Artefacts on shooting RAW video

Started by YaDeniska, May 31, 2017, 06:00:44 PM

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YaDeniska

Hello! I have a problem in my RAW video.
When I shoot some scenes, there is an unpleasant pixel color defect, usually it is visible in the openings of the foliage of trees, and also on small white objects.
Does anyone know this problem? Thanx.
Canon 5d Mark 2.

erikbaldwinson

Looks like a bit of a moire/fringe/hot-pixel mash-up. What lens are you using? Have you tried using the "bad pixel fix"?

You can expect lots of bad stuff like that to happen when you shoot fine detail in front of an over exposed sky.

Work around..

- Don't clip highlights
- Use lens with no fringing problems
- Bad Pixel Fix or "Remove hot pixels"
- Shoot shallow DOF and close subject so background trees etc are soft & out of focus.

I see you also cranked the exposure which will make all the artifacts worse.

Walter Schulz

Not that much information given.
- Crop mode or non-crop mode? 5D2 - like most other Canon DSLRs - is using "line skipping" in non-crop mode. Means: Only every third sensor line is used. Prone to moire.

Workarounds:
-> Non crop mode: Use anti-aliasing filters designed to minimize moire. Lookup VAF.
-> Use crop mode: ML crop mode is using a cropped area but all the lines within. FOV is diminished.

YaDeniska

Quote from: erikbaldwinson on June 01, 2017, 07:46:15 AM
Looks like a bit of a moire/fringe/hot-pixel mash-up. What lens are you using? Have you tried using the "bad pixel fix"?

You can expect lots of bad stuff like that to happen when you shoot fine detail in front of an over exposed sky.

Work around..

- Don't clip highlights
- Use lens with no fringing problems
- Bad Pixel Fix or "Remove hot pixels"
- Shoot shallow DOF and close subject so background trees etc are soft & out of focus.

I see you also cranked the exposure which will make all the artifacts worse.

Using Canon 50mm f1.4, Aperture on f11.
I don't think that this is bad pixel problem, because I checked the camera for the bad/hot pixels - everything is clear. The frame was not overexposed.
This only can be seen in places of  frame, where small white light details, also on the ground with small white stones and others objects.
I also noticed that this is more evident in the MLVProducer, on MLVRAWViewer this problem is noticeably less, But still there.
Attached an image
free image upload

YaDeniska

Quote from: Walter Schulz on June 01, 2017, 08:02:16 AM
Not that much information given.
- Crop mode or non-crop mode? 5D2 - like most other Canon DSLRs - is using "line skipping" in non-crop mode. Means: Only every third sensor line is used. Prone to moire.

Workarounds:
-> Non crop mode: Use anti-aliasing filters designed to minimize moire. Lookup VAF.
-> Use crop mode: ML crop mode is using a cropped area but all the lines within. FOV is diminished.
Used non-crop mode, mlv_rec, please tell me how to use anti-aliasing filters? Because on the power lines are also visible problems.

Levas

This is normal for all camera's except the 5d3
This is color aliasing due the line skipping sensor readout.
Buying an anti-aliasing filter is one solution.

But this can also be fixed (most of the times) with software.

For best detailed results, you should checkout the raw editor RawTherapee, it's free/open source.
It's a raw photo editor and has multiple options for debayering, in my opinion the LMMSE debayering works best for lineskipping raw video files from magic lantern.

Check out the RawTherapee workflow
http://www.youtube.com/watch?v=MweH3RAssXs
www.RawTherapee.com

For a quicker workflow for getting rid of all those colored speckles, you could separate the video file in Luma and chroma channel and do a blur effect on the chroma channel. This can be done in many video editors, also in the free version of Blackmagic DaVinci Resolve software.
In Resolve, change colormode on a node to LAB and disable the L(uma) channel, now do a blur effect on the same node.

Also, the colored speckles turn up more with wide angle lenses, and supersharp lens settings like from 2 stops closed down diafragma (f8 and f11).
So, shooting with diafragma wide open can help a little, just as closing down to f16 or f22, the lens is less sharp at minimum and maximum diafragma.
That said, I shoot a lot of video with the Canon 6D and the sharp 35mm f2.0 IS and use it a lot at f8 and f11, and all color aliasing can be removed with RawTherapee.

YaDeniska

Quote from: Levas on June 01, 2017, 09:39:35 AM
This is normal for all camera's except the 5d3
This is color aliasing due the line skipping sensor readout.
Buying an anti-aliasing filter is one solution.

But this can also be fixed (most of the times) with software.

For best detailed results, you should checkout the raw editor RawTherapee, it's free/open source.
It's a raw photo editor and has multiple options for debayering, in my opinion the LMMSE debayering works best for lineskipping raw video files from magic lantern.

Check out the RawTherapee workflow
http://www.youtube.com/watch?v=MweH3RAssXs
www.RawTherapee.com

For a quicker workflow for getting rid of all those colored speckles, you could separate the video file in Luma and chroma channel and do a blur effect on the chroma channel. This can be done in many video editors, also in the free version of Blackmagic DaVinci Resolve software.
In Resolve, change colormode on a node to LAB and disable the L(uma) channel, now do a blur effect on the same node.

Also, the colored speckles turn up more with wide angle lenses, and supersharp lens settings like from 2 stops closed down diafragma (f8 and f11).
So, shooting with diafragma wide open can help a little, just as closing down to f16 or f22, the lens is less sharp at minimum and maximum diafragma.
That said, I shoot a lot of video with the Canon 6D and the sharp 35mm f2.0 IS and use it a lot at f8 and f11, and all color aliasing can be removed with RawTherapee.

Thank you bro very much, I'll try your methods  :D
I decided to double-check for the presence of hot pixels, and it turns out I have about 100 of them, it's terrible!

YaDeniska

Quote from: Walter Schulz on June 01, 2017, 08:02:16 AM
Not that much information given.
- Crop mode or non-crop mode? 5D2 - like most other Canon DSLRs - is using "line skipping" in non-crop mode. Means: Only every third sensor line is used. Prone to moire.

Workarounds:
-> Non crop mode: Use anti-aliasing filters designed to minimize moire. Lookup VAF.
-> Use crop mode: ML crop mode is using a cropped area but all the lines within. FOV is diminished.
How to use crop mode in 5d mark II?

ilia3101

Quote from: YaDeniska on June 09, 2017, 04:01:32 PM
How to use crop mode in 5d mark II?
Just press the zoom button which you use to zoom in to pictures(top right), and it will zoom in 5x. Now begin recording, the framing you see however will not be accurate, the recording will have a wider field of view... you can get an accurate black and white preview with global draw, though slow and pixelated.