# Change angle of view in post



## gold333 (Dec 13, 2013)

A 16mm image is an image with a certain amount of barrel distortion because it is a wide angle image. 

A 24mm image is an image with _slightly less barrel distortion.


Photoshop allows me to distort, skew, warp images any way I like. In photoshop I can turn them inside out for discussions sake.



I'm looking for a way to distort a 16mm image so that it is distorted in such a way that the barrel distortion it displays is equivalent to a 24mm image. I'm assuming this will be a variation on the "pinch" feature. But I need to be exact.


The image is a 16mm shot of a 2/3's view of a person against a gray sweep at 3 feet distance. The person's features are showing a little too much barrel distortion for my liking, exactly the difference between 16mm and 24mm._


----------



## 480sparky (Dec 13, 2013)

You're not seeing barrel distortion, you're seeing perspective distortion.  You're shooting your subject too closely.


----------



## Ysarex (Dec 13, 2013)

How about just get a 16mm lens that doesn't have barrel distortion. I'm curious why you don't just remove the distortion for both lenses. In any case there's no set formula you can apply since the distortion you're seeing is a function of the design of your specific brand/model lenses and not a typical characteristic of all 16mm or all 24mm lenses. You can get versions of those that are without barrel distortion.

Joe


----------



## gold333 (Dec 13, 2013)

480sparky said:


> You're not seeing barrel distortion, you're seeing perspective distortion.  You're shooting your subject too closely.




Sigh.

I know.

I'm looking for a way to _distort _a 16mm image so that it is distorted in such a way that the _perspective _distortion it displays is equivalent to a 24mm image. 

I'm assuming this will be a variation on the "pinch" feature. But I need to be exact.


----------



## Ysarex (Dec 13, 2013)

480sparky said:


> You're not seeing barrel distortion, you're seeing perspective distortion.  You're shooting your subject too closely.



Lenses don't distort perspective.

Joe


----------



## 480sparky (Dec 13, 2013)

gold333 said:


> 480sparky said:
> 
> 
> > You're not seeing barrel distortion, you're seeing perspective distortion.  You're shooting your subject too closely.
> ...



Try _Lens Distortion_.  But I guess we would know what software you're trying to create this effect with.


----------



## 480sparky (Dec 13, 2013)

Ysarex said:


> Lenses don't distort perspective.
> 
> Joe




I didn't say they did.


----------



## Ysarex (Dec 13, 2013)

gold333 said:


> 480sparky said:
> 
> 
> > You're not seeing barrel distortion, you're seeing perspective distortion.  You're shooting your subject too closely.
> ...



Then you'll have to move the camera.

Joe


----------



## gold333 (Dec 13, 2013)

Am I really being this unclear?


Ok again, the shoot was in the past. I cannot reshoot, as the topic says this is about _post.
_
Again: I cannot reshoot, this is about post.



I _wanted_ a certain amount of distortion in the image I shot. 

I shot with 16mm and got perspective distortion that a 16 millimeter lens gives you.


I should have shot with 24mm because that is the distortion that I should have wanted.


Now in _post:_


I want to change the perspective on the image from being 16mm equivalent to being a 24mm equivalent amount of distortion.


This is something akin to the "pinch" feature in Photoshop but I need to be precise and not do it manually.

I'm looking for help from someone that would know how to do this.

PS: The software doesn't matter, money is no issue, I just need to be precise.


----------



## Ysarex (Dec 13, 2013)

gold333 said:


> Am I really being this unclear?
> 
> 
> Ok again, the shoot was in the past. I cannot reshoot, as the topic says this is about _post.
> ...



Lenses don't distort perspective. So your 16mm lens did not distort perspective. The perspective was rendered in a way you're not happy with by the position of your camera. You can't change that after the fact.

