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Photoshop CS4-Anti Alias

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transcript of video presentation - using Anti Alias

Using Anti Alias


Welcome back, ladies and gentlemen, to another lesson on creating selections in Adobe Photoshop CS4, in this case. We use this in creating Vinyl Banners And today we are going to talk about anti-aliasing. And what anti-aliasing is, is it’s Photoshop’s way of partially selecting pixels to create the illusion of a smooth edge. And we are going to demonstrate that here with this image, which is from the lesson on the Pen Tool, if you remember.

Why don’t you go ahead, when you have a chance, and download ANTIALIAS1.PSD and that will allow you to follow along. But first what I would like to do is to start a new document, so let’s go to the File menu, click on New, and I am just going to make it 10 X 10, with a resolution of 72. I am not going to name it, I am just going to say OK. Now I want you to make sure your default colors are selected here, so if they are not, hit D on the keyboard.

That will set the foreground color to black, and the background color to white.

And then I want you to fill the entire image right now, the background layer, with black. And to do that hit ALT + BACKSPACE on your keyboard. This is going to help me demonstrate anti-aliasing.
Now there are only certain tools that allow you to use anti-aliasing, and they are the elliptical Marquee tool, all of the Lasso tools, and finally the Magic Wand tools.

And you can see the anti-alias checkbox right here. And we are going to demonstrate it like I said.

Let’s get the elliptical marquee tool, folks, and go ahead and draw a selection about like that. Now I want to fill this selection with white. And to do that, I am going to hold down the CTRL key and hit BACKSPACE on the keyboard. Now what I want to do is create another selection.

And this time I am going to anti-alias the selection. So I am going to click on Anti-Alias.

And this checkbox must be checked BEFORE you make your selection, okay? So this one was NOT anti-aliased. The next one I draw WILL be anti-aliased.

Next I want you make sure that this little icon is highlighted, so we are going to add to the selection, see the little plus mark there? And we are going to go ahead and draw, the same thing again, and we are going to fill it with white again, so hit CTRL + BACKSPACE.

And here we have two selections: one aliased, one anti-aliased. Let’s save this selection, just in case we want to look at it again, and to do that you go to the Select menu, and click on Save Selection.

And we are going to name it DEMO. Click on OK. Now let’s deselect by hitting CTRL + D on the keyboard. And you can see right away, the difference. You will see it easier if I go to 100% so to do that, hit CTRL + 1 on your keyboard and that will give you 100% view size here.

And now you can easily see the difference: this nice smooth edge, created with the anti-alias checkbox checked, and this NON, anti-aliased selection up here. Big difference, folks.

And what’s happening here, let me zoom in, and to do that, I want you to hold down the CTRL key and simultaneously hold down the SPACEBAR; that’s going to give you the Zoom tool. And then I want you to marquee right in this area right here, and then release. That’s going to zoom us in; you can take a look at both selections right here.

On the bottom we have got the anti-aliased selection; on the top we have the aliased selection. You can see the stair-stepping that’s occurring here on this ellipse that we drew. So what does that mean?

A pixel here is either fully selected or fully NOT selected. Whereas down here, Photoshop is partially selecting the pixels, okay, to give you that smooth edge. And you can see what’s happening right here: it’s partially selecting these pixels.

Let me get the Eyedropper Tool and I will show you exactly how it’s working. I have got the grayscale ramp up here. If you don’t have it, just go ahead and select it right here, grayscale slider. I am going to click in the white area here.

You can see now I have 0% black, okay, so that represents 100% selection.

Out here, if I click, I have 100% black. Okay, that represents 100% NOT selected. You can see these pixels, right? They begin with 0, and they go up the grayscale ramp, all the way, partially selected, this represents transparency folks. All the way up until they are 100% selected right there. Hit CTRL + 1 on your keyboard to go to 100% view size. And there you have it folks. That’s how anti-alias works.

What’s the practical application? Let me go back to this document right here, ANTI-ALIAS1.PSD and we are going to demonstrate it.

Now you might remember this Toyota Prius here, from the lesson on the Pen Tool. What I did back then, if you remember, is I saved that path that I drew with the Pen Tool. And here it is right here. Go ahead and click on it, and you will see that vector-based path now. Okay?

We are going to turn that into a selection. We are going to turn that into two selections, actually. One will be aliased, one will be anti-aliased, and I will show you the difference, so go to this fly-out menu right here, and choose Make Selection, and the first one we are going to leave aliased, so do NOT check this check-box here. Click on OK. And as you can see, it selected not the Prius, but everything BUT the Prius.

To change that, let’s go ahead and hit CTRL + SHIFT + I on your keyboard for Invert. That’s going to invert the selection. Now we have just the Toyota Prius selected.

Let’s go to the layers palette. Now what I want to do is jump that selection to its own layer. So hit CTRL + J, and we are going to call this ALIASED. Alright…

Now we are going to make another one. Okay. Select the background layer again, let’s go to the paths palette, click on that, let’s make another selection, and this one we are going to Anti-Alias. Say OK. Once again, same drill. IT selected everything but the Prius.

Hit CTRL + SHIFT +I to invert that selection. Let’s go to the layers palette, and let’s jump this to its own layer by hitting CTRL + J, and this one we will call ANTI-ALIASED. Alright. Now we will take a look at the difference here.

To make it easy, I am going to create a black background layer, folks. And to do that, we are going to create a new layer, and to create a new layer under the layer that you have selected, hold down the CTRL key on the keyboard and click right here. Now we have a new layer, and we are going to fill that with black. And to do that, with black as our foreground color, hold down the ALT key, hit the BACKSPACE key, and now we have the Toyota Prius on a black background.

Let’s take a look at the aliased selection first and you can see the jagged edges already. Let’s go into 100% view size by hitting CTRL + 1 on the keyboard. And there is 100% view size.

And on this black background, it’s very easy to see the jagged edge created by not using the anti-alias feature in Photoshop. And it’s all around the car here.

It’s very easy to see. Let’s turn that off and turn on the anti-aliased and you can see the nice, smooth edge we get.

Okay? Much, much better. There is almost no time that I can think of, when you would NOT want to use anti-aliasing. It just looks so much better. And there are even better ways to get a nice, smooth edge. And that is in the Refine Edge dialog box. And we are going to talk about that in the very next lesson.




end of video transcript
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