Skin Tone color corrections, CYMK or RGB?

[Ken Fournelle]

Duv,

I think you are pretty close, if not right on. Her cyan is 20% of Magenta.
And for this type of caucasian skin is in the 15-25% people recommend.

K

[Jann Lipka]

Proper skintones would be within 30 ( 0-255 scale )
units from each other in Adobe RGB .
R220 G190 B160 would make a nice caucasian skin color .
That what I've been told, and it comes close when converted to RGB .

[john_opitz]

Originally Posted by jayk2

Hello all,

I'm very interested in skin tone correction and have a question. Almost every tutorial and book says to edit skin tones using cymk and basically make sure the yellow reads 3-5% higher then Magenta. I work in Adobe RGB and wondering if that percentage rule applies only to CYMK? or can I apply that rule when using RGB?

I'm posting a few images from a shoot I had a few weeks ago and color corrected in RGB using the CYMK rules. Just wondering if I can get some ideas as to if the yellow percentage works in RGB, or if there's a different way I should be doing it? My work flow is unsharp mask, Levels adjustment, slective color adjustment (yellow and red only) and whatever color the backdrop is.

Thanks
Jay

http://www.tossthebox.com/clients/images/IMG_0228.jpg

http://www.tossthebox.com/clients/images/IMG_0368.jpg

http://www.tossthebox.com/clients/images/IMG_0433.jpg

This might be of help to you.

color recipe

You wiil have to sign up at "colortheory" group to get this page. Sign up is free.

colortheory list

This is in the "file" section of this group. This is an elite group on colortheory.
Like the Navy Seals of the armed forces.

[Jann Lipka]

john , what file on the color theory list is related to skin color ?

[john_opitz]

Originally Posted by jann@lipka.se

john , what file on the color theory list is related to skin color ?

Good Morning, Jann

The page gives you the ratios in rgb,cmyk, and l*a*b. The page gives ratios of different colors. If you just want to know just skintones. I will post the ratio for you as this is a known color.
Skin tones.... are yellowish red... this means..in cmyk...Yellow is the highest, (at the least equal) to magenta, cyan is the lowest of the three, cyan can be between 1/5 to 1/3 (sometimes 1/2) that of the magenta.

In rgb, this relates to the red highest, blue lowest, green closer to the blue.

In L*A*B, this comes to...the "b", highest and positive. The "a" more than half as high as the "b" and positive. The L can be anything. The L just sets your contrast, not color.

See the pattern here.



Their are no correct numbers for skin tones per say... they will vary in the subject. The important thing to remember is the ratios. Not exact numbers for skintones, as these will vary.

For more info on other skintone ratios of different cultures.

color by the numbers







Look for p100_revised.pdf
Revised version of the "Color Recipe Book" on p. 100 of "Professional Photoshop, 4th Edition" .


On the color theory list.

[Chain]

This is an answer to the original post; the rest of the thread was too long to read this late :P

You should NOT convert to CMYK for this. Using your color sampler tool and the info-panel (Window>Info) you can read what your skin colors would look like in CMYK and even see that live while adjusting - without ever leaving RGB.

Note: Some like to use curves in CMYK but this is just because they have never learnt how to use them properly in RGB i think (The RGB and CMY sliders work roughly opposite for color and does the same adjustment, although in CMYK a lot of the shadow/luminosity info has moved to the K channel for a party. Use blending modes if you need to protect luminosity or color.)

[andrewrodney]

Originally Posted by Chain

You should NOT convert to CMYK for this. Using your color sampler tool and the info-panel (Window>Info) you can read what your skin colors would look like in CMYK and even see that live while adjusting - without ever leaving RGB.

That is oh so true! What a complete waste of time to convert to CMYK for the purpose other than preparing that document to be output to a very specific CMYK device and condition! CMYK is a very highly device dependent color space. Its numbers are solely used to define how some ink (colorant), and specific paper and specific output device reproduce color. This idea of correcting by using CMYK values predates Photoshop, when high-end scan operators had the job of converting data into CMYK for a very specific press condition they understood after years of work. They had to target skin, neutrals and other “memory colors” to a CMYK mix that they knew produced a desired color appearance to their device.

Take one RGB document, load any number of CMYK profiles (use Convert to Profile) and examine how far they differ in the values they provide using the Info palette.

When someone gives you some kind of CMYK ratio, without defining the exact profile or process the CMYK conversion uses, they are blowing smoke up your behind. They might as well send you instructions in a language you can’t speak. Its that useless. This old CMYK by the numbers idea should have died with film plates and CMYK output only drum scanners in the early 1990’s.

You can do exactly the same job in RGB! You have to have a defined RGB working space but nearly all the ones you have installed in Photoshop will work just fine and are far more similar than the thousands of different flavors of CMYK.

In fact, if you work in say Adobe Lightroom, its super easy with the percentage scale. See a relationship with the ratios:

http://digitaldog.net/files/LR_Skintone_Ratio.jpg

You can find good quality, known skintones like I have used above, start viewing the RGB values and in no time, you’ll get an idea of a good mix (or easier and just as effective, use a well calibrated and profiled display and work visually!). Another tip is once you do end up with a group of images of skin you’ve worked on and have seen output as you desire, keep em handy. Use them as a visual and numeric guide as you work on other images as references. In Lightroom, I keep a collection of just such images.

Note: Some like to use curves in CMYK but this is just because they have never learnt how to use them properly in RGB i think (The RGB and CMY sliders work roughly opposite for color and does the same adjustment, although in CMYK a lot of the shadow/luminosity info has moved to the K channel for a party. Use blending modes if you need to protect luminosity or color.)

