Adjust for Wide Angle lens distortion

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Ken Ellis wrote:
> So anyway.... There's alot of tools in potoshop. I'm no expert..but i
> suspect you might be able to create an action that would give
> you a vanilla correction.
>
> Fundamentally, it's a loaded question, because imo you are paying for
> that "distortion" by going wide angle - it's what it does. The best
> correction might be using a longer lens - or factor, and making a pan.
[]
> Ken

Ken, some of the confusion here is because there are typically two image
"defects" to correct:

A - lens faults, typically barrel distortion in wide-angle lenses - a
failure to photograph a brick wall without some curved lines

B - perspective "distortion" (I don't like that word), because of the
viewpoint being used (e.g. tipping the camera upwards to get all of a
building in).

It seems that whilst both Paint Shop Pro and Photoshop have native tools
for (B), only Paint Shop Pro can do (A) natively, although they both have
plug-ins which can do the job.

I hope I've read that correctly.

Cheers,
David

 

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Bart van der Wolf wrote:

>
> "Rudy Benner" <bennerREMOVE@personainternet.com> wrote in message

>>> Image -> Transform -> Perspective. (Not a plugin). Easy to use.
>>>
>> .
>>
>> There is no such function on my copy of Photoshop 8 CS.
>
>
> Alan just made a small typo.
> First "Select-> All, and then EDIT -> Transform -> Perspective.

I don't know about PS CS 8. In Photoshop Elements 2.0, the sequence is:
From the very top menu (File Edit Image Enhance Layer Select ...)

DO: Image -> Transform -> Perspective

I haven't had the need to get CS 8, but I do kick myself for passing up an
electronic coupon offer for $299.

Cheers,
Alan

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David J Taylor wrote:

> B - perspective "distortion" (I don't like that word), because of the
> viewpoint being used (e.g. tipping the camera upwards to get all of a
> building in).

I agree it's a 'difficult' word for the context, but it is appropriate esp. for
shots like the one you mention. Oddly, and I make this mistake myself, the
distortion can look manageable when you take the shot and a disaster when you
make the print...

Cheers,
Alan

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Alan Browne wrote:
> David J Taylor wrote:
>
>> B - perspective "distortion" (I don't like that word), because of the
>> viewpoint being used (e.g. tipping the camera upwards to get all of a
>> building in).
>
> I agree it's a 'difficult' word for the context, but it is
> appropriate esp. for shots like the one you mention. Oddly, and I
> make this mistake myself, the distortion can look manageable when you
> take the shot and a disaster when you make the print...

I've taken some vertical panoramas and joined then together successfully
when I needed a huge vertical FOV. Of course, a really wide-angle PC lens
would have been a better solution.

What I do find is that if you correct 100% for the "perspective
distortion" so that straight lines are 100% straight, it looks as is
you've overdone it and the building is tilted towards you. It seems
better if you leave just a little skew in the image. I expect the Greeks
would have understood about making the building appear "correct"!

Cheers,
David

 

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David J Taylor wrote:


> I've taken some vertical panoramas and joined then together successfully
> when I needed a huge vertical FOV. Of course, a really wide-angle PC lens
> would have been a better solution.
>
> What I do find is that if you correct 100% for the "perspective
> distortion" so that straight lines are 100% straight, it looks as is
> you've overdone it and the building is tilted towards you. It seems
> better if you leave just a little skew in the image. I expect the Greeks
> would have understood about making the building appear "correct"!

