Forum: Photography


Subject: Correcting Perspective Digitally

ASalina opened this issue on Feb 27, 2002 ยท 10 posts


ASalina posted Wed, 27 February 2002 at 1:34 AM

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...