Possible Fix for CA / Color Fringing? at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XH Series HDV Camcorders

Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


Reply
 
Thread Tools Search this Thread
Old April 11th, 2007, 12:51 PM   #1
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
Possible Fix for CA / Color Fringing?

When experimenting with the VividRGB preset created by Steven Dempsey, I happened upon an observation when using the modded preset below...what appears to completely eliminate objectionable color fringing, aka chromatic aberration. It seems wholly disappeared from my observations, marginal vestiges at the extremes remain at most. Anyone want to try this out? You have to use the presets below, exactly, doesn't work for gamma Cine1. If someone can duplicate the observation, we can begin deviating from the preset to narrow down the contributing variables.

Gamma: Normal
Color Matrix: Normal
Color Gain: 25
Color Phase: 0
Knee: Auto
Black: Middle
Master Ped: -5
Setup Level: 0
HDF: Mid
H/V Detail: 0
Sharpness: 0
NR1: Off
NR2: Off
Coring: 0
Red Gain: -2
Green Gain: -2
Blue Gain: -3
RG Matrix: 0
RB Matrix: 0
GR Matrix: 0
GB Matrix: 10
BR Matrix: 0
BG Matrix: -13
Tom Roper is offline   Reply With Quote
Old April 11th, 2007, 01:01 PM   #2
Trustee
 
Join Date: Jan 2005
Location: Plainview, N.Y.
Posts: 1,944
Tom, any idea how a preset could erase a lens deficiency?
Ken Ross is offline   Reply With Quote
Old April 11th, 2007, 01:09 PM   #3
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
According to what Chris Hurd and A.J. DeLange have been saying all along, it's not a lens phenomenon, agree or disagree as you choose. But if it was, why would this fix it? So we seem to be in agreement about that.

Anyone else try this yet?
Tom Roper is offline   Reply With Quote
Old April 11th, 2007, 01:54 PM   #4
Inner Circle
 
Join Date: Aug 2006
Location: Poland
Posts: 4,086
One important factor is that with lower contrast the fringing is less visible. And not engaging cine (gamma or colours) simply diminish the contrast, hence the result...IMHO:)
__________________
Sony PXW-FS7 | DaVinci Resolve Studio; Magix Vegas Pro; i7-5960X CPU; 64 GB RAM; 2x GTX 1080 8GB GPU; Decklink 4K Extreme 12G; 4x 3TB WD Black in RAID 0; 1TB M.2 NVMe cache drive
Piotr Wozniacki is offline   Reply With Quote
Old April 11th, 2007, 02:03 PM   #5
Trustee
 
Join Date: Jan 2005
Location: Plainview, N.Y.
Posts: 1,944
Quote:
Originally Posted by Tom Roper View Post
According to what Chris Hurd and A.J. DeLange have been saying all along, it's not a lens phenomenon, agree or disagree as you choose. But if it was, why would this fix it? So we seem to be in agreement about that.

Anyone else try this yet?
I guess the thing I don't understand is if it's not CA, why does it tend to show up on the edges of the frame where you would expect CA to show? If it's electronic, wouldn't that manifest itself in many parts of the frame?
Ken Ross is offline   Reply With Quote
Old April 11th, 2007, 02:40 PM   #6
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
Quote:
Originally Posted by Piotr Wozniacki View Post
One important factor is that with lower contrast the fringing is less visible. And not engaging cine (gamma or colours) simply diminish the contrast, hence the result...IMHO:)
There's more contrast to the gamma Normal setting. Cine1 flattens the highlights. It's already a high contrast setting by virtue of the Master Pedastal -5 setting. That's why someone needs to try this so we can stop guessing.
Tom Roper is offline   Reply With Quote
Old April 12th, 2007, 03:03 AM   #7
Major Player
 
Join Date: Dec 2005
Location: Kelkheim, Germany
Posts: 375
Tom, I'll give it a try today in bright sunlight.
__________________
Michael
Michael Mann is offline   Reply With Quote
Old April 12th, 2007, 02:36 PM   #8
Major Player
 
Join Date: Dec 2005
Location: Kelkheim, Germany
Posts: 375
Meanwhile I tested the preset:
Frankly, I don't see significantly less fringing than with any other preset I have used so far. The fringing seems to have less contrast but it is still visible.
__________________
Michael
Michael Mann is offline   Reply With Quote
Old April 13th, 2007, 05:50 PM   #9
Major Player
 
Join Date: Mar 2005
Location: Northampton, England
Posts: 500
Today I did some tests to see if I could find out if changing the preset settings helped to make any difference to the CA / green-magena colour fringing.

I found an area high contrast (a tall white ornament against a dark wall) and positioned it towards the edge of the frame on a wide lens.

What I found surprised me. With the custom presets off there was very little fringing at all, but as I started switching between different custom presets it became very apparent that the presets make a large difference to how obvious the fringing appears. VIVIDRGB setting showed a little more fringing than with presets off, and Wolfgang's new preset showed a huge amount of fringing (which is a shame because I wanted to use that preset!)

