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Luminosity blending the best techniques?

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  #1  
Old 04-02-2008, 05:53 AM
mayday mayday is offline
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Luminosity blending the best techniques?

Another topic Markzebra touched on in another thread was the difference between colour and tone so I want to open a thread on luminosity blending this is a method used to improve tone.

A simple way of doing this with skin is to use a channel mixing layer set to mono the green channel +100 (as attached). Then set this to Luminosity blending mode. This often improves the skin tones.

What other Luminosity blending techniques and methods are using?
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  #2  
Old 04-02-2008, 04:39 PM
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Markzebra Markzebra is offline
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Re: Luminosity blending the best techniques?

Good idea for a thread Mayday. A great idea for discussion, will be interesting to see what others take on this is..

My input - Although this is quite a crude introduction, to a very large subject.. One way to approach the issue of color and tone is to view them separately and its a good exercise to try balancing them completely separately.

Although at first glance this may seem crude, its not. You can concentrate on tone first by creating a grayscale, where the tones are exactly where you want them to be, contrast is controlled. This is where you concentrate on good focus in an image, where the subject usually has good tonal distribution. In CS3 one of the easiest ways is to use a greyscale adjustment layer. In previous versions a Channel mix, or the "Russel Brown" technique can effectively do the same thing in more steps. If using a channel mix the thing to watch for is good gradation of tones in the channels you choose to use, blue (or yellow in CMYK) is usually the worst channel to use for this. Check the histogram. These layers can if you want a quick fix, be set to Lum blend.

The next step can be to reintroduce the original hue values - and control these, Selective color and color blended curves are a good and subtle way of doing this, but again its really too large a subject to cover in one post.

I'm not saying that this is a technique you want to use every day but its certainly a worthwhile exercise

Its not true to say as someone said in another thread that curves are difficult with skin, you just have to use them very subtly. Personally I don't like Color balance or particularly levels as color correction tools. As I said in another thread a few months ago now you can also have all your 10 channels embedded in one file, and thats really limitless power.
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Old 04-02-2008, 07:25 PM
KR1156 KR1156 is offline
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Re: Luminosity blending the best techniques?

i work with a retoucher that instructs me to mask the skin, then desat it a bit, but not too far, i usually use a hue/sat layer and desat the reds & yellows, and the overall sat like 35% depending on the file.

this step really helps to smooth out the tone and the transitions. especially on digital photography...skin tones and all the hues that it has get very choppy very easily. and there are almost always red/magentaish hot spots here and there.

so, after i desat skin, with that same mask, i add a new curve (color mode) so that i only re-introduce color. i don't shift the original tone.

after that, a new layer with the same mask, this time set to luminosity so the hue does not shift, and i can control the contrast of the skin tone easily.

--if i client says i love the color, but it's too flat...i can easily just go into my luminosity curve and pump it up a bit, without worrying about straying from the color that the client liiked.
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Old 04-03-2008, 03:48 AM
mayday mayday is offline
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Re: Luminosity blending the best techniques?

Quote:
Originally Posted by KR1156 View Post
i work with a retoucher that instructs me to mask the skin, then desat it a bit, but not too far, i usually use a hue/sat layer and desat the reds & yellows, and the overall sat like 35% depending on the file.

this step really helps to smooth out the tone and the transitions. especially on digital photography...skin tones and all the hues that it has get very choppy very easily. and there are almost always red/magentaish hot spots here and there.

so, after i desat skin, with that same mask, i add a new curve (color mode) so that i only re-introduce color. i don't shift the original tone.

after that, a new layer with the same mask, this time set to luminosity so the hue does not shift, and i can control the contrast of the skin tone easily.

--if i client says i love the color, but it's too flat...i can easily just go into my luminosity curve and pump it up a bit, without worrying about straying from the color that the client liiked.

KR115 this technique is very good for keeping a even skin tone.
Nice workflow tip!
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Old 04-03-2008, 04:48 AM
CaptainHook CaptainHook is offline
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Re: Luminosity blending the best techniques?

This place suddenly gotten very interesting.
Thanks for prompting it KR, and to Chris too.

I am especially interested in all threads related to color.
The title of this disguised it a litte, but i got here eventually.
I kinda wish there was a sub-forum itself titled 'Color',
but i digress.

Markzebra and everyone, keep it coming!
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Old 04-03-2008, 08:05 AM
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cricket1961 cricket1961 is offline
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Re: Luminosity blending the best techniques?

KR

A little different than what I am used to. Different enough that I tried it. Normally I completely separate the luminosity and the color altogether, literally, and place each in their own groups. Every thing is clipped so it is nearly impossible for me to screw it up by adding a density move to the hue or vice versa. I don't do it often so it is a action I made up for when I get old. If I find the action I'll break it down and post it up here.

When I tried your method, I had a little difficulty getting the color back into the image after desaturation. Kind of looked like I had done a fill with color oa (wasn't worried with a mask just to try it out ). I know it probably depends on the image, but is there some kind of ratio that you use to determine how much to desaturate?

Chris
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Old 04-03-2008, 08:15 AM
mayday mayday is offline
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Re: Luminosity blending the best techniques?

Does anyone ever use Gradient maps to change Luminosity?
I think it can also work well
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Old 04-03-2008, 08:28 AM
Hendrik Hendrik is offline
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Re: Luminosity blending the best techniques?

I’m not an expert and maybe not the best approach, but ...

I used the degrunge method on the skin, but with a high radius (3 times the radius you would use to smooth the skin). The texture is not affected and you eliminate the tonal differences in the skin.
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Old 04-03-2008, 08:37 AM
mayday mayday is offline
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Re: Luminosity blending the best techniques?

Quote:
Originally Posted by Hendrik View Post
I’m not an expert and maybe not the best approach, but ...

I used the degrunge method on the skin, but with a high radius (3 times the radius you would use to smooth the skin). The texture is not affected and you eliminate the tonal differences in the skin.
I think you have the wrong end of the stick Hendrik this is not about skin smoothing, its about tone and some of what KR is talking about is colour

Last edited by mayday; 04-03-2008 at 09:12 AM.
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Old 04-03-2008, 09:18 AM
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Re: Luminosity blending the best techniques?

Mayday

I use gradient maps on a daily basis. Its my second favorite tool. It does work well for luminosity changes if set right. Its also great for masking but thats another thread all together.

As far as lum goes, try this. Default black and white, click reverse, hit ok and then lower the opacity to 0%. Also change the blend mode to Linear Dodge. Now up the opacity in 1% increments and watch the image open up while retaining color. Unfortunately it does change saturation but it is easily fixed. If you click back into the gradient for the mesh and slide the hilite triangle to the left you can limit how the opening up affects your higher end.

There is so much to do with this tool. Its easy to get lost in it.
Chris
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