how to remove THIS noise

[acki]

Hi all.

I'm desperate calling from help here... It seems this _UGLY_ yellow patches
(undoubtfully caused by a poor AGC system in my DV cam) can't be removed
with any available filter... or better said, I can't find a filter to remove these.

I tried several filters already: CNR2 with several different options, tried ExpSat,
tried changing saturation levels, quite a few spatial smoothers, dust removers,
and etc, etc, etc with pretty unpleasant results every time.

These annoying yellow patches appear under no sunlight conditions, under low to mid light condition, and of course with Automatic Gain Control ON (turning it off yields a dark-as-hell picture).

As additional information, these artifacts seem to "stick" to surfaces, they don't move unless the object/person you are shooting moves or you just move the camera from them.

The question is: Is there anyone that had faced (and hopefully solved) this
ugly effect before ? And how ?

If not, any suggestions would be extremely welcomed.

Thanks,

acki.

Samples: [*removed*]

[MOmonster]

@acki
I don´t work with such sources, but I think these lumaartefacts are called rainbow. Search for derainbow.
For analoge sources I heard that removedirt and removegrain are good and fast filters, Maybe they would work also for this case. Removedust is a function that use removedirt and can maybe give better results.
Just try it. There are other many other members who are more involved in denoising filters. :)

[acki]

These are digital sources. Mini DV JVC cam.
I don't think these are rainbows anyway, but I tried a couple of de-rainbowers too.
Tried removedust, grain and dirt also, with no results....

But thanks anyway for your reply.


acki

[Chainmax]

IIRC, this kind of artifact is called "color bands" in the Analog Capture guide. They recommend to use Cnr2("xxx",4,5,255) (http://128.206.52.235/~kes25c/cnr2_v261.zip) to remove it.

[neuron2]

He already tried CNR2.

My advice: get a new camcorder; that one is hosed.

[Mug Funky]

actually, that stuff isn't a big deal. it's low-level noise, and could probably be dealt with using:

temporalsoften(2,0,4)

this'll put a light temporal smooth on the chroma only. shouldn't give you any nasty artefacts unless you raise the 3rd number (chroma threshold) too high. 4 is a guesstimate - it may need more but i doubt it.

if that doesn't work, try removedirt on the chroma channels only.

[edit]

hang on... you tried removedirt? hmm. these splotches aren't in the same location every frame are they? if they are then your camera is b0rk.

if they're random, temporalsoften should work. if they're constant, you can make a mask and invert the splotches if you use just the right settings and overlay (or layer, or yv12lutxy...)

[acki]

actually, that stuff isn't a big deal. it's low-level noise, and could probably be dealt with using:

temporalsoften(2,0,4)

this'll put a light temporal smooth on the chroma only. shouldn't give you any nasty artefacts unless you raise the 3rd number (chroma threshold) too high. 4 is a guesstimate - it may need more but i doubt it.


Thanks for the advise. I'll try that when I get home and let you know.


these splotches aren't in the same location every frame are they? if they are then your camera is b0rk.


I'll give an example:

Let's say I'm shooting (indoors, artificial light source) a room with people walking around... If I follow
a person's face with the camera, the patches remain more or less in the same places on his/her face (considering ambient lighting). They only tend to change when the object (a person in this case) moves either really close or far away from the light source.



if they're random, temporalsoften should work. if they're constant, you can make a mask and invert the splotches if you use just the right settings and overlay (or layer, or yv12lutxy...)


I'll give these solutions a try too. Thank you so much for your suggestions. :thanks:
I'll keep you informed.

acki

[MOmonster]

@acki
What DV-cam creates this results?
Just to know, what I shouldn´t by in the next time. :D