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Skin Tone color corrections, CYMK or RGB?

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  #1  
Old 02-11-2005, 11:49 AM
jayk2 jayk2 is offline
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Skin Tone color corrections, CYMK or RGB?

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
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  #2  
Old 02-11-2005, 01:29 PM
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Duv Duv is offline
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I myself haven't a clue how to adjust skin tones using RGB. I've always converted to CMYK to do my skin correction and then back to RGB. There seems to be a lot more information on CMYK skin correction. Although I haven't noticed anything, I'm wondering if converting back and forth may introduce other subtle problems. The tones you acheived are spot on. I never considered using Selective Colors to do my correction. I'll have to give it a try. Can I ask why you adjust yellow and red as opposed to magenta/yellow/cyan and black?

Cheers
Dave
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  #3  
Old 02-11-2005, 01:52 PM
jayk2 jayk2 is offline
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Thanks for the reply Duv,

I also wonder the same, if I'll loose some quality in the convert and working back and forth?

I was once told that to get proper skin tones in "white" (for lack of a better term) people, it's yellow and red. I was told by another photogrpaher that he never adjusts for skin tones, just boots up the saturation by +15 or so.

I'm going to try and do a correction via the cmyk,

I'm scared lol.
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Old 02-11-2005, 02:16 PM
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Hope you show your results.

Dave
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  #5  
Old 02-11-2005, 02:48 PM
jayk2 jayk2 is offline
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Here's a quick mock up of what I did. According to the cymk, this image was fine to start with. I was under the assumption that pretty much every portrait image needed to be retouched?!

http://tossthebox.com/clients/cmyk.jpg

When I get a chance, I'll pick a better image
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  #6  
Old 02-12-2005, 03:19 AM
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v.bampton v.bampton is offline
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We have a portrait and wedding studio, and whilst there are benefits to correcting in CMYK, we do almost all of our adjustments in RGB. Because of the difference in the size of the gamut, converting to CMYK and then back to AdobeRGB for our lab does affect some of the colours. If you're concerned about watching the CMYK numbers, then make sure your info palette will show RGB and CMYK, and the same rules will apply. There's also a speed factor - I don't have time to convert everything back and forth when I'm working on hundreds of images a week.

I've got perfectly good results using RGB, sometimes boosting the saturation, more often just adjusting the red and yellow slightly (highlights and slight midtones in levels or curves) to give a healthy warm glow. Most of it I have set up as actions, so whilst we do retouch every image we sell, it's usually only minor tweaks that we need to do manually.
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  #7  
Old 02-12-2005, 03:10 PM
jayk2 jayk2 is offline
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Quote:
Originally Posted by v.bampton
We have a portrait and wedding studio, and whilst there are benefits to correcting in CMYK, we do almost all of our adjustments in RGB. Because of the difference in the size of the gamut, converting to CMYK and then back to AdobeRGB for our lab does affect some of the colours. If you're concerned about watching the CMYK numbers, then make sure your info palette will show RGB and CMYK, and the same rules will apply. There's also a speed factor - I don't have time to convert everything back and forth when I'm working on hundreds of images a week.

I've got perfectly good results using RGB, sometimes boosting the saturation, more often just adjusting the red and yellow slightly (highlights and slight midtones in levels or curves) to give a healthy warm glow. Most of it I have set up as actions, so whilst we do retouch every image we sell, it's usually only minor tweaks that we need to do manually.
Thanks bampton,

Thats what I was wondering. When I did the above pics, I was going by the cymk values but adjusting in rgb. I wasnt sure if the rules applied to rgb as they did for cymk. So for now, I'll just continue adjusting

thanks all
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  #8  
Old 02-13-2005, 08:04 AM
edgework edgework is offline
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Quote:
Originally Posted by jayk2
Thanks bampton,

