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How to apply Pantone skin tones

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  #31  
Old 01-26-2016, 12:44 PM
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Re: How to apply Pantone skin tones

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Originally Posted by skoobey View Post
I never disagreed with you, I just said that there is more options out there... that obviously makes you very angry and has nothing to do with me.
Options working numerically for correction of skin tones? Go ahead.
Aside from speaking for others, it's not a very good idea to incorrectly interpret the feelings of others; I'm not angry I simply disagree with you and await a post from you that aids the OP and others.
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  #32  
Old 01-26-2016, 01:22 PM
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Re: How to apply Pantone skin tones

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Originally Posted by Tony W View Post
HSB is not the same thing at all.
B in HSB is brightness while L in Lab is lightness and you're correct, they are not the same.

Brightness is a perceptual phenomena. Lightness is a perceptually scaled component of color, the axis seen in Lab (Lstar) from light to dark. It IS the L in HSL. Luminance is measurable. Brightness is the perception of Luminance.

Difference between Lightness and Brightness video (short and sweat):
https://www.youtube.com/watch?v=tq2y...ature=youtu.be

Last edited by andrewrodney; 01-26-2016 at 01:47 PM.
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  #33  
Old 01-26-2016, 02:00 PM
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Re: How to apply Pantone skin tones

Interesting video thanks.

BTW: Your links to that very good photographer Greg Gorman much appreciated. What he achieves in both colour and monochrome is wonderful. I particularly like the campaign shots for Pirates .. and King Arthur along with so many others
I also understand that he is somewhat of a colour guru.
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  #34  
Old 01-26-2016, 03:38 PM
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Re: How to apply Pantone skin tones

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Originally Posted by Tony W View Post
I found it myself rather than any reference (although I am sure there must be many). AFAIK Lab is the only colour space where the 'numbers' remain the same and the image colour is identical regardless of colour space (within the gamut limits of the particular colour space). Whereas the same image colour in any other RGB space or HSB requires quite different values to look the same.
Okay I looked at the experiment. It appears you set LAB values in each case. I think the HSB values are going from your document space, which is interesting. That aspect is implementation defined rather than a limit of the color space though. It's worth noting that the swatches would have different LAB values if they were defined with respect to what is displayed on screen in each instance.

LAB can describe a wider range of colors, and it's designed to approximate human vision. It's not decorrelated with respect to cone group the way lms is (), but it works well enough. It has also been tested with different illuminant values in some specialized use cases. The issues of brightness, lightness, etc (which I mostly ignore for practical purposes) are covered in RWG Hunt's book, which you could probably obtain on library loan if you're interested. You might enjoy it or Fairchild.

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Originally Posted by Tony W View Post
The attached illustrates this with two documents one in sRGB one in ProPhoto. Each filled with the same values in Lab L76, a20, b47. Note the change in HSB and RGB values
I'll have to go through it myself. Those don't look saturated enough to clip, so a drastically different appearance on your screen should yield different LAB values. It's just a matter of determining how they come up with that. Photoshop's underlying color engine (ACE) does use LAB as its profile connection space.

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Originally Posted by Tony W View Post
I am not sure that you can regard Adobe RGB as device independent.

It is my understanding that sRGB was modeled on a theoretical CRT display.

Adobe RGB (1998) was designed to deliver most of the colours achievable on CMYK colour printers using RGB primary colours of a display. So again I think it designed to mimic a device (theoretical).
It was, I believe somewhat of a mistake as it was based on SMPTE 240M figures but some were not correct due to errors at Adobe. However they thought that it was nevertheless a useful space and named it accordingly Adobe RGB (1998)
It's at least somewhat device agnostic, and it refers to a specific discretized weight function rather than a class of them (RGB). I read that sRGB was intended to mimic the average CRT in 1993 or something like that. It could be incorrect, and there is a disturbing degree of inconsistency between sRGB implementations.
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  #35  
Old 01-26-2016, 08:13 PM
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Re: How to apply Pantone skin tones

Yes, sRGB (again, simply a theoretical color space) is based on a CRT with P22 phosphors derived from the HDTV standard ITU-R BT.709/2 from the mid 1990's.
Everything you thought you wanted to know about sRGB, from it's daddy (Michael Stokes):
https://www.w3.org/Graphics/Color/sRGB.html

