Film-Tech Forum ARCHIVE: How to fix low contrast/milky blacks on HDMI input (christie series 2)?

This is topic How to fix low contrast/milky blacks on HDMI input (christie series 2)? in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Andrew Thomas (Member # 7000) on 04-13-2014, 01:43 PM:

Hi guys,

I've noticed that all my sources on the HDMI (well, HDMI over DVI) inputs has really poor contrast and elevated black levels compared to DCP material. This is even the case when playing stuff like ad content from a USB stick on my blu-ray player vs. the same ad converted to DCP.

Any settings I can change to improve this?

Posted by Carsten Kurz (Member # 5396) on 04-13-2014, 02:13 PM:

Christie/DVI defaults to 'extended range' (0-255), while most HDMI sources default to standard range, 16-235.
To be picky, 'extended' or 'standard' is referenced to HDMI, because for DVI aka computer signaling, 0-255 should be considered 'normal range'.

Check the setup menu of your BluRay Player for adjustment options.

You can also set it in the Christie channel setup. Best is probably to have one DVI set to 0-255 and the other to 16-235. Typical choices are 0-255 4:4:4 RGB for DVI/RGB sources ('computers') and 16-235/YCbCr 4:2:2 for HDMI consumer entertainment devices.

http://www.audioholics.com/home-theater-calibration/hdmi-black-levels-xvycc-rgb

- Carsten

Posted by Marco Giustini (Member # 4544) on 04-13-2014, 02:49 PM:

Hi Carsten

I have asked the question before, I believe someone said it could be done but never said how.
Are you sure that YCbCr implies "video" levels?

Posted by Carsten Kurz (Member # 5396) on 04-13-2014, 03:14 PM:

I can only say 'usually'. RGB defaults to 4:4:4 RGB 0-255 and YCbCr to 4:2:2 16-235

I have seen separate extended/normal range and RGB/YCbCr settings on some few devices. Though I am guilty of not investigating into it further ;-)

I understand that for practical reasons, BluRay player manufacturers need to find simple options to connect a player to 'proper' HDMI sinks like TVs, but also HDCP enabled DVI inputs on computer monitors. To simplify this, YCbCr should default to 16-235 and RGB to 0-255. At least that's what I found out when I tried various computer monitors on BluRay players.

- Carsten

Posted by Andrew Thomas (Member # 7000) on 04-13-2014, 07:52 PM:

I figured it was along those lines. Thanks, I'll try once our last shows end.

Posted by Andrew Thomas (Member # 7000) on 04-13-2014, 09:31 PM:

Hmmm, there is no option besides RGB on the DVI inputs.

Posted by Carsten Kurz (Member # 5396) on 04-14-2014, 07:44 AM:

That's right for series I and series II 'native' DVI inputs (means: no IMB/IMS).

In this case, you either need to find a proper RGB-full setting on the player, or use a scaler with that functionality.

- Carsten

Posted by Marco Giustini (Member # 4544) on 04-14-2014, 03:17 PM:

I'll give it a go, thanks. I believe you can still select the proper colour space by using the TI software.

Posted by Carsten Kurz (Member # 5396) on 04-14-2014, 04:16 PM:

I don't know. Regarding 16-235 I have no idea how they deal with it and wether TI DC software supports that mode.

- Carsten

Posted by Marco Giustini (Member # 4544) on 04-15-2014, 03:45 PM:

It doesn't, but you should still be able to select YCbCr on a Barco - even though I'm not sure about it.