Thats what I was wondering. When I did the above pics, I was going by the cymk values but adjusting in rgb. I wasnt sure if the rules applied to rgb as they did for cymk. So for now, I'll just continue adjusting

thanks all
I do the same thing when I have to work in RGB. The rules are roughly similar, but keep in mind that Photoshop simulates the qualities of light in RGB, and ink on paper with CMYK. One significant difference is that in CMYK, applying a curve to any channel will affect both color and lightness in a very different way than with RGB. A rule of thumb is that you use the individual channel curves in RGB to adjust color, and you use the master curve to adjust contrast. Because Red, Green and Blue are all equal in intensity (equal values combine to produce dead neutral) the master curve can be used effectively to make lightness moves without altering the hue and saturation (although the lightness channel in lab mode is far more efficient). In CMYK, since cyan is such a crappy ink, it requires about 10% more than Magenta and Yellow to balance the other two and produce neutral. Using the master curve in CMYK is very dangerous, unless you are using it in luminosity mode.

I was trained to use CURVES, and CURVES only, (and only in CMYK) since most of the other adjustment tools are more or less subsets of what curves are capable of doing. However, I've found that using selective color in the way previously mentioned, is a great quick fix. If, for example, a face has yellow highlights and hot red shadows, pulling magenta and adding yellow to the reds, and pulling yellow and adding magenta to the yellows brings the tones into balance, albeit a flat kind of balance.

Another trick for skin (this is for CMYK corrections): I've never found a face that cannot be improved by making a contrast move to the magenta channel in luminosity mode. Flat skin tones are almost always the fault of the magenta plate, and even if the numbers are within a realistic range, the lack of contrast can make the skin appear too hot overall. Heightening the contrast in magenta, but keeping it in luminosity mode can open up detail in an instant, without messing up the color.

As for converting back and forth, the areas of RGB that extend beyond CMYK are far more extensive in the Greens and blues. The truth is, any colors in RGB that are outside the CMYK gamut aren't going to look all that appropriate in skin tones anyway--greens, blues, hot reds and day-glo oranges. If realism is the desired goal, moving into CMYK before correcting the color will weed out a lot of unrealistic tones. But if intensity and bright colors are the visual goal, and the target is RGB output, or the WEB, keep it in RGB.

One problem with CMYK that is non-existent in RGB is ink density. Because there is a limit to the quantity of ink a press can handle without turning the result into mud, the CMY channels will usually flatten out to a single tone in the shadow range, shifting the detail information into the black plate. This can be a problem if you have shadows that carry a cast, either hot or cool. Moving an image into CMYK will usually turn the dark areas neutral, which will be a problem if the mood of the original art called for overall warmth or coolness. I often use selective color for these situations too, pulling cyan from black and adding magenta and yellow, or the other way around to cool them down. Pay attention to the darkest shadows as well as dark hair: it's easy for rich brunettes to become dingy blacks in the translation.
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  #9  
Old 02-13-2005, 09:15 AM
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Good stuff here from V. Bampton and Edgework. I especially like the tip on boosting contrast luminosity in the magenta channel.
I hope everyone understands that Edgework is NOT suggesting a 10% higher Cyan value than Magenta and Yellow for skin tones.

Cheers
Dave
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  #10  
Old 02-13-2005, 03:49 PM
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Flora Flora is offline
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Hi everybody,

I'd like to join Dave in thanking v.bampton and edgework for the great explanations on this topic!
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  #11  
Old 02-15-2005, 11:07 PM
charlotte charlotte is offline
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Skin tones and adjusting them . Sometimes I wonder if I will ever master it. I have no understanding of where to start. Usually I just use levels. But I know there are other ways and that you can watch the numbers in the info but I have no clue about all that. Would love to see more info on this topic . Maybe even a long ,slowwww, : ) in depth tutorial for us over 40 brains . I appreciate the info so far .Will read and reread it many many times . : /
Charlotte
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  #12  
Old 02-16-2005, 01:14 AM
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v.bampton v.bampton is offline
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Ok, nice and easy...

