03 Force Parallel tool
So to fix this perspective in this picture, I need the Force Parallel tool, and this is circled here on the top toolbar. When you select this tool, the screen switches to a side-by-side view, with the image you’re correcting on the left and a preview of the corrected version on the right.
04 Draw your parallel lines
Now you click on the left image and drag out two lines, following the edges of two lines in the picture that should be parallel. I’ve created one to line up with the left side of the building and one to line up with the right side. These lines have control handles at either end – I’ve circled these in red – so that if your positioning isn’t quite perfect at your first attempt, you can adjust them to try again.
Over on the right you’ll see that the sides of the building are now perfectly parallel – it’s that simple!
In fact, it’s only that simple because DxO Optics Pro has done such a good job of fixing my wideangle lens’s barrel distortion with its default corrections – otherwise, I wouldn’t have had any properly straight edges to line up with.
05 Apply the correction
Once you’re happy that the preview image on the right looks strait, click the ‘Close’ button below. This applies the correction and returns you to the main screen, where you can make any other corrections or switch to the Process module to export a finished image.
06 The corrected photograph
DxO has worked so hard at making Optics Pro simple and intuitive, that there’s not that much to do! The default corrections are so close to the settings that you’d probably apply manually anyway that it’s often not necessary to change them. And the perspective correction tools, like the DxO Force Parallel tool, are quick, simple and intuitive.
Incidentally, I could have used the Force Rectangle tool on this picture too, but here you need to be a little careful. The Force Rectangle tool fixes both horizontal and vertical perspective at the same time, and while that sounds like a good idea, you should really keep it back for situations where it’s definitely necessary, and not use it as a matter of course. Why? Well, there are two reasons:
a) For most images, only one axis of correction is needed, and it’s usually vertical. Horizontal convergence is rarely as annoying in a picture as vertical convergence, and when you do correct horizontal convergence, the picture can sometimes look subtly odd and unnatural.
b) The stronger the perspective correction, the more DxO has to crop off the edges of the picture, so if you’re correcting perspective issues that aren’t really a problem in the first place, you’re sacrificing areas of the image unnecessarily.