Was I Drunk or What?
Sometimes it happens, and one may not really be sure why, but the camera is not quite level during a shot. It could be that the photographer was shooting fast, the background happened to move, taking pictures while traveling on a vehicle, or some other reason :)
This can be very disturbing when vertical or horizonal lines are within the image. It could be the wall, as above, or it could just be the horizon on a landscape shot. Fortunately, in many cases in Lightroom, Photoshop, or several other editing programs, there is a solution.
Many photographers are aware of the ruler (or align) tool in their editing program. This shot shows an image from Lightroom. Grab the ruler tool, draw a line along a vertical or horizontal line within the image and in many (not all) cases the image is now level. This is often at the expense of cropping out part of the image as seen above the process has cropped out a portion to the bottom and right of the image (Hint: It is almost always a good idea to shoot a little wide).
Lightroom also has additional tools when the ruler just does not work for an image.
The transform section in the develop module of Lightroom can potentially save an image when the ruler of a simple crop will not straighten a image. The dialog box has several buttons as well as some manual control over the photograph. My experience has been the vertical button can be the most useful. Lets take a look at one more image below:
The image to the far left is well...slanted. In this case the ruler tool did not help much. If we take a look at the transform box and select the vertical button, we get a crop similar to the second image. The tool has cropped the right and left side of the image quite substantially leaving white space to either side of the shot. We could of course continue to crop out the white space, but here is yet another option within the transform box. By scaling and adjusting the aspect of the image we are able to get close to what we hoped for in the original picture. Again, as with the ruler tool, one can see that a substantial portion of the image still is absent from the final product.
Of course you can always experiment with the other sliders such as the vertical horizontal slider, to see what works best for your final image. The "Auto" button seems to generally result in the worse results. Also keep in mind, there is also LENS CORRECTION tool also found in Lightroom that may also be able to help.