If you're working on a decently exposed image, then you shouldn't have a problem. Find the blackest point in the image (that's supposed to be black), and watch the info pallette as you adjust. Move the end point of your levels or curves individual channels that black point reads a neutral number, (ie. R5, G5, B5). The move to the highlights, find the lightest point that's supposed to be white (not a specular highlight) and make it, say R245, G245, B245. If you haven't got a true white and black point in the image then it's a bit more complicated, so practise on ones that do.

Once you've got a neutral white and black point, you're mostly corrected. See if there is anything else that's supposed to be a neutral midtone - maybe some ones suit, or church stonework. Beware that if the point you pick isn't actually supposed to be neutral, then your midtone colours will be thrown off. Again you're trying to get a neutral - where your R, G, and B number are all about the same.

Once your image looks (and is by the numbers) neutral, you can adjust for taste. I tend to add an additional adjustment layer on top for my personal adjustments, leaving the neutral adjustments as they are. That way if I don't like my adjustments I can always go back to neutral without having to start again.

I tend to add red and yellow to the highlights and midtones. Something like R 0, 1.05, 250, 0, 255. G 0, 1.0, 255, 0, 255. B 0, 0.93, 255, 0, 250. It's not exactly neutral, but adds a nice warm glow to the skin which for portraits is ideal.

Hope that helps a bit.
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  #13  
Old 02-20-2005, 08:38 AM
john_opitz john_opitz is offline
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If you want to go back and forth, from rgb to cmy and back to rgb again for editing. Try this profile. You can go back and forth with no/min. loss in gamut.
Caution: this profile is not for cmyk printing (output). This profile exceeds the TIL for printing.

Wide gamut cmyk profile
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  #14  
Old 02-20-2005, 11:31 PM
charlotte charlotte is offline
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Interesting v.bampton. Thanks for posting.
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  #15  
Old 03-07-2005, 07:04 AM
hpycmpr hpycmpr is offline
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Good thread

This is a great thread since it touches on a few topics I'm interested in. I'll try to respond separately on each topic to avoid confusion.

To provide some context to my posts, here's my PS experience so far. I've been teaching myself PS for two years, relying on books and tutorials. My favorite authors include Eismann, Haynes and Margulis. I rely heavily upon curves and by the numbers for my corrections, and not so much upon masks, painting, and channel mixing, all of which I'm now trying to get better at. So far I have been correcting my landscape photos from film scans, and now I'm beginning to correct portraits.
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  #16  
Old 03-07-2005, 07:13 AM
hpycmpr hpycmpr is offline
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More rgb than cmyk?

Quote:
Originally Posted by jayk2
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?
With the exception of books by Eismann and Margulis, most of the books tend to teach correcting with rgb, skin tones or otherwise.

I almost use only rgb exclusively. One reason is my weakness in knowing how to mix channels, and another is the fear of losing data when changing modes between rgb and cmyk. Margulis goes into quite a bit of detail on channel mixing. I can follow his theory, but find it hard to put into practice without detailed tutorials.
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  #17  
Old 03-07-2005, 07:18 AM
hpycmpr hpycmpr is offline
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Mode conversion

Quote:
Originally Posted by Duv
I myself haven't a clue how to adjust skin tones using RGB. I've always converted to CMYK to do my skin correction and then back to RGB. There seems to be a lot more information on CMYK skin correction. Although I haven't noticed anything, I'm wondering if converting back and forth may introduce other subtle problems
I recall reading somewhere that the conversion to/from the LAB mode is lossless. Using LAB as an intermediate mode may be a solution. I haven't tried or tested this, so take this with a big grain of salt. <g>
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  #18  
Old 03-07-2005, 07:47 AM
hpycmpr hpycmpr is offline
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Curves