A good point and in the image I linked I get that impression. At Chichen Itza I
was shown something odd: The steps up the pyramids widen slightly to the top
such that they appear rectangular (eg: "correct") to the eye at a distace away!
http://www.aliasimages.com/images/Mexico/Chichen_Itza_0060.JPG

Cheers,
Alan


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Alan Browne wrote:

> David J Taylor wrote:
>
>
>> I've taken some vertical panoramas and joined then together
>> successfully when I needed a huge vertical FOV. Of course, a really
>> wide-angle PC lens would have been a better solution.
>>
>> What I do find is that if you correct 100% for the "perspective
>> distortion" so that straight lines are 100% straight, it looks as is
>> you've overdone it and the building is tilted towards you. It seems
>> better if you leave just a little skew in the image. I expect the
>> Greeks would have understood about making the building appear "correct"!
>
>
> A good point and in the image I linked I get that impression. At
> Chichen Itza I was shown something odd: The steps up the pyramids widen
> slightly to the top such that they appear rectangular (eg: "correct") to
> the eye at a distace away!
> http://www.aliasimages.com/images/Mexico/Chichen_Itza_0060.JPG

Ooops ... re-looking at that image, there is in fact perspective distortion on
the steps as they go up, so to hell with that! Deleted the file above.

(But I was 'told' the fact that I mentioned above).

Cheers,
Alan


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"Tumbleweed" <Shovels@five.paces> wrote:

> It's all there in "Help"
> I tried it after seeing this post and it's just great for getting rid of
> converging verticals.
>
>
>

Converging verticals aren't distortion. I believe the OP was asking about
barrel and/or pincushion distortion.

 

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On Mon, 14 Feb 2005 18:09:57 -0000, "David J Taylor"
<david-taylor@invalid.com> wrote:

>Alan Browne wrote:
>> David J Taylor wrote:
>>
>>> B - perspective "distortion" (I don't like that word), because of the
>>> viewpoint being used (e.g. tipping the camera upwards to get all of a
>>> building in).
>>
>> I agree it's a 'difficult' word for the context, but it is
>> appropriate esp. for shots like the one you mention. Oddly, and I
>> make this mistake myself, the distortion can look manageable when you
>> take the shot and a disaster when you make the print...
>
>I've taken some vertical panoramas and joined then together successfully
>when I needed a huge vertical FOV. Of course, a really wide-angle PC lens
>would have been a better solution.
>
>What I do find is that if you correct 100% for the "perspective
>distortion" so that straight lines are 100% straight, it looks as is
>you've overdone it and the building is tilted towards you. It seems
>better if you leave just a little skew in the image. I expect the Greeks
>would have understood about making the building appear "correct"!
>
>Cheers,
>David
>

Indeed they would David <g>, and i must say initially i had perhaps
misunderstood the post's request. But it's been informative and i
think we're all on the same page; and now i'm intrigued to see what
'all "native" effects of photoS will do the job..or what i need in it
to accomplish that. The paintS thing sounds really usefull. It would
be interesting to compare/contrast - though i think the photoS
case would be better served by someone more knowledgeable than
I.

In any event..I have to come to grips with this as i have an cannon
10-22 ef-s that i love and have been podering the problem of course.
All my current corrections have used the transform tools.

Interestingly, this discussion really belongs in a photoshop group...
but as long as no-ones complaining.

Ta
Ken

 

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Ken Ellis wrote:

> Interestingly, this discussion really belongs in a photoshop group...
> but as long as no-ones complaining.

.... since we're in the realm of what the photographer did with what lens on what
subject, the line is a bit blurry...


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In article <hgv111dn66rfkk2v2mf3ogi47fu2se579m@4ax.com>,
Ken Ellis <kenellis@nycap.rr.com> wrote:
>
>Interestingly, this discussion really belongs in a photoshop group...

Not really - not everybody uses photoshop as their image editor of choice.

Personally, for perspective correction, removal of barrel distortion,
etc. I use the Panorama Tools another poster has mentioned.
I use the hugin front end, which works quite well for me.

