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The elusive alpha channel remains one of the most misunderstood yet powerful tools in Photoshop. Alpha channels are collections of luminance data that control the transparency of an image, and they inform just about every aspect of Photoshop. As he builds transitional blended layers, fashions a depth map, makes edge adjustments, and takes on extreme channel mixing, Omni Award-winning expert Deke McClelland teaches Photoshop users that where there's a will, there's a way. Photoshop CS3 Channels and Masks: Advanced Techniques covers mapping texture on an image, turning flesh into stone, using vector masks, working with all different channels, creating a rustic edge effect, and much more. Exercise files accompany the tutorials.
Download Deke's customized keyboard layouts for Channels and Masks from the Exercise Files tab."
This exercise marks the beginning of the third and final project of this chapter. In case you are sitting there going, what were the first two projects, well, we have that overarching almost Blue project, obviously, the one that we just finished up a couple of exercises ago. Inside of that we have that meta project with the lightning inside of the clouds. So that's why I am calling this the third project, and obviously it involves still more advanced blending inside of Photoshop. This time we are using the blending in order to match images that really don't go together. So we are going to be taking this image right here that's called PhotoSpin girl.tif, named for the PhotoSpin image library.
She hails form this library called PhotoSpin and you can find out more information about PhotoSpin by going to www.photospin.com, lots of wonderful images from wonderful people. We are going to take this very, very cool image, that is to say, it has a lot of cool colors going on, so a lot of cool greens and blues and violets. She is even lit with cool lighting so that we have some blue showing up inside of her eyes right there. We are going to take this image and we are going to composite it against a very warm background filled with yellows, and reds and oranges and these warm shades of green as well.
Also this background, which is called by the way, Backyard blur.jpg from no image library, it comes form my own backyard. I just stepped out on my deck and shot this image. And I shot it out of focus, that's why it appears out of focus. It's an optical, a true optical blur effect. So there is a lot of differences going on. This image is obviously naturally lit, it's an outdoor photograph. This image right here is an indoor photograph. It's like a night club. It has sort of a night club disco feel to it. She is generally in focus, although, she has some out of focus edges going on, thanks to a strobe coupled with a long exposure. Whereas, this image is of course completely out of focus, so we are having to do a lot of reconciling in both the edge and the coloring territory as you will see.
But I think that we would start things off with a look at how I created the mask. So just as we ended the previous project with a look at the mask, we are going to begin this project with a look at the mask. I should say, this is a purely optional exercise. I am not really going to be communicating all that much new information. I provide just by way of yet another means for you to gain more practical experience with masking inside of Photoshop. So if you go to the Channels palette, and once again, I am inside of this image called PhotoSpin girl.tif, inside the 10_advanced_blend folder. If you go to the Channels palette, you will see that there is a list of channels, a list of the color-bearing channels, of course, the RGB channels culminating in this alpha channel right here that's called final and that's the mask that we are going for. So here is how I got it.
First of all, I peruse the channels, of course, to see which channel was going to serve as the best base channel. Here is the right channel, not too good, not a whole heck of lot of contrast going on. She and her background pretty well match each other. We are losing a lot of the hair detail around the edges. Here is the Green channel, better, definitely a better channel and then here is the Blue channel which is the best of them all, contains a ton of contrast. So we are going to start with Blue. I am just going to go ahead and drag the Blue channel down to that little page icon at the bottom of the Channels palette and I am going to rename this channel mask or something along those lines. Now naturally she needs to be white against the black background, so I could invert her, but I am going to pass along another way to invert an image inside the Levels dialog box.
So as you are increasing the contrast of the image you can invert it as well, by pressing Ctrl+L or Command+L on the Mac. Then here is what you do. See these Output Levels options down here at the bottom of the dialog box. Just go ahead and take the black triangle and the white triangle and switch places with them. Or you can change the first value to 255 and the second value to zero. That's going to map black to white and white to black and just like that, Bob's your Uncle, you have got an inverted image, that's all it takes. Now you could adjust the levels traditionally in order to increase the contrast. The one difference is that now white is black and black is white. So if I adjust this white slider triangle here, I am actually making the blacks darker, because white has been remapped to black right over here. So I am going to go ahead and change this value, this third Input Levels value here for the white point or the black point, now of course to 170. Then I am going to change the black point cum white point to 60 in order to lighten up the whites a little bit. Having sort of inverted my brain enough at this point, I am going to go ahead and click OK in order to accept that modification.
Now she is looking a lot worse for the wear at the this point and I just kind of want to let you know, this is by way of a warning to those of you who like to work with Photoshop while your models are peeking over your shoulders. Don't mask in front of your models, don't be doing this because masking can bring out the worst in people, especially, when you are in the intermediate zones of a mask. I mean, she is a beautiful young lady, but not looking so good inside of the alpha channel at this point. Now, I am just going to go ahead and get my Lasso tool, because there is a pretty good margin between the stuff on the inside of the image and the stuff on the outside. So I am going to use the Lasso tool to Alt+Click or Option+Click around the edges like so of the stuff that I kind want to just get rid of, right off the bat here. I am working pretty broadly here. Tat is a good enough selection at this point. So I did that by Alt+Clicking or Option+Clicking with the Lasso once again. Now I am going to fill that area with white by pressing Alt+ Backspace or Option+Delete on the Mac.
