munsell authority today is a company called Gretag Macbeth. I imagine they have voluminous data related to the color-chips they sell. The only numbers I know of that they publish are the D50 Lab and D65 sRGB numbers for a small set of colors on their 'Color Checker' cards. I wrote an interpolator based on the old renotation data. It agrees with the numbers for the Color Checker card almost exactly. I regret to inform that so far I have only written code for the conversion that goes the opposite direction from what the OP requested (a year ago, as I type this). It goes from sRGB to Munsell. I click on an image, and the program displays the sRGB and Munsell notations for the area clicked upon. I use it for oil painting.
Footnote: CIE has a standard that is analogous to Munsell. It is called LCh subscripted with a,b. It is Lab* in polar coordinates. The hues are in degrees. Chroma numbers are approximately 5 times the C in Munsell HVC. LCh has its problems though. If you have ever used a photo editor to pump up the vividness of the sky, only to see the blue turn to purple, the program was probably using LCh. When I started writing my program, I was unaware that Bruce Lindloom had done work that parallels what I was doing. His web site was invaluable to me as I finished the project. He designed a space he calls UPLab, which is LCh straightened out to align with Munsell. I had already re-invented LCh and (essentially) UPLab before I discovered Mr. Linbloom's site, but his knowledge of the subject far exceeds mine.
Colour, our open source Python colour science package allows to perform that conversion.
From Munsell Renotation System to CIE xyY Colourspace
The following two definitions based on Centore (2012) method converts between Munsell Renotation System and CIE xyY colourspace:
From CIE xyY Colourspace to sRGB Colourspace
Converting from CIE xyY colourspace to sRGB colourspace is done by first converting to CIE XYZ tristimulus values and then to sRGB colourspace using the following definitions:
Implementation
Here is an annotated complete example using the above definitions:
[ 0.96820063 0.74966853 0.60617991]
You can also perform the reverse conversion from sRGB colourspace to Munsell Renotation System:
4.2YR 8.1/5.3
References
- Centore, P. (2012). An open-source inversion algorithm for the Munsell renotation. Color Research & Application, 37(6), 455–464. doi:10.1002/col.20715
For completeness, here's the archive.org version of my page, that contains the colors in 3 colorspaces, Munsell, Yxy and Lab:
References
- 151 O'Brien, W.J., Groh, C.L., and Boenke, K.M. A new, small- color-difference equation for dental shades. J.Dent. Res. 69:1762-1764, 1990.
- 152 O'Brien, W.J., Groh, C.L., and Boenke, K.M. Unpublished data. University of Michigan School of Dentistry, Ann Arbor.
There is a free R package munsell which will (among other things) convert Munsell codes to RGB:
Rgb To Munsell Converter Mp4 Converter
Free ConsultingThere's a page I've found here: munsell-to-rgb.blogspot.com that seems to be doing exactly what you are after. It seems unfinished at the moment, but the owner of the blog plans to update it regularly with as many Munsell-to-RGB conversions as he can (and he takes requests!).
It's amazing how hard it is to find accessible conversion tables for these colour systems; hopefully this will be our answer! :D
I'm late to the party, but I found another resource that may be useful on this topic.
Someone at the 'Munsell Color Science Laboratory' dug up some 1943 data from Munsell, all based on 1930s Munsell research: http://www.cis.rit.edu/research/mcsl2/online/munsell.php
The page refers to an Excel spreadsheet with the 'real colors only' subset of the data that falls within the 'Macadam limit', which appears to mean the gamut of colors that can actually appear on reflective surfaces. The spreadsheet link doesn't work, however, but on a hunch I guessed that it left out one level of the directory tree. I tried the URL http://www.cis.rit.edu/research/mcsl2/online/real_sRGB.xls -- and it worked. (I wouldn't be surprised if the owner of the site eventually notices it, and fixes the link, which is likely to break my link.)
I messed with that spreadsheet a little to get it to generate HTML to show me the RGB colors, and added these cells to the spreadsheet:
The table needs one line each of the ones starting with A2 through A1626, and one each of the others.
I hope this helps.
SteveSteveDespite this old post, to update Steve's answer, here are 'corrected' links to RIT's repositories of Munsell data:
And a direct link to spreadsheet of the sRGB converted values of the 'real' Munsell colors:
It's a spreadsheet which includes a conversion from Munsell HVC notation to xyY, then to XYZ_C, then converted to D65 illuminant, then to floating point sRGB, then quantized to 8bit sRGB values (which they call dRGB).
As for the OP's question: sRGB is (obviously) an RGB additive color model. But the differences to other color models such as subtractive CMYK are complex enough that a 'simple' algorithm won't handle the conversion — while color model transformations can be approximated with a matrix, more often a LUT (Look Up Table) is preferred, such as a LUT in an ICC profile or a 3D LUT as used in film production. (Not all ICC profiles are LUT based, but a LUT based conversion IMO is what is needed here).
The Munsell data certainly falls into this category, as not only is it a different color model, it is not only a subtractive model it is based on perception, while sRGB is based on a simple relationship between red green and blue light.
The spreadsheet is the useable look-up-table, so then a program to convert things like your dental chart to sRGB would take in that data and reference the LUT contained in the spreadsheet, and return the sRGB values.
