ChromaKey with EX1? at DVinfo.net

Ken Hull · November 23rd, 2007, 02:53 AM

For some time I've been hearing that, for chromakey work, the HVX200 is the way to go, because of its 4:2:2 color encoding. But when I saw still frame comparisons of the HVX200 and the EX1, the latter was obviously more detailed. So my question is: For chromakey work, does the greater detail of the EX1 trump the 4:2:2 encoding of the HVX200?

And now that many of you have an EX1, anyone done a chromakey comparison test between the HVX200 and the EX1?

Steven Thomas · November 23rd, 2007, 07:50 AM

Pull up the 1080 30P samples for the EX1 and HVX200. look at the red car in the bottom left corner. I believe the EX1 is going to key well.
I'm amazed at how natural the image looks without the nasty artifacts that are seen in this image from the HVX200.

Joseph H. Moore · November 23rd, 2007, 09:02 AM

The other thing to consider is that there is a new batch of keyers coming onto the market that have designed to deal with subsampled color resolution. The author of DVMatte has been on the boards showing some results he's got from a little HV20, and it's pretty amazing.

I think we're getting to a place that if you have a high resolution, progressive image, that the color sub-sampling is becoming a non-issue. It also seems that the desktop tools are progressing such that the limits on keys are fats becoming more from the operator than the tool.

Chris Forbes · November 23rd, 2007, 09:52 AM

Hey guys I am going to do some real testing today with chroma keying. I am going to capture 10 bit out of the HDSDI port and record at the same time to the expresscard. To see how much of a difference that makes. I post some stuff this weekend.

Joseph H. Moore · November 23rd, 2007, 09:57 AM

You da man!

Steven Thomas · November 23rd, 2007, 03:35 PM

Thank you Chris!

Steven Thomas · November 23rd, 2007, 06:52 PM

At least based on the 1080P stuff, it's obvious that a better key would come from the EX1.
Here's the red car comparison.
Again, I believe the HX200 holds up a lot better using 720P.
One on the best improvements needed for the HVX200 would be in noise levels.
If the HVX200 had improved noise, the 4:2:2 images would look a lot better, although
would still be soft would directly compared to the EX1.

Joe Carney · November 24th, 2007, 01:13 PM

Quote:

Originally Posted by Chris Forbes

Hey guys I am going to do some real testing today with chroma keying. I am going to capture 10 bit out of the HDSDI port and record at the same time to the expresscard. To see how much of a difference that makes. I post some stuff this weekend.

10bit output for chroma keying is why I'm interested in this cam. Looking forward to your tests.

Sebastien Thomas · November 24th, 2007, 04:35 PM

The picture with the red car is so damn sharp it looks like if there was peaking on it :)
One good thing with a real native HD format is the precision you'll have when keying. But due to the 4:2:0 sampling, you may have to tweek the settings a lot more to go through the subsampling problem.

I would love to get some footages of green/blue screen. Maybe somone will post soon ?

Cheers !

Stelios Christofides · November 25th, 2007, 03:29 PM

Wow the picture with the red car is stunning. Please God let me save some money for the EX1!

Stelios

Thomas Smet · November 25th, 2007, 08:14 PM

Well here is something to think about.

Usually when people do keying it is a pretty complex setup in a stage sort of environment. No matter what camera is used you will always get much better results by capturing live from the head. This is even true with the Cinealta F900 used in Star Wars Episode 2. All the shots were captured to a system so they could have high quality 10 bit material to work with.

With that said the EX1 would totally blow away the HVX200 for live uncompressed capture. The chips are better, the SDI is better then component and it is 10 bits instead of 8 bits. In every single way you can think of, a live capture from the EX1 will be better.

So if you really do want the best quality for keying stop thinking of the camera recording format and move on to where the real quality is. No matter what format from the camera you use you will be dealing with some form of compression compromise and DCT based image artifacts.

There are plenty of HD format options instead of uncompressed such as Bitjazz and Cineform.

Brett Bevelacqua · November 25th, 2007, 08:50 PM

I'll tell you one thing, I'll never touch a debut Sony model again, I learned my lesson with my FX-1 and Z-1. So I guess I'll just suffer with the results of my 2 lackluster HVXs. With the money I spent repairing the Sonys at Mack Camera I could have almost paid for a third HVX.

Barlow Elton · November 25th, 2007, 10:30 PM

I hate to be the bearer of bad news...but I think the EX1 is truncated 10 bit (8bit with two bits set to zero) just like the H1 and G1.

Chris and I captured some tethered SDI material via 10 bit Sheervideo codec capture within FCP. We shot the sky at dusk from my backyard and I couldn't see a difference between 8 bit and 10 bit capture. The gradient was still reasonably smooth but still looked like 8 bit to me.

Jack Zhang · November 25th, 2007, 10:42 PM

^Looks like the DSP for this camera aren't as advanced as it seems... But it does work for the compressed formats they're recorded to. We might see a EX7 with MPEG422 codec or a AVC (preferably Intra) codec having higher precision.

Barlow Elton · November 25th, 2007, 10:55 PM

I don't think it's the DSP. I think it's market segmentation.

November 23rd, 2007, 02:53 AM	#1
Ken Hull Major Player Join Date: Nov 2007 Location: San Diego, CA Posts: 240	ChromaKey with EX1? For some time I've been hearing that, for chromakey work, the HVX200 is the way to go, because of its 4:2:2 color encoding. But when I saw still frame comparisons of the HVX200 and the EX1, the latter was obviously more detailed. So my question is: For chromakey work, does the greater detail of the EX1 trump the 4:2:2 encoding of the HVX200? And now that many of you have an EX1, anyone done a chromakey comparison test between the HVX200 and the EX1?

