What's the difference between auto exposure and auto level?

[Joe Linn]

Does anyone know if there are written descriptions anywhere of what the various video filters do?

I've got some video that is overexposed because I accidentally had the backlight setting engaged on my camera. I've been trying the auto exposure and auto level video fitlers to see which does a better job of correcting it. Sometimes the results are very similar. Sometimes auto level has a more dramatic effect. Sometimes auto level produces undesirable color shifts in the middle of a clip. Auto level does a better job with some video that I shot on a foggy day.

Can anyone tell me the difference between the two filters?

Thanks!

Joe

[chinito]

Great question, thanks for asking. I'll also be watching.
Chino

[David_S]

Me too!!

[sjj1805]

I will not profess to know the answer but I can suggest to you a way to find out using the powerful abilities of the program itself.

Take one small clip of say 15 seconds.
Place the same clip on video tracks 1 and 2, one above the other.

Now use the Picture in Picture effect (in the "Moving Path" Section)
to place the two tracks side by side on the screen.

Apply Auto Level to the left hand clip
Apply Auto Exposure to the right hand clip

Now render the clip and watch the playback.
A picture tells a thousand words.

[rwernyei]

Auto exposure calculates the best aperture-shutter speed combination for lighting conditions, while auto level will analyze and stretch the dark and bright points to true black and true white.

[Terry Stetler]

Translation/suggestion:

Auto Levels should be renamed Auto BLACK Levels.

Otherwise people will take it to mean an automatic RGB level in lieu of the Color Correction tools.

[Devil]

If the auto filters don't do what you want, try brightness/contrast and colour correction. This is not auto, but gives you more control. A word of warning: a tiny manipulation may produce an enormous difference; avoid being heavy-handed. If the over-exposure has resulted in lens flare, there is little can be done (at least easily) to counter this.

[Joe Linn]

Thanks everyone! My main goal was to get a clearer understanding of what the various filters did so that I would know when it is appropriate to use each. This has been very helpful.

Thanks again.

Joe

[Nilsy]

I assume some stuff here, as I am an amateur in vid editing.
Generally in using filters etc I assess its use from what I know from photographic work.

Auto Levels:
As someone already said here, this normally spreads the scene between true black and white.
This is an excellent filter, but one that you can't just trust blindly.
While it spreads the outside extremes to the 100% black and white spot, the center may be off center depending on your footage.
So, adjust that manually.

But be careful, this is sensitive.

Auto Exposure:
Auto Exposure I would assume works in a similar fashion to photo work.
This is normally that the picture you have gets calibrated according to a neutral grey card.
The neutral grey is normally set at around 30% black.

This is why, if you "Auto Exposure" set a scene with snow, the resulting image will be grey.
As the calculation will Automate the average picture to the Grey Card.

This is also why, if you "Auto Exposure" an evening, the result can easily become generally overexposed, yet dark.

The filter effect will try to compensate to get to this Grey Card level.

Conclusion:
Generally speaking, I would never recommend the Automatic settings for this stuff, as they make their calculations from standards, that have little to no chance of being correct for you.

However, they are great at placing the starting point for correction.