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Alright, so great now I have got you thinking, I am going to slap you the next time I see you and I am not, I am not that kind of person at all. It reminds me though of Golden Eye, did you ever play that game, the game not the movie, the 007 game. And if you ran out of weapons, you could run around and slap each other and you could slap each other so much that what if you died it was that much slapping. They just fell down and died, which I thought was really cool. Now you couldn't make your opponents say Gaussian. If you could have done that I would have won that game every single time, good times. Alright so here we are inside the rectangles.psd image, we are looking at the top pair of layers.
The Gaussian Blur image on the left and the Box blur image on the right. I am going to press the end key to go down to the lower pair of rectangles. Those layers, I have so far are not modified, I am going to though in this exercise, so I will click on the Layers palette and click on 3BL in order to select this bottom left layer right here. And the idea this time is we are going to check out, we are going to move away from the Blur submenu onto the Filters menu for just a moment. We are going to move away from the Blur submenu onto the Filters menu for just a moment here and we are going to check out the Noise submenu instead and we are going to take a look at a couple of key averaging functions, features that average pixels instead of blurring them.
Go up to the Filter menu and choose Noise. The idea is all of these commands are supposed to either add noise or in the case of the other four commands remove noise from an image. A noise is random straight non-information bearing pixels basically, so just random pixel variations. Add Noise allows you to add random pixel variations if you want to and you can check that filter out on your own if you want to. Despeckle, just goes ahead and removes individual pixels of Noise, completely isolated individual pixels of Noise.
I will go ahead and show you what it looks like just for larfs. This is it, alright that's it. That little tinny thing that it did, that's what it does. It is these days I would go so far as to say completely outmoded, a very ancient command that they should drop from the software in my opinion. It is just taking up space. Anyway, I will go back up to the Filter menu, and I am going to choose Noise once again. We have got Dust and Scratches and Median, I will come back to those too.
Those are the two that we are going to look at inside of this exercise actually and then reduce Noise a big function, big useful function actually and we are going to use it later in this chapter. We will use it in order to remove Noise from a digital image, but we will take a look at it in a creative context as opposed to in an analytical context here. Let's start off with the Median command, which you can see is another key filter at least insofar as I am concerned because I have given it a keyboard shortcut in my D keys, which is Shift+F8 if you have loaded them.
Alright, go ahead and choose the Median command and I am going to go ahead and center this of course and then raise this radius value once again to 20 pixels, because 20 pixels is what we have been applying so far both inside Gaussian Blur and inside Box Blur. And notice this time instead of blurring the pixels, Photoshop goes through and averages them and it's scrubbing through the image actually in these big 20 pixel diameter brushstrokes.
So you can think of it as working that way anyway and that means that it completely gets rid of the low level noise, this low level texture at least at this high radius setting it does. And then when it comes to a big edge, it goes ahead and rounds off the corners, notice that, so it rounds off the corners here and it rounds off the corners here and those are some pretty jagged transitions. If I Ctrl+Click inside the image or Command-Click in Mac, you can see that we have a jagged transition with a little bit of extra softness on the outside and just a tiny bit on the inside as well.
Alright, I am going to Alt+Click or Option-Click in the Mac in order to zoom back out and I am going to apply that filter, that's all I am going to do, so we just have this one radius value inside Median and that's it, go ahead and click OK to apply it. Now let's go to this next door layer by going to the Layers palette clicking on 4BR, 4 Bottom Right. Press F7 again to hide that palette from view at least on my screen because I don't have that much room to work.
Then I am going up to the Filter menu. I am choosing Noise and I am choosing Dust and Scratches. Now the important thing to know about Dust and Scratches is it's based on the Median filter, the Median filter is really like its father. Dust and Scratches just goes ahead and adds one more option a Threshold function as we will see, that's the only difference between it and Median. It has an extremely misleading name. Dust and Scratches has nothing to do with this filter. It removes neither dust nor scratches. That's how far off this naming is. In fact, I would go so far as to say it leaves behind only dust and scratches because it averages the big stuff and leaves the little stuff like these little tiny textures behind. I will show you what I am talking about. Go ahead and choose Dust and Scratches and notice that we have got a radius value right here and a threshold value.
The radius value I will set it to 20, so you can see the radius value behaves just like the one inside the Median dialog box. When I have the Threshold set to 0, this command Dust and Scratches behaves identically to Median, so these two images right here are pixel for pixel identical to each other. Alright, I will bring this backup on screen. Now as we raise the Threshold value, remember the threshold value from the Unsharp Mask dialog box, it rules out very small pixel transitions. So if in this case if two neighboring pixels are less than 10 luminosity levels different from each other they don't get averaged. Only neighboring pixels that are at least 10 luminance levels different from each other are going to get blurred, alright so it's leaving the little stuff behind and it blurring the big stuff, sounds like Dust and Scratches alright, no it doesn't. Anyway I am going to go ahead and raise this to let's say about 15, so you can see that I have got some nice texturing left behind but I have rounded off the corners and I have not, as it turns out rounded off the big corners because they just aren't different enough to qualify. So I will click OK in order to accept that modification, so we have got Median here on the left, Dust and Scratches on the right, just in case you are curious.
This is how they compare the blurring, so this is blurring Gaussian Blur versus Box Blur and this is averaging Median versus Dust and Scratches here inside Photoshop.
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