Joe


----------



## 480sparky (Dec 13, 2013)

Ysarex said:


> Lenses don't distort perspective. So your 16mm lens did not distort perspective. The perspective was rendered in a way you're not happy with by the position of your camera. You can't change that after the fact.
> 
> Joe



So it's impossible to defish a fisheye lens shot?  Funny, I can do that in post.

And I can adjust the perspective distortion in an image as well in post.


----------



## Ysarex (Dec 13, 2013)

480sparky said:


> Ysarex said:
> 
> 
> > Lenses don't distort perspective. So your 16mm lens did not distort perspective. The perspective was rendered in a way you're not happy with by the position of your camera. You can't change that after the fact.
> ...



defishin a fisheye is a different process that does not alter the perspective rendered by the camera placement. And yes you can distort the rendered perspective in software but the rendered perspective determined by the camera placement is just that and in and of itself it is not a distortion.

Joe


----------



## Ysarex (Dec 13, 2013)

gold333 said:


> Am I really being this unclear?
> 
> 
> Ok again, the shoot was in the past. I cannot reshoot, as the topic says this is about _post.
> ...



You may be able to achieve something along the line of what you're imagining using this: Introduction | www.dxo.com

Joe


----------



## 480sparky (Dec 13, 2013)

Ysarex said:


> defishin a fisheye is a different process that does not alter the perspective rendered by the camera placement. And yes you can distort the rendered perspective in software but the rendered perspective determined by the camera placement is just that and in and of itself it is not a distortion.
> 
> Joe



Are we still talking about perspective distortion?

If so, it can be adjusted in post.  More or less barrelling is _easy_ to do.


----------



## 480sparky (Dec 13, 2013)

gold333 said:


> .........PS: The software doesn't matter,........



Well, yes it does.  In order to give you precise instructions, we need to know the software you're using.


----------



## Ysarex (Dec 13, 2013)

480sparky said:


> Ysarex said:
> 
> 
> > defishin a fisheye is a different process that does not alter the perspective rendered by the camera placement. And yes you can distort the rendered perspective in software but the rendered perspective determined by the camera placement is just that and in and of itself it is not a distortion.
> ...



Barreling is lens distortion -- that's a different topic and obviously the OP used the wrong term.

Assuming we're talking about using a box camera which I think the OP is (no view camera and no tilt-shift lens), how can such a camera distort perspective? Minus lens distortion (again a separate topic), a camera lens combination renders the perspective determined by the camera position. How is that a distortion?

Joe


----------



## robbins.photo (Dec 13, 2013)

Ysarex said:


> 480sparky said:
> 
> 
> > Ysarex said:
> ...



Dear God.. that's dangerously close to .. science...  {shudder}

Ok, I need to walk away now.. just walk away.. lol


----------



## Josh66 (Dec 13, 2013)

It's called cropping.  People do it all the time.


----------



## robbins.photo (Dec 13, 2013)

O|||||||O said:


> It's called cropping.  People do it all he time.



Arggh.. more science.. must flee!!!


----------



## 480sparky (Dec 13, 2013)

Ysarex said:


> Barreling is lens distortion -- that's a different topic and obviously the OP used the wrong term.
> 
> Assuming we're talking about using a box camera which I think the OP is (no view camera and no tilt-shift lens), how can such a camera distort perspective? Minus lens distortion (again a separate topic), a camera lens combination renders the perspective determined by the camera position. How is that a distortion?
> 
> Joe



Until the OP comes back and tries to sort out this mess, I think I'll just shut up now.


----------



## gold333 (Dec 13, 2013)

I can buy any software to do this with. 

I am using photoshop and CR (camera raw) at the moment but am not limited to it.

I understand that the lens distortion feature in photoshop CR can adjust barrel distortion but I would like a method to specifically edit my 16mm image so that it shows (more or less) exactly the barrel distortion a 24mm equivalent image taken from the exact same place would have shown. And not guess what that might be.


EDIT: I feel like I am in the twilight zone.


Look a portrait taken with a 16-35mm at 16mm from 3 feet away is a wide angle shot with the person looking fat.