Side Note: I want to mention for clarity that although some color-space or color-model transforms can be done reasonably with an algorithm/matrix, 3D LUTs are preferred particularly when the LUTs are created from measured data of a given color-model/space, which maps the many non-linearities inherent in some models.
An extreme example is an sRGB image on your computer monitor vs how that image is printed onto paper and appears on the cover of a magazine sitting on a newsstand illuminated with florescent light. That requires a 3D LUT for an accurate transformation!
In the feature film industry (where I mostly work) we use 3D LUTs throughout the image pipeline, not just for converting/transforms, but for 'viewing' and for applying/emulating 'looks.' For instance taking an image shot with a digital camera and applying a LUT of a certain film stock to that image to make it appear as film.
Not the answer you're looking for? Browse other questions tagged colorsrgbhslhsbcolor-theory or ask your own question.
I am hoping I could get some help developing a an idea I have for archaeologists/soil scientists using an arduino and the TCS3200 colour sensor. The idea I have is a simple device which can determine munsell colours with more accuracy and speed. The current conventional method is to use colour chips/swatches found in the Munsell system booklet and match them as close to examples of sediment/soil found at archaeological sites. The problem with doing this method is that it is highly subjective, and time consuming.
My idea is to use the Adafruit TCS34725 to read and detect the RGB colour of the sediment (in the RBG colour space) and convert the data into the Munsell System. I have all the data of what RGB ratio corresponds to each Munsell colour -- which I have downloaded from this site: www.cis.rit.edu/research/mcsl2/online/real_sRGB.xls
My problem is that when I use the sketch provided, I can not figure out how to use the 'if' statement to 'Serial.print' what the munsell colour corresponds to the RGB colour detected by the sensor.
My ultimate goal is to modify the colour view sketch here see: colorviewI would like to keep the everything provided but change two things, I would like to convert RGB into Munsell using the data provided by the RIT link and also add a screen and button to start the read process and display the colour.
If some one would be willing to help me that would be great!,
1 Answer
Rgb Color Converter
I have some thoughts on your task. First of all colorimetry is a science on its own. I know people working in this field for decades with equipment costing many millions of €. They all share some basic wise words. One is: 'Because we all see colours we think measuring colous is an easy task. The opposite is true. Many of the best colorimetrists are colour blind.' One second is: 'Without light there is no colour'. I will write on this later.
Colorimetry in fact is a complex matter. Between a colored piece of stone and a numerical value normally lie a lot of transformations and convolutions. And inbetween there are also lurking many error sources.
This said, I'm sure it will be possible to produce somewhat acceptable results with your sensor. Provided you do a proper calibration and add a calibratable light source.
Speaking of light source. A piece of stone can only reflect incident light (except some uranium/radium salts, you don't want to deal with). Pigments are basically LTI-systems (aka passive filters). This means they can only reflect wavelengths which are present in the incident light. And the will reflect a well defined and individual proportion of each wavelength regardless the luminous flux of the incident light. This means, if your incident light contains nearly no blue light then the stone or whatever you want to examine will reflect only the fraction of 'nearly no light' it typically does reflect of any amount of blue light.
So the remission spectra of all pigments get shaped (multiplied) by the spectrum of the incident light. Your sensor sees only the reflected light and therefore will give totally different results for one and the same object depending on the incident light. Look up the spectra for daylight and incandescent light and think about the results of your sensor.
To make a long story short, you can only yield reproducable measurements if you supply your own light source along with the sensor. This is in fact the way all colour meters work.The only other way was to measure the full spectrum of the incident light. Reasonable portable spectroradiometers for this purpose cost 5000 €. So it's better to go for a light source :).
Convert Munsell To Pantone
As they are rather affordable I recommend using LEDs to make up a light source for examination. But LEDs suffer from several drawbacks. They tend to change their output spectrum with their chip temperature and ageing processes. So you have to supply a proper calibration procedure for your measuring equipment. And you better do the calibration sequence before every measurement.
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You then have to design an apparatus which allows the light from your LED fall onto your samples (stones, sediments or so) but prevents other scattered or direct light to enter your sensor. Otherwise all measurements will be crap.
While this is not a direct answer to your question, I think the topic is important enough to write an elaborate pamphlet.
Update
Now some more words more closely related to your problem.
In general loading a huge excel table into your arduino is not necessarily a good idea, even if a big 'if'-code array was possible. Storage is scarce on this platform.
If you combine a lookup table with interpolation, you can save much space. You would have to omit 90% of all datapoints and estimate all in between when measuring. Still the table will be rather big, because you have three degrees of freedom.
Another drawback of big tables and LUT with interpolation is, that it makes calibration difficult. Normally, when you calibrate your sensor, you have to adjust the parameters along the calculation. If you rely on a table, you have to exchange the whole table, regardless if it is something like that excel thingy or a condensed lookup table.
If you go for an analytical solution, as suggested in one comment, the number of parameters you have to update after calibration reduces drastically. Effectively you have to adjust some factors and offsets in the equations for this problem. Of course you will have to learn the ropes of the photometric equations, but you will have to do that anyway, I think.
Some more words on the design of your appartus. Your idea of a cylinder in front of your probe is good. I recommend to fit it with a rim of black foam rubber, so you can seal light coming from outside. And you have to paint the inside of your cylinder as black as you can. See the interiour of a camera objective for reference.
If it is white you will have multiple reflections and multiple filtering which deteriorates your measurement results vastly.