The original image of a couple kids being photographed by their mother.
All colors except for blue are desaturated using the saturation curve of the HSV tool.
Fine tune in CIECAM using the JS Lightness and Saturation algorithm.
That's it folks.
But, of course, with RT editing nothing is ever finished. So here is the new stuff you can create when you switch to the all algorithm and start draggin' them sliders around. The hidden artist titles this 'Cindy's Nightmare - Do you have to tell wicked step moma you caught me sneaking out to the Prince's Rave?'
The hue slider gives a full range of of colors
When ISO6400 noise is all the same color it becomes artistic texture. Fine tune that with the Noise Reduction Chromatic sliders
The other CIECAM sliders work pretty much as expected but with different intensities. For example the Q brightness slider is stronger than the L lightness slider and at 100% washes everything except the colors to white
Happy exploring your own Hidden Artist
Processed with RawTherapee 18.104.22.168 which can be found at http://rawtherapee.com/downloads