Had I zoomed in slightly (from the same spot) they would have looked a little less fat.

I want to find a way to (perspective/lens/barrel distortion/whatever) correct a bunch of these 16mm images so the person looks (exactly!) as fat as they would have looked had I zoomed in to 24mm before taking the pictures.

It is a simple perspective/lens distort/whatever feature in most post processing programs but I need one that can specifically change the distortion between set mm equivalents. And not do it by eye.


It's basically the manual lens correction feature in camera raw, the "distortion slider" to be specific. I need to set it to the right but I don't know by how much to mimic 24mm on a 16mm image.


----------



## Josh66 (Dec 13, 2013)

Two things.


gold333 said:


> I can buy any software to do this with.


You don't have to.




gold333 said:


> Look a portrait taken with a 16-35mm at 16mm from 3 feet away is a wide angle shot with the person looking fat.
> 
> Had I zoomed in slightly (from the same spot) they would have looked a little less fat.
> 
> ...


What you describe is called cropping.  Even the most basic photo editors can do it.

I don't think it will have the effect that you think it will have though.  They wouldn't have looked 'less fat'.


----------



## robbins.photo (Dec 13, 2013)

gold333 said:


> I can buy any software to do this with.
> 
> I am using photoshop and CR (camera raw) at the moment but am not limited to it.
> 
> ...



As far as I know?  Nope.  Post processing software is designed to remove barrel distortion, not increase it.  You might be able to get something like the effect your looking for using Photoshop, Free Transform, and warp - but you'll have to do it by eye and there isn't going to be any sort of precise control.

Now, if you'll excuse me, I must run screaming from the room like a little girl before any more science is discussed.. lol


----------



## 480sparky (Dec 13, 2013)

OK, let's make this simple:

Given:  This is the original image:








Do you want to do this to it:?









Or this:?


----------



## robbins.photo (Dec 13, 2013)

480sparky said:


> OK, let's make this simple:
> 
> Given:  This is the original image:
> 
> ...



Ok, I have to go throw up now.. rotfl


----------



## 480sparky (Dec 13, 2013)

gold333 said:


> ...........It is a simple perspective/lens distort/whatever feature in most post processing programs but I need one that can specifically change the distortion between set mm equivalents. And not do it by eye...........




I seriously doubt such a function exists.  More to the point, _can it even be created_?...... given the absolute _staggering_ number of different lenses on the market, and the different ways each one renders an image at a given focal length.  What I mean by this is... a Nikkor 14-24 @ 24mm is going to have a different barrell distortion than, say, a 24-120 at the same 24mm.  And every Nikon lens will each have a different rendering of the distortion.  As well as Canon, Pentax, Voigtlander, Leica, Casio, Kodak, Panasonic, Minolta, Vivitar, Rokinon, Tokina, Tamrom, Promaster, Samyang, Ricoh, Zeiss, Sigma, Spiratone........ad nauseum, ad infinitum.


----------



## Ysarex (Dec 13, 2013)

O|||||||O said:


> Two things.
> 
> 
> gold333 said:
> ...



Josh is correct here.



gold333 said:


> Had I zoomed in slightly (from the same spot) they would have looked a little less fat.



This is false. Had you zoomed in from the same spot you would have cropped the scene but the perspective would not change. Your portrait subject would appear equally fat in both photos. You are confused. To change the perspective you MUST move the camera. There is no post software option that can actually alter your photo to allow you to move the camera after the fact. There is however post software that can distort your image and may produce an effect similar to what you're fantasizing about. I gave you a link to the best: DXO Viewpoint. Photoshop also has a filter that might help you it's called Adaptive Wide Angle.




gold333 said:


> It's basically  the manual lens correction feature in camera raw, the "distortion  slider" to be specific. I need to set it to the right but I don't know  by how much to mimic 24mm on a 16mm image.


