Monday, March 1, 2004

Adjusting background distortion


By David Gewirtz

Last week, we awarded ImageAlign Pro our Plug-in of the Month award. That's a tool that'll help you adjust your images to correct lens distortion. But at $199, it's not for everyone. This week, I'm going to show you a few simple tricks to fix up your own images using some simple transforms in Photoshop (this will also work in Elements).

Figure A shows a picture of Arte Fontane, IBM's Senior Marketing Manager. I took this picture when we were down at Lotusphere last month, covering some IBM announcements.


Arte's looking spiffy, but the picture needs some work. (click for larger image)

Because of the flash blowback (you can see it to the left of Arte's face), we didn't run this picture in DominoPower. But it's ideal for our purposes because of the striped wallpaper in the background. As you can see, the stripes aren't vertical in the picture. I shot the image at about 30mm, and the lens distorted the background.

This is pretty easy to fix. As you look at the above image, you'll notice a selection rectangle and some handles. That's because I selected the entire image, and then chose Transform->Distort from the Edit menu. By moving the top right handle in slightly to the left, the stripes were returned to vertical, as shown in Figure B.


Now the walls are more straight up and down. (click for larger image)

One minor side effect of moving the wallpaper was that the picture frame was no longer horizontal. Honestly, I don't think it was fully level when the image was taken, but we can help things along, can't we? Once more, I selected the entire image and used Transform->Distort, this time to slightly drop the top, left handle, and to move the top, right handle a slight bit further to the right.

You can see this in Figure C.


Let's make that picture frame level. (click for larger image)

One of the reasons I tend to show more of the canvas outside the image is to give me space to move the distortion outside the image. Sometimes you'll need to stretch beyond the picture's boundaries, and this will give you some workspace.

Of course, now that we've done our adjustments, some of the background shows through. A simple crop cleans it all up, and you can see the final image in Figure D.


Everything's on the straight and narrow now. (click for larger image)

Sometimes, plug-ins are the only way to get something done. But there's so much built into modern image editing tools, pictures can often be radically improved with only a few menu selections, using built-in capabilities.