Figure 1 shows a raw file that has been opened in a raw converter (Camera Raw). It is easy to see that the shoreline on the far side of the lake is tilted. This is easy to fix using the Straighten tool in the converter.
Inevitably, the question will come up, "Which method is best?" The answer to such questions is almost always, "It depends". It depends on ones priorities. For me, this is a rather straightforward issue; image quality is almost always my first priority. With that priority in mind, straightening images in the raw converter is my first choice. In general, manipulation of images in raw converters produces less image degradation than manipulation of images in image editing programs (the technical reasons for this are out of the scope of this article).
In those cases where it is not possible to straighten an image in a raw converter, and the file has layers, my next choice is to use the Measure tool. This is simply because this method can be used with layered images without any unusual problems (I have had some problems with the Lens Correction filter when used with layered images). If an image does not have any layers, then, the Lens Correction filter will work equally well.
The Lens Correction filter is the best choice if additional corrections need to be made to the image (i.e., barrel distortion, pincushion distortion, vignetting, perspective, or chromatic aberration)
In order to get the best quality when straightening images, a few points should be kept in mind.