split channel B&W - question

ivar

Introduction: I have no idea on *how* things work most of the time when it comes to PS. I do what I do because of repetition, and I see what happens. I hate that, because I'm someone who once I know the basics can remember them apply them, and play with them. So I'm trying to read some books and follow along with examples to give myself a better understanding.


I understand the splitting channel part, but now I want to create a B&W out of those channels. From the book:

You can re-create the 70/30 Channel Mixer version by dragging the green document on top of the red document ...[snip]... Change the Layer Opacity to 30 percent. You can duplicate any Channel Mixer blending effect that uses positive slider values (that add up to 100) by stacking the documents in layers and adjusting the relative opacities.

So, 70/30 (red/green) would mean I set the top layer (let's say red) to have an opacity of 70, but I leave the green layer at 100, correct?

So, if I want to have a 60/30/10 (red/green/blue) I can have Red layer on top of Green on top of blue, and them respectively having an opacity of 60, 30 and 100?

Does it matter what order the layers are in?

Thanks!

pathfinder

Ivar, let me begin by saying that I have not played with using the channels in this way for B&Ws. I did read about it recently in Kelby's book I think.

But it is my understanding that one of the limitations of splitting channels, versus Channel Mixer, is that when splitting channels you cannot make one channel greater than 100. Makes sense, because 100% opacity is 100%. Perriod.

But with Channel Mixer you can have a blue channel of +200% and a red channel of - 125% You give up the freedom of working on layers in Channel Mixer, while Splitting Channels can be saved as a psd to be worked on later.

I could be wrong about this though:D

I don't know about the order of the layers though. I doubt that it matters since they are layers now, not channels. What would it matter to you? For more Blending possibilities?

ivar

pathfinder wrote:

Ivar, let me begin by saying that I have not played with using the channels in this way for B&Ws. I did read about it recently in Kelby's book I think.

I read about this particular example in Skin.

pathfinder wrote:

But it is my understanding that one of the limitations of splitting channels, versus Channel Mixer, is that when splitting channels you cannot make one channel greater than 100. Makes sense, because 100% opacity is 100%. Perriod.

But with Channel Mixer you can have a blue channel of +200% and a red channel of - 125% You give up the freedom of working on layers in Channel Mixer, while Splitting Channels can be saved as a psd to be worked on later.

I could be wrong about this though:D

I doubt that you are wrong. Also because the book says the same thing

The only advantage I see is that you could use masking and locally change the ratio of R/G/B, instead of using opacity.

pathfinder wrote:

I don't know about the order of the layers though. I doubt that it matters since they are layers now, not channels. What would it matter to you? For more Blending possibilities?

Well, not entirely sure. I doubt that I would ever really use this. I'm just starting to understand how to use the Channel Mixer, so this is still a little too advanced for me for daily use. However it bugs me that I don't fully understand it. I played around with it a bit, and the order doesn't seem to matter really.

Where it started to go wrong, was that I thought "for a 60/30/10 split channels conversion, I set the opacities to 60, 30 and 10 percent." That didn't work out too well and the entire image became opacic I think I figured out that the lowest layer needs to have a 100% opacity, and will 'show' as whatever is left if you add the other layers' opacities.

plumkrazy

ivar wrote:

The only advantage I see is that you could use masking and locally change the ratio of R/G/B, instead of using opacity.

Exactly