Anyway, my test wasn't particularly scientific. I wasn't recording, just mucking around. And I didn't have long to try it out. So I started making changes to the presets to see if I could understand what was going on, but I'm not really certain so far. Cine Gamma and colour Matrix seem to make the fringing look worse. And running the colour gain higher also makes it more obvious. But I need to get a bit more time experimenting with this to see if I can work it out.
__________________
Alex
Alex Leith is offline   Reply With Quote
Old April 13th, 2007, 08:45 PM   #10
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
So it sounds like we're just making what's already there more or less apparent.

By increasing color saturation we're enhancing the fringing as well.

I still find some support in the observation about the Cine1 gamma showing more fringing. It seems noticeably less as the contrast setting swings to more, not what you'd think.
Tom Roper is offline   Reply With Quote
Old April 14th, 2007, 08:28 AM   #11
Major Player
 
Join Date: Mar 2005
Location: Northampton, England
Posts: 500
With a little more time and an only-very-slightly-more-scientific approach (I wrote down what settings I was using!) I've found that there is very little in the custom presets and gamma settings that effects the actual amount of Chromatic Aberration / Green-Magenta Fringing in the image. However, the fringing may be hidden in the image better by some presets, depending on the nature of the scene you're shooting at that moment.

The only two controls that apparently effects the amoung of fringing in the image are HDF (Horizontal Detail Frequency) - low shows less fringing than mid, which shows less fringing than high; And DHV (Horizontal Vertical Detail Balance) - lower numbers show less fringing than higher numbers.

So, my conclusion is that you could significantly reduce fringing by setting HDF to LOW and DHV to -9, but obviously there is a significantly detremental effect to the quality of the image!

The attached images are a 1:1 resolution (click to see them at full size) showing the lower-right-hand area of the HDV frame, with the lens zoomed to widest angle.
Attached Thumbnails
Possible Fix for CA / Color Fringing?-ca-test-01.jpg   Possible Fix for CA / Color Fringing?-ca-test-02.jpg  

Possible Fix for CA / Color Fringing?-ca-test-03.jpg   Possible Fix for CA / Color Fringing?-ca-test-04.jpg  

Possible Fix for CA / Color Fringing?-ca-test-05.jpg   Possible Fix for CA / Color Fringing?-ca-test-06.jpg  

Possible Fix for CA / Color Fringing?-ca-test-07.jpg   Possible Fix for CA / Color Fringing?-ca-test-08.jpg  

__________________
Alex
Alex Leith is offline   Reply With Quote
Old April 14th, 2007, 08:34 AM   #12
Trustee
 
Join Date: Jan 2005
Location: Plainview, N.Y.
Posts: 1,944
Quote:
Originally Posted by Alex Leith View Post
With a little more time and an only-very-slightly-more-scientific approach (I wrote down what settings I was using!) I've found that there is very little in the custom settings that effects the actual amount of Chromatic Aberration / Green-Magenta Fringing in the image. However, the fringing may be hidden in the image better by some presets, depending on the nature of the scene you're shooting at that moment.

The only two controls that apparently effects the amoung of fringing in the image are HDF (Horizontal Detail Frequency) - low shows less fringing than mid, which shows less fringing than high; And DHV (Horizontal Vertical Detail Balance) - lower numbers show less fringing than higher numbers.

So, my conclusion is that you could significantly reduce fringing by setting HDF to LOW and DHV to -9, but obviously there is a significantly detremental effect to the quality of the image!

The attached images are a 1:1 resolution (click to see them at full size) showing the lower-right-hand area of the HDV frame, with the lens zoomed to widest angle.
So it's pretty apparent that this is indeed a lens issue and not an electronic issue.
Ken Ross is offline   Reply With Quote
Old April 14th, 2007, 08:56 AM   #13
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
Great work Alex!

Thanks for posting those. I'd really like to see them in full rez 1920 x 1080 to observe what other differences beside CA change with DHV and HDF, resolution wise. I'm assuming it was the server that reduced the size of your images to 640x360.
Tom Roper is offline   Reply With Quote
Old April 14th, 2007, 09:47 AM   #14
Major Player
 
Join Date: Mar 2005
Location: Northampton, England
Posts: 500
Quote:
Originally Posted by Tom Roper View Post
Great work Alex!

Thanks for posting those. I'd really like to see them in full rez 1920 x 1080 to observe what other differences beside CA change with DHV and HDF, resolution wise. I'm assuming it was the server that reduced the size of your images to 640x360.
It's a full-size crop from an HD frame. It was just filmed against a blank wall, so there wasn't anything to see (apart from my home-made CA tester chart).

If I get a chance I'll shoot a frame later on today with something in it to see how it looks with those changes to DHV and HDF.
__________________
Alex
Alex Leith is offline   Reply With Quote
Old April 14th, 2007, 09:53 AM   #15
Major Player
 
Join Date: Mar 2005
Location: Northampton, England
Posts: 500
Here are some of the full rez frames (just for reference). Not a lot going on. Just some peeling wallpaper in a room that's due to be decorated ;-D
Attached Thumbnails
Possible Fix for CA / Color Fringing?-ca-test-10.jpg   Possible Fix for CA / Color Fringing?-ca-test-11.jpg  

Possible Fix for CA / Color Fringing?-ca-test-12.jpg   Possible Fix for CA / Color Fringing?-ca-test-13.jpg  

__________________
Alex
Alex Leith is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XH Series HDV Camcorders

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 05:23 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network