NEO U9-H HDMI colorspace problems

Hi all
I run my NEO U9-H with Android 6.0.1 and the latest firmware 008 with Kodi. I tried to calibrate my projector, but the results are poor.
It seems that the "colorspace" output on the HDMI-port is somehow "compressed":
For calibration, I need the unchanged data (video-testcharts) with rgb values 16-235 (video-standard) on the hmdi-output.
Has anyone else seen this problem?
Thanks and regards
d-vine, thanks for the answer.
Yes, I use the patterns you mentioned with the hcfr-calibration-software. But the results are not good.
So, my question is:
Does the GPU of the U9-H convert/change the rgb values from the kodi-player in any way, or does the GPU
only send the values to the hdmi-port, aka "passthrough"?
Probably someone from the minix-developers knows the answer...
Hi Cpt_Future,

As d-vine indicated, try switching to the latest CoreElec with Kodi 18.

With a 4K HDR demo, these are the results I got:

- Android Kodi 17.6: 4K59.933 420 BT2020 10b HDR 371MHz

- CoreElec Kodi 18: 4K59.933 422 BT2020 12b HDR 593MHz

Make sure you have HDMI cables which support 18Gbps (600MHz pixel clock).