Quote:
Originally Posted by edgework
I do the same thing when I have to work in RGB. The rules are roughly similar, but keep in mind that Photoshop simulates the qualities of light in RGB, and ink on paper with CMYK. One significant difference is that in CMYK, applying a curve to any channel will affect both color and lightness in a very different way than with RGB. A rule of thumb is that you use the individual channel curves in RGB to adjust color, and you use the master curve to adjust contrast. Because Red, Green and Blue are all equal in intensity (equal values combine to produce dead neutral) the master curve can be used effectively to make lightness moves without altering the hue and saturation (although the lightness channel in lab mode is far more efficient). In CMYK, since cyan is such a crappy ink, it requires about 10% more than Magenta and Yellow to balance the other two and produce neutral. Using the master curve in CMYK is very dangerous, unless you are using it in luminosity mode.
Excellent points about the difference between rgb and cmyk. I also adjust individual curve channels first, and leave adjusting the composite at the end and only when necessary. Now that I'm beginning to correct portraits, it gives me motivation to try cmyk.
Quote:
Originally Posted by edgework
I was trained to use CURVES, and CURVES only, (and only in CMYK) since most of the other adjustment tools are more or less subsets of what curves are capable of doing. However, I've found that using selective color in the way previously mentioned, is a great quick fix. If, for example, a face has yellow highlights and hot red shadows, pulling magenta and adding yellow to the reds, and pulling yellow and adding magenta to the yellows brings the tones into balance, albeit a flat kind of balance.
Curves is my main tool. After that, I will use other tools to do whatever I cannot do with Curves.
Curves pros:
- They can do a whole lot of things.
- A steep portion of a curve boost contrast.
- I kind of feel like "knowing" what is being done to the pixels.

Curves cons:
- Needs patience.
- Steepening a portion of a curve flattens another (losing contrast). Can't have my cake and eat it too!
Quote:
Originally Posted by edgework
Another trick for skin (this is for CMYK corrections): I've never found a face that cannot be improved by making a contrast move to the magenta channel in luminosity mode. Flat skin tones are almost always the fault of the magenta plate, and even if the numbers are within a realistic range, the lack of contrast can make the skin appear too hot overall. Heightening the contrast in magenta, but keeping it in luminosity mode can open up detail in an instant, without messing up the color.
I'll definitely keep this in mind.
Quote:
Originally Posted by edgework
As for converting back and forth, the areas of RGB that extend beyond CMYK are far more extensive in the Greens and blues. The truth is, any colors in RGB that are outside the CMYK gamut aren't going to look all that appropriate in skin tones anyway--greens, blues, hot reds and day-glo oranges. If realism is the desired goal, moving into CMYK before correcting the color will weed out a lot of unrealistic tones. But if intensity and bright colors are the visual goal, and the target is RGB output, or the WEB, keep it in RGB.
Good point. For printing on a desktop inkjet, this may even be a less issue.
Quote:
Originally Posted by edgework
One problem with CMYK that is non-existent in RGB is ink density. Because there is a limit to the quantity of ink a press can handle without turning the result into mud, the CMY channels will usually flatten out to a single tone in the shadow range, shifting the detail information into the black plate. This can be a problem if you have shadows that carry a cast, either hot or cool. Moving an image into CMYK will usually turn the dark areas neutral, which will be a problem if the mood of the original art called for overall warmth or coolness. I often use selective color for these situations too, pulling cyan from black and adding magenta and yellow, or the other way around to cool them down. Pay attention to the darkest shadows as well as dark hair: it's easy for rich brunettes to become dingy blacks in the translation.
It took me a long time to figure out that the ink density is handled differently between a press printer (cmyk) and a desktop inkjet printer (rgb). On the inkjet, the ink density is NOT (solely?) controlled by rgb or cmyk values.
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  #19  
Old 03-07-2005, 08:10 AM
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Quote:
Originally Posted by Duv
I myself haven't a clue how to adjust skin tones using RGB. I've always converted to CMYK to do my skin correction and then back to RGB. There seems to be a lot more information on CMYK skin correction. Although I haven't noticed anything, I'm wondering if converting back and forth may introduce other subtle problems. The tones you acheived are spot on. I never considered using Selective Colors to do my correction. I'll have to give it a try. Can I ask why you adjust yellow and red as opposed to magenta/yellow/cyan and black?

Cheers
Dave
Well now, don't I feel a bit silly quoting myself. I reread Eismann and realized I could have the best of both worlds.

