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GIMP Tutorial #13 - How to Remove Barrel Effect from Your Photos

GIMP is an extremely versatile free image-editing program that offers all the tools, filters and effects necessary to edit, retouch, and create astonishing images. Besides, GIMP's functionality can be expanded via plugins increasing the number of possibilities beyond expectations. In this tutorial I'm going to tell you how to remove the barreling in your digital photos.

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So, what is the barrel effect? Is a typical distortion from most digital cameras that make objects to look deformed, specially those with vertical straight lines like buildings, windows and doors. Let's get our noses to the grindstone and remove that barreling from our favorite photos.
The first step is to open the image you want to fix with GIMP, for that go to File → Open... and in the explorer-like dialog browse for it among your folders.

Once the image is opened select the Perspective tool from the Toolbox.

Click anywhere over the picture and you'll see that a grip box will appear on all four corners along with the Perspective dialog box.

Grab one of the superior grip points and stretch it till the vertical lines align with the border next to them like this.

And now the other side:

Once you are happy with the result go to the Perspective dialog and click on the Transform button.
In this dialogs you'll find the parameters to make fine adjustments if you need to.

As you will see next the image is rectangular again and the barrel effect is gone. Some small areas near the borders are lost but you gain in the realism and accuracy of the image.

Here you can see the work finished:

And a side by side comparison of before and after applying the Perspective tool.

Cool huh?
This is a subtle correction but in other kind of images like window or door photos you'll find that th difference is enormous.

Final Words

Correcting the barrel distortion in your favorite digital photos is, as you can see, really easy and simple if you do it with GIMP, a couple of steps and voilà! your photos look astonishing and realistic. Download GIMP right now by clicking on the “Download Now” link below, it's totally for free and you'll not even have to register anywhere to get your full version!!