Fading an image by a given percentage (partially transparent white overlay)

[techjp]

With the command line, I can apply a partially transparent white overlay on top of an image to "fade" it, essentially desaturate it, to make it better for website category images that then have text placed on them. The command line command is:

magick convert input.png -fill white -colorize 40% -quality 65 -strip output40.jpg

Of course that also converts to JPG and strips any EXIF data, but it's the "-fill white -colorize 40%" part that I have not been able to recreate in Magick.NET.

I've spent hours trying to make this work with Magick.NET and am no further ahead than when I started. Help, please?

[techjp]

How embarrassing, moments after posting the above question I found that it worked in the most obvious way possible:

img.Colorize(New MagickColor("White"), New Percentage(40))