There is no method of adjusting the colorspace or resolution because these are controlled by the source device. There are multiple stages in the conversion of the video signal to emulate the Raspberry Pi Camera, and after being received the signal is also manipulated in the Raspberry Pi GPU.
Originally you were trying to resolve the color issue you are seeing with a PC source, but you have switched to a camera – the solutions may be different for different sources. Which source are you most interested in using with PiCapture?
If you are working with a PC, starting with the gamma settings as described above are a good first step. For cameras which may not have output controls, it may be necessary to manually adjust the white balance settings on the Raspberry Pi side. You mention using the PiCamera library, but it may be easier to start with using Raspivid to adjust settings until you are satisfied with the color.