This information applies to versions 6 and newer
Soft proofing is a method of simulating how an image will appear when transposed from one color space to another. It is commonly used to check how an image will look when printed on paper, but it can also be used to emulate another monitor or device for the same purpose. When applying soft proofing, an ICC profile is loaded which emulates the new display medium (for example a physical print or a different device or display) in order to show how your image will appear.
Please note that an appropriate ICC profile must be loaded on your computer and selected in DxO PhotoLab 6 for any given combination of printer and paper. You can find these for free on the websites of printer and paper manufacturers as well as online printing services. For the best results, we always recommend working with a calibrated monitor.