Yup, spot on, well said! CMYK is the devils color space <g>. An RGB working space is far more useful (when any RGB values are equal, you know you have a neutral). You never need to convert from the native RGB space, saving you time and data loss. One less value to worry about. And its Quasi-Device Independent, nothing like CMYK which has values that can radically be different depending on what flavor of CMYK is currently being used (SWOP V2, Euro coated, GRACOL7, Newspress etc).

[Chain]

Try to go to Image > Adjustments > Desaturate on a CMYK image and tell me how gray that turns out.. :P.

[Chain]

Originally Posted by andrewrodney

When someone gives you some kind of CMYK ratio, without defining the exact profile or process the CMYK conversion uses, they are blowing smoke up your behind. They might as well send you instructions in a language you can’t speak. Its that useless. This old CMYK by the numbers idea should have died with film plates and CMYK output only drum scanners in the early 1990’s.

So true. It's annoying to get some "design manual" and all the colors are given as CMYK values (usually nicely rounded to the nearest 5-10%), but no mention of what profile was used...
Luckily they often define it as some Pantone color as well (although it often seems they mixed the CMYK first and then found a Pantone they thought looked similar). Oh well, if they want their logo to be in slightly different colors everywhere then that is their choice i guess... :P

[ray12]

I know this is an old thread...and sometimes older threads get resurrected if they still contribute some useful discussion. I found john_opitz link to the article "color by the numbers" to be a great read. Im always interested in retouching... and especially in how to manage skin tones.

We once did some tests using "Numbers" for flesh tones and found it quite challenging to sort out. We ended up producing a chart for our skin tone references and listed the RGB and CYMK numbers in the tone. It was helpful to be able to "Get a Look" by the numbers. We even found ourselves using the color picker tool and copying a chip visually some times.

The biggest thing we found is that there were usually 5 different "Skin Tone Numbers" on a face. The skin color chart below shows 10 skin tone pallets. Each pallet is of 5 colors from the same model in the same image and setting. Some pallets are ethnic models. Look at the general color ranges, and the differences, and the numbers.

When trying to get a "Number for the face" which RGB or CYMK color are you talking about? With 5 different color ranges on most faces...which one is right? Where on the face did you pick your color?

This is why we had to put the RGB and CYMK numbers in each color square after a while. We were able to create some generalities about the numbers from looking at the chips and studying the numbers. What threw us off sometimes with "the right number" is that ethnic variables, makeup colors, specially lit, or time of day shots, introduced color differences that changed the numbers in very unexpected ways. So did hi-key, low-key, natural light, or strobe shooting conditions...even with the same model on the same day. Each of these variables changed the number.

Everybody seems to have their own perception of... and their own preferred "skin color". In a room of 10 people - you might get 6 different comments on the same image (I like it warmer, yellow is better, too red, too dark). With eyeballs and color preferences like these on the same image...its "tough to get the skin numbers RIGHT!" Whose favorite skin color are you talking about?? Where is the sample taken from?? And, what changes did the exposure, makeup, and the lighting contribute to the number?

We still use numbers to get us into the ballpark...but a lot of stuff these days is done visually with the client and the art director right over the shoulder... viewing the SAME color corrected monitor...and sometimes arguing on what skin color is right.

There is a higher resolution chart below that you can download if you like.

http://www.screencast.com/t/MTM0NjFhYmQ

Ray12

[Chain]

That's great Ray!
Useful chart for those who needs a skin color reference!

Not to look a gift horse in the mouth, but here's two minor improvements;
- you might want to add to the chart what color space the values are taken from (they would differ quite a bit between AdobeRGB and sRGB, or SWOP/Euroscale).
- compress the chart with PNG if possible; not blurry JPEG

[ray12]

Chain,

You are right on.

If you are a pro...then the color space IS important... and jpeg images average the neighboring colors on every save they do... to make smaller file sizes possible.

I do have the original image in Adobe RGB color space and as a tiff or psd file. The file size is a bit large so I shrunk this one down here and gave it an sRGB color space so it would show up well in a browser based viewing environment. If you put an Adobe RGB or PRO Photo color space On-Line...browsers can only accurately represent sRGB to the user...so the image would look desaturated and dark to most all web viewers...thus... the low file size and s-RGB image.

The skin tone image above (and the download link especially) is good for a lot of general use. Its only the high-end guys that deal with $2000 calibrated monitors, multiple color spaces, and a professional distribution environment that would ever notice much.

I see you are a sharing and helpful kind of individual by some of the other stuff you do...so, if you would like a copy of the larger Adobe RGB Color Space image... you can PM me here and I will set you up with a download link. Its a big file because of the 50 layers and TIF file format.

Cheers,

Ray12

[Chain]

Thank you for the kind offer, but I do not really need the original file.

As you say the values are only a guide and can't be used "perfectly" anyway due to the variations from image to image (and even from pixel to pixel within one image). But it might be useful in other situations to know that if you convert it to sRGB (dithering turned off) and save-for-web as PNG the color values should be perfectly fine (for sRGB) - and the file size will be very small (possibly smaller than the jpeg due to the illustrative nature of the image). <3 PNG.
You could save it as AdobeRGB as well; and even if it might show up wrong in someone's browser, they are going to use it in Photoshop where it will view correctly (and either way the values are preserved).

Ps: JPEG however doesn't store an image as RGB, but as YCbCr (usually with lower resolution and heavier compression for the color channels), so the color values might shift just from that; in addition the compression-artifacts in JPEG isn't due to averaging of values so it can't really be trusted for anything that requires accurate values.