Share a Blackshade for RED EPIC.

[luigivaltulini]

hello guys,
I will try to share with you black shade, with the new firmware 4 , can export the folder Calibration.
Maybe you can take the best Black shade so as not to waste time.
What do you think?

this is my:

time base 25 fps.
Good as 25fps to 120fps.
thanks

https://www.dropbox.com/s/06zejcb3hthda4a/Calibration.zip

Luigi

 

[Johnny Friday]

How can we share blakshades? This should be camera or Sensor specific based on your cameras or sensor pixels....and each has its own characteristics...or did i mis-understand something in sensor 101 class?

 

[Nick Gardner]

Yeah, that doesn't work.

Nick

 

[Michael Mayda]

Calibrations are sensor-specific.

 

[luigivaltulini]

guys, you can try to see what happens.

 

[Mike Harrington]

Doesn't black shade map dead pixels as well?

Don't think that would be useful on a different camera

 

[TheBied]

This will not give good results. The calibration is sensor specific.

 

[Patrick Tresch]

I think there is a real need for a withe paper on blackshading.
As this is nearly the only stage (with exposure) where we can really screw the RAW file.

(Up until BS calibration will only be manufacturer business (which IMHO it should be)).

- perform
- export
- import
- don't
- limitations
- user VS factory

Pat

 

[luigivaltulini]

I think there is a real need for a withe paper on blackshading.
As this is nearly the only stage (with exposure) where we can really screw the RAW file.

(Up until BS calibration will only be manufacturer business (which IMHO it should be)).

- perform
- export
- import
- don't
- limitations
- user VS factory

Pat

+1.

 

[Björn Benckert]

Question if we shoot something and the black shading is far off, then would it be / or is it possible to take the "gray blackshade frame" thats been used by the camera and alter it and then apply the correction in post?

We have done such things when we have shot with the phantom that has quite big blackshading issues. Then we just shot a gray card and our technical guys managed to use some mathops / difference stuff so they later could negate the blackshade issues and the picture then looked perfect even if it was captured very poorly.

 

[Patrick Tresch]

Question if we shoot something and the black shading is far off, then would it be / or is it possible to take the "gray blackshade frame" thats been used by the camera and alter it and then apply the correction in post?

Good question. But what program would you use to remap the pixels?

Pat

 

[Mike Harrington]

You could do it in fusion with a custom tool node....
I would assume nuke as well....

 

[TheBied]

Question if we shoot something and the black shading is far off, then would it be / or is it possible to take the "gray blackshade frame" thats been used by the camera and alter it and then apply the correction in post?

We have done such things when we have shot with the phantom that has quite big blackshading issues. Then we just shot a gray card and our technical guys managed to use some mathops / difference stuff so they later could negate the blackshade issues and the picture then looked perfect even if it was captured very poorly.

Yes, it's doable, but won't be perfect.

With your 'bad' settings, you'd need to take a high quality dark frame, or series of dark frames and create a single offset map for each pixel. Then apply the offset map to your footage. You would also need to make sure to re-introduce the native black offset of the images before subtracting the offset map.

It won't be perfect since you are dealing with encoded data, but you may be able to rescue the footage.

 

[Björn Benckert]

Yes, it's doable, but won't be perfect.

With your 'bad' settings, you'd need to take a high quality dark frame, or series of dark frames and create a single offset map for each pixel. Then apply the offset map to your footage. You would also need to make sure to re-introduce the native black offset of the images before subtracting the offset map.

It won't be perfect since you are dealing with encoded data, but you may be able to rescue the footage.

Fixed camera shooting a gray card would go pretty far, or no? Then do a compound of 50 frames, or so. Then blur the compound and differ out the high detail noise from the blured image and the compound.

 

[TheBied]

Fixed camera shooting a gray card would go pretty far, or no? Then do a compound of 50 frames, or so. Then blur the compound and differ out the high detail noise from the blured image and the compound.

Sure, and ideally you could use both to get even better results. But, with a covered sensor, you'll ensure everything in the optical path isn't adding anything to the equation.

 

[luigivaltulini]

just to give you an idea .... 3 bodies red epic .. project time base 25, frame rate 120fps shutter 1/240 5kws. To test this I went to 12800iso and 'the result ....
BUt only exceeding 75 fps, 25p or 50p frame rate in base 25 all good ...

same environment, same procedure, same temperature, etc. ....
3 black different, and every time I make a black to these settings and 'always different ... yet the temperature and exposure remain the same ..
I thought it was a problem with the lcd, however I find him also on file ..
If I set the cameras to 23.98 at 121 all right without this ...
Or if I leave the black in default, everything ok without line but with the stain all right ..
I am going crazy ...:001_unsure:
All work by the black shading? or no one is aware of this?

TheBied help.....

 

[Patrick Tresch]

Hello Björn,

I think it would be possible for those pixels that aren't higher than the 0 value. Higher plixels could be lowered to 0 but will be prone to clipping if they reached 100% value before the other one.

ONLY SPECULATION HERE!!!

Pat

 

[Patrick Tresch]

Sure, and ideally you could use both to get even better results. But, with a covered sensor, you'll ensure everything in the optical path isn't adding anything to the equation.

Could black shading be used in a similar way we have in the "old days" when we flashed the negative to push the vail level and gain some sensitivity?

Making a blachshading with some very small amount and uniform light could lower the sensor sensitivity? -> 100 asa?

I understand what happen to the pixels that are tagged +5 but what happens to the pixels that have a negative value -2? Is this even possible?
If not, are those "different pixels as the others" making a hole in the top levels values (whites) by never reaching 100%?

As as of today we still have access to BS settings, I wonder what we could achieve in an creative way?

I would love to know much more about what happens electronically when a BS is performed.

Patrick