Generally, edge haloing is a result of over sharpening and too much edge contrast. You can see test the effects of over sharpening yourself using the Unsharp Mask. Zoom in a bit on a photo to see objects with hard edges more closely. Using the Unsharp Mask, keep the threshold setting very low and gradually increase the intensity and radius sliders. You will quickly start to see increasingly wide haloing along the edges.
It is a fine line (pun intended) between the right amount of sharpening and over sharpening. Using the Unsharp Mask is not recommended for images captured with lenses where DxO has provided a lens profile.
When a lens profile is available use the Lens Softness Correction feature instead. While Lens Softness Correction is less prone to creating strong halos it can still create them if the settings are too high,. Try not to over apply it. The default amount is usually sufficient and for many photos it may even be a bit too high.
Lens Softness Correction is not available for images captured with lenses for which there is no DxO lens profile available. For those images use the UnSharp Mask instead. When using the Unsharp Mask you need to learn through experience how a combination of various intensity, radius, and threshold settings affect the sharpness of your images.
Those who are new to post processing often tend to over process their images by applying too much sharpness and contrast.
DxO ClearView Plus can introduce haloing rather easily. (Fortunately this can be applied as a local adjustment instead of a global adjustment.) So can chromatic aberrations even after they’ve been corrected. (Unfortunately, that’s more of a problem with the lens.) Or too much of any contrast adjustment.
@joanna:
When using a local adjustment, how does one “reduce” ClearviewPlus (CVP)? I’m on a PC and cannot reduce CVP - it starts at 0 on the left edge of the slider and cannot go to negative values. I can reduce contrast/microcontrast.
Thanks!