The distortion slider in ACR removes lens distortion (barrel/pincushion) which is entirely unrelated to perspective and the problem you're complaining about which was caused by you being too close to the subject. Distorting your photo by simulating pincushion distortion isn't what you're looking for. DXO Viewpoint will come as close as possible for you.

Joe


----------



## amolitor (Dec 14, 2013)

You guys are wonderful blessings to the forum, jesus saves.

What the dude wants to do is make the parts of the person that were closer to the camera smaller, as if the person was shot from a little farther away. Yes, he's wildly unclear, and he doesn't realize that he'd need to zoom in -- _and step back_, but if you're following along and paying attention it's obvious. He was too close when he took the shot, he used a wide angle setting. The noses are too big, the bellies are too big, the feet and ears are too small, everything looks distorted and unflattering.

This is gonna be hard, OP. You need to make selective adjustments to every element of the person that's in frame. The parts that were closest to the camera (noses, bellies, whatever) need to be shrunk slightly. The parts that were farther away need to be enlarged a bit. What makes this hard is that often the parts that need to be enlarged are tucked in behind something that needs to be shrunk. Imagine you took a close up face shot:

The tip of the nose, shrink it. The bridge of the nose, shrink it, but progressively less as you go up it., the eyes, enlarge a little. Chin, enlarge a bit MORE, it's farther from the center of the lens than the eyes, ditto forehead. Ears, enlarge quite a bit.

It's a 3D puzzle. Software cannot do it, because the 2D image doesn't have the 3D information needed to fix the picture, although I suppose it could guess. You can probably mitigate the effects of lens distortion a little with these sorts of adjustments, but push it too far and errors are going to creep in that make it look extremely weird.


----------



## 480sparky (Dec 14, 2013)

amolitor said:


> You guys are ******..........



So, just because you're the first one to figure out what the OP really means and want to accomplish makes the rest of us idiots worthy of swearing at?


Merry Christmas to you, too!


----------



## astroNikon (Dec 14, 2013)

I thought the OP was talking about the facial distortions too, such as in this article.
The camera DOES lie: Proof that a lens can be the difference between pretty and pretty ugly | Mail Online

but, I just try to avoid wide angle when I take people photos.
But the OP is trying to fix previous photos.  Which sounds very difficult to do.


----------



## pixmedic (Dec 14, 2013)

lets all keep it nice guys. 
at least until the holidays are over. maybe a little longer. we'll let you know. 
thanks.


----------



## amolitor (Dec 14, 2013)

Merry Christmas to you too, pixmedic!


----------



## Ysarex (Dec 14, 2013)

amolitor said:


> You guys are wonderful blessings to the forum, jesus saves.
> 
> What the dude wants to do is make the parts of the person that were closer to the camera smaller, as if the person was shot from a little farther away. Yes, he's wildly unclear, and he doesn't realize that he'd need to zoom in -- _and step back_, but if you're following along and paying attention it's obvious. He was too close when he took the shot, he used a wide angle setting. The noses are too big, the bellies are too big, the feet and ears are too small, everything looks distorted and unflattering.
> 
> ...



Yes the OP is confused and it did take a few posts to figure out what he wanted to do. He did however make it clear enough that he has multiple photos to deal with and he's looking for an "enter a number in the box" solution. Responding to that with you need to shrink the nose and enlarge the ears isn't an idiotic suggestion?

The OP needs to distort his photos, but he needs an automated solution to do that. If you read back through the thread you'll find that one of us idiots did suggest a software solution that will at least simulate the effect the OP wants and can automate the process for multiple photos. I don't think I see any other real practical help being offered for the OP's present problem. Good thing for him an idiot was around and, Merry Xmas to all.

Joe


----------



## leeroix (Dec 14, 2013)

What version of Photoshop? Some tools are not available on earlier versions...


