Join Deke McClelland for an in-depth discussion in this video Selecting a base channel, part of Photoshop CS3 One-on-One: Beyond the Basics.
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Alright, so how do you go about creating a channel based mask you may ask yourself. No, no, ask me I know the answer, here let me show you. Go to the RGB image for starters here inside the channels palette. Actually you know what I am going to do, I am going to make these little thumbnails a little bigger here and I am going to do that by right clicking in this empty area down here below the channel names and I am going to choose Large. Another thing you can do if you don't have an empty area down there or its just too slim to get to as it is now for me then you could click on the little menu icon and choose palette options and that will bring up these bizarre little silhouettes as it turns out, they are silhouettes of tiny little wizards with magic wands sitting on a paint palette, believe it or not that's what they actually are and go ahead and select the largest of the group and then click OK.
So that works too. But anyway that way we can see big versions of our thumbnails here. Now when you are anticipating creating a channel based mask by which I mean we are going to create one of these a mask inside of an alpha channel that's all that's about but it's also based on one of the existing color channels inside of the document which means that we need to peruse the channels, we need to sort of stroll through the channels and see what's going on here. So just so that you are on board with me here we are working it in the FaceInTheDark.tiff image, we are looking at the channels palette of course.
Here is the RGB version of the image at the top and that's just the full color composite, that's the blended version of the red, green and blue channels. Now each one of red, green and blue channels is a separate grayscale document and each one conveys different information. So let's take a look at each one of them. I am going to stroll through these three channels by pressing the keyboard shortcuts. Notice that there are these little keyboard shortcuts over here on the right side of the channels palette that's a Control 1, Control 2 and Control 3 and those would be Command 1, 2 and 3 on the Mac and they allow you to switch between the channels.
So here's Control 1 for red, here's Control 2 for green and here's Control 3 for blue and notice that they are getting increasingly dark inside of this image. So red is the brightest channel, green is the sort of moderately bright channel and then blue is the dimmest channel of the bunch and that just turns out to be the case because we are looking at a flesh based person here so somebody who trends toward the warmer colors as we all do, I am not implying that this woman is somehow warmer than other people out there, any picture of a human being is going to resonate more inside of the red channel than inside of the green or blue channels.
Green is always going to be second and blue is always going to be third. What we are looking for isn't so much the brightest channel or the dimmest channel or anything along those lines, we are looking for the channel with the most contrast and that is going to be the red channel right here, it's the closest to the end mask. Because she is very light, her hair is moderately light, her background is very dark, how much closer could we get? So this is the channel that we are going to start with. What happens when you are creating a mask is you begin with the channel and then you start in editing it, you start making the bright brighter and the dark starker but we don't want to do that yet, right.
If I started manipulating the red channel I would mess up my image, I would muck up that red information and that would affect the RGB composite as well. So instead I want to click on the red channel to make it active and then I want to duplicate it which I am going to do by dragging the red channel down to this little page icon, see it down here at the bottom of the channels palette. That little page icon when you see it in any palette indicates that you are going to create a new something rather right. So inside this palette it means new channel inside the Layers palette, it means new layer and so on.
So I am just going to go ahead and duplicate the red channel here and I will name it "My Mask" just so that I can keep it separate from the one that I gave you Mask, alright and you can name it anything you want. Just go ahead and give it a name there. I am also going to make my palettes a little wider by dragging them over to the left so that I can see this name uninterrupted without that dot, dot, dot. Alright so this becomes the base channel for my mask, we will see how we turn it into a mask beginning in the next exercise.
Ready for more Photoshop CS3 training with Deke? Check out Photoshop CS3 One-on-One: Advanced Techniques.
Note: Photoshop CS3 One-on-One: The Essentials is a recommended prerequisite to Photoshop CS3 One-on-One: Beyond the Basics.
Download Deke's customized keyboard layouts for Photoshop from the Exercise Files tab.
- Understanding what Photoshop CS3 is and what it can do.
- Zooming, scrolling, and getting around an image.
- Making the most of the new-and-improved CS3 interface.
- Using Adobe Bridge to organize and manage images.
- Saving workspaces for maximum comfort and efficiency.
- Correcting colors using the Variations and Hue/Saturation commands.
- Taking on the professional-grade luminance editors, Levels and Curves.
- Resampling an image and selecting an interpolation setting.
- Cropping and straightening a photograph.