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2.1 Lens and Perspective Corrections

In this lesson we’ll learn about the types of distortion (vertical, horizontal, spherical) and their causes, and then make the necessary corrections to our image within DxO OpticsPro.

2.1 Lens and Perspective Corrections

Welcome to chapter two. In this chapter we'll use DxO OpticsPro to neutralize our image. In this lesson we'll discuss the types of lens distortion and their causes. As I mentioned previously, when the DxO module corresponding to your lens and camera combination were installed, the program corrected a number of issues for you. Let's discuss those corrections pertaining to lens and perspective corrections. One of the things that DxO did was correct the darkening of the corners of the image, otherwise known as vignetting. Let's head over to the LIGHT palette located on the right-hand side. And we'll go ahead and expand that palette, and then we'll head down to Vignetting. You can tell which settings have been activated by the small blue button on the left-hand side of each of the sections' names. You can expand the Vignetting tools by selecting the left arrow. And to close it, you select that same arrow. We'll leave ours open as we look at the options. Within the Correction dropdown menu, it tells you that the corrections made were Automatic with the DxO Optics module. And beneath that you do have a Manual option where you can manually adjust the intensity of your vignetting corrections. And as you see here, as I adjust that slider, it fills in the color information around the edges of the image. We'll actually leave this on Automatic because the adjustments made were specially formatted with the camera and lens that were used to shoot the image. If you click on the question mark, in the upper right-hand corner, it will actually give you a description of what the tool does, which is very handy. And select the question mark again, and it collapses that information. And we'll go ahead and collapse the Vignetting tools within the LIGHT palette. Now, DxO also correct lens distortion with the image. We'll go ahead and collapse the LIGHT palette by selecting on its name, and it collapses that palette. Now, DxO will also corrected lens distortion with this image. Lens distortion is caused by the optical design of your lens, or by the angle at which you take your photo. The warping of your image can be slight, or it can be quite noticeable. And there are various kinds of lens distortion. You have vertical lens distortion, where vertical lines in the image are not straight, due to your camera pointing up or down. You have horizontal lens distortion, which occurs when your camera's pointed left or right, and causes horizontal lines that should be parallel to the ground to appear skewed. And then you have spherical lens distortion where an image is not sharply focused in its center and edges due to a spherical lens refracting light that enters near the edge more than the center. To see the distortion adjustments made to this image, let's head over to the GEOMETRY palette and take a look at the Distortion tools at the very bottom. If it's not open, you can select the arrow on the left-hand side to open up those options for you. And as you can see, the type of correction made was again based on the DxO module. And if you select the drop down menu, you are able to make manual adjustments to your image. In this case we will leave it on a specific DxO module that we installed. And you have your slider which adjusts the intensity of the distortion correction that you're making. And so as we slide that to the left, it updates the preview in the center image. We'll leave it on the automatic correction. If you've moved your slider, and you'd like to go back a step, you can head up to Edit > Undo Distortion. Or you can select Cmd + Z on your keyboard to restore that value. You can also reset the values of the sliders by selecting the small wand icon directly to the right of the slider. And we'll go ahead and close the GEOMETRY palette. And finally, in a reference to lens corrections, DxO corrects the chromatic aberrations in the image, also known as color fringing. And it occurs along the edges of certain objects in your image. Let's head over to the DETAILS palette, and let's head down to Chromatic Aberration. And using the arrow on the left-hand side, we will expand those adjustments, so that we can see them. You'll notice that we have an eye crossed out next to the name Chromatic Aberration. This is letting you know that you need to zoom into your image more than 75% in order to see the corrections that have been made. And currently, we're sitting at 8%, which is why it's giving you this warning with the crossed out eye. So let's head up to the menu above our image, and let's zoom in to 100%, a one to one ratio. And when we do that, you will notice that the eye icon disappears. Now the corrections that have already been made are based on our specific gear. Now, specifically, this tool is targeting artifacts that appear in areas of high contrast. You have your Intensity slider, which is adjusting the degree of correction that you are applying to the image. And then you have the Size slider, which allows you to change the width of the artifacts that you are targeting. And beneath that, you have your Purple Fringing check box, which allows you to target the purple fringing that occurs in high contrast areas of your image. And selecting that box doesn't make too much of a difference because it's not a big issue with our image. We'll leave these corrections as they are, and we'll close the Chromatic Aberration tools and then close up the Detail palette for now, and let's zoom our image to fit in the window. If you head up to the Compare button and hold it down, you will see what our image looked like before those perspective adjustments were made. And then when you release it, it shows you what it looks like now. That brings us to the end of this lesson. We chatted about the automatic corrections that DxO made to our image. We also explored the lens correction tools within the program. In our next lesson, we'll explore the corrective adjustments made to the exposure and contrast of our image. And we'll also further customize these settings.

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