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Hans Pool · February 20th, 2006, 01:24 PM

I did some tests with my new GY-HD101 and found some really strange effects. I made a shot of a walking girl with some purple boots. I analysed the footage frame by frame, and I saw some purple "haze" also in the next frames. It made the image looking a kind of blurry. I also noticed this effect on a blue shirt. The "smooth motion" was turned off. Is there another setting or is it typical JVC, or is it a bigger problem?

Tim Dashwood · February 20th, 2006, 01:44 PM

Can you please post a frame grab so we can see what you are describing? It sounds a bit like CA, but not quite. It could be artifacts to do blue/purple with 4:2:0 MPEG2? I'd have to see it with my own eyes.

Joe Russ · February 20th, 2006, 02:17 PM

It sounds either like CA or it may be a function of the compression technique employed by JVC. I got my camera about 2 weeks ago and did some extensive testing, I found out what breaks the compressor very quickly.

One of the things...I shot high motion out of focus and it became obvious that the compressor (pre-compression) is using a sort of surface blur (or similar, check it out in photoshop) for large out of focus areas.

This would make perfect sense, if you want the meat of the data going to some1s face thats in focus and you dont want to waste bits compressing a soft background that no1 will look closely at, you smooth it a bit and it will compress much better with no real visible loss in quality. I think it's very smart, but it makes (for me) certain shots unusable (such as fast panning with a certain amount of out of focus elements).

Hope this helps, If I were at home I'd post screen grabs/footage to show this, but it will have to wait until work ends, hah.

Jiri Bakala · February 20th, 2006, 02:27 PM

Quote:

Originally Posted by Joe Russ

...some1s face thats in focus and you dont ...no1 will look...

Interesting spelling...kind of hard to read, I have to say. :-)

Hans Pool · February 20th, 2006, 02:32 PM

http://www.26000gezichten.nl/view.php?id=147

This is a smal film about a Iraqi girl in Holland. It's very difficult to see in this quality, but even then you are able to see the colour of her boots in the next 3 or 4 frames. I've worked with many camera's but I didn't noticed this effect until this day with this camera.

Tim Dashwood · February 20th, 2006, 02:47 PM

Yeah. It looks like something purple and fast went through one frame in the middle of a GOP and left an MPEG "ghost." Is this the way it is in the original m2t, or was this caused when the video was encoded for the internet?

Hans Pool · February 20th, 2006, 03:00 PM

This "effect" is in the original material. I have it in all my footage, when the object is moving (fast) or the camera is moving?

Diogo Athouguia · February 20th, 2006, 03:25 PM

Are you refering to a pink "ghost" on the girls boots? Never seen anything like that on my camera. Nice footage by the way.

February 20th, 2006, 01:24 PM	#1
Hans Pool New Boot Join Date: Nov 2005 Posts: 9	blurring image I did some tests with my new GY-HD101 and found some really strange effects. I made a shot of a walking girl with some purple boots. I analysed the footage frame by frame, and I saw some purple "haze" also in the next frames. It made the image looking a kind of blurry. I also noticed this effect on a blue shirt. The "smooth motion" was turned off. Is there another setting or is it typical JVC, or is it a bigger problem?

February 20th, 2006, 01:44 PM	#2
Tim Dashwood Wrangler Join Date: Aug 2005 Location: Toronto, ON, Canada Posts: 3,637	Can you please post a frame grab so we can see what you are describing? It sounds a bit like CA, but not quite. It could be artifacts to do blue/purple with 4:2:0 MPEG2? I'd have to see it with my own eyes. __________________ Tim Dashwood

February 20th, 2006, 02:32 PM	#5
Hans Pool New Boot Join Date: Nov 2005 Posts: 9	blurring image http://www.26000gezichten.nl/view.php?id=147 This is a smal film about a Iraqi girl in Holland. It's very difficult to see in this quality, but even then you are able to see the colour of her boots in the next 3 or 4 frames. I've worked with many camera's but I didn't noticed this effect until this day with this camera.

February 20th, 2006, 02:47 PM	#6
Tim Dashwood Wrangler Join Date: Aug 2005 Location: Toronto, ON, Canada Posts: 3,637	Yeah. It looks like something purple and fast went through one frame in the middle of a GOP and left an MPEG "ghost." Is this the way it is in the original m2t, or was this caused when the video was encoded for the internet? __________________ Tim Dashwood

February 20th, 2006, 03:00 PM	#7
Hans Pool New Boot Join Date: Nov 2005 Posts: 9	blurring image This "effect" is in the original material. I have it in all my footage, when the object is moving (fast) or the camera is moving?

February 20th, 2006, 02:17 PM	#3
Joe Russ Regular Crew Join Date: Jul 2003 Location: New York, NY Posts: 99	It sounds either like CA or it may be a function of the compression technique employed by JVC. I got my camera about 2 weeks ago and did some extensive testing, I found out what breaks the compressor very quickly. One of the things...I shot high motion out of focus and it became obvious that the compressor (pre-compression) is using a sort of surface blur (or similar, check it out in photoshop) for large out of focus areas. This would make perfect sense, if you want the meat of the data going to some1s face thats in focus and you dont want to waste bits compressing a soft background that no1 will look closely at, you smooth it a bit and it will compress much better with no real visible loss in quality. I think it's very smart, but it makes (for me) certain shots unusable (such as fast panning with a certain amount of out of focus elements). Hope this helps, If I were at home I'd post screen grabs/footage to show this, but it will have to wait until work ends, hah.

February 20th, 2006, 03:25 PM	#8
Diogo Athouguia Major Player Join Date: May 2005 Location: Portugal Posts: 282	Are you refering to a pink "ghost" on the girls boots? Never seen anything like that on my camera. Nice footage by the way.