Any Dark Spot Removal Techniques?

The place for questions about shooting with Blackmagic Cameras.
  • Author
  • Message
Offline

Ben Tobin

  • Posts: 76
  • Joined: Mon Apr 22, 2013 3:22 pm

Any Dark Spot Removal Techniques?

PostThu May 16, 2013 9:23 pm

Hi,
I just got my camera yesterday and went to try it out today. Totally blown away by the results. I did, however, encounter the fabled dark spots. I've been frantically searching for a solution in resolve or after effects. I'm new to resolve but I was wondering if there might be a tutorial I could watch or some technique to get rid of it. I saw one phrase somewhere that I hope isn't true that it's an indicator of damage.
Ben Tobin
Offline
User avatar

AdrianSierkowski

  • Posts: 929
  • Joined: Sun Feb 17, 2013 4:59 pm
  • Location: Los Angeles.

Re: Any Dark Spot Removal Techniques?

PostThu May 16, 2013 11:19 pm

you'd just have to motion track something to cover it up with. motion tracking in resolve is pretty amazing, so basically you'd do correction to make the black the same color as the surrounding what have you, and then motion track it through the scene.
Adrian Sierkowski
Director of Photography
http://www.adriansierkowski.com
adrian@adriansierkowski.com
Offline

Ben Tobin

  • Posts: 76
  • Joined: Mon Apr 22, 2013 3:22 pm

Re: Any Dark Spot Removal Techniques?

PostFri May 17, 2013 3:14 am

Thanks, I'm still figuring Resolve out...not had too much success yet. I've also seen sort of a square block of feint lines surrounding the black spot in the middle of the sun. I was lucky in that only one test clip had this problem. I'm trying to get a grasp on how to avoid the issue if I need to get the sun in the shot.
Ben Tobin
Offline

spike

  • Posts: 68
  • Joined: Thu Feb 14, 2013 2:57 pm

Re: Any Dark Spot Removal Techniques?

PostFri May 17, 2013 8:02 am

AE has a good clone stamp tool that works well on steady shots... you could also use clone stamp and motion track with a null object on a moving image? Or buy an F5;)
BMD products: -
ATEM 1 M/E
Teranex 2D
GPI/Tally
SDI distribution
HDMI to SDI converter
Sync Gen
Smartview HD
Smartview Duo
Ultrastudio Mini Recorder

popcornflix

Re: Any Dark Spot Removal Techniques?

PostFri May 17, 2013 9:37 am

bztobin wrote:Thanks, I'm still figuring Resolve out...not had too much success yet. I've also seen sort of a square block of feint lines surrounding the black spot in the middle of the sun. I was lucky in that only one test clip had this problem. I'm trying to get a grasp on how to avoid the issue if I need to get the sun in the shot.


This is a great reason to subscribe to Adobe Creative Cloud. After Effects now comes with Mocha AE bundled. There's a real easy workflow for this: You take one frame of the sun into Photoshop, and clone out the spot and faint lines. Then in Mocha AE, you roto the spot and track the roto throughout the footage. Then Mocha AE will replace the tracked roto with the clean plate you made in Photoshop.

Offline

Ben Tobin

  • Posts: 76
  • Joined: Mon Apr 22, 2013 3:22 pm

Re: Any Dark Spot Removal Techniques?

PostFri May 17, 2013 4:08 pm

Awesome! I'm actually more familiar with After Effects. I was hoping there might be a workflow I could lock down for when I'm doing actual projects. I'm using ProRes mode, will this method still work for that? This particular clip is a little tricky as it's a pan going up a tree. The black spot changes as it goes through the branches. I'm just glad I haven't seen any moire at all, a single bad spot is much more manageable.
Ben Tobin
Offline

Ben Tobin

  • Posts: 76
  • Joined: Mon Apr 22, 2013 3:22 pm

Re: Any Dark Spot Removal Techniques?

PostFri May 17, 2013 8:27 pm

Out of curiosity are the lines surrounding the black spot a part of that artifact or is it some other weird thing?
Ben Tobin
Offline

masterok

  • Posts: 39
  • Joined: Mon Apr 01, 2013 11:44 pm

Re: Any Dark Spot Removal Techniques?

PostSat May 18, 2013 1:30 pm

Actually it is very interesting indeed how would/should we go about that black spot if the sun goes through the leaves of the tree. you cant really mask that, and it is a very frequently used shot setup. isnt it fixable with firmware?
Offline
User avatar

AdrianSierkowski

  • Posts: 929
  • Joined: Sun Feb 17, 2013 4:59 pm
  • Location: Los Angeles.

Re: Any Dark Spot Removal Techniques?

