Join Deke McClelland for an in-depth discussion in this video Selecting a Blend If channel, part of Photoshop CS3 Channels & Masks: Advanced Techniques.
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All right gang, we're still hard to work on this almost blue composition right here which features the three pinnacles Drei Zinnen from the Eastern Dolomites as captured by a photographer Loic Bernard. Set against this photograph of this woman wearing blue goggles brought to us by Kevin Russ. The name of this image if you're just joining us is Vague Haze.psd found inside of the 10 Advanced Blend folder. So called because it does resemble a vague haze especially when compared to the final version of the composition that we seek to create here. The name of this file is Study in blue.psd incidentally. You can see that it just rife with these wonderful highlights, and we've got these clouds going against her goggles. We have neither mountains nor clouds set against her flesh.
So in this exercise, we're going to peel the mountains and clouds away from her flesh. So that she shines through, so that we can see that peachy pale flesh just shining through with nothing in front of it unadorned by other layers. We're going to do that of course using Luminance blending combined with an option called Blend If that allows us to Luminance blend according to the contents of a single color Channel. All right. So check it out. Let's return to the Vague Haze.psd file. I am going to bring up my Layers palette, and I am going to double-click, actually first I am going to press the F key, so that we switch to the Full Screen mode, so that I have a little more wiggled room in terms of moving her around on screen, so that we can keep an eye on her while we have the big old Layer Style dialog box up on screen.
All right. I want you to double-click on the Multiply layer in order to bring up the Blending Options panel. Now, she is in the background. We want to force the display of her flesh through the dolomites. So we want to work with this Underlying Layer slider right there. She is light; her background is a little bit darker. So we're going to drag the White triangle in order to force through the lightest colors. Notice that as we drag this White triangle over to the left, we reveal her flesh.
Problem is, we also start to reveal her goggles. Notice that we're revealing all kinds of brightness value inside of the goggles there. We haven't quite finished revealing her flesh yet. She's got this kind of chin strap going underneath her jawline right there. So basically, no matter what we do with this Underlying Layer slider, we're not going to be able to simultaneously reveal all the flesh tones and keep the clouds inside of the goggles. So what do we do? Well, we take advantage of Blend If. Notice this Blend If function right there allows us to Luminance blend once again according to the contents of single color Channel, Red, Green or Blue. Right now, it's set to Gray which is a Blend If options way of saying the composite RGB image. I am not sure why it's called Gray.
But anyway, before we decide which Channel we're going to use, we need to check out what the image looks like, what that background layer looks like, since we're trying to force it through on a Channel by Channel basis. So let's go ahead and cancel out of the dialog box by clicking on the Cancel button. I am going to turn off the Multiplying Screen Layers by Alt+Clicking or Option+Clicking on the Eyeball in front of the background layer. Now, let's take a look at the individual color Channels in reverse order. Let's start with Blue. I am going to press Ctrl+3 or Command+3 on the Mac to switch to the Blue channel, and you can see that her goggles are very light, in fact they're white. The background is pretty whitish as well. Her skin is actually fairly dark imaged Channel, her lips are very light, and her hair is the only really truly dark thing in this Channel.
Now, let's switch to the Green channel in which the background begins to darken up a little bit, and her flesh is lightening up as well. But, we don't have a ton of contrast going on between her flesh and the goggles and so forth. In the Red Channel, which I get to by pressing Ctrl or Command+1. We see a high degree of contrast, her flesh is very, very light, the goggles are very dark by comparison. The background is dark as well. You can see that even this jawline right here is lighter than the background. The Red Channel is the Channel that we want to blend according to.
So I am going to press Ctrl+Tilda or Command+Tilda to switch back to the RGB view of the image. I am going to Alt +Click on that Eyeball once again, Option+Click on that Eyeball on the Mac in order to re-display the Multiplying Screen Layers. Let's double click on Multiply. I am going to change Blend If from Gray to Red. Now, when you're blending according to the contents of the Red channel, it's not like you're just blending the Red channel independently of Green and Blue. You are blending everything, the whole composite image according to the contents of the Red channel, and that's something that's important to bear in mind.
All right. Now, let's go down to the Underlying Layer option, drag the White Slider Triangle over to the left, and you can see that we're able to control the flesh tones. We're able to bring up those flesh tones independently of all the blues inside the image. Now, at this point, once I take it down to 92, we're starting to reveal some of the edges inside of the blue areas, but not much. Now, let's create a little softness here. I am going to move the White triangle down to 80 as you can see right there, and then I am going to Alt +Drag or Option+Drag the right half of the White triangle over to 170 in order to create some softness between 80 and 170 inside the image.
So now we're saying anything that has a brightness value of 80 or darker, is not being forced through. Anything that has a brightness value of 170 or lighter is being forced through and that is by the way 170 or lighter inside of the Red Channel is being forced through inside of the composite image. Then, 80-170 is our fuzziness range. All right. Now, I am going to go ahead and click OK in order to accept that modification and note that we just affected both the Multiply and Screen layers because Screen is masked by the Multiply layer. Multiply affects the contents of both. There it is, we have done a very nice job of bringing up those flesh tones. We still have some work to do where the highlights are concerned and we're going to do that work in the very next exercise.
Download Deke's customized keyboard layouts for Channels and Masks from the Exercise Files tab."
- Distorting and shading with a DMap
- Understanding bits and channels
- Creating paths with the Pen tool
- Using blend modes and the Dodge and Burn feature
- Understanding channel mixing
- Using layer masks, clipping masks, and knockouts
- Applying Smart Filters