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Difficulty using lens distortion filter

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Difficulty using lens distortion filter Leonard Evens 18 Apr 22:20
  Difficulty using lens distortion filter Alexandre Prokoudine 19 Apr 00:24
   Difficulty using lens distortion filter Leonard Evens 19 Apr 17:08
    Difficulty using lens distortion filter Alexandre Prokoudine 19 Apr 17:23
   Difficulty using lens distortion filter Leonard Evens 19 Apr 17:12
Leonard Evens
2011-04-18 22:20:46 UTC (almost 14 years ago)

Difficulty using lens distortion filter

I keep posing questions about this but so far I haven't gotten a useful response.

There used to be a pnorama tools plugin which allowed one to enter corrections for specific lenses which I was able to find on the web. That worked very well. But I haven't been able to find that plugin for recent versions of gimp.

There is a lens distortion filter, but you have to use it by trial and error. I haven't found any specific recommendations to use for specific lenses anywhere. And in some cases, nothing I try works. I attach an example below. It was taken, I believe with a Nikon 18-55 mm lens at 18 mm. You will notice that there is no distortion at the sides but significant barrel distortion as you move in from the sides. No combination of major and edge correction that I've tried does any good.

Can anyone suggest how I should go about it.

P.S. I understand that ahd I shot raw with my Nikon, I might have been able to do the correction more easily using ufraw. Also, it might be possible using hugin to correct the distortion. But I would like to be able to do it with gimp if I can.

Alexandre Prokoudine
2011-04-19 00:24:04 UTC (almost 14 years ago)

Difficulty using lens distortion filter

On 4/19/11, Leonard Evens wrote:

I keep posing questions about this but so far I haven't gotten a useful response.

You think reference to LensFun is not useful?

P.S. I understand that ahd I shot raw with my Nikon, I might have been able to do the correction more easily using ufraw. Also, it might be possible using hugin to correct the distortion. But I would like to be able to do it with gimp if I can.

http://lensfun.sebastiankraft.net/

Alexandre Prokoudine http://libregraphicsworld.org

Leonard Evens
2011-04-19 17:08:16 UTC (almost 14 years ago)

Difficulty using lens distortion filter

On Tue, 2011-04-19 at 04:24 +0400, Alexandre Prokoudine wrote:

On 4/19/11, Leonard Evens wrote:

I keep posing questions about this but so far I haven't gotten a useful response.

You think reference to LensFun is not useful?

I don't remember being told about this.

But it turns out that I had a lensfun library installed. I didn't have the actual plug-in. So I compiled it and put the plug-in in my personal plug-in directory. It seems to work quite well. It examines the exif entry to determine the lens and lens setting.

What I don't understand is how I managed to have the library installed without the plugin.

P.S. I understand that ahd I shot raw with my Nikon, I might have been able to do the correction more easily using ufraw. Also, it might be possible using hugin to correct the distortion. But I would like to be able to do it with gimp if I can.

http://lensfun.sebastiankraft.net/

Alexandre Prokoudine http://libregraphicsworld.org
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Leonard Evens
2011-04-19 17:12:46 UTC (almost 14 years ago)

Difficulty using lens distortion filter

On Tue, 2011-04-19 at 04:24 +0400, Alexandre Prokoudine wrote:

On 4/19/11, Leonard Evens wrote:

I keep posing questions about this but so far I haven't gotten a useful response.

You think reference to LensFun is not useful?

I don't remember being told about this.

But it turns out that I had a lensfun library installed. I didn't have the actual plug-in. So I compiled it and put the plug-in in my personal plug-in directory. It seems to work quite well. It examines the exif entry to determine the lens and lens setting.

What I don't understand is how I managed to have the library installed without the plugin.

P.S. I understand that ahd I shot raw with my Nikon, I might have been able to do the correction more easily using ufraw. Also, it might be possible using hugin to correct the distortion. But I would like to be able to do it with gimp if I can.

http://lensfun.sebastiankraft.net/

Alexandre Prokoudine http://libregraphicsworld.org
_______________________________________________ Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user

Added later. One t hing was clarified but adds another mystery. I was misled by the black columns in the image. After the distortion is eliminated the sides of the columns are vertical, a s the should be, but the highlighted lines one the columns are still curved. That was what was confusing me.

The still unresolved question is where those highlighted lines on the columns came from.

Alexandre Prokoudine
2011-04-19 17:23:48 UTC (almost 14 years ago)

Difficulty using lens distortion filter

On Tue, Apr 19, 2011 at 9:08 PM, Leonard Evens wrote:

What I don't understand is how I managed to have the library installed without the plugin.

UFRaw depends on it.

Alexandre Prokoudine http://libregraphicsworld.org