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-   -   Chroma noise & color grading (https://www.dvinfo.net/forum/high-definition-video-editing-solutions/20371-chroma-noise-color-grading.html)

Helen Mets January 25th, 2004 11:35 PM

Chroma noise & color grading
 
Hi folks,

I'll be getting my hands on HD10U in a few weeks, so I did some research work on some of the HD10 clips and screencaps I've downloaded from different places.

Chroma noise seems like the biggest problem with the camera, so I set out to get rid of it and ended up with quite successful results.

Here's an example:

www.liisikoikson.com/store_compare.jpg

I chose this one as an example, because the chroma noise is most evident (and distracting) here, (very low light level while shooting).

If chroma noise can be successfully reduced, then under proper conditions this camera could produce excellent results.

Peace

Ken Hodson January 26th, 2004 10:42 AM

So do tell! What was your process of chroma reduction? The Virtuadub filter?
Ken

David Newman January 26th, 2004 07:23 PM

CineForm is also developing a chroma noise filter for our Premiere Pro product. The camera's chroma noise is very interesting and removable to significant degree without impacting sharpness and detail.

Here is a frame from one of the worst chroma noise examples I have seen online. As the chroma for this very dark scene was low I have boosted the saturation which only makes the noise worse. See the before and after noise filtering.

http://www.cineform.com/downloads/Matrix1000.jpg

Ken Hodson January 26th, 2004 08:59 PM

Only for the Premiere Pro product? Why not in the Premiere 6.5 product as well?
Ken

David Newman January 26th, 2004 09:51 PM

It should work with Premiere 6.5 as well, although I haven't done any testing under 6.5 recently has Aspect HD for Premiere Pro is being prepared for release.

Ken Hodson January 26th, 2004 10:05 PM

It better ;>)
PPro isn't really an upgrade it is a whole different program. A program I really don't want to learn.
Ken

Helen Mets January 27th, 2004 02:20 AM

The 'matrix' comparison is interesting. I tried to use the virtualdub filter, but with no good results, so I went for standard Photoshop commands instead.

Here's what I came up with:

http://www.liisikoikson.com/web/matr...ma_compare.mpg

David Newman January 27th, 2004 10:41 AM

That is a pretty nice job. What filters did you use under photoshop?

Heath McKnight January 27th, 2004 11:10 AM

I've moved this to editing because the discussion headed there. Great one, though!

heath

Helen Mets January 27th, 2004 11:29 AM

filters I used in Photoshop:

color range (selections)
color balance
curves
median (under filters-noise)

that's it.

Paul Mogg January 27th, 2004 11:34 AM

Those are fantastic results folks!, if this works on the JVC footage it will improve the picture quality 100%, and for me this Chroma noise has been my biggest problem with the picture.
Does anyone know of a good Chroma noise reduction filter for FCP or After Effects by any chance?

Thanks

Heath McKnight January 27th, 2004 11:41 AM

I am seeing a lot on my film's footage.

By the way, FCP 4 is so different from FCP 3 that I can't figure out how to make a jpeg of clips. Anyone?

heath

Graeme Nattress January 27th, 2004 12:55 PM

If you spec what you need from a chroma-noise reducer, I'll build it into my DVNR for FCP plugin.

Graeme

Till Krueger January 27th, 2004 01:20 PM

Helen,

thank you for answering my email offline...your results are so encouraging, that i will continue this here.

so i understand that you do what you do, by first saving out an image sequence, and then batch processing those in Photoshop with an action that you created...this action is - in a nutshell - a series of:

color range (selections)
color balance
curves
median (under filters-noise)

please forgive me if i seem like i want trade secrets from you (as professionals we all have our cherished tricks), but i hope that i am not being too pushy by asking about some details.

i have just tried what you suggested, and it does work excellently to some extent...however, i do not understand some of the subtleties of your methodology.

do you select and process the magenta and green "spots" in separate steps? i was able to get the magenta to all but disappear, but the green had to be addressed in a separate step, and even after all that i am still a bit away from your almost flawless results.

being that the Chroma Noise has a similar make-up in every scene with this model HD-cam, can some of this be automated?

and more directly: could you share a Photoshop action that would do this (i am sure the user would have to do some tweaks to the parameters to account for different scenes)?

if you don't feel comfortable about just posting such an action (understandably so), i am sure that many people wouldn't mind sending you a PayPal contribution to get access to your methodology...Fred Miranda at http://www.fredmiranda.com has shown that there is a market for such a service...i particularily like how he started to wrap some of his processing steps into the PS plug-in architecture...this would make such a series of steps usable in Premiere Pro as well, being that it accepts PS plug-ins as well as PP and AE plugs.

you mentioned (in your email) that processing times of up to 5 hours per second of HD-video are not untypical on a fast machine...what speed machine are you using to arrive at those results?

thanks so much for what you have already contributed! the mpeg clip you have linked to is a revelation...outstanding!

best,
till

David Newman January 27th, 2004 01:43 PM

"5 hours per second" -- eekk thats is 10 mintues per frame! Makes me feel not so bad about my filter's 1-second computing time per frame of HD. It is isn't complete yet, but it should only get faster not slower.


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