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How to reduce gradient jumps

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Mark Gin
How to reduce gradient jumps
on Jul 25, 2011 at 8:56:12 am

Hi,

Got this problem with my t2i (after some post enhancement):
http://img694.imageshack.us/img694/7317/mvi0911dnxhd0001116.jpg

How can I at least reduce these transition jumps (in post - AE) so they won't be so noticed?

Thanks,
Mark.


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John Kaley
Re: How to reduce gradient jumps
on Jul 25, 2011 at 3:29:55 pm

In AE: Effect/Noise&Grain/Noise
Season to taste.



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Mark Gin
Re: How to reduce gradient jumps
on Jul 25, 2011 at 4:47:41 pm

Why should random noise help in this case?

I don't have AE on this station but I have used Gimp's "HSV nosie" on the frame I sent here.
The result is a little grainy image (that would also create a harder job for the encoder) - the imaged is still posterized well:
http://img843.imageshack.us/img843/1353/mvi0911dnxhd00011162.jpg


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John Kaley
Re: How to reduce gradient jumps
on Jul 25, 2011 at 5:14:15 pm

Noise will help blend the gradients together, but it require too much "noise". You also may want to have a look at "Magic Bullet DeNoiser".



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Tom Nelson
Re: How to reduce gradient jumps
on Jul 25, 2011 at 6:49:19 pm

I would consider this to be more of a banding issue. GenArts' Sapphire effects has a DeBanding plugin that could take care of them - you can download it for free for three weeks before you have to pay the $2800 to keep it.

Tom Nelson
Videographer/Editor
Essex Television Group


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Mark Gin
Re: How to reduce gradient jumps
on Aug 1, 2011 at 2:49:15 pm

Great plug-in! Seems to be not too filtered and has good edge preserving (at the right settings of course).
Thanks!


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Joseph W. Bourke
Re: How to reduce gradient jumps
on Jul 28, 2011 at 5:47:03 pm

Hi Mark -

You don't say in your post whether the banding is in your original T2i footage, or whether it's being introduced in post (which I assume it is). If it's not in the original image, you may want to change the color bit-depth settings in your AE project, if that's what you're using. You have the option of using 8, 16, or 32bpc (bits per channel), and this can have a great effect in reducing gradient banding. Check out this info from Adobe:

http://help.adobe.com/en_US/AfterEffects/9.0/WS81984DEB-D195-4822-9A06-EA0D...

If you look at Todd Kopriva's info at the bottom (and you're using CS5), there's specific info on reducing gradient banding in his link.

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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David Johnson
Re: How to reduce gradient jumps
on Jul 28, 2011 at 5:53:22 pm

You might also search the COW for many detailed tips on reducing banding such as grain and adjusting individual color channels ... has come up very often over the years in the After Effects forum.


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Mark Gin
Re: How to reduce gradient jumps
on Aug 1, 2011 at 3:07:15 pm

Hmm, good idea.
I haven't done this before because I didn't know the anomaly's name. :)
Great stuff can be found here


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David Johnson
Re: How to reduce gradient jumps
on Aug 1, 2011 at 11:11:01 pm

[Mark Gin] "I haven't done this before because I didn't know the anomaly's name."

Yes, I suppose "gradient jumps" wouldn't return many search results. ;~) At the same time, my curiosity to know what a "gradient jump" is lead me to read the post in the first place and I imagine the same is true for others so it was effective to a degree.

[Mark Gin] "Great stuff can be found here"

Indeed the COW host a wealth of information going back many years so there's not much that one can't find here.


Sorry I can't help with the specifics of DSLR workflow/issues.


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Mark Gin
Re: How to reduce gradient jumps
on Aug 1, 2011 at 3:03:50 pm

Hi Joe,

My footage comes from the t2i with Technicolor CineStyle picture style.
http://www.technicolor.com/en/hi/cinema/filmmaking/digital-printer-lights/c...
It passes Technicolor's LUT in AE and then I add edge enhancement.

I changed it to 16bpc and the result is great! Unfortunately, final encoding will pass through 8bpc.


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Joseph W. Bourke
Re: How to reduce gradient jumps
on Aug 1, 2011 at 4:07:32 pm

Hi Mark -

You may want to think about changing your workflow a bit and shooting your T2i footage Neutral, then doing the FX pass in 16 bit in After Effects. I think you can pretty well approximate the in-camera presets in AE, and get them looking squeeky clean, then output to 8bit if you have to. I'm hoping someone will weigh in here who knows a bit more about the DSLR workflow. I have a T2i, and always shoot in Neutral, then so any FX work in post with AE.

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Peter Burger
Re: How to reduce gradient jumps
on Aug 2, 2011 at 7:08:42 am

Hi, Joseph!

What do you think are the advantages of shooting neutral over using the Technicolor Cinestyle?
I was using neutral most of the time and avoided whenever possible the so-called "flat styles".
I was stunned, when first trying the Technicolor Cinestyle. Especially in low-light situations this style is awesome. Gives you a very clean picture and is - even without using the LUT - quite easy to grade.

------------------------------------------
"Tragedy is a close-up; comedy, a long shot." - Buster Keaton


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Joseph W. Bourke
Re: How to reduce gradient jumps
on Aug 10, 2011 at 7:40:36 pm

Hi Peter -

Sorry I didn't catch your response sooner. I generally use the neutral style not for any real specific reason other than that I've always followed the rule, both in audio, and video (not the DSLR world), to leave all my source material "dry", so to speak, with no effects on it.

In that way, I can almost always achieve in the post process what I've left out in the shoot, but I can't remove a color effect, or a settings tweak, once it has been recorded that way. I guess it's more of a "how I've always done it" thing, not a right or wrong thing.

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Joseph W. Bourke
Re: How to reduce gradient jumps
on Aug 10, 2011 at 7:53:18 pm

Hi Peter -

Some more confusion on this - I did a Google search on Neutral vs Cine style and found this:

http://www.learningdslrvideo.com/cinestyle-vs-neutral/

It looks to me as if there's noise introduced in the non-neutral style setting. You be the judge. Probably the best thing to do would be to test it both ways, and see what looks best with our own cameras.

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Peter Burger
Re: How to reduce gradient jumps
on Aug 11, 2011 at 9:24:02 pm

Thanks, Joseph!

Didn't know that video! Much appreciated!

------------------------------------------
"Tragedy is a close-up; comedy, a long shot." - Buster Keaton


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