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In this exercise we are going to begin the real world task of sharpening for source and specifically, we are going to be compensating for the anti-aliasing and interpolation that our function of the demosaicing process that I explained a few exercises back. We are also going to be adjusting for the softness that's a natural phenomenon under the photographic process, especially when we are converting the analog world into the digital realm of pixels and specifically, inside of this exercise, I am going to show you how to adjust for chromatic aberrations, which are misalignment of colors as a function of the light refracting through the lens element.
Now we are starting fresh here. I am looking at the Bridge and I have got the Bridge strained on this Festive ornaments.dng file inside of the 05_For_Source folder, which you will find inside the exercise files folder. I am going to go ahead and press Ctrl+R, or Command+R on the Mac in order to open that image inside of Camera RAW hosted by the Bridge. Now I could just go ahead and press Ctrl+Alt+0 or Command+ Option+0, which would zoom in on the center of the image, which happens to be me reflected on this silver ball. But that's not a very representative detail of this image.
I want something that shows off the best and the worst of the image. Now the focus happens to be locked more or less on this red ball down here in the lower left corner and bear in mind that I was working with an 18/ 135 millimeter lengths and I have got it zoomed all the way. So the focal length is a 135 millimeters. So this is quite the telephoto shot and I let auto-focus be in charge and the auto-focus happen to lock on best to this red ball down here at the bottom portion of the image and if I was to scroll up here you would see that this gold ornament that is poking out on us.
The mid-area of this image, the sort of mid-ring right there is in sharp focus. The point is in front, it's forward of the focal plane and the rest of the ornament is a little bit in back of the plane. But the portion in the image that I think is most representative, I will go ahead and zoom out here and scroll down by spacebar-dragging, the portion that I think is most representative is this gold ball right here with the texture and the reflections and so on. It's basically the best. As I say the best and the worst of all possible worlds where this image is concerned.
So I am going to go ahead and click a couple of times with my Zoom tool to zoom in and I will zoom in until I see that my zoom level down here in the lower left corner is 100%, which of course allows me to preview the sharpening settings. Now I will go over to this Detail tab right there or I could press Ctrl+Alt+3 or Command option 3 on the Mac and I am going to max out my Amount value. I am going to set it to its maximum which happens to be a 150%, which is lower than what you get inside Unsharp Mask and Smart Sharpen. They both allow you to go as high as 500%, bang in is the Amount value is much stronger here inside Camera RAW than it is inside Unsharp Mask or Smart Sharpen.
So 150% is more than a 150% inside of those dialog boxes. I am not going to tell you there is like a 150% equals 350% in the others because that is not actually true. It's a different algorithm. But it is a very strong amount. Now I am going to go ahead and max it out. The reason being, I want to be able to gauge what to set the other settings to. So setting the Amount value to it's maximum as a temporary measure, because obviously this is going too far, it's a great way to gauge the other settings. Now I am going to go ahead and zoom in on this highlight right there and I am going to zoom as far as I can, which is 400%.
Now as my magnifying glass gets empty at this point showing that I cannot go any farther. Known as these weird colors that are surrounding the highlight, they are actually, surrounding all of the highlights on this ball. They are most noticeable on this ball incidentally and we are seeing that we have a green edge along the right side of the highlight and a red, crimson, magenta edge over here on the left side of the highlight. This is a function of chromatic aberration. Now chromatic aberration is a function of the light refracting differently around the edges of the lens element than it does at the center of the lens element.
So all camera lens elements are calibrated so that the light refracts its absolute best right through the center of the lens element, but around the edges depending on your focal length, you are going to end up getting different sorts of chromatic aberrations to different degrees. So that's again another reason to crank up that amount value so you can see those chromatic aberrations. They contribute to dim focus inside of an image because we have a misregistration of detail and we can clear that up by going over here to the lens corrections functions.
So I'll go ahead and click on that tab or you can press Ctrl+Alt+6 or Command+Option+6 on the Mac. Here are two sliders that are available to us to fix the chromatic aberrations. We can either adjust the degree of Red/Cyan Fringe or we can adjust the degree of Blue/Yellow Fringe. Now in our case, its really neither of those. It is more like a red/green fringe, which makes me think we have got some cyan and yellow mixing up on one side and probably, some red and blue mixing up on the other side. Now what you do, notice that both values are zeroed out and zero means that the slider triangles are set right in the center.
No correction is being applied. In order to apply a correction you can drag this slider either way. I am going to take it over just for the sake of figuring out what I should be doing. I am going to take it over to the left and by the way, I should say that you do have to be zoomed in to a 100% or larger to see the effects of chromatic aberration. If I were to take this out, I am just going to zoom out until we get to 66.7% notice that any signs of what we are doing have disappeared from view. Even though there is no warning, we do have to be zoomed in to a 100% or better in order to see chromatic aberration.
Alright, so I am going to press Ctrl+plus a few times in a row, or Command+plus on the Mac until I am zoomed into a 400% once again. You can see that I am going in the wrong direction. Basically, I am making the problem much worse by dragging the slider triangle to the left. What does that mean? I need to drag it the right. Is basically what it comes down to and notice how it fixes the problem on the fly. So it is really great. You can really keep tabs on what is going on on screen here. I will take this value to something like 25%, lets say, which does seem to get rid of the colors we had before, that red-green scheme that we have before.
Now we have something of a violet-yellow scheme going on. So lets try adjusting the other slider and if we take it positive we make the problem worse as you can see. So lets take it negative instead. Notice those details as we move around. Basically, what Camera RAW is doing, it's a wonderful thing. Camera RAW is effectively rotating the color channels independently of each other and its doing it as it figures out what those colors should be. So its both manufacturing the channels and rotating them on the fly, very sophisticated technology at work here.
Now those values +25 and -10, just do wonders in order to get rid of this problem. Lets go ahead and turn off the Preview checkbox. So this is before and this is after. So obviously, we have done a great deal of good. There is still a little bit, if you look very closely there you can see that we still have a little bit of violet over here on the left hand edge and a little bit of weird saturation at any rate going on on the right hand edge of this highlight and I will show you how to fix that, very subtle, but it is fixable.
Now I will show you how to do that in the next exercise.
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