Duplicate your RGB image
Convert to CMYK and make your adjustments
Drag it back onto the RGB layer and change blend to Color to bring back original RBG luminosity values

I've tried it quite a bit and it works like a charm.

Cheers

Dave
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Old 03-07-2005, 08:13 AM
hpycmpr hpycmpr is offline
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Neutrals

Quote:
Originally Posted by v.bampton
Ok, nice and easy...

If you're working on a decently exposed image, then you shouldn't have a problem. Find the blackest point in the image (that's supposed to be black), and watch the info pallette as you adjust. Move the end point of your levels or curves individual channels that black point reads a neutral number, (ie. R5, G5, B5). The move to the highlights, find the lightest point that's supposed to be white (not a specular highlight) and make it, say R245, G245, B245. If you haven't got a true white and black point in the image then it's a bit more complicated, so practise on ones that do.

Once you've got a neutral white and black point, you're mostly corrected. See if there is anything else that's supposed to be a neutral midtone - maybe some ones suit, or church stonework. Beware that if the point you pick isn't actually supposed to be neutral, then your midtone colours will be thrown off. Again you're trying to get a neutral - where your R, G, and B number are all about the same.

Once your image looks (and is by the numbers) neutral, you can adjust for taste. I tend to add an additional adjustment layer on top for my personal adjustments, leaving the neutral adjustments as they are. That way if I don't like my adjustments I can always go back to neutral without having to start again.

I tend to add red and yellow to the highlights and midtones. Something like R 0, 1.05, 250, 0, 255. G 0, 1.0, 255, 0, 255. B 0, 0.93, 255, 0, 250. It's not exactly neutral, but adds a nice warm glow to the skin which for portraits is ideal.

Hope that helps a bit.
Correcting the neutrals is how I start with each image. An ideal image for this kind of correction is one with true neutrals at highlight, midtone and shadow. But as you pointed out, sometimes this is not as simple or even possible with some images. In order of difficulty, here are some examples:

Some images are shot in certain lighting conditions with a desireable color cast that should not be removed, such as landscape scenes at dusk or dawn. Whether these images have any true neutrals is irrelevant.

Some images do have true neutrals but they are difficult to identify, such as several statues with different shades of "gray" marble.

Some images do have true neutrals that are easy to identify, but are not at all three points of highlight, midtone and shadow.

An image shot in a studio under controlled lighting and the inclusion of a gray wedge will not have any of the above problems.
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  #21  
Old 04-13-2005, 02:15 PM
McCombs707 McCombs707 is offline
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tried them all, here's what I do now....

First off, Dan Margulis is a genius, and I think his work is incredible. But, wanting to just work in RGB myself (though I work in the commercial printing field, where it's all CMYK) for my own personal photography, which will be printed on Fuji Frontier or similar equipment via sRGB, here's my formula for skin tones, at least for caucasian kids (adults are very similar)....

This is really very simple, just takes a while to 'splain'.....

After adjusting highlights and shadows via Levels, take a reading using the eyedropper with a 5x5 pixel setting of a good area of skin tone, not rosy cheek, middle of forehead works well normally. Set the eyedropper tool to display a reading in the info pallette by clicking it in the toolbar while holding down Alt (PC only, I forget which key to use on a Mac right now).

Using Curves, watch the setpoint you set in the Info Pallette and adjust the individual RGB channels to match what's below.

*** Only adjust from the UPPER RIGHT point in the Curves dialog, NOT from the midpoint or any point between lower left and upper right! Just for now, trust me!

Green - keep this constant
Red = 112.3 % of Green
Blue = 97.7% of Green

After correcting skin tone color doing the above, convert to LAB mode, and adjust contrast in Curves selecting only the Lightness channel, while viewing all channels, and adjust contrast to taste. This allows contrast adjustment without altering color range.

After all the methods I've tried, this works best, especially if you want to stay in the RGB colorspace.
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  #22  
Old 07-01-2005, 01:19 PM
jenjen jenjen is offline
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Quote:
Originally Posted by McCombs707
Using Curves, watch the setpoint you set in the Info Pallette and adjust the individual RGB channels to match what's below.


