Distortion Correction - Photoshop

Friday, December 14, 2012

Distortion Correction

(Photoshop)

Introduction

     I've briefly discussed this topic before,so I thought I'd expand on it. I'm going to introduce just some simple tools to correct the distortion in a condo building near me. In architectural photography, there are some basic rules that need to be followed. One of these "rules" for the basic building rendition is no distortion. An "illustrative architectural" photo is more glamourous and creative, and as such,   distortion is allowed.

    Because building are large and may be located in tightly-framed areas (e.g. downtown), you may not have enough space to work with. In other words you may not be able to back up to avoid distortion downtown, compared to a building located in the suburb with lots of landscaping around it.

     Most of the time, you'll be working wide a wide-angle or extreme wide-angle lens to be able to frame the building in its entirety.  As such, there will be distortion. Nikon and Canon make special tilt/shift lenses that help "correct" some of the distortion, but you need a really wide-angle for buildings, and then you end up with distortion nevertheless. These tilt/shift lenses developed from the view camera. You still will get distortion, but not as much had you not used the lenses.

    There are also special distortion-correction software that are stand-alone and plugins for Photoshop, and Photoshop had more advanced methods that what I will show you today.

    Finally, one very important fact to mention. Pro photographers know how to take quality photographs, especially when doing architectural photography. I would especially say so for the older and more-experienced photographer (myself included). There are a lot of facts to know when taking a building or structure photograph, and Photoshop cannot help you if you don't know how a building should be photographed. Of course, I have seem real-estate agents do their own photography,and they do sell real estate. But if you look at the big names in real-estate (e.g. Sotheby's), they're not using amateurs or their relatives - they're using pros!

Adjusting Photoshop Preferences

     One of the preferences in Photoshop is the grid. You want to define the spacing and number of lines to to be able to check that your corrections are correct to remedy both vertical and horizontal distortion. 

Preferences >>> Guides, Grid, & Slices

My current setting set for smaller photos.

This setting will have too many lines for the larger-sized photo that I will be working with.

A setting of 1 gridline every 8 inches is very good for this larger-image.

The file size from a Canon T3i (18 MP)

Notice  that there are too many lines for this photo!
The setting was the one I use for smaller photos.

Starting the Corrections

Don't forget to make a backup copy (never use the original photo).

As well make a duplicate layer to work on a copy rather than the open image.

And make sure to rename the image.

Notice that I haven;trenamed the image yet!

 Select >> All

Transform >>Distort

(I'm going to  counter-distort to correct the distortion)

Here's a nice condo in my neighbourhood.

I've pulled the top left and right squares to straighten out the vertical lines.

They're not 100% vertical.

To check you can drag the building next to a line.

 The corrections with the grid

The corrections without the grid

The vertical are almost OK

The arrows are pointing to the distortion

Notice how the building sides are converging (coming together)

I'll grab the same 2 squares to continue correcting the vertical sides of the building, 

so that they are parallel with each other

The  Finished Image.

There is some disproportionate left to right size distortion, but this isn't as bad as the original photo.

I'm going to finish here, so that you can read this post and study it. In tomorrow's post, I'll do some regular Photoshop cleanup (colour, contrast, shadow/highlight) for the photo.

Thanks for dropping by,

and have a nice day, wherever you may be.

Stacey