Chroma Sampling at DVinfo.net

Aaron Shaw · May 2nd, 2005, 09:57 PM

Hey guys,

I've been interested in Graeme's chroma upsampling algorithms for some time now but since I don't have FCP I haven't had the chance to utilize them. This is something that would really help me out.

I know we have some excellent programmers around here somewhere. Would it be resonable to try to create an open source upsampling algorithm? I've played around with C++ now and then but I don't know nearly enough to try this on my own.

Any thoughts? Ideas? Maybe I should just go get a mac already ;).

Rob Lohman · May 5th, 2005, 05:16 AM

If you have Sony Vegas it comes with a chroma blur filter that reduces
problems with the chroma channel as well (works great on the red channel).

The algorithms are probably available on the net. The question is, in which
programs do you want to have it which currently do not have such a feature!?

Aaron Shaw · May 5th, 2005, 10:27 AM

Well, right now I'm thinking After Effects.

Most programs do have a chroma blur but I'm talking more along the lines of smart upsampling. Recreating the lost data rather than just bluring the color channels if that makes sense.

Graeme Nattress · May 5th, 2005, 03:25 PM

Doing a chroma blur works pretty well, but for NTSC you want it horizontal only. PAL is tricky, as for 4:2:0, you've got to deal with the fields seperately.

My G Nicer algorithm is proprietary, but it uses the luma as well as the chroma information to help get much better edges than you would with a blur.

Instead of a blur, you could also linear interpolate or bicubic interpolate.

I'm also just getting ready a new FCP plugin that uses a sharpening method to improve the chroma, and that's producing very nice results on all video formats.

Hope that helps,

Graeme

Aaron Shaw · May 5th, 2005, 03:47 PM

Thanks Graeme.

Any chance your plugins will be ported to PC someday? I'd love to use them!

Graeme Nattress · May 5th, 2005, 03:50 PM

All I can say, is, "you never know".... Thanks.

Graeme

May 2nd, 2005, 09:57 PM	#1
Aaron Shaw Major Player Join Date: Jul 2004 Posts: 587	Chroma Sampling Hey guys, I've been interested in Graeme's chroma upsampling algorithms for some time now but since I don't have FCP I haven't had the chance to utilize them. This is something that would really help me out. I know we have some excellent programmers around here somewhere. Would it be resonable to try to create an open source upsampling algorithm? I've played around with C++ now and then but I don't know nearly enough to try this on my own. Any thoughts? Ideas? Maybe I should just go get a mac already ;).

May 5th, 2005, 05:16 AM	#2
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	If you have Sony Vegas it comes with a chroma blur filter that reduces problems with the chroma channel as well (works great on the red channel). The algorithms are probably available on the net. The question is, in which programs do you want to have it which currently do not have such a feature!? __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

May 5th, 2005, 03:25 PM	#4
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	Doing a chroma blur works pretty well, but for NTSC you want it horizontal only. PAL is tricky, as for 4:2:0, you've got to deal with the fields seperately. My G Nicer algorithm is proprietary, but it uses the luma as well as the chroma information to help get much better edges than you would with a blur. Instead of a blur, you could also linear interpolate or bicubic interpolate. I'm also just getting ready a new FCP plugin that uses a sharpening method to improve the chroma, and that's producing very nice results on all video formats. Hope that helps, Graeme __________________ www.nattress.com - filters for FCP

May 5th, 2005, 03:50 PM	#6
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	All I can say, is, "you never know".... Thanks. Graeme __________________ www.nattress.com - filters for FCP

May 5th, 2005, 10:27 AM	#3
Aaron Shaw Major Player Join Date: Jul 2004 Posts: 587	Well, right now I'm thinking After Effects. Most programs do have a chroma blur but I'm talking more along the lines of smart upsampling. Recreating the lost data rather than just bluring the color channels if that makes sense.

May 5th, 2005, 03:47 PM	#5
Aaron Shaw Major Player Join Date: Jul 2004 Posts: 587	Thanks Graeme. Any chance your plugins will be ported to PC someday? I'd love to use them!