Automatic lens correction and Defringe

- [Instructor] In this movie I'll introduce you to automatic lens correction inside Camera. And we'll also take a look at how you can get rid of chromatic aberrations and color fringing. So here I am in Adobe Bridge, which you can get to by choosing browse in Bridge from the file menu inside Photoshop. And we're looking at the contents of the 27 ADV camera folder. And bear in mind if you're working along with me, you'll see more files than this because I'm adding photos as I go. Now notice this image of my old Jeep here.

It's not especially glamorous but if I press the space bar to enter the full screen mode, you can see how it offers some straight lines along the contours of the car here that bow outward. And that tells us that we have some barrel distortion that was caused by the wide-angle lens that I used. Alright I'm going to escape out so that you can see that I've converted this raw photograph to Adobe's open standard DNG format which means that I can save any changes I make directly to the file. And you can likewise convert your raw images to DNG using Adobe's free DNG converter which is available at their site.

Alright now I'll go ahead and right-click in the image and choose open in Camera. Or you have that keyboard shortcut of control r on the PC or command r on the Mac. Now in my case Camera is coming up in a floating window. If you'd prefer to have it take up the entire screen then either click on the full screen button or just go ahead and press the f key. Now notice down here underneath the image preview next to the file name, we're seeing the make and model of the camera, which in my case is a Canon 5D Mark III, meaning that Camera is aware of how I captured this image.

And that's a function of the Exif data, which the camera captures and saves along with the metadata contained inside the image file. Alright now I'm going to click on the six icon in lens corrections and notice here in the most recent version of Camera we have two tabs: profile and manual. For now we're interested in the profile tab. Now I first introduced you to these options back in chapter 12 of the fundamentals course. But they're so very important that you should use them with every image you edit.

So I'm going to start by turning on enable profile corrections. And as you can see that's going to go ahead and apply some corrections to the image automatically. So notice before we've got that barrel distortion and we also have some dark vignetting in the corners. That's caused by the shading of the lens element. Whereas as soon as I turn on this checkbox, notice that the barrel distortion goes away and we start having straighter lines along the contours of the car. And Camera brightens up the corners as well.

Now if you feel like the pin cushioning in this particular case is going too far then you can dial down the distortion value to bring back that barrel distortion. Or you can make it go away even more by cranking the distortion value up to its maximum of 200. The same goes for vignetting. If you want to bring back some of those dark corners, you can reduce the vignetting value, or if you want to brighten up the corners even more go ahead and crank that value up to in my case its maximum of 200.

Alright now I'm going to go ahead and give this guy a scrubby zoom here by dragging in the upper-right corner of the image. So that we can see this green and purple border, which is known as the chromatic aberration. And that's a function of the different waves of light entering the lens at different angles. And the effect is most pronounced in the corners of the image. Whereas at the center of the image, all the wavelengths should be pretty well aligned. Now one way to get rid of that effect is to turn on the remove chromatic aberration checkbox, which is based once again, on the make and model of your camera, as well as the camera lens, which in my case is a 17 to 40mm wide angle.

And I'll just go ahead and zoom in a little more here so that you can see that that will leave a little bit of residual edge detail behind. So this is how things looked before with these very green edges right there. And this is how things look now. Quite better though not necessarily perfect. It's just something to bear in mind. Now if you're still seeing a little bit of residual purple or green then you want to click on the manual tab and again this assumes that you're working in the most recent version of Camera.

If you're working in an older version you'll find these defringe values as well as the chromatic aberration checkbox located in a color tab. Now to get rid of this little bit of purple edge there I'll crank this purple mount value up and you can see that the color goes away, leaves behind a little bit of gray but at least we're desaturating that edge. Now I generally recommend that you take this value up as low as you can go. So I generally start with zero and then press the up arrow key until I see the effect go away.

Which in my case happens at about three. Now you also have control over the definition of purple, because after all your edges might be a little bluer or a little warmer. And so notice if I go ahead and open this slider up to include all of purple's neighboring hues then I may start to do a real number on this image. Notice these little patches of gray that are showing up on the side of this rock wall. These artifacts become even more pronounced if I crank up the purple amount value. Notice now we're getting these sort of beige areas as well as this grayish square.

So you have to be very careful as you work here. Any defringing you apply can look good in one detail but have very unfortunate effects elsewhere. Anyway I'm going to go ahead and take these values down. And by the way the default range is 30 through 70. And I'm going to tighten things up just a little bit like so. And now to take in the entire image I'll press control zero here on the PC or command zero on the Mac. And that is how you apply automatic lens correction as well as account for chromatic aberrations and color fringing here inside Camera.