Possible Fix for CA / Color Fringing?

Tom Roper · April 14th, 2007, 11:40 AM

Well the CA looks not as bad from the standpoint of the full frame image.

You can download some wallpapers to fix the other problem in post ;-)

Thanks for posting those. The reason I'm curious about the full frame grabs is not related to the CA, but the observation I had while viewing on the small LCD screen that when viewing barcodes (vertically and horizontally), that the HDF set to "low" increased the resolution and contrast in the horizontal direction, and that DHV set to +9 increased the apparent contrast and resolution in the vertical direction. But it was not scientific at all, I didn't have a proper monitor connected, so moire and aliasing could contribute to a false conclusion being drawn from the LCD screen alone.

Michael Mann · April 18th, 2007, 02:12 PM

Quote:

Originally Posted by Alex Leith

...Wolfgang's new preset showed a huge amount of fringing (which is a shame because I wanted to use that preset!)

After 3 days of shooting with Wolfgang's presets I have to agree. I like the preset very, very much, but I get quite a lot of fringing.

Thanks, Alex, for your tests!

Tom Roper · April 18th, 2007, 06:19 PM

Although it's been proved that the optical component of the fringing does not completely go away, the observation that Wolfgang's preset makes the problem worse is some justification to say that presets do have an influence. We may disagree on how significant, but the preset I'm using, basically Steven Dempsey's VividRGB but with normal gamma, seems very good about minimizing CA for me with still vibrant color. I really like this preset.

But I should try Wolfgang's also...dumb question but where can I find them?

Michael Mann · April 19th, 2007, 01:25 AM

Tom, here is the the link:

http://www.fxsupport.de/20.html

Just go to line that says:

"Alle vier Presets zum Downloaden: PRESET.zip [ZIP 1KB]"

I used the (slightly modified) -3db preset, the first of Wolfgang's four presets you find in the folder. I'd be very interested in how you like them.

Nathan Quattrini · April 19th, 2007, 07:46 AM

is this with a wide angle or the normal lense on the A1? (or G1?) How bad does it fringe in normal filming?

Alex Leith · April 19th, 2007, 08:31 AM

The fringe is not visible in normal filming. You only see it on areas of particularly high contrast when zoomed out wider than half way.

Robert Petersen · July 5th, 2007, 07:21 PM

I downloaded the promotional video for the XH-A1/G1 from Canon (I think they took it out of circulation) and many of the scenes had fairly significant CA. I have to say that it does not look like the CA that I am used to with still cameras, it was not a sharp fringe, but a gradual color shift around edges that looks more like a prism effect. It may be a design issue with the prism that is used to split the colors up for the three sensors. It is the most significant issue that is keeping me from buying the XH-A1. If you just look at the central part of the image, it looks very good.

Robert Petersen · July 10th, 2007, 02:30 PM

Quote:

Originally Posted by Robert Petersen

I downloaded the promotional video for the XH-A1/G1 from Canon (I think they took it out of circulation) and many of the scenes had fairly significant CA. I have to say that it does not look like the CA that I am used to with still cameras, it was not a sharp fringe, but a gradual color shift around edges that looks more like a prism effect. It may be a design issue with the prism that is used to split the colors up for the three sensors. It is the most significant issue that is keeping me from buying the XH-A1. If you just look at the central part of the image, it looks very good.

I did some further tests. The fringing that I see on the computer monitor is not as noticeable on a 1080P 65" DLP TV. It is still there, but you have to look for it. I think that most people would not notice it. I saved the frames to a USB key, which plugs into the TV to display 1920x1080 pixel images full screen. The pictures look very good. I compared them to images from a Sony FX7/A1U Camcorder and they were comparable. The Canon images were slightly less vibrant, maybe a little flat, but still very pleasing. In some instances, you would probably prefer the less vibrant (more filmlike) images from the Canon.

April 19th, 2007, 01:25 AM	#19
Michael Mann Major Player Join Date: Dec 2005 Location: Kelkheim, Germany Posts: 375	Tom, here is the the link: http://www.fxsupport.de/20.html Just go to line that says: "Alle vier Presets zum Downloaden: PRESET.zip [ZIP 1KB]" I used the (slightly modified) -3db preset, the first of Wolfgang's four presets you find in the folder. I'd be very interested in how you like them. __________________ Michael

April 19th, 2007, 07:46 AM	#20
Nathan Quattrini Major Player Join Date: Jan 2007 Location: Warwick, Rhode Island Posts: 740	is this with a wide angle or the normal lense on the A1? (or G1?) How bad does it fringe in normal filming? __________________ Cinematography Site

April 19th, 2007, 08:31 AM	#21
Alex Leith Major Player Join Date: Mar 2005 Location: Northampton, England Posts: 500	The fringe is not visible in normal filming. You only see it on areas of particularly high contrast when zoomed out wider than half way. __________________ Alex

April 14th, 2007, 11:40 AM	#16
Tom Roper Trustee Join Date: Jun 2004 Location: Denver, Colorado Posts: 1,891	Well the CA looks not as bad from the standpoint of the full frame image. You can download some wallpapers to fix the other problem in post ;-) Thanks for posting those. The reason I'm curious about the full frame grabs is not related to the CA, but the observation I had while viewing on the small LCD screen that when viewing barcodes (vertically and horizontally), that the HDF set to "low" increased the resolution and contrast in the horizontal direction, and that DHV set to +9 increased the apparent contrast and resolution in the vertical direction. But it was not scientific at all, I didn't have a proper monitor connected, so moire and aliasing could contribute to a false conclusion being drawn from the LCD screen alone.

April 18th, 2007, 06:19 PM	#18
Tom Roper Trustee Join Date: Jun 2004 Location: Denver, Colorado Posts: 1,891	Although it's been proved that the optical component of the fringing does not completely go away, the observation that Wolfgang's preset makes the problem worse is some justification to say that presets do have an influence. We may disagree on how significant, but the preset I'm using, basically Steven Dempsey's VividRGB but with normal gamma, seems very good about minimizing CA for me with still vibrant color. I really like this preset. But I should try Wolfgang's also...dumb question but where can I find them?

July 5th, 2007, 07:21 PM	#22
Robert Petersen Regular Crew Join Date: May 2006 Location: Girard, Ohio Posts: 103	I downloaded the promotional video for the XH-A1/G1 from Canon (I think they took it out of circulation) and many of the scenes had fairly significant CA. I have to say that it does not look like the CA that I am used to with still cameras, it was not a sharp fringe, but a gradual color shift around edges that looks more like a prism effect. It may be a design issue with the prism that is used to split the colors up for the three sensors. It is the most significant issue that is keeping me from buying the XH-A1. If you just look at the central part of the image, it looks very good.