----------



## Ysarex (Dec 14, 2013)

astroNikon said:


> I thought the OP was talking about the facial distortions too, such as in this article.
> The camera DOES lie: Proof that a lens can be the difference between pretty and pretty ugly | Mail Online
> 
> but, I just try to avoid wide angle when I take people photos.
> But the OP is trying to fix previous photos.  Which sounds very difficult to do.



That is an incredibly bad article. It's probably that kind of junk that's responsible for the OP's confusion in the first place.

Joe


----------



## amolitor (Dec 14, 2013)

Except that dxo won't do it. It's just applying algorithmic alterations with some sliders. It completely fails to deal with the on-axis perspective problems, of one thing behind another appearing too small, the "noses are too big" problem.

The OP wants to do this in an editor and I a) told him what's necessary and b) why it's essentially an intractable problem.

dxo is just a slightly more advanced perspective correction tool.

You cannot actually solve the "make this portrait look like it was taken with a longer lens" problem without a pretty accurate 3D model of the scene.


----------



## Ysarex (Dec 14, 2013)

amolitor said:


> Except that dxo won't do it. It's just applying algorithmic alterations with some sliders. It completely fails to deal with the on-axis perspective problems, of one thing behind another appearing too small, the "noses are too big" problem.
> 
> The OP wants to do this in an editor and I a) told him what's necessary and b) why it's essentially an intractable problem.
> 
> ...



I didn't say DXo Viewpoint would do it. I said this, "There is no post software option that can actually alter your photo to  allow you to move the camera after the fact. There is however post  software that can distort your image and may produce an effect similar  to what you're fantasizing about."

Yes it is an intractable problem which, as you can see, I said. Viewpoint can distort the OP's image and may be able to do so in a manner that will make the OP happier than he is now. It's the best pragmatic option that has been offered him under the circumstance.

Joe

P.S. People don't look good with big ears -- just look at my avatar.


----------



## gold333 (Dec 14, 2013)

Thanks everyone.

To the guy who suggested I needed something called the "crop" tool thank you. 



As a final attempt I will try to be as clear as I can (sorry for mixing up my terms earlier):



I am trying to do composite photography whereby I match a model shot in a studio against a backdrop shot outside. I shot both at 16mm. 


Now I want to experiment with the "look" of my composites and am wondering what would have happened if I had altered the focal length between the model and the background. I now want to transform the image of the model into a field of view that is no longer 16mm but exactly 24mm.


@Amolitor:

Thanks so your saying that the liquify tool in Photoshop is my only solution. That's kind of extreme I was really hoping for an automatic FOV perspective changer or failing that some sort of pincushion or vanishing point tool before applying masks and liquifying ears and noses lol 


@480: It's the first (basically the difference between 16mm and 24mm)

I have a bunch of pics that look (a little more like) the left, I want to turn them into (a little more like) the right.








Same principle, I have pics that look like at 16mm I want to make them look more to the left, specifically 24mm:







That's easy to do using pincushion, manual lens distortion or any other fisheye to rectilinear projection tool,..... but I was hoping for something that can automatically alter the FOV of a certain focal length image into (something close to) the FOV of another certain focal point image. Without having to take 2 shots, compare, and having to "undistort" things by hand.


PS: The lens profiles in PS don't do this, they just take out the optical "barrel" distortion that most lenses have built in and reduce it by a certain set amount. If I shoot using a fish eye and open the RAW and apply a 600mm lens profile in PS I don't magically get rectilinear projection. It just brightens up the edges a bit and takes out "some" optical distortion and whatnot, it does not change the FOV completely.


----------



## amolitor (Dec 14, 2013)

Once again, there isn't any way to do what you want. The dxo tool will do an approximation, more or less by stretching and shrinking things based on how far away from the center of the frame they are. The problem is that you have to alter the dimensions of objects based on how far away from the center of the lens they are.

In cases where there's an easy geometric mapping of the 2D picture to a "distance from lens", then you can simply use that. This is what T/S lenses or the equivalent "perspective correction" tool can do, when you're talking about rectilinear structures. The dxo tool can do a more generalized version of the same thing, but still assumes that things farther from the center are farther from the lens -- and that this is all that's going on.  If you're taking closeup pictures of people's faces with a wide lens then there is no such simple mapping.


