This information applies to versions 6 and newer
Images edited in earlier versions of DxO PhotoLab can still be opened in version 6 and newer. By default, any images imported from a previous version will use the 'legacy working color space'. You can then choose to convert them to the new color space, in order to take advantage of the expanded editing possibilities offered by DxO PhotoLab. To do this, please use the “Working Color Space” palette under the “Color” tab. Choose “version / DxO Wide Gamut” from the menu.
Please note that changing the working color space of an image may result in slightly different hues for some colors.
Even after choosing to update the working color space of an image to the new DxO Wide Gamut, you can still revert to the legacy one at any time.
To find out more about DxO Wide Gamut colorspace, we have put together some brief information under this link and more detailed information and background under this other link.