Adobe RGB (1998) is kind of an embarrassing hack. Adobe introduced RGB working spaces in Photoshop 5 back in 1998. They found spec's for SMPTE-240M from SMPTE on their web page, thought it would be a good addition to other working spaces they were going to provide in Photoshop (ColorMatch RGB, sRGB, Wide Gamut RGB etc). Problem was the chromaticity values on the web site for at least one primary had a typo! Adobe didn't check. After Photoshop 5 was released, SMPTE told them: Nope, that's wrong. So Adobe changed the name to, you guessed it, Adobe RGB (1998) in Photoshop 5.5. Seems the tiny differences in the typo wasn't a 'big deal' and since the toothpaste was out of the tube, a new working space was created.
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  #36  
Old 01-27-2016, 05:57 AM
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Re: How to apply Pantone skin tones

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Originally Posted by klev View Post
... It appears you set LAB values in each case. I think the HSB values are going from your document space, which is interesting.
Setting Lab values is correct and the thrust of the argument because they are one set of values that remain constant regardless of colour space. Rarely bother setting HSB values but I do expect them to change with a change of colour space

Quote:
... It's worth noting that the swatches would have different LAB values if they were defined with respect to what is displayed on screen in each instance.
If you mean by selecting a different colour area Lab values would be different - of course! But again the point is use those same Lab values in any other RGB space will get you the same 'colour look' although the RGB and HSB values will be different for each colour space.

You do need to be aware of what you are doing using Lab values as you could push too far and exceed colour space gamut without realising.

I very much doubt that this would be the case for any acceptable range of skintones values for the population of this small planet but...

The attached is an example of going too far. The selected colour looks quite different on screen with the same Lab values for a ProPhoto and an sRGB document. You can see that the colour picker has stuck to the edge of the sRGB doc. while staying comfortably within the ProPhoto colour picker.

To bring the image to the same level (using Bruce Lindblooms excellent calculator) would require a Red channel setting of -58 in sRGB and also a minus figure in Adobe RGB. Only within ProPhoto does it appear to be in range.
However I do not really know how it looks due to the fact that it exceed the gamut of my monitor (99% of Adobe RGB) and is likely to exceed any ink/ paper combination. Again I would need to test print to find out if acceptable!
Attached Images
File Type: jpg OOG_sRGB.jpg (227.9 KB, 15 views)
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  #37  
Old 01-27-2016, 07:56 AM
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Re: How to apply Pantone skin tones

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Originally Posted by marameo View Post
Hi,

I run across this project where the artist defines human skin color by using Pantone: http://io9.gizmodo.com/5924115/human...pantone-colors

Now, I wonder what the best technique is to apply Pantone skin color to a portrait I take either on film or digital (Non flagship Canons are said to have weak red channel and color filter array). Reason is I assume both of them might add their tints whereas I want a fixed skin color that makes confortable during printing process.

As far as I know the red channel has most of the skin color range. My idea is so select red channel, create a new layer above the background and reveal the selection, then I pick the Pantone color I prefer and brush over the skin and change opacity to fine tune. I have had mixed feelings with the outcome.

Any better ideas?

Thanks
Hi Marameo,
Sorry if the thread seems to have become somewhat diverted. To try and get back OT.

IMO there is no reason why you cannot use Pantone colours as a starting point for different skin types. But you should be looking at a minimum of three values (a)Midtones (b)Highlights and (c) Shadows for each ethnicity.

The problem as Redcrown pointed out is the lack of information that Pantone releases. This is due to the fact that Pantone charge for their colour charts £100+ per chart type or you can buy the Pantone Colour Manager CD. This will also give values in sRGB. For most of us this is probably overkill and there are other effective ways to do this.

You can paint over your image or better still use a gradient map based on the selection of tones you have already established for each skin type.

