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Viewing a quick mask by itself


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Viewing a quick mask by itself

In this exercise I'm going to show you how to modify a selection in a Quick Mask mode and view the mask independently of the RGB image, which can help to remove some of the ambiguity, so you know exactly what you're doing. So I'm still working on this image called Duckbill in tent.tif and I'm working on this imperfect selection right there and I've gone ahead and made some modifications. Mostly, I just painted away this scene, here inside the Quick Mask mode. Now if I want to see whether I really got rid of that scene or not, then here's what you do, you go over to the Channels palette, make sure it's up on screen.

And you can switch bounce very easily in the Quick Mask mode. It's not a limiting mode, the way the Free Transform mode is or the way the Crop mode is. You can do anything you want inside this mode. It's really great. But what I would like you to do is go to the Channels palette and then turn off the eyeball in front of RGB. And just like that, as soon as the RGB image goes away, you get rid of that color overly and you just see the image by itself because what you're really working on is a black and white mask not a sort of color overly mask, nothing like that going on.

All right, so now we see that the line is gone from the image where we have a lot of other problems that we need to reconcile. And the first thing that I need to do, and this is a really standard masking technique that I'm about to share with you, is you want to go ahead and increase the Contrast of this mask. Because if you look carefully, you're going to see that you have some light gray areas inside of the dinosaur and then you have some dark gray flags outside of the dinosaur and you need to get rid of those light grays and those dark grays. We want some nice whites inside the dinosaur and some pure blacks outside the dinosaur.

And you can do that, using a good friend of ours, go to the Image menu, choose Adjustments and choose Levels. On rare occasions you need to resort to Curves, but generally speaking Levels is your guy. Go ahead and press Ctrl+ L, Command+ L on a Mac. Now right away you may go, hey Deke, why are you applying a static adjustment? Why don't we apply an Adjustment layer, those are so much better? Well, you can't. So layers can have channels associated with them, and layers can also have layer masks associated with them, but masks and channels cannot have layers inside of them. So you cannot pile layers onto an independent channel. In other words you have to apply static adjustments, just like way back in old days.

So when you are masking inside a Photoshop you are essentially performing Photoshop 2.0 modifications, and it really is that way. I mean that's one of the wonders of masking, is even though it's a really super wickedly powerful tool that's available to you inside Photoshop, really a group of tools, it hasn't changed very much in more than a decade. All right, so here we are inside of Levels. I'm going to go ahead and increase this black point value until we've got the black point all the way over to the right of this hump of shadow colors. And another set I'm even including this tiny bit of shadow colors right there. And as a result I'm changing that black point value to 60. So any pixel with the luminance level of 60 or darker becomes black. So we're clipping a lot of colors. You want to clip colors when you're working inside of a mask. That's a desirable thing. So masking is not like continuous tone image editing in that regard.

And then I'm going to go ahead and take this 255 value, the white point value here, and I'm going to reduce it. I'm going to press Shift+Down arrow and I'm going to take it down 60, just as I took the black point value up 60, until I reduce that value to 195. Now this isn't the kind of thing you need to do on a regular basis. You don't need to increase the black point value and decrease the white point value by the same amount. It just happens to just work out pretty nicely for this image. So, I'm saying any pixel with luminance level of 195 or lighter now becomes white and as a result we have some nice black background colors and some nice white foreground colors. Click OK.

Now at this point you can see that we're closer to our goal but we still have some schnills here and there that we need to get rid of. So I'm going to increase the size of my brush, my foreground color is white, so that's a dreamy wonderful thing, and I'll just paint these away and it's pretty easy painting. You are not painting all the edges. You are just painting near the edges, as you can see. Just get rid of that stuff that obviously needs to go. Now I've painted too far. So I'll go ahead and undo that modification. Try again. Paint this area away. It's usually better to paint too little instead of too much in a single paint stroke, in that way, if you have to undo you haven't undone a ton of stuff. So I'm just painting away this garbage here and painting away like this garbage, so let's go in for the kill here, going a little smaller with the brush or that is to say, and go ahead and paint in these details. I can paint in this right here and then I'm going to increase the size of my brush again, press the X key to paint with black and let's paint this garbage away right there.

So you need to spend a little bit of time making sure that the perimeter of your image is in good shape, so don't be zoomed in too far at the end here. Now let's go ahead and turn the RGB image back on to make sure that we got everything that we wanted to get and it's looking pretty darn good, I might zoom in a little bit here to the top of the snout to make sure I got everything I wanted, and it looks like I didn't quite get everything I wanted. So I'll reduce the size of my brush, press the X key to make sure that foreground color is white. And then I'll click, Shift- click, Shift-click, that kind of thing in order to paint in straight segments like so. And I just want to sure I'm getting as much as I can get.

Now as a general rule of thumb I'll tell you, you want to under select instead of over select because if you select too much of the edges, if you go too far out, then you're going to end up with some halos and some other weird edge artifacting, and you don't want that. If you go ahead and choke your selection in a little bit and if you select too little of the image then you are going to eliminate some of those color halos. This looks pretty darn good. I want to tell you one more thing, here's a little tip and trick from me to you by the way of a keyboard shortcut that you should know about. If you want to hide the RGB image on the fly, you press the tilde key and that is the key that's' just above the tab key and below the Escape key, and to the left of the 1 key on an American keyboard, press tilde again to view both image and mask at the same time. I'm noticing that I have a little bit of garbage right there, let's go ahead and paint that in to make sure we get in.

You know we have some ruddy edges up here that you might want to paint in the place, totally up to you, how far you want to go with this, how exact you want to be. This looks pretty swell. Tell you what we're going to do. In the next exercise we're going to exit the Quick Mask mode, we're going to take this dinosaur composited against the different background and see how it looks.

Viewing a quick mask by itself
Video duration: 6m 40s 13h 7m Advanced

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Viewing a quick mask by itself provides you with in-depth training on Design. Taught by Deke McClelland as part of the Photoshop CS4 One-on-One: Mastery

Subjects:
Design Photography
Software:
Photoshop
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