Dodging and Burning in L*a*b

warszawski

it is my first post here ...

i am interested in removing rings around models's eyes when working in the LAB colour space, when i dodge in the L channel, the color of skin goes into grey what is bad, i thought that would stay in the range of color skin ?

i will be interested to get some insights of your experience in this field :-)

Andy

Welcome to Dgrin!

I betcha your answer is in one of the eight chapter discussions of Margulis' Lab Color Discussion Group

DavidTO

Be a bit more specific about what you're doing, and post a crop of the eye showing the effect of dodging in LAB, then we can be more help.

DavidTO

Also, I'm pretty sure that whatever you're doing with dodging and burning would be better done with a different tool. Dodging and burning are destructive and difficult to control. There are better options.

pathfinder

Welcome to dgrin, and great first post if I might say so.

My first suggestion for the Dodging and Burning Tools is to not use them. If you feel you must, do them as an adjustment layer where you can carefully blend in the effect.

A better tool is an Overlay Blend with the brush tool and use a black or white color to control the darkening or lightening effect. Even better is to use the Overlay Blend mode with the Brush Tool on an adjustment layer. Overlay Blending works nicely on the L channel in LAB. SO does the Highlight/Shadow tool work nicely on the L channel in LAB. The Shadow command works better on the L channel in LAB, the Highlight command works better in RGB.

I have not finished Margulis book yet, so I am unaware of a spefic rec re: dodging and burning in LAB.

In Chapter 11, which I am due to report on in a few weeks, begining on page 233, Margulis does describe using the burn tool on the A or B channel - not to change highlights or shadows - there are no highlights or shadows, ONLY color, in the A or B channel. He uses the burn tool to slightly shift color values that he then will blend with the Blend Option sliders.

Addendum: Warszawski - I took a look at your homepage, very lovely work and I am not sure that I am the right person to answer your question, as I am an amateur and you are not, But Dave's comment about dodging and burning being destructive, agrees with my understanding of the Dodging and Burning tools also.

Dodging or Burning the L channel should NOT have any effect on the hue of the image as the L channel only controls the luminosity. BUT, if you make the L channel significantly lighter, yes the image will be more luminous, lighter, less colored ( greyer??) perhaps as converted to RGB? As you get to brighter luminosities in RGB, you get less and less color due to the way RGB defines color 255,25,255 being the brightess posssible AND pure white. An impossible color in LAB should be possible to keep from losing the color with the translation back to RGB. This would be better done as an adjustment layer and a blend to control the final result

What is the strength of the Dodging tool set at? I would never use the Dodging tool( when I rarely do use it ) at any higher than 7-10% Any higher than this, and it is just too difficult for me to control well.

warszawski

working example for Dodge in LAB Color
i am very happy for all your interest and advices,
i will definetely go deeper into Dan Margulis technics, i just started to read his marvelous book and went too quickly to play with, i understand that i have to be patient and read all a book ...
in the meantime i provide here the illustration for this "task" of getting rid of rings around eyes, i've suceeded (?) in RGB space, I dream to do better job and learn more in LAB color,
here is the state of my experience click on the link below please ...
http://20gp.ovh.net/~lafaktor//dodge_exo_1.jpg

warszawski

droping dodging for Levels on L etc.
i wanted to find out another way to get rid of nasty rings around eye, when in LAB color, i used another idea explained in in the following picture.

http://www.dgrin.com/attachment.php?attachmentid=8997&stc=1

by the way, i have a question: is there a difference , matematically speaking, between applying adjustement Level in LAB color on "lightness" V.S. adjustment Levels in RGB on "RGB" ?

do you have any other & better solution(s) & ideas(s) to "dodge" i mean by "dodge" == "u n i f y the skin tones that looks badly" ?

DavidTO

Here's a technique for smoothing out skin...not sure how well it will work as something as large as that shadow, but here goes. Oh, and it's an RGB method.

First make a copy of the layer.

Apply a Gaussian Blur to it that is large enough to blur out the defect your trying to remove. Don't worry about the image being REALLY blurry. Just do enough to achieve the result you want.

In the history palette, select the box next to the blur you just applied, and then select the state above. Your blur should go away from the image.

Now select the History brush, set the blending mode to lighten and make sure it's the right size and softness for the image.

Then just paint with the history brush and the darker aspects of the face will blend away.

When you're done you can play with the opacity of that layer to perhaps put back in some of the original...it's all to taste...

warszawski

great technique , thougth not for this shadow...

DavidTO wrote:

Here's a technique for smoothing out skin...not sure how well it will work as something as large as that shadow, but here goes..

great technique DavidTO, tnx, unfortunately not successful for this shadow...
yes, it works really well on the skin with some "minor" problems but on this shadow of mine it just doesn't work, because it looses the details ...

in some sort of conclusion, i've got promising results when:
(see my previous posts)

a) in RGB color, dodging & re-painting on 50% grey layer with blend set to "soft light", on top of the layer with problem,
(strange the same seems not work well in LAB color)

b) in RGB and LAB, adjustment Level and lowering gamma on the dark part of skin

edgework

warszawski wrote:

it is my first post here ...

i am interested in removing rings around models's eyes when working in the LAB colour space, when i dodge in the L channel, the color of skin goes into grey what is bad, i thought that would stay in the range of color skin ?

i will be interested to get some insights of your experience in this field :-)

Keep in mind that in both RGB and CMYK, as a color approaches dark and/or light, it also moves toward neutral. That's the topic of Chapter 8 in Dan's book, a summary of which can be found here. So when you attack the Luminosity channel with the dodge tool, you are bringing the value more in line with the surrounding skin tones, but leaving the colors in their original neutral that was converted from RGB. LAB, of course, can spec colors that are totally dark or light, yet also totally saturated. This is a meaningless concept outside the realm of theory since no monitor can display them, no inks can create them and it's kind of difficult to even imagine them. Check out the techniques in the Chapter 8 summary which take advantage of this very situation. While that chapter deals with blown out areas, the technique is applicable to your situation for precisely the same reason.