Color space

general questions about Neat Video
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Joined: Mon Aug 11, 2008 7:33 am

Color space

Post by jpsdr » Mon Aug 16, 2010 7:58 am


I'm wondering. In the VDub pluggin, actualy only RGB input are supported (maybe it will change in the future), but, internaly, you said in the manual that you convert to YCbCr (if the mode of the filter is set to this mode).
My question, is, that now, with the several existing mode (BT.709 for HD, BT.601 for SD wich are the most common used), what color space/matrix is used for the internal convertion ?
Can it be possible to have somewhere an option where you can chose in what color space you are working ? Option, of course, wich will be used only when RGB <-> YCbCr convertion will be involved.
Option even more 'requiered' if the next VDub version will sill not work with native YUV format (YV12,YUY2,YV16,YV24, etc...).

I've developped my own VDud filter RGB <-> YCbCr, where you can chose the color matrix convertion.
I've made the following test : I've a 1080p YV12 video in input, and do 2 differtents output video, one using RGB convertion from internal VDub (i assume it must be using BT.601), and another with my RGB convertion filter, using BT.709 (wich was the one for my input file). I thought that result would be the same, as my ouput was also converted back to YCbCr. So even if you use the wrong matrix format, if both convertions are made with the same matrix, i thought it should matter. I was wrong, there was differences in the video. I've extrated a picture of the same frame on each video, and do planar differences in Photoshop, and result show differences.
So, it seems that color matrix have an impact.

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Post by NVTeam » Mon Aug 16, 2010 9:10 am

An alternative internal working color space is used inside the filter but it is not not related to the color space of the original video data in any way so there is no need to adjust it in relation to input data's color space.

Color conversion YCbCr <-> RGB is handled by VirtualDub, so, assuming its back and forth conversions are accurate, there shouldn't be any problem.

Our internal conversions are accurate.

Since we currently support only RGB input, there is no room for wrong color conversions in our VirtualDub->NeatVideo->VirtualDub dataflow.

Image Image Neat Video team
noise reduction for video and photos

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