I think the problem is coming from the change you made to the virtual stage. Leave the Virtual Stage at its original resolution (1920x1080) and you’ll only need to zoom out, which results in less loss of quality.

video in watcher to projector to a virtual stage. Make the virtual stage 1920 x 1080 pxSpin the projector 90 degrees.In the projector turn OFF keep aspectchange zoom to ±55% and width to 178Use Get Stage Image of virtual stage to bring the rotated image in the correct orientation into my scenes.

Best regards

Jean-François 

@jaio

If you can find a suitable cube LUT, for converting rec 2020 to rec 709, you could use my 'color grading' shader (TROIKATRONIX : ISADORA - DX – PY – Cube2LUT – ColorGrading).

This should allow you to convert the color, but will not be as true to source as making the conversion in something like Davinci Resolve (my recommended option).