November 23rd, 2007, 06:52 PM	#7
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	At least based on the 1080P stuff, it's obvious that a better key would come from the EX1. Here's the red car comparison. Again, I believe the HX200 holds up a lot better using 720P. One on the best improvements needed for the HVX200 would be in noise levels. If the HVX200 had improved noise, the 4:2:2 images would look a lot better, although would still be soft would directly compared to the EX1. Attached Thumbnails Last edited by Steven Thomas; November 23rd, 2007 at 07:00 PM. Reason: more to add

November 25th, 2007, 03:29 PM	#10
Stelios Christofides Trustee Join Date: Jul 2003 Location: Nicosia, CYPRUS Posts: 1,080	Wow the picture with the red car is stunning. Please God let me save some money for the EX1! Stelios __________________ My Blog: http://steliosc.blogspot.com "I hope for nothing, I fear nothing, I am free" Nikos Kazantzakis

November 25th, 2007, 08:50 PM	#12
Brett Bevelacqua New Boot Join Date: Jan 2005 Location: Palisades, NY Posts: 15	I'll tell you one thing, I'll never touch a debut Sony model again, I learned my lesson with my FX-1 and Z-1. So I guess I'll just suffer with the results of my 2 lackluster HVXs. With the money I spent repairing the Sonys at Mack Camera I could have almost paid for a third HVX. __________________ http://www.hmpfilms.com/

November 23rd, 2007, 07:50 AM	#2
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	Pull up the 1080 30P samples for the EX1 and HVX200. look at the red car in the bottom left corner. I believe the EX1 is going to key well. I'm amazed at how natural the image looks without the nasty artifacts that are seen in this image from the HVX200.

November 23rd, 2007, 09:02 AM	#3
Joseph H. Moore Major Player Join Date: Oct 2005 Posts: 362	The other thing to consider is that there is a new batch of keyers coming onto the market that have designed to deal with subsampled color resolution. The author of DVMatte has been on the boards showing some results he's got from a little HV20, and it's pretty amazing. I think we're getting to a place that if you have a high resolution, progressive image, that the color sub-sampling is becoming a non-issue. It also seems that the desktop tools are progressing such that the limits on keys are fats becoming more from the operator than the tool.

November 23rd, 2007, 09:52 AM	#4
Chris Forbes Regular Crew Join Date: Mar 2006 Location: Salt Lake City, Ut Posts: 155	Hey guys I am going to do some real testing today with chroma keying. I am going to capture 10 bit out of the HDSDI port and record at the same time to the expresscard. To see how much of a difference that makes. I post some stuff this weekend.

November 23rd, 2007, 09:57 AM	#5
Joseph H. Moore Major Player Join Date: Oct 2005 Posts: 362	You da man!

November 23rd, 2007, 03:35 PM	#6
Steven Thomas Trustee Join Date: Sep 2005 Location: Gilbert, AZ Posts: 1,896	Thank you Chris!

November 24th, 2007, 04:35 PM	#9
Sebastien Thomas Major Player Join Date: Nov 2007 Location: Paris, France Posts: 210	The picture with the red car is so damn sharp it looks like if there was peaking on it :) One good thing with a real native HD format is the precision you'll have when keying. But due to the 4:2:0 sampling, you may have to tweek the settings a lot more to go through the subsampling problem. I would love to get some footages of green/blue screen. Maybe somone will post soon ? Cheers !

November 25th, 2007, 08:14 PM	#11
Thomas Smet Trustee Join Date: Mar 2004 Location: Milwaukee, WI Posts: 1,719	Well here is something to think about. Usually when people do keying it is a pretty complex setup in a stage sort of environment. No matter what camera is used you will always get much better results by capturing live from the head. This is even true with the Cinealta F900 used in Star Wars Episode 2. All the shots were captured to a system so they could have high quality 10 bit material to work with. With that said the EX1 would totally blow away the HVX200 for live uncompressed capture. The chips are better, the SDI is better then component and it is 10 bits instead of 8 bits. In every single way you can think of, a live capture from the EX1 will be better. So if you really do want the best quality for keying stop thinking of the camera recording format and move on to where the real quality is. No matter what format from the camera you use you will be dealing with some form of compression compromise and DCT based image artifacts. There are plenty of HD format options instead of uncompressed such as Bitjazz and Cineform.

November 25th, 2007, 10:30 PM	#13
Barlow Elton Major Player Join Date: Mar 2005 Location: UT Posts: 945	I hate to be the bearer of bad news...but I think the EX1 is truncated 10 bit (8bit with two bits set to zero) just like the H1 and G1. Chris and I captured some tethered SDI material via 10 bit Sheervideo codec capture within FCP. We shot the sky at dusk from my backyard and I couldn't see a difference between 8 bit and 10 bit capture. The gradient was still reasonably smooth but still looked like 8 bit to me.

November 25th, 2007, 10:42 PM	#14
Jack Zhang Inner Circle Join Date: May 2005 Location: Burnaby, BC, Canada Posts: 3,053	^Looks like the DSP for this camera aren't as advanced as it seems... But it does work for the compressed formats they're recorded to. We might see a EX7 with MPEG422 codec or a AVC (preferably Intra) codec having higher precision.

November 25th, 2007, 10:55 PM	#15
Barlow Elton Major Player Join Date: Mar 2005 Location: UT Posts: 945	I don't think it's the DSP. I think it's market segmentation.