DxO's wide angle perspective correction stand-alone and plug-in utility
DxO ViewPoint is a stand alone utility that can also be used as a plug-in for Photoshop and compatible programs, and as a plug-in for Lightroom to correct various types of perspective distortions, like (above) falling verticals (keystone correction) as well as wide angle spacial perspective distortions, or or volume anamorphosis, that stretch objects to the sides of the frame and pull details into the corners of the frame. There are also controls for levelling horizons and optimal cropping. We've had a brief play with ViewPoint and have discovered that it can be rather effective.
ViewPoint is designed to compensate for distortions related to perspective - not to correct lens optical distortions. In fact you are advised to make lens distortion corrections, like barrel and pincushion distortion, before putting an image through ViewPoint. Such corrections are basically subjective so it's down to the user to apply as much or as little correction as required. In fact you may not even want perfectly vertical sides as this can look unnatural. The software can't see around corners so where a wide angle lens has been used to take a portrait very close to the subject' face any details out of the field of view that might have been visible with a longer lens will remain hidden. However, ViewPoint can make a face in such a situation look much more normal, without the exaggerated features that are closest to the lens. First, let's look at Volume Anamorphosis, which is where the perspective has the effect of stretching details at the sides and corners of the frame when using an extreme wide angle lens.
Diagonal Anamorphosis
Here is a typical group self-portrait taken with a very wide angle lens very close to the subjects. That's me on the right and I am holding the camera with my right arm pointing back at me, my cousin's husband, Jonas, and his son on his lap. People that know me will attest that my head is not really that shape! And neither is Jonas' father's head shaped like that in the top-left of the frame.
Now, after using corner correction mode for Anamorphosis you can see that we all look quite normal again. There is a cost in terms of peripheral areas of the frame as the program has pulled the sides and the corners in, but this is unavoidable and in such situations you should allow some extra space in the framing where possible. You may notice that after correction some formerly straight lines are now curved. This is also unavoidable but is usually much less objectionable than other areas of the image before correction.
Horizontal and Vertical Anamorphosis
If the areas of importance are near to the sides or top and bottom of a frame then the best correction simply pulls the sides in. This is is horizontal or vertical Anamorphosis correction. In the example above it's the man in yellow to the right and the man wearing the cap in a white shirt to the left. They are stretched laterally by the wide angle perspective . The man in the jacket at the centre, however, looks normally proportioned.
After the correction everyone now looks normally proportioned and the man near the centre of the frame has changed very little. The correction effect is stronger as it nears the side of the frame. Overall, the effect brings the sides closer in and does not affect the height. The frame is now more square than before. Unlike the Corner Anamorphosis correction none of the frame perimeter needs to be lost.
Keystoning
Falling verticals are perennial problem for photographing buildings as this scene from St. Mark’s Square in Venice shows. Viewpoint’s keystoning correction mode makes short work of this kind of correction.
You simply need to position linear points along vertical details like building sides and the program will straighten things. You can also fine tune the result in case it looks unnatural. This kind of correction does constrain the sides of the frame, but nothing vertically need be sacrificed. There is also an option to identify and straighten rectangular structures in the frame, combining horizontal and vertical perspective correction.
Add to that horizon straightening and what adds up is a comprehensive and focused tool.
We'll be reviewing DxO ViewPoint in more detail in the near future. In the mean time you can download a 31 day trial version from the DxO website.
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