----------



## Derrel (Dec 14, 2013)

One of the biggest problems in this thread is the MIS-use of traditional terms. Like early on when Ysarex said there is no way to change the perspective, except to move the camera's position in relation to the subject. See, Ysarex understands the term "perspective" using the CORRECT definition. In the latest post, immediately above, the OP is referring to the "FOV" of one lens versus that of another, using the term FOV entirely incorrectly.

Early on in this thread, the terms "perspective", was being mis-understood to mean "apparent perspective distortion", with all sorts of arguing among people who don't seem to know the difference between the two issues, nor the difference between "apparent perspective distortion" and barrel distortion, and so on. All in all, a giant *cluster-copulation* of misunderstood terms, misappropriated terms, and arguing at cross purposes.

As far as the images in the shots above, the desire for a software solution to change close-range, wide-angle images into images that look like they were shot from farther away with a longer focal length lens...with precision, millimeter conversions...I'm not aware of anything that is that cut-and-dried, but there might be something.


----------



## Ysarex (Dec 14, 2013)

gold333 said:


> Thanks so your saying that the liquify tool in Photoshop is my only solution. That's kind of extreme I was really hoping for an automatic FOV perspective changer or failing that some sort of pincushion or vanishing point tool before applying masks and liquifying ears and noses lol



As Amolitor suggested earlier you'd have to have your image 3D mapped in order to use a tool that would alter FOV. Such tools exist but only in the world of 3D modeling. You can fake it with 2D tools that distort the image and liquify away.

Joe


----------



## Ysarex (Dec 14, 2013)

Derrel said:


> One of the biggest problems in this thread is the MIS-use of traditional terms. Like early on when Ysarex said there is no way to change the perspective, except to move the camera's position in relation to the subject. See, Ysarex understands the term "perspective" using the CORRECT definition. In the latest post, immediately above, the OP is referring to the "FOV" of one lens versus that of another, using the term FOV entirely incorrectly.
> 
> Early on in this thread, the terms "perspective", was being mis-understood to mean "apparent perspective distortion", with all sorts of arguing among people who don't seem to know the difference between the two issues, nor the difference between "apparent perspective distortion" and barrel distortion, and so on. All in all, a giant *cluster-copulation* of misunderstood terms, misappropriated terms, and arguing at cross purposes.
> 
> As far as the images in the shots above, the desire for a software solution to change close-range, wide-angle images into images that look like they were shot from farther away with a longer focal length lens...with precision, millimeter conversions...I'm not aware of anything that is that cut-and-dried, but there might be something.



Amen to that!


----------



## amolitor (Dec 14, 2013)

You could probably do it pretty well with some mapping software. To really do it right you'd need to be able to tell the software "this point is in front of/behind this other point" and by about how much, creating an approximate model of the person. This is not super hard, but there is a bit of user input to do it. They you throw up a wireframe rendering for checking (or, if you're smart, you assume it's a standard human face). After that it's just geometry and bog-standard image processing.

Adobe is working on something that might come close:

Sneak Peek : Perspective Warp in Photoshop | Adobe Technology Sneaks 2013 | Adobe TV

This doesn't build full-on models, but does allow you to essentially build "enough" of a box model to fake it. This isn't available, alas, but illustrates some of the problems.


----------



## Josh66 (Dec 14, 2013)

gold333 said:


> I have a bunch of pics that look (a little more like) the left, I want to turn them into (a little more like) the right.


The way to do that (in camera) would be to use a longer lens and stand farther away.  It can't be done without moving the camera.


Doing that after the fact, in PP ... I couldn't say off the top of my head how to do it, but I'm sure it's 'possible'.  It may be more work than it's worth though - it would certainly be better to just get it right in the camera...


----------