Now you can bring your model back in the room and they can watch you mask some more, okay. Now it's all right because the gruesomeness is over. Now I went ahead and deselected the image clicking outside of the selection. I am now going to switch over to the Paintbrush tool and I am going to start by painting with white, just because I want to make sure that we retain as much of the edges of our hair and so forth as we can, and I am going to, of course, switch the mode to Overlay by pressing Shift +Alt+O or Shift+Option+O on the Mac. The Opacity is a 100%, Flow is a 100%, that's fine. I have got a pretty big brush going but I might make it even bigger. Then I am just going to sort of give a paint around the edges of the hair a little bit just to make sure that we have -- if any anything selected more hair than we need, because again we are going to be doing so much blending that is better to select too much than too little. So quite by contrast to the advice that I gave you a couple of chapters ago.
Now let's press the X key in order to switch the foreground color to black and I am going to paint pretty aggressively around the shoulders to get rid of some of that light area that was down in the lower left region of the image. Same with the lower right hand portion of the image, I need to go ahead and get rid of those light grays as well. Now I am just going to paint the rest of the light grays away in order to make sure that we have some nice blacks to work with and I am going to go ahead and zoom in to this region of the hair. Notice this little bit of hole in her hair that is we are seeing through to the background, whatever background that maybe. I am going to click once in order to darken it a little bit. Then I am going to press the 5 key to reduce the Opacity value to 50% and I am going to click again.
So just a little bit of darkening of that hole, just to make sure that it shows up. I think that will make the image look a lot better and make the final composition look better. Next, I need to check my work. I need to see how much of the image I have really, truly made white, and how much, I have really, truly made black. I am going to enlist the help of the Magic Wand tool for this. This is a really great use for the Magic Wand incidentally. I am going to go ahead and select the tool and I am going to change the Tolerance value, notice up here, to zero and I am going to turn off Anti-alias. Now you have Contiguous turned on and now I am going to click inside of the model's head to see if I have gotten everything that I need to select selected.
I have selected most of what I need to select. I do have a few little schnibbles here and there around the edges. So I am going to go get my Lasso tool and I am going to Shift+Drag around these areas that I also want to send to white. The reason I am Shift+Dragging around these areas as opposed to just creating a new selection is because those marching ants. If I Shift+Drag then I can keep an eye on those marching ants as I add to the selection. That's really going to be essential, because I really can't see the grays all that well. So the marching ants are really my friends in this case. I might just go ahead and be pretty aggressive about this and grab some of these areas.
So by Shift+Dragging around these areas, by adding them to the selection I am saying, these areas are going to turn white as well. I am going to change those areas, I am going to fill these areas with white too. So I will go ahead and select these pixels. I think that's good enough, I think I have got about everything selected that I need to. There is a few other little guys here and there around the edges that I am not necessarily too terribly concerned about, but even though I say I am not concerned, I am still selecting them, what's that about. All right, so anyway, I have got enough stuff selected. I am now going to press, what would it be? I have got, let's see, the background color is now set to white, so I will press Ctrl+Backspace or Command+Delete on the Mac in order to fill those areas with white. Then if I feel like I need to do a little extra work, because if I zoom in toward the top of her hair, the deal is this. Let's go back to the RGB image for a moment.
She has got a ton of these Blue highlights going on in her hair and you can see some of these blue highlights are very light indeed. If we don't take care of them, if we don't get rid of them, it's going to basically make it look like she has got these just weird holes in her hair out of nowhere. The thing is her hair is not really wild. It does have a few little hairs popping off here and there, but she is obviously taking the time to comb her hair. It's supposed to be nicely manicured. There is some probably some hair spray going on as well. So we don't want a really sort of free- for-all hair look where this image is concerned. I'm going to manicure things here inside of the mask by switching back to my Brush tool here. I'm going to reduce the size of my brush a little bit. I am going to switch to the Normal mode by pressing Shift+Alt+N or Shift+Option+N on the Mac and you can see that the mode is now Normal.
I am going to press the X key or whatever I need to do to get white as my foreground color and then I am just going to paint these areas away. Actually, I am painting with 50% Opacity, let's go ahead and take the Opacity up to a 100% by pressing the 0 key. Then I will just paint those little sort of black areas away just so that they are not interfering with the final composited effect that will run into later. All right, that looks pretty good now. There is an area over by her shoulder that needs a little bit of work as well. We are over here on the right side of the image. This is her left shoulder, of course, in case that makes any difference to you. I am going to switch back to the Overlay mode by pressing Shift+Alt+O or Shift+Option+O on the Mac and then I will just go ahead and take a pass at this shoulder in order to make it nice and light. Then I will press the X key to switch to black and I will paint in the background just a little bit. I need to get in that corner a little bit as we can see there, in order to make that darker as well.
That's pretty much it folks. If you switch to the final version of the mask, there are some differences going on. There will be differences for you as well, but that's essentially the approach I took in order to get that final version of the mask. Now you can work with either one you want. You can either work with the mask you created or you can work with the final version of the mask, the one that I created for you. I am going to go ahead and actually save up this image, so you can choose to work with this final, final version of the mask that I just created. Whatever mask you work with, we are going to make it work. We are going to make the composition work, by taking advantage or a few more advanced blending techniques in Photoshop as we will begin to see in the very next exercise.
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