Hi Rick, curious if there has been any progress made on this in the recent Paint.NET builds? I've come across a 4:4:4 image that is beautiful, when edited and "saved" by Paint.NET it drops the quality down to 4:2:0 with no option to preserve the bits. It's a crazy complex image and the downgrade is quite noticeable. I've tried the OptiPNG-file-type-plugin but found that through several trials with different settings, the quality is preserved (awesome!) but the file size is not reduced relative to a standard PNG file.
Original File: 4:4:4 ~ 5mb
Save as JPG (100%): 4:2:0 ~ 3.5mb
Edit, Save as PNG ~ 11mb
Save with OptiPNG ~ 11mb
... so, curious about the 4:4:4 option and when this might be made available? If nothing else, I'm a little concerned now in learning that Paint.NET doesn't AT LEAST preserve the original JPG settings when re-saving ... even when selecting the 100% setting in the save-as dialogue.