Lightroom Tutorial: Correcting distortion of correction lenses

Have you ever filmed some of the buildings in the city that look like they're leaning backwards? Or is it possible that the top of the building looks wider than the bottom? These types of lens distortions are actually quite common, but in previous versions of Lightroom, to fix these problems, you had to go to Photoshop to manually adjust the images. Fortunately, Lightroom3 not only fixes the lens distortion problem, but it can often automatically complete the correction. With its help, presumably you go out to shoot landscapes and buildings will never worry about it.

Please open an image with a distorted lens (by the way, this feature can also automatically correct edges and chromatic aberration issues, which we'll talk about later, but only focus on geometric distortions). In this case, the photo I used was taken with a 10.5 mm fisheye lens, although a Third-party plugin could be purchased to correct the eye distortion due to the lens, but because it is now built into the Lightroom, we do not have to use them. See the image shown in the picture, and the roundness of the pitch (and the text "bulls").

Scroll down to the lens correction panel. There are two options at the top of the panel: profile (it automatically corrects the problem) and manual (we correct the problem ourselves). Let's start with an automated approach, so click the profile and select the Enable profile correction check box. After you complete the operation, the image is corrected (see the image correction effect in the illustration). To create such a small miracle is because it reads the EXIF data that was embedded in the photograph when it was taken, and therefore knows the manufacturer and model of the lens used in the image (Adobe offers many camera and lens profiles, including popular Nikon, Canon, Tamron, and sigma lenses.) Below the lens configuration section, you will see the lens manufacturer and model, as well as the lens profile type applied. It's really amazing that all the processing is done instantaneously.

You can fine-tune automatic correction by using the quantity slider at the bottom of the panel. For example, if you feel that it eliminates too much of the distortion, you can drag the warp slider to the left to reduce the number of linear corrections applied to the photo (note that the foreground area is a bit back-bent, and the distortion around the left and right is less). So you can see more of the background). Using this simple slider to adjust the result of an automatic correction is fairly easy (the frequency of using it may be beyond your imagination).

Now, we look at another picture. In this case, the image looks a little inflated (see the Middle Bridge, it looks a little curved), and the buildings on both sides seem to tilt backwards. When the profile correction checkbox is turned on, no changes are seen, and "None" is displayed where the lens manufacturer and model are usually listed. This is because for some reason the image is not embedded with any EXIF data (perhaps the image is copied and pasted to a blank document; perhaps when importing to Lightroom, the least embedded metadata check box is selected, so that EXIF data is stripped; maybe it's just because Lightroom The database does not support this shot file). Whatever the reason, it is necessary to tell the brand of the lens that it is using, and what kind of shot it takes, and then it can apply automatic correction.

In the Lens profile section of the panel, select the brand from the manufacturer's Drop-down list (in this case, Nikon, so I choose Nikon). Then select the type of lens to use from the Model drop down list (this photo is actually taken with the camera's own lens (i.e. "18-200mm"), which is the f3.5-5.6g IF ED.

Once you have selected the configuration file closest to the actual lens from the model Drop-down list, it will try to automatically correct it. The correction is good, but it's not perfect. I tried to drag the warp slider, but I still couldn't fully meet the requirements. My process is this: click Manually (at the top of the panel) to display the Transform slider group, and I drag the Twist slider to +23 to eliminate the bending and swelling in the central bridge, but the building is still leaning backwards. To correct this problem, I drag the vertical slider to +25 to correct the tilt problem and straighten the building. By the way, when you move the cursor over the transform slider, you'll see that the grid is superimposed in the picture, which helps us align all the elements (this is especially useful when we're correcting the arched horizon, or when we rotate the picture using the Rotation slider).

The observation chart finds that the area at the top of the image is filled with gray. This is because when you use a vertical or horizontal transformation slider, the image plane is found to tilt, leaving a gray gap in some areas (depending on which slider is moved). In this case, because we drag the vertical slider to the right, causing the gray gap to be at the top of the image, you must crop the photo. Fortunately, this process can now be done automatically. If you click the Cropping Overlay tool (near the toolbox at the top of the right panel area, just below the histogram panel), the cropping overlay option appears below it. Select the lock to distort check box, which automatically adjusts the size of the cropping box to crop out all the gray junk (which is a technical term that Adobe will never endorse).

Now all you need to do is press RETURN (Pc:enter) to lock the crop and the image will be corrected. I included the original image in the diagram so you can see the curved bridge and the backward leaning building. Note: Because the profile does not match the specific lenses used to take this photo, I also try other Nikon lens profiles (selected from the Model Drop-down list) to see if I can find a better processing profile in the file. Although this photo was not taken with a fisheye lens, I tried the fisheye. When the profile is configured, it works fairly well (but still needs to use the Vertical transform slider in manual mode to correct the building). You might as well try it and feel the effect.

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Category:

• PS Image Processing