Work-in-progress examples (and links to the tools used) can be found at

<http://jfwaf.com/Panoramas/>

 

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johnf@panix.com (John Francis) wrote in news:cur03d$ikb$1
@reader2.panix.com:

> Work-in-progress examples (and links to the tools used) can be found at
>
> <http://jfwaf.com/Panoramas/>
>

Nice. It is always hard to get seamless stitching in water.
When it is ice on the lakes here in Sweden it is much easier


/Roland

 

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Alan Browne wrote:
> Alan Browne wrote:
>
>> David J Taylor wrote:
>>
>>
>>> I've taken some vertical panoramas and joined then together
>>> successfully when I needed a huge vertical FOV. Of course, a really
>>> wide-angle PC lens would have been a better solution.
>>>
>>> What I do find is that if you correct 100% for the "perspective
>>> distortion" so that straight lines are 100% straight, it looks as is
>>> you've overdone it and the building is tilted towards you. It seems
>>> better if you leave just a little skew in the image. I expect the
>>> Greeks would have understood about making the building appear
>>> "correct"!
>>
>>
>> A good point and in the image I linked I get that impression. At
>> Chichen Itza I was shown something odd: The steps up the pyramids
>> widen slightly to the top such that they appear rectangular (eg:
>> "correct") to the eye at a distace away!
>> http://www.aliasimages.com/images/Mexico/Chichen_Itza_0060.JPG
>
> Ooops ... re-looking at that image, there is in fact perspective
> distortion on the steps as they go up, so to hell with that! Deleted
> the file above.
> (But I was 'told' the fact that I mentioned above).

That's why I mentioned the Greeks - they applied "perspective correction"
as they were building their buildings!

Cheers,
David

 

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David J Taylor wrote:

>>Ooops ... re-looking at that image, there is in fact perspective
>>distortion on the steps as they go up, so to hell with that! Deleted
>>the file above.
>>(But I was 'told' the fact that I mentioned above).
>
>
> That's why I mentioned the Greeks - they applied "perspective correction"
> as they were building their buildings!

No, I didn't get you in the prior post. Are you sure about that? I thought the
Greeks liked to stick to the Golden Mean (whatever you want to call it)?

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Alan Browne wrote:
> David J Taylor wrote:
>
>>> Ooops ... re-looking at that image, there is in fact perspective
>>> distortion on the steps as they go up, so to hell with that! Deleted
>>> the file above.
>>> (But I was 'told' the fact that I mentioned above).
>>
>>
>> That's why I mentioned the Greeks - they applied "perspective
>> correction" as they were building their buildings!
>
> No, I didn't get you in the prior post. Are you sure about that? I
> thought the Greeks liked to stick to the Golden Mean (whatever you
> want to call it)?

I was thinking of how temple columns were tapered, but you are now at the
limit of my knowledge.

Cheers,
David

 

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David J Taylor wrote:

> I was thinking of how temple columns were tapered, but you are now at the
> limit of my knowledge.

And at the limit of my interest! (eg: I won't Google on this one).

Cheers,
Alan

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Alan Browne <alan.browne@freelunchVideotron.ca> wrote in
news:cutabf$sjg$3@inews.gazeta.pl:

>> I was thinking of how temple columns were tapered, but you are now at
>> the limit of my knowledge.
>
> And at the limit of my interest! (eg: I won't Google on this one).
>
>

The greeks did two things I know of.

1. The tapered the columns. Simple even width columns does not look
as good as tapered. Modern architecture has them - but we are used
to it. So we don't mind

2. Beams shall be slightly bent - highest at the middle. Perfectly straight
beams look slightly bent down. Thats an illusion. But the illusion can
can be nullified by the greek trick. The same goes here. We don't care.


/Roland

 

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> Alan Browne <alan.browne@freelunchVideotron.ca> wrote in
> news:cutabf$sjg$3@inews.gazeta.pl:
>
>>> I was thinking of how temple columns were tapered, but you are now at
>>> the limit of my knowledge.
>>
>> And at the limit of my interest! (eg: I won't Google on this one).
>>
A good example of this is the Taj Mahal. (No, I know it's not Greek)
where the architect was obsessed with perfection. From the Turrets to the
inlaid decorationit was designed to cateer for perspective.
It's utterly brilliantly executed and you have to reach out and touch to
convince your brain that your eyes have been deceived.