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xmb
05-11-2003, 03:16 PM
what can one do about it?
i never get to solve this problem. even if i set to 10/ 16 bit or floating, nothing happens. there are still banding artefacts...

any tips how to avoid it or how to remove? thanks in advance

georgy porgy
05-12-2003, 08:28 AM
Hi xmb,

a few days ago I posted the following in the discreet forum:

"Hi out there,

I have problems with banding. For example a fractal noise filter on a solid layer with:

Amount: 100%
Time Slice: no matter
Octaves: 1
H/V Scale : no matter but 100 % is good to see it

On the Computer Monitor is shows slightly but on my framebuffer DPS Reality it is good to see--- BANDING!!!!

I did not see that since the bad old 16-Bit (Hi-Color) days around 1994 or so.

My first thought was: “It must be the bit-depth.” But changes in the Layer and in the Composite to 16 Bit were not successful. I even saved the 16-Bit Image to Photoshop—BANDING!!!

I had to realize that it is the same with Gradients.

Has anybody a solution????

Best regards, Georgy"

I just wanted to say it feels good not to be alone with this.

Cheers, Georgy

beaker
05-13-2003, 04:59 AM
xmb: it would be helpfull if we knew what application you were using.

georgy porgy
05-13-2003, 08:12 AM
Sorry for that,

I use combustion 2.0 and it looked to me if xmb has the same problem like I have.

Do you use C2 too xmb?

Regards, Georgy

jeferichardson
05-14-2003, 05:23 PM
One thing you could do is clamp the white and blacks. CC it so that the blacks arnt pure black and same with whites.

joconnell
05-15-2003, 11:12 AM
Depending on what footage you are using, using 16 bit mode mightn't make any difference. Say for example you capture dv, beta or digibeta footage then you have an 8-bit source. Changing your comp to 16 bit colour will make colour correction a bit more accurate but you are still working with your 8 bit source in a 16 bit colour space. More colour information doesn't magically appear in 8 bit footage if you change your comp to 16 bit. If you are doing really heavy colour correction then you should work in float space if possible or try and look at your colour correction and figure out if you can combine a few operators to give you the same result with less steps - you'll loose less data. Ideally you should try and light your footage as closely to the final look as possible - if you can't then a little bit of noise or blur can break up the banding.

xmb
05-16-2003, 09:01 AM
i use combustion 2 too.

but i'm having banding problems with completely synthetic generated images.

usually i render stuff out from softimage-xsi in the softimage.pic format.

which would be the best filetype to avoid banding as much as possible?

i dont think .tga would do a difference. but i need to check if there are some more settings in the rendering options (channels, etc.)

georgy porgy
05-16-2003, 10:43 AM
Hi everybody,

thank you for your response.

Like xmb I have this problem not with external footage but with the footage produced by the Filters in Combustion 2 itself.

For example I need a slight changing and moving background I think of fractal noise with low octave and not much detail, animate the time slice, put an animated CC on it and so on....

So far so good!

But when I use the apporpriate settings (like I did describe in my mail above), I get BANDING. When I drive the details up (what I do not want in ths case), banding can not be detected anymore because of the higher contrasts (I do not want to have them in this case), but I think either the algorithm is not resolution independent or otherwise somehow limited. Because with a real fractal algorithm even 8-Bit resolution in the luminance should be enough for a smooth gradient.

The same with smooth and slight gradients in Paint.

While I'm writing I get an idea why this could occurr:

Could it be that the 8-Bits are always reserved for the complete scale from 0 to 255? So if you want a slight change from 128 to 148 the dynamic of 8-Bit is not adapted to this change?

Instead the dynamic is fixed by the difference which is in my example 20 decimal and 14 Hex. This I can code in 5 Bit - 1 0100. Am I working in 5 Bit resolution in this case????

While this maybe explains the problem we still need a workaround.

Maybe somebody can help????

Best regards,

Georgy

GrantKay
05-16-2003, 10:56 AM
Hi,

I've been trying to replicate this banding you mentioned and I haven't seen anything as bad as you describe.

Would you mind telling me if your display is set to 16 bit or 32 bit display?

I am working 32 bit and its fine. If I switch to 16 bit then I get banding. This is a display setting rather then the software.

Regards
Grant

DISCREET UK

georgy porgy
05-16-2003, 11:04 AM
Hi Grant,

I am working in 32 Bit resolution. My card is a Fire GL 3. The banding is not so much visual on my computer monitor (although it is there), but on my framebuffer (dps reality) and in my Videowork (Avid Mediacomposer) it is clearly to be seen.

Best regards,

Georgy

DSedov
05-16-2003, 11:11 AM
XMB: There are several formats that use either nonlinear colorspace which is a float, and 64bit images, like Cineon and tiff.

I would recomend tiffs though to save space, but if it is something special, and you really need to have a dynamic range of values in your picture for cc, then use cineon.

GrantKay
05-16-2003, 12:09 PM
Hi Georgy

I wonder if you could export out a few of these frames and send them to me for examination?

Please put them in a zip file (2 or 3 will do) and send them to grant.kay@discreet.com

Regards
Grant

DISCREET UK

georgy porgy
05-23-2003, 10:49 AM
Yippee, I have cured myself!!!

Put a little grain on the layer with the banding will dither the gradient, so the banding lines will disappear.

Maybe this is a sollution for the footage xmb has problems with...

Regards, Georgy :thumbsup:

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