Dodging and Burning on Channels?

[snook305]

Hello all, I have read in several threads that people like to work on certain channels that show more defects for Dodoging and Burning and also for Nosie reduction in a single channel.
What I am a little lost, as I have not done it in a while, But My assistant was talking about it the other day and I said, Yeh some guys like to Dodge and Burn on the "green" channel so they see what they are doing better.
Well when he started to try that when he went bakc to the RGB channel there were Purple/Magenta spots everyhwere he had D&Bed..
I said that is weird!!
We were using CS4.
Does anybody know the proper way to work on the seperate channels..
Anohter example is I have heard of people throwing a noise filter on a certain channel.
A little freshher upper would be nice.
Thanks for any help
Snook

[holgaman]

Hi Snook,
I'm not as familiar with the noise reduction part of your question, so this only applies to the dodging and burning. First make two new layers from your original. Hide the top layer and select the one below. Desaturate that layer and go to image - apply image. Use background in the layer box, channel set to blue and blending to multiply. Hit return and add a black adjustment layer and change blending mode on layer to luminosity. Select the other of the two new layers and desaturate again, in apply image set channel to red, with blending to screen or lighten (may have to set opacity to around 70% for screen). Hit return and add black mask and change blending to luminosity again.

Here's the part where you can show the defects - above your D&B layers add two new blank layers and fill both with black. Set blending on top layer to color and bottom to overlay, choose the two layers and make a new group. The shadows fall off very quickly so when you want to see a bit more just lower the opacity on the overlay layer. No work is done on these layers, they are only meant to be toggled on and off for reference, but you do have them on during much of the D&B. I usually also group the D&B layers also and toggle both to see my progress. The painting on the D&B masks is usually with a white brush at 10% opacity, 20% flow.

Sorry if I went over stuff you already knew, just wanted to give you the whole picture. Hope this helps with part of your question.

[Cuervo79]

What you're describing is not working on the green channel, but a way to see the skin defects better, If you're working directly on a certain color channel and you change the luminosity it will give a difference when looking at the 3 channels.

What you want to do if you want to see what each of the channels is doing but not actually mess with them, is make a channel mixer adjustment layer check the grayscale box, then put all the channels in 0%, next on the channel that you want to see move the slider to 100%.
Other techniques talk about using 2 solid color layers one set to saturation the other set to soft light both in black, that will let you see the problems better but it lessens the details in the shadows. You can also use a curves adjustment layer set to an S curve so everything becomes more contrasty.

[snook305]

Thanks guys, But I remember a retocuhing here on the fourms one tme talking about he liked working in the green? channel when dodging and burning skin so he could see the defects better.
I have also heard on other forums about doing the same. It was a long time agao and do not remember what they said exactly.

Also if you want to denoise a certain channel, the channel with most noise, do you make a copy and then denoise the green channel then click on the RGB icon again?

Thanks
Snook

[holgaman]

Hi Snook,
I think this is what you may be looking for -
http://www.graphic-design.com/Photoshop/glamour.html

Sorry for my long trip down the wrong path.

[Cuervo79]

the link holgaman posted is what I was saying, they use the green channel to see, not to retouch over

[CaptainHook]

I know what you're talking about snook, i remember such things being said but
i don't know the answer sorry.

I have definitely heard about running noise reduction on the blue channel only.
(generally the noisiest and source of most noise)

But also taking skin from the red channel (or green) as it usually shows less
imperfections, like d&b on just the green channel with what you said.

Although as you say, even a subtle adjustment to one of the channels throws colors
out of whack. So i wonder if it's just a case of copying a channel to a layer and putting
it into luminosity/whatever and masking/working on that.

In which case, nothing new.

[cricket1961]

Hey Snook

When you are using a 50% grey soft light layer to do your "D&B", it is possible to work just one channel while viewing all. Just select the channel you wish to work on by clicking on it in the Channels Panel. THen turn the eyeball back on the composite channel at the top.

You can switch between channels while doing this so as to keep the odd coloring from happening. Works great for a lot of things.

I don't know if this is what you are looking for, but I'm sure it will help you at some point.

As for running filters on only specific channels, I can't imagine doing this except with a sharpen or noise or blur filter.

Chris

[CaptainHook]

Originally Posted by cricket1961

Works great for a lot of things.

Thanks Chris, any more info into which situations this is a good solution?