Correcting barrel effect in pictures

Richy

Greetings, PA digital photography experts!

I have some pictures I took last weekend. The idea is, I stand in place, take lots of pictures of whatever is in front of me while rotating, then combine them into a larger panoramic picture. Combining them is easy, I use the Autostich software. Problem is, when I'm taking a picture of something close by, such as a building face, I get some very bad barrel distortion, as you can see here:



How can I correct that? I found some tutorial on using Photoshop for it, but my version is too old for some of the tools they mentioned, and the ones that I do have don't do the trick. Is there a software I can use (a free one preferably)?

finral

I use picasa to crop the black out of the pictures, but I'm pretty sure the cropping is only viewable through the picasa program.

soxbox

I can't give specific help, but:

http://www.google.com.au/search?q=correct+lens+distortiion+gimp

or if you're comfortable with command lines:

http://www.google.com.au/search?q=correct+lens+distortion+imagemagick (Specifically http://www.imagemagick.org/Usage/distorts/#barrel)

Mojo_Jojo

If you have the mental and physical fortitude to use not only GIMP but an open source plugin for it, then this can do just that. Although, it's not a correction you apply to your current image, it's one you perform during stitching.

Or, I found this little snippet for ye olde photoshop:

Before Photoshop CS2

Back in the dark days of Photoshop CS and before I usually used the "Spherize" command under FILTER > DISTORT > SPHERIZE. Increase your canvas size 50 - 100% first so you correct the whole image.

Although I image that is what you tried?

Richy

Yeah, the spherize thing is one I tried already. I had no luck with it.

EggyToast

One thing that will give you much more control over the final image is to take more pictures at the outside of the panorama -- like a bowtie. Or take two rows of panorama and then crop accordingly. This not only ensures you get the panorama you're looking for, it lets you make adjustments like for barrel distortion. Of course, the problem is that when you're shooting wide pictures from one place, you tend to get distortion of some sort at the edges.

Count Funkula

There is a sourceforge project called Hugin which sounds like it might do what you need.

http://hugin.sourceforge.net/

There are some tutorials on the site, one is about removing perspective effects:

http://hugin.sourceforge.net/tutorials/architectural/en.shtml

Richy

None of these do the trick They all end up distorting the image worse than before.

Jeix

I know Adobe Camera Raw and Lightroom both have options for lens correction that you can simply enter your lens information and it auto corrects it for you. I'm not sure how accurate it is though.

Also, it wont work unless you have a brand name lens. My top of the line Nikon lens is listed but my other Tamron lens is not.

I know you are looking for a free program but why not give lightroom a free trial?

Edilith

There is probably a much neater/precise way to do it, but you could try the "free transform/warp" modes in Photoshop. You didn't say what version you had, but I'm sure it would have this option.

Paste your photo on a new layer, and go to Edit > Free Transform (or press Ctrl + T). By holding Ctrl and clicking/dragging on one of the corner handles you can transform the angles of the photo. On the top right somewhere you should see this:



By selecting that first button you can warp the image until you think it looks right just by dragging each segment. A quick fool around made this:



Obviously you have some manipping to do once you crop since there's sky missing, but I hope that helps!

Richy

I have Photoshop 6.0 and Gimp 2.6. This Warp tool doesn't seem to be in either
This is precisely what I want! How else can I get this?

evilmrhenry

GIMP:
Filters->Distorts->Curve Bend?

Richy

I spent hours playing with that tool, and I can't get the image looking like what Edilith has.

Richy

Well, more work with the GIMP curve bend tool allowed me to make the pictures look more or less normal. But it's still done by hand - time-consuming for results that are not exactly straight. There's got to be a better way of doing this...

MushroomStick

Download the trial of photoshop and use the warp tool.