Green - keep this constant
Red = 112.3 % of Green
Blue = 97.7% of Green

After correcting skin tone color doing the above, convert to LAB mode, and adjust contrast in Curves selecting only the Lightness channel, while viewing all channels, and adjust contrast to taste. This allows contrast adjustment without altering color range.

After all the methods I've tried, this works best, especially if you want to stay in the RGB colorspace.
How exactly do you figure out the percentages? Green keep it the same right? Red 112.3% or green? How is that possible? I guess i'm calulating this all wrong. I've been trying to figure the whole skin color thing for weeks now. Thanks!

Jen
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  #23  
Old 07-01-2005, 04:09 PM
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Stroker Stroker is offline
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Quote:
convert to LAB mode, and adjust contrast in Curves selecting only the Lightness channel
Or...
Stay in RGB mode, Curves Adjustment Layer, and set to Luminosity.
Few other notes about this, but should be good enough for most.
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  #24  
Old 08-01-2005, 04:13 PM
inskip inskip is offline
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Quote:
Originally Posted by McCombs707

*** Only adjust from the UPPER RIGHT point in the Curves dialog, NOT from the midpoint or any point between lower left and upper right! Just for now, trust me!

Green - keep this constant
Red = 112.3 % of Green
Blue = 97.7% of Green
How do you determine where you ned to grab on the curve line? Can someone elaborate a little on the above formula for me? I'm not sure what
Red = 112.3% of Green means??? Keep Green constant??? Does that mean don't change it?
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  #25  
Old 08-02-2005, 09:07 AM
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Quote:
Originally Posted by inskip
How do you determine where you ned to grab on the curve line? Can someone elaborate a little on the above formula for me? I'm not sure what
Red = 112.3% of Green means??? Keep Green constant??? Does that mean don't change it?
If I understand his post correctly, on the sample Original I put a sampler marker on her cheek and got readings of 219, 148, 109. Based on his percentages I should take the green value(148) and multiply it by 1.123 which gives me 166 for red. For blue I take .977 of the green value (148) which gives me 144. Therefore, I need to adjust my curves to get 166, 148, 144. He is suggesting pulling the curve from the top right corner only..not from anywhere on the curve.
I posted a Corrected Image based on the percentages and I can assure you it's not a skin tone that I find plausible. Perhaps I don't understand and need further clarification but I honestly can't see how a fixed percentage of colors can give you what you want. It certainly wouldn't work for a dark skinned person.

Cheers
Dave
Attached Images
File Type: jpg Original.jpg (36.2 KB, 115 views)
File Type: jpg Corrected Image.jpg (34.5 KB, 125 views)
File Type: png info pallet.png (7.0 KB, 81 views)
File Type: png Curve.png (8.8 KB, 73 views)
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  #26  
Old 08-02-2005, 10:07 AM
inskip inskip is offline
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Well Dave, it may not be perfect but it's definately improved quite a bit.
He said NOT to sample from the cheek, but rather the forehead which is generally not as rosy. Don't know how much difference that would make...

I'm still unclear as to how you determine where to pull on the curve-in general.
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  #27  
Old 08-02-2005, 10:09 AM
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Cameraken Cameraken is offline
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Duv

I also had a go with McCombs707 method. You have read his steps the same way I did.
His last step is to convert to LAB and adjust the lightness.
My attachment is your picture plus the last step.

I don’t look too bad to me.

Ken
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File Type: jpg Ken_Corrected Image.jpg (84.4 KB, 116 views)
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  #28  
Old 08-02-2005, 10:49 AM
fat0n3s fat0n3s is offline
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I agree with Duv on this one.

The method that is posted above, is really only changing the white point of the image. If there was a color cast, only in the highlights, then this meathod might work. If the color cast was in the midtones and shadows, this really wouldn't do any good.

There is not a magic formula for correcting skin tone. If there were, photoshop's auto color would work everytime.

