I need to do some pretty severe perspective adjustment to this photo:
 

 
The crest is about 20 feet up on the side of the building, and the only place I could take the shot from was at ground level, so as you can see, it's got a lot of distortion.
 
I can use it like this, but ideally, I'd like to adjust it back to its 'correct' rectangular shape - as if I'd been able to take the photo head-on.
 
This is the best I've managed so far in PS Elements or Gimp, but as you can see, the correction has left the straight lines still a bit wobbly in places:
 

 
 
So I wondered - has anyone got the tools and the knowledge to do this properly and could perform the adjustment for me if I sent you the full-size image file?
 
Many thanks in advance

I can't think of anything harder Steve.
 
Goodness, what a challenge.
 
If I absolutely had to pull it off I would attempt an experiment by working with the perspective tools on segments of the photo. I would use the seams to define the edges of various segments, and hope it could all be assembled into the whole after each segment is flattened.
 
Honestly, I don't think that will work because the cornice seems to be a curved shape and it is not just skewed by a distortion of your lens.
 
In other words, I don't think you could have solved your puzzle with a tilt/shift lens so I don't think it's going to work in a post process either.
 
I can imagine that you could do extensive hand work and fake it, but because you intend to print these I doubt you will get the job done with out noticeable artifacts. If you were preparing the photo for web or video you might be able to hide the artifacts in the lower resolution.
 
I do a lot of "painterly" type work with photo shop so I can imagine that with enough effort you could use the data you have in your photo to create an astonishingly real illustration... if you use that approach you'll just have to see if yo can pull it off.
 
I think I'd defer to the fact that the original image is probably what most people see with their eyes and it should feel very familiar.
 
If you want to make some small improvement the obvious choice is too shoot from as far back as you can with the longest lens you can use so as to minimize the effects of lens distortion and the perspective. If you are going to try that... why not bring a ladder? Remember to use a aperture that provides a depth of field that accounts for the curved masonry as it falls off on the sides. (you already know that... bu sometimes you can forget when you are up on a ladder etc.) 
 
Good luck. It sure seems like a good project.
 
best regards,
mike

 
Thanks Mike.
 
I tried the segment idea by splitting it up into 6 vertical strips and shearing each one accordingly. The straight-line edges are more convincing, but the inner parts of the image no longer match.
 
And you're right, the cornice is arched outwards, so I guess the only real way to flatten it would be to shoot perpendicular.
 
As you can see, I can't even get any further away to help lessen the perspective:
 

 
I even popped into the restaurant to ask if I could gain access to the upper storeys above them, but they don't own that part of the building and it's been unoccupied for a while.
 
This is likely to appear on the front cover of the calendar I'm helping assemble, so print quality has to be spot on. It will actually be resized to fit widthways on A4, so it's going to be pretty big.
 
I'll have another go in Gimp, their Cage Transform feature allows you to draw a framework around the image, add moveable nodes and then drag them around, a bit like how you edit an envelope in SONAR actually:
 

What happened to you Steve? When I met you in Londontown you were not all green like that?

Twenty-foot pole.
Attach camera to pole, set to auto-shoot.
Raise camera to height of crest.
Hope for the best.
 

I should be able to help.  PS6 has lots of tools just for this.  Do you have a link to the full photo?

 
Good thinking Greg!
 
Ed, I just got back - sorry I missed your call. I'm here for half an hour if you want to ring back
 
And I am now that green as I eat a lot of plutonium vindaloo.
 
Here's my latest attempt, much happier with this:
 

 
 
Now I just need to remove the pigeon crap

Use the Healing Tool to remove the pigeon crap.

 
Cheers Craig. I do use that, and the Clone Stamp tool as well.

 

craigb
I should be able to help.  PS6 has lots of tools just for this.  Do you have a link to the full photo?

Thanks mate
 
If you PM me your email, I'll send you a link to the original RAW file.