I've been reading about large format view cameras lately, and envying their ability to correct for perspective distortion when photographing large structures with tall vertical elements, such as buildings, tall trees, etc. Perspective distortion is the phenomenon of tall parallel lines bending toward each other as the rise up above the level of the camera. Imagine a photograph of a tall building taken as close as possible to get all of it in the frame. The base of the building will appear to be much wider than the top. That's perspective distortion in action. I decided to try an experiment using The Gimp (which is a Photoshop clone for use beleagered and bedraggled Linux users). The Gimp has a multi-purpose tool that allows you to rotate, shear, scale, and most importantly, manipulate the perspective of an image, layer, or selection. My guess is that Photoshop has a similar type of tool (probably better in quality, right now, than The Gimp's). It took several tries, squeezing the bottom portion of the image together and stretching out the top portion, but I like the results I got. It's interesting to me and my untrained eye, which I carry with me wherever I go, That I didn't notice the perspective distortion in the original image (above), but when seen side by side with the corrected image (below), the distortion becomes quite apparent. So much so that I now can't NOT notice it in the original. I guess that's a good thing...

Corrected image.

Personally, I have found perspective disortion fascinating. I use skew tool from photoshop to do jobs like that. I really like that pic btw. Both of them. .n

That's a good job you've done there ASalina, and I see what you mean about not being able to ignore the distortion once you've seen the corrected image! Very nice photo(s)! This brings to mind a question for me though - how does the brain perceive perspective? It's not an optical illusion is it? The eye sees parallel lines converging as distance increases...so the distortion is the true representation, is it not? Interesting to think about...(or then again, maybe not! LOL) :-)>

The Gimp?!? lol - Dunno about elsewhere in the world but that word has a bit of an overt meaning over here!!! Personally I don't like the corrected image - like Punk says, we see convergence as a natural thing - to me the house now looks as though it's been built wrong, wide at the top.....I guess it works better on things a bit of a distance away, though. I understand Andromeda do a perspective plug in for PhotoShop which is apparently quite good. (",)

Interesting experiment & you've done a good job there, the house looks right in the second one but I feel as though I'm no longer sure of my view point, as PC pointed out I think the brain expects to see distortion.

Wow. We had all better take notice on this one. Thanks. Nice picture you made there, too. Joe

In case anyone cares, and would like to find out more on this topic, This distortion is called "Keystoning" In the world of Architectural photography it is a HUGE No,No. I have never used photogimps tools to correct this. (have always been lucky enough to have access to a view camera) ASalina......looks like you did a great job with your available tools. It's good to know that they are Quite useable. (can't always pack a view camera around)

Attached Link: http://www.photo.net/photo/dead-trees/view-camera-technique.html

I think the matter of whether perspective "distortion" is a Good Thing or a Bad Thing is largely subjective. My guess is that the person who coined the term "perspective distortion" considered it a Bad Thing. I think a better way to look at it is as "perspective control", in that in some cases, especially with extremely wide angle shots, the bending of what were straight lines can be so extreme that it draws the viewer's attention from the intended subject. And on the other hand perspective "distortion" can be used to the photographer's artistic advantage. Having control over the effect can only be a Good Thing. :-)

One of the things that a View Camera can do that I haven't
been able to duplicate in postprocessing (aside from the
ultra-high resolution inherent in large format film) is to
tilt the lens and film planes. I wonder if it's even
possible for software to correct poor focus at all. I
suppose not.

P.S. For a really striking example of the sharpness of large
format photography, go to the link above and click on the
thumbnail of the photo of the joshua tree. Absolutely stunning.

If it's not sharp on the negative, I don't care how many filters and tools you use, You will NEVER be able to correct for an unsharp exposure. especially compared to a view camera ; )