Here is a good tutorial on curves. Page 3 of this tutorial gets into color correction.

http://www.gurusnetwork.com/tutorial/curves/1/

The tutorial dosen't get into great depth, but it is a good start.
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  #29  
Old 08-02-2005, 11:13 AM
Ken Fournelle Ken Fournelle is offline
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Duv,

I use your method for duplicating the RGB image, converting to CMYK, correcting and then pasting back into the original RGB image.

But don't your convert back into RGB from CMYK before your paste the duplicated image back into the original RGB image?

We discussed this in the past, and I thought that was your methodology.

k
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  #30  
Old 08-02-2005, 02:54 PM
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Hate to be an old fuddy duddy here but I think my correction and Ken's are worse than the original. It's impossible for this caucasian woman to have 50% cyan with 50% magenta. Take a reading off the whites of her eyes. They've got more blue and green than red. Does that make sense? The last time I checked I had a whole pile of blood vessels in my whites which would make red the predominate color.
I've posted one here using values of about 9/42/44/0 on the marker. Cheek, forhead, nose..but it should be higlight, no shadow, makeup or natural blush if possible. This isn't suppose to be definitive or anything but using known rough values of CMYK for caucasian skin gets me one heck of a lot closer than this percentage idea. IMHO.
Ken, When you have your corrected CMYK file..flatten it, select all, copy and paste back into the original RGB file. Then change the blend mode to color.
BTW, I've tried the percentage routine on a number of images will equally poor results so maybe the original poster is not explaining something.
Inskip, if you pull from the corners of Curves you'll get more extreme changes to highlights and shadows. If you want you're change to be more transitional, pull down along the curve. For example if you want to change from 196 to 176, run your cursor along the curves line. You will see the numbers change. Locate on the curve where 196 is, click on the curve and bend it up or down to get your 176 number.

Cheers
Dave
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  #31  
Old 08-02-2005, 03:56 PM
Ken Fournelle Ken Fournelle is offline
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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
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  #32  
Old 04-07-2006, 12:53 PM
Jann Lipka Jann Lipka is offline
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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 .
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  #33  
Old 04-07-2006, 03:02 PM
john_opitz john_opitz is offline
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Quote:
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.
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  #34  
Old 04-07-2006, 10:20 PM
Jann Lipka Jann Lipka is offline
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john , what file on the color theory list is related to skin color ?
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  #35  
Old 04-08-2006, 06:56 AM
john_opitz john_opitz is offline
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Quote:
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.

Last edited by john_opitz; 04-08-2006 at 07:35 AM.
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  #36  
Old 09-07-2010, 03:45 PM
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Re: Skin Tone color corrections, CYMK or RGB?

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.)
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  #37  
Old 09-07-2010, 05:04 PM
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andrewrodney andrewrodney is offline
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Re: Skin Tone color corrections, CYMK or RGB?

Quote:
Originally Posted by Chain View Post
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.

Quote:
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).
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  #38  
Old 09-08-2010, 12:07 PM
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Re: Skin Tone color corrections, CYMK or RGB?

Try to go to Image > Adjustments > Desaturate on a CMYK image and tell me how gray that turns out.. :P.
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  #39  
Old 09-08-2010, 03:40 PM
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Re: Skin Tone color corrections, CYMK or RGB?

Quote:
Originally Posted by andrewrodney View Post
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
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  #40  
Old 09-23-2010, 09:45 AM
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Re: Skin Tone color corrections, CYMK or RGB?

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
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Last edited by ray12; 09-23-2010 at 09:54 AM.
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  #41  
Old 09-24-2010, 10:51 AM
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Re: Skin Tone color corrections, CYMK or RGB?

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
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  #42  
Old 09-24-2010, 01:09 PM
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Re: Skin Tone color corrections, CYMK or RGB?

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

Last edited by ray12; 09-24-2010 at 01:35 PM.
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  #43  
Old 09-25-2010, 01:04 PM
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Re: Skin Tone color corrections, CYMK or RGB?

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.

Last edited by Chain; 09-25-2010 at 01:05 PM. Reason: (clearification)
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