PostSat May 18, 2013 4:59 pm

It was fixable for Red via firmware.
Even behind a tree, I suppose you could somehow work to get it fixed.. i mean you could certainly fix it frame by frame in photoshop if needed (don't do a lot of color correction but I know i could fix that in a still). You could do it, I would assume with a secondary-- first selecting the main area, and then within that area, selecting based off of luminance (0 as it's black), then adding in a correction to make it white, or whatever color needed, and then motion tracking it through a shot.

Then again, it probably wouldn't be nearly as noticeable behind a tree.
Adrian Sierkowski
Director of Photography
http://www.adriansierkowski.com
adrian@adriansierkowski.com
Offline

Ben Tobin

  • Posts: 76
  • Joined: Mon Apr 22, 2013 3:22 pm

Re: Any Dark Spot Removal Techniques?

PostSat May 18, 2013 10:26 pm

I called Blackmagic and they said they'd never heard of the lines before and to send a screencap. The black dot they reiterated is firmware fixable eventually. I think I'm just going to be really careful about the sun. I likes me a good lens flare but I hate lines and dark spots. I'm not nearly confident enough with Resolve to try that out. I'd feel ok using the after effects if the shot were still or panning in one direction uninterrupted by branches. I've seen footage though where people have gotten shots with the sun or through branches without any trouble.
Ben Tobin
Offline
User avatar

AdrianSierkowski

  • Posts: 929
  • Joined: Sun Feb 17, 2013 4:59 pm
  • Location: Los Angeles.

Re: Any Dark Spot Removal Techniques?

PostSun May 19, 2013 4:22 am

I wonder if a simple diffusion filter could help this out-- or hurt it horribly-- by spreading out the "blow out" over a lower area. Just kinda rambling in my head and of course have no BMCC with me (canceled order waiting for pocket, makes more sense) but might be worth testing with something like a BPM 1/4 or 1/8
Adrian Sierkowski
Director of Photography
http://www.adriansierkowski.com
adrian@adriansierkowski.com
Offline

Stuart Dye

  • Posts: 37
  • Joined: Tue Apr 16, 2013 5:12 am
  • Location: London, UK

Re: Any Dark Spot Removal Techniques?

PostTue May 21, 2013 11:34 pm

bztobin wrote:
I just got my camera yesterday and went to try it out today. Totally blown away by the results. I did, however, encounter the fabled dark spots. I've been frantically searching for a solution in resolve or after effects


Hi im looking to maybe buy a BMCC 2.5k. Ive seen dark spots on bright light sources before BUT on cheaper cameras...The only thing i can think of is the luma (brightness)
is peaking WAY beyond 800mv and is peaking/crushing so high that the Luma inverts and goes black!
On some older SD 3CCD cameras this crushed white would go yellow. So BMD would have to make a firmware to CLIP the luma before it shoots stupidly high and crushes beyond 800mv
(you heard it here first).
Is this what you are seeing? watch at 57sec in the upper left of the image (the bright street lamp has a black spot in the center:

This doesent seem to be a problem on all cameras, so it might be during the Image Censor calibration stage???
stuart.
Offline

Pete Proniewicz-Brooks

  • Posts: 277
  • Joined: Sun Sep 09, 2012 6:06 pm

Re: Any Dark Spot Removal Techniques?

PostThu May 23, 2013 4:32 pm

Stuart Dye wrote:bztobin wrote:
I just got my camera yesterday and went to try it out today. Totally blown away by the results. I did, however, encounter the fabled dark spots. I've been frantically searching for a solution in resolve or after effects


Hi im looking to maybe buy a BMCC 2.5k. Ive seen dark spots on bright light sources before BUT on cheaper cameras...The only thing i can think of is the luma (brightness)
is peaking WAY beyond 800mv and is peaking/crushing so high that the Luma inverts and goes black!
On some older SD 3CCD cameras this crushed white would go yellow. So BMD would have to make a firmware to CLIP the luma before it shoots stupidly high and crushes beyond 800mv
(you heard it here first).
Is this what you are seeing? watch at 57sec in the upper left of the image (the bright street lamp has a black spot in the center:

This doesent seem to be a problem on all cameras, so it might be during the Image Censor calibration stage???
stuart.



Black Sun is a well know problem with CMOS sensor cameras an is a result of the pixel being overloaded with light and not reporting anything. In short it's temporary damage to the sensor (though prolonged exposure could result in perminent damage. RED have expereienced it on their very expensive cameras, it's not just a cheap camera problem.

There are ways to mask the issue in firmware, use an algorythem to identifiy it happening and just put white at max value in. This however hides the indication that you are exposing the sensor at potentially damaging levels.

Return to Cinematography

Who is online

Users browsing this forum: Michael_Andreas and 34 guests