12 Replies Latest reply on Jun 30, 2010 7:37 AM by Bill_Janes

    Recommended Skin values in ACR?

    Meyers03
      Hi Group,



      I have searched high and low but have yet to find a set of guidelines
      for correcting skin in RGB values. I am trying to do as much editing as
      possible in ACR6 and would like to find reference values for skin tones in the
      values that ACR gives when I sample. The closest I have found is R>G>B and in
      Lightroom (completely different scale)

      R: B +(15-20)

      G: average of R and B

      B: R - (15-20)



      I understand that this will not replace masking, curves and CMYK
      evaluations in Photoshop, but I would like to as much editing non-destructively and
      prefer the ACR6 interface.

      I shoot RAW, and my workflow is to export in sRGB. I think this means
      that ACR shows me values in the sRGB 0-255 space?



      Thank you for any information you can provide.

      Megan
        • 1. Re: Recommended Skin values in ACR?
          Jeff Schewe Level 5

          Meyers03 wrote:

           

           

          I shoot RAW, and my workflow is to export in sRGB. 

           

           

          If you set your Workflow Settings to sRGB, yes...the RGB readouts will be 0-255 in Red, Green & Blue based on the sRGB color space...but as to "recommended colors" for skin tone, I think you are barking up the wrong tree...assuming all things being equal, there really isn't really a series of numbers that are optimal for skin. Aside from the obvious problem of various skin color, you have the problems of dealing with different light sources and white balance.

           

          If you get your neutrals to be properly neutral and you have a reasonable color profile to use, the skin tone colors should fall into place. If you need to do some tweaks in HSL, do so but if you think there's some sort of magic numbers that will make skin color "perfect" I think you are gong to be rather disappointed. Aside from the fact there are no real numbers, there's no way in Camera Raw/Lightroom to do RGB Curves...so even if you had some sort of numbers to try to achieve, there's no tool set in Camera Raw/Lightroom to change the numbers...

          1 person found this helpful
          • 2. Re: Recommended Skin values in ACR?
            Level 4

            Color correction by the numbers…  sounds like someone needs to Google Dan Margulis and regress to the stone age. 

            • 3. Re: Recommended Skin values in ACR?
              Yammer Level 4

              Surely everyone's skin is a different colour, and different lighting will affect everyone's perceived skin colour too. I don't think you can generalise so exactly. I just measured the skin in a random photo and Red value was 40 higher than the Blue value. You should see me after I've been on holiday, I need ProPhoto to get the red in my skin.

              • 4. Re: Recommended Skin values in ACR?
                Meyers03 Level 1

                Thank you for the replies.  I understand that there will be a big variation and no "magic set of numbers", but I still would like to

                have some guidelines.  I am on a calibrated monitor and tend to do most by eye, BUT I do get fooled and would like to have references just to check that I am in the ballpark (just like the LR values in the example).

                 

                Megan

                • 5. Re: Recommended Skin values in ACR?
                  Curt Y Level 7

                  Probably best to set your own.  Find pictures with the "perfect skin color" and take readings.  Do that for about 10 pictures and see what kind of a range you get for "your standard".

                   

                  Not only are skin tones different in most people, the skin tones that are viewed as "perfect" can also vary by users.  Some like a well tanned skin, and other like a skin more like a baby.

                  • 6. Re: Recommended Skin values in ACR?
                    Level 4

                    Here, go crazy sampling different skin tones on this very reduced number of skin color samples:

                     

                    Century_Color_target.jpg

                    Command-click on thumbnail to see larger image on new tab

                    • 7. Re: Recommended Skin values in ACR?
                      Level 4

                      …or these:

                       

                      Getty_Images_Test_Image.jpg

                      Command-click on thumbnail to see larger image on new tab

                      • 8. Re: Recommended Skin values in ACR?
                        Hopsternew Level 1

                        Unfortunately both kangaroos and pineapples do exhibit a range of tonal variations in the wild

                        For example we have red kangaroos and at least two species of grey kangaroos. Pineapple portraits are somewhat less in demand so you may find that Adobe fruit bowl Standard will suffice in most studio situations.

                        • 10. Re: Recommended Skin values in ACR?
                          John Blaustein Level 4

                          Tai....

                           

                          I like your variation on the old theme!  Great photo!

                           

                          I don't know about the color of kangaroos, but the pineapples we get in California sure have unripe coloring.

                           

                          John

                          Printer Test file.jpgPDI Test Image.jpg

                          • 11. Re: Recommended Skin values in ACR?
                            John Blaustein Level 4

                            Megan,

                             

                            On a more serious note....

                             

                            As Jeff pointed out, if you can get your neutral colors to be neutral (without a color cast), then skin tones and every other color will reproduce as correctly as possible.

                             

                            One way to produce neutral grays is to use a gray card like this:

                            http://store.rmimaging.com/digitalgraycard-100.aspx

                             

                            If you are doing a series of portraits, for example, put the gray card in the first photo.  In LR, PS or ACR, you can use the eyedropper and click on the gray card.  That will set the white balance to a neutral color.  You can then copy that to the other images.

                             

                            Another good technique when shooting portraits in a controlled setting is to use the Preset White Balance setting in your camera.  In essence, you shoot a picture of the gray card (it must fill the frame completely) using the same light source that you will use for the portraits, and the camera automatically creates a neutral white balance setting that is then applied to all of the images taken with that Preset setting.  I use this technique all the time and find that images rarely need much adjustment at all in ACR or LR other than a small exposure tweak.

                             

                            Hope this helps a bit.

                             

                            John

                            • 12. Re: Recommended Skin values in ACR?
                              Bill_Janes Level 2

                              Tai Lao wrote:

                               

                              Color correction by the numbers…  sounds like someone needs to Google Dan Margulis and regress to the stone age. 

                              Actually, correction by the numbers is not that unreasonable. If you do a Google Scholar search with the key words skin and color, you will find many articles on the subject, since identification of skin color is valuable in face recogntion software. Human skin colors cluster in a small region in a color space as shown in this link (among others):

                               

                              http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.44.8168&rep=rep1&type=pdf

                               

                              This is not surprising, since skin color is determined largely by 3 pigments in various concentrations: melanin, hemoglobin, and carotenoids.  Two main types of melanin exist: pheomelanin (red) and eumelanin (very dark brown). Eumelanin in small concentations appears yellow (as in blonde hair), and large concentrations appear more brown and finally very dark brown (black). Caretinoids are yellow (as in carrots) and hemoglobin is, of course, blood red.

                               

                              Since L*a*b has magenta and yellow as opponent primaries, this may explain its usefulness in color balancing of fleshtones as explained by Dan Margulis in his LAB book. iCorrect Portrait is a Photoshop plugin that can correct flesh tones for both light and dark skinned subjects. I don't know exactly how the algorithm works, but it likely places the skin tones in the human skin color space as described in the link.