Fixing wrong Colorimetry from capture card

SquallMX · 16th December 2014, 21:39

Hi.

I just brought a cheap hdmi capture card, quality is decent, but after some text I start to notice that the colours are a bit off vs the original source.

Original:

Captured MP4:

Colormatrix() almost fix the issue, but is not perfect:

Any ideas for improvements?

foxyshadis · 16th December 2014, 23:05

Maybe it's going through some kind of filtering step during capture? What are you using to "display" the picture to the capture card? Maybe that system is tweaking the output some. It can be really tough to track down that stuff, since video card settings, ICC profiles, directshow settings, and player filtering can all affect it (or their analogues for hardware players).

SquallMX · 17th December 2014, 00:25

Just a PS3 with automatic settings, no weird options. The comparative was made using DGIndexNV + VDubMod.

The ColorMatrix() output is good enough, I'm just trying to find a better option.

hello_hello · 18th December 2014, 01:11

If there's a difference between the original and colormatrix screenshots in respect to colour, I'm having trouble seeing it. They're not exactly the same, but I think I'm just seeing encoding differences, not colour differences.

ChiDragon · 21st December 2014, 19:01

The PS3 playing back in "file" mode can only output RGB. To get a straight YCbCr capture you need to play an authored disc (Blu-ray, AVCHD, DVD) and have all the relevant options set in the Video Output settings. Verify whether you can get accurate luma and chroma planes this way.

Otherwise you are relying on both the PS3 and capture device to use accurate matrices, and you will still get rounding errors, etc.

16th December 2014, 21:39	#1 \| Link
SquallMX Special SeeD Join Date: Nov 2002 Location: Mexico Posts: 333	Fixing wrong Colorimetry from capture card Hi. I just brought a cheap hdmi capture card, quality is decent, but after some text I start to notice that the colours are a bit off vs the original source. Original: Captured MP4: Colormatrix() almost fix the issue, but is not perfect: Any ideas for improvements?

16th December 2014, 23:05	#2 \| Link
foxyshadis Angel of Night Join Date: Nov 2004 Location: Tangled in the silks Posts: 9,559	Maybe it's going through some kind of filtering step during capture? What are you using to "display" the picture to the capture card? Maybe that system is tweaking the output some. It can be really tough to track down that stuff, since video card settings, ICC profiles, directshow settings, and player filtering can all affect it (or their analogues for hardware players).

17th December 2014, 00:25	#3 \| Link
SquallMX Special SeeD Join Date: Nov 2002 Location: Mexico Posts: 333	Just a PS3 with automatic settings, no weird options. The comparative was made using DGIndexNV + VDubMod. The ColorMatrix() output is good enough, I'm just trying to find a better option.

18th December 2014, 01:11	#4 \| Link
hello_hello Registered User Join Date: Mar 2011 Posts: 4,829	If there's a difference between the original and colormatrix screenshots in respect to colour, I'm having trouble seeing it. They're not exactly the same, but I think I'm just seeing encoding differences, not colour differences.

21st December 2014, 19:01	#5 \| Link
ChiDragon Registered User Join Date: Sep 2005 Location: Vancouver Posts: 600	The PS3 playing back in "file" mode can only output RGB. To get a straight YCbCr capture you need to play an authored disc (Blu-ray, AVCHD, DVD) and have all the relevant options set in the Video Output settings. Verify whether you can get accurate luma and chroma planes this way. Otherwise you are relying on both the PS3 and capture device to use accurate matrices, and you will still get rounding errors, etc.