Author Topic: How can I use the XMP deflicker files?  (Read 24497 times)

saltador

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Re: How can I use the XMP deflicker files?
« Reply #50 on: October 04, 2013, 02:05:45 AM »
thanks so much...

I gave up on test cause i was spending too much time and had other things to take care off.

renato...I...yes..i didn't think about inetrvalometor having to be longer..i fixed it later..and test came similar.
and 1'6 was meant to be slowest shutter speed 1/6...I will try your suggestion ..thanks thou..i willl post a clip as soon as i get one to show. cheers

Doyle..I didn't know i had to go the exiftool to get the deflicker done...i was just importing straight to LR..I thought exiftool was just making each frame a exposure higher or lower..
what setting i should use for exiftool?  exposure -0.05%?
also will try you percentile at 75%
thanks a lot.


One thing i'm still trying to understand and maybe someone have the time to explain...ETTR seems to me to be a bit more inconsistent that if i just set an exposure and ramp the AV, or ISO...am i wrong? in terms of the posibility of ETTR making one frame a bit diferent than the one before..where if the set exposure will render the same exposure.

I'm asuming ETTR and deflicker is the best way to go..bacause i see all smart people talking about it..hehehehe..i guess i just have to get it right. will keep practicing...thanks to all here.

RenatoPhoto

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Re: How can I use the XMP deflicker files?
« Reply #51 on: October 04, 2013, 03:40:14 AM »
Doyle..I didn't know i had to go the exiftool to get the deflicker done...i was just importing straight to LR..I thought exiftool was just making each frame a exposure higher or lower..
what setting i should use for exiftool?  exposure -0.05%?
also will try you percentile at 75%

I have doubts about this.  As far as I know exiftool should only be used to bump up or down all the exposures by a a certain amount.  I work on PC and never used this tool to change anything ever!

One thing i'm still trying to understand and maybe someone have the time to explain...ETTR seems to me to be a bit more inconsistent that if i just set an exposure and ramp the AV, or ISO...am i wrong? in terms of the posibility of ETTR making one frame a bit diferent than the one before..where if the set exposure will render the same exposure.

ETTR is a module to expose your images to the right so as to maximize the signal-to-noise ratio, meaning have lower noise in your shadows and probably better color.  ETTR has nothing to do with deflicker, it is just exposing each image to the best of the cameras abilities to try to capture all the details possible.  This module has become more complicated and powerful and now you have better control of what is that you are trying to capture best.  For more information go here: http://www.magiclantern.fm/forum/index.php?topic=5693.0

If the change in exposure from one shot to the next is extreme, then ETTR will be going all over the place trying to adjust to each exposure.  For this reason it could seem that exposure ramp via AV or Auto ISO is smoother.  I have experienced this kind of variation when the interval time  in the intervalometer is very long, ie 2 minutes.  I never use ETTR with and interval time longer then 1 minute.  I had a situation with passing clouds where the exposure was varying quickly and ETTR produced very bad results so a shorter interval time is always better.  In some cases it may be better to use other exposure methods.

ETTR is not an instant perfect photo mode, what I mean is that it can take more than two shots to get the software to converge into an ideal exposure to the right.  So if the exposure changes from one shot to the next then ETTR is in a hunting mode.

I'm asuming ETTR and deflicker is the best way to go..because i see all smart people talking about it..hehehehe..i guess i just have to get it right. will keep practicing...thanks to all here.

Deflicker is another beast all by itself.  I dont know the math behind this but it must assume some kind of average exposure ramp and it adjusts each shot via xmp file so as to bring the exposure of that shot very close to the average exposure ramp.  I assume that this algorithm can also get somewhat screwed if there are a lot of exposure changes from one shot to the next.

Assuming that all is working properly, when you import a cr2 file into ACR or lightroom, it has an exposure adjustment of zero, but when the software reads the xmp file, then the exposure will be adjusted by some amount sufficient to bring the exposure to some predefined standard by the Post Deflicker algorithm.  For example when I open the files in ACR without the xmp files and I walk through the images, it is clear that the exposure is changing from one image to the next.  If I open the same files accompanied by the xmp file, then the exposure change from one image to the other is minimal, and I can see how the exposure slider changes from one image to the next.

Make sure you read carefully the
Flicker Free ETTR Timelapse: - -Beginners Guide & Basic Post Processing --
http://www.magiclantern.fm/forum/index.php?topic=5705.0
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Doyle4

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Re: How can I use the XMP deflicker files?
« Reply #52 on: October 05, 2013, 03:51:47 AM »
Exiftool first for sure :)

RenatoPhoto's comment above this one is a very good read, read it.. re read it, use it :) haha. itll come to you eventually, im still learning to get the perfect flicker free.

Also what i learnt not to do was NOT to meter on a building etc, my skys where getting completely different exposures as the building was getting correctly exposed.. lesson learned there for me ;)

Danne

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Re: How can I use the XMP deflicker files?
« Reply #53 on: October 05, 2013, 08:14:32 AM »
I, d say the xmp files follows the first exposure in the timelapse and applies all the way to the last. Tried a night to day timelapse which resulted in heavily underexposed daytime shots. Going from day to night gives me overexpoed nighttime shots.
For daytime timelapse xmp deflicker is the best. Maybe even for sunsets and so on but it will need some post software to ramp the exposures.

classicbs

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Re: How can I use the XMP deflicker files?
« Reply #54 on: December 28, 2014, 06:56:04 PM »
Hi there I'm trying to use exiftool to reduce exposure on all the photos in a time-lapse sequence

Quote
On mac put all your images and xmps in one folder.
open up terminal, enter this, exiftool -Exposure2012+=+*.** /drag folder here containing cr2's and .xmp's

Where the *.** is enter the amount you want to set, eg 0.05, next to the number you have chosen, too the left is +, +=over expose for under add -

I tried this but I just get an error saying "no file specified"

Any ideas?  Many thanks