Finding the tones is quite easy:
  • Bring an image where you want to find the skin values into PS
  • Click on the Foreground Colour square to bring up the Colour Picker dialogue.
  • Use the colour dropper to sample those areas of interest and take note of the Lab values (so in future you can use these in any colour space to arrive at the same rendering)
  • You can even save these samples and others to add on to your palette
  • You can also check what the closest match is in the Pantone colours by clicking on Color Libraries and selecting a Pantone swatch. It will report the colour back to you in either Lab or CMYK

Hope this of some help
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  #38  
Old 01-27-2016, 09:34 AM
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Re: How to apply Pantone skin tones

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The problem as Redcrown pointed out is the lack of information that Pantone releases
Why Pantone did not provide l*a*b information for their palettes?

Aside from that, what is the different in "thiking" between l*a*b* and CMYK?

I know that skin is very often described in terms of cmyk because it's easier to define the relationship between the magenta and yellow which makes up the red and therefore the description is more precise then in rgb.

Different skin types have some typical readings in the info cmyk palette. Looking at caucasian skin essentially is red but yellow is the most dominant component often by just a few points.

Quote:
But you should be looking at a minimum of three values (a)Midtones (b)Highlights and (c) Shadows for each ethnicity.
I think the following link demonstrate a good gradient map that does what you suggest.
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  #39  
Old 01-27-2016, 09:51 AM
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Re: How to apply Pantone skin tones

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Originally Posted by marameo View Post
Why Pantone did not provide l*a*b information for their palettes?
Lab is a universal metric of color and lots of people need to know how any color value translate to and from Lab. For example, if you have a printer profile that defines an output condition and you wish to know if a Pantone color falls within it's color gamut. You need Lab for that. Or you want to find the nearest none Pantone color, or you want to find another color in relationship to that; you need Lab. And the Pantone values are created FROM Lab values!

Quote:
Aside from that, what is the different in "thiking" between l*a*b* and CMYK?
Huge difference. CMYK is a highly device dependent color space meaning it's based on inks, a paper, the conditions of a device that makes the colored output. Every device can be different and produce different values of the same color appearance, Lab doesn't. That's why there are thousands if not more recipes for CMYK to produce the same color appearance! The very opposite is true for Lab.

Quote:
I know that skin is very often described in terms of cmyk because it's easier to define the relationship between the magenta and yellow which makes up the red and therefore the description is more precise then in rgb.
That's like saying to a 4 year old from China that English is easier to speak than Chinese for your 10 year old kid. It's easier because you understand it. For that one output condition. But it's silly because every CMYK value is unique based on the specific output conditions. Illustrated in my video. And you can try this yourself. Take a Lab value and maybe one in say sRGB. Convert to half a dozen CMYK profiles that are provided to you in Photoshop. They will all be different. Some by a lot. Which is correct? ONLY the values in CMYK converted for the output conditions. All other values are wrong. Now play with black generation and the possible values for a CMYK conversion increase to another level of magnitude.

CMYK is about the most device dependent color space you can work with. IF you work with one CMYK output condition and that's defined by a profile for that output, you could memorize all the differing conditions that produce acceptable skin tone, Skoobey's strange and un-skinlike conditions aside. That's exactly what the old drum scan operators from the last century did. Their old scanners which were of course RGB devices only output CMYK ready data. If a scanner operator spent years scanning film with skin and other items, he would get pretty good at targeting values that produced a good result on press. And isn't that the topic? How to target skin tone values to produce acceptable appearing skin? Doing that today in CMYK is prehistoric thinking and workflow! You'd be better off trying to memorize the blackjack table in Vegas than trying to memorize all kinds of CMYK values to target for more than a couple of CMYK output devices. OR you can learn Lab and only worry about two values in terms of skin and that lesson is true for ALL color spaces!
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  #40  
Old 01-27-2016, 09:51 AM
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Re: How to apply Pantone skin tones

One more question about skin tone; can someone explain what happens when in the channel mixer I set red and green to zero and blue to +100 in each channel and then blend the adjustment layer on mulitply mode? What's the point in pushing the blue channel in multiply mode? Sometimes on top of that I see a second untouched curve adjustment blended in multiply mode. Those layers in multiply mode are normaly lowered in opacity.

Thanks

Last edited by marameo; 